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In this paper, we study the time‐dependent vorticity–velocity–pressure formulation of Stokes problem in two‐ and three‐dimensional domains provided with nonstandard boundary conditions, related to the normal component of the velocity and the tangential components of the vorticity. This problem is discretized by implicit Euler's scheme in time and spectral method in space. We prove an optimal error estimate for the three unknowns. [ABSTRACT FROM AUTHOR]

This article deals with the error analysis of a Galerkin‐mixed finite element methods for the advection–reaction–diffusion Brinkman flow in porous media. Numerical methods for incompressible miscible flow in porous media have been studied extensively in the last several decades. In practical applications, the lowest‐order Galerkin‐mixed method is the most popular one, where the linear Lagrange element is used for the concentration and the lowest‐order Raviart–Thomas element, the lowest‐order Nédélec edge element and piece‐wise constant discontinuous Galerkin element are used for the velocity, vorticity and pressure, respectively. The existing error estimate of this lowest‐order finite element method is only O(h)$$ O(h) $$ for all variables in spatial direction, which is not optimal for the concentration variable. This paper focuses on a new and optimal error estimate of a linearized backward Euler Galerkin‐mixed FEMs, where the second‐order accuracy for the concentration in spatial directions is established unconditionally. The key to our optimal error analysis is a new negative norm estimate for Nédélec edge element. Moreover, based on the computed numerical concentration, we propose a simple one‐step recovery technique to obtain a new numerical velocity, vorticity and pressure with second‐order accuracy. Numerical experiments are provided to confirm our theoretical analysis. [ABSTRACT FROM AUTHOR]

We show that the winter Beaufort High (BH) index defined by sea level pressure (SLP) has a robust negative trend under the scenarios SSP5‐8.5 and SSP2‐4.5, with a reduction by about 5 hPa and 2 hPa, respectively, by the end of the 21st century. The negative trends in the BH SLP are associated with the changes in the background SLP over the Arctic basin. However, the vorticity of the winter BH tends to intensify under SSP5‐8.5, but shows no robust increase under SSP2‐4.5. The intensification is associated with the enhanced ridge over the Western Arctic. Therefore, it is necessary to take into account the dynamic aspects of the BH, such as vorticity. Based on this assessment, under the most likely emissions scenario, the winter BH is likely to weaken through the 21st century, in terms of SLP, but shows no robust changes in term of vorticity. Plain Language Summary: We used the latest IPCC global climate model outputs to investigate the wintertime changes in the Beaufort High (BH). Under the climate change scenarios, during winter, the sea level pressure (SLP) over the BH region is expected to decrease. The SLP reduction is up to 5 hPa by the end‐of‐the‐century. Thus, the BH seems to become weaker. However, its vorticity tends to increase under SSP5‐8.5, mostly due to the intensification of the ridge over the western North America. Key Points: The Beaufort High (BH) index defined by sea level pressure (SLP) decreases under warming climate scenariosMeanwhile, the BH vorticity tends to intensify due to the change in the ridge over the Western ArcticBesides the SLP, impact studies of the BH on the Arctic Ocean need to consider its dynamics such as vorticity [ABSTRACT FROM AUTHOR]

This study investigates the background rotational influences on the secondary eyewall formation (SEF) in tropical cyclones (TCs) in quiescent f‐plane environments. For given initial structures, simulated vortices tend to experience earlier SEF at lower latitudes. Yet the size of the secondary eyewall does not change monotonically with the latitudes. Specifically, ∼20°N provides the optimal amount of background rotation for the largest secondary eyewall size without considering other environmental forcings. Different background rotation rates affect SEF mainly by modulating the outer‐core convection as well as the wind structures. Specifically, the lower rotation rate causes more outer‐core surface fluxes, thus facilitating the outer rainbands (ORBs) at larger radii. Yet the secondary eyewall does not necessarily form at larger radii at lower latitudes since the transition from the ORBs to secondary eyewall is localized in a region of boundary layer (BL) convergence preceded by accelerated tangential winds. Budget analysis reveals that the differences in the acceleration of outer‐core tangential winds among vortices at different latitudes are dominated by the radial flux of absolute vorticity. Due to the non‐uniform influences of background rotation on the BL inflow and absolute vorticity, the most efficient spin‐up of outer‐core tangential winds is achieved at a medium latitude of 20°N, which leads up to SEF at the largest radii. By comparison, for TCs at lower (higher) latitudes, the lower outer‐core absolute vorticity (radial inflow) limits the acceleration of outer‐core tangential winds, thus placing SEF at smaller radii. Plain Language Summary: Secondary eyewall formation (SEF) and eyewall replacement cycles often cause intensity oscillation and size growth in intense tropical cyclones (TCs). Predicting SEF is difficult, since it is influenced by both internal TC dynamics and external forcings from the environment. In this study, we find the time and location of SEF are sensitive to the background rotation associated with different latitudes in idealized f‐plane simulations. Specifically, SEF tends to occur earlier at lower latitudes as a lower rotational rate facilitates faster organization of outer rainbands. But the largest secondary eyewall occurs under a moderate background rotational rate (∼20°N) facilitated by the fastest accelerations of outer‐core tangential winds. These findings indicate that the background rotation affects SEF by modulating the outer‐core convection and wind structure of TCs, which are expected to enhance the understanding of the interaction between internal and external dynamics of SEF. Key Points: Secondary eyewall formation (SEF) is affected by background rotation rates of different latitudes in idealized f‐plane simulationsLower latitude facilitates earlier SEF and 20°N provides the optimal amount of background rotation for secondary eyewall sizeBackground rotation rates affect SEF by modulating the activities of outer rainbands and the wind structures [ABSTRACT FROM AUTHOR]

The Surface Water and Ocean Topography (SWOT) mission provides a good opportunity to study fine‐scale processes in the global ocean but whether it can detect balanced submesoscale eddies is uncertain due to the "contamination" by unbalanced inertial gravity waves. Here, based on concurrent observations from SWOT and a mooring array in the northwestern Pacific, we successfully captured two submesoscale cyclonic eddies with negative sea level anomalies (SLAs) in spring 2023. We find that the SLA amplitude and equivalent radius of the first (second) eddy are 2.5 cm and 16.0 km (2.0 cm and 18.8 km), respectively. For both eddies, their vertical scales are around 150 m and their horizontal velocities and Rossby numbers exceed 15.0 cm/s and 0.4, respectively. Further analysis suggests that similar submesoscale eddies can commonly occur in the northwestern Pacific and that SWOT is capable to detect larger submesoscale eddies with scales greater than ∼10 km. Plain Language Summary: The Surface Water and Ocean Topography (SWOT) mission measures sea surface heights with a spatial resolution an order of magnitude higher than the prior nadir altimetry missions. However, whether SWOT can detect oceanic submesoscale eddies that play key roles in oceanic energy cycle and vertical material transports, is uncertain. To investigate this issue, we deployed a mooring array beneath a SWOT orbital swath in the northwestern Pacific. Based on the concurrent SWOT and mooring data, we successfully captured two submesoscale cyclonic eddies in spring 2023. Radii of the submesoscale eddies are found to be between 10 and 20 km and their horizontal velocities exceed 15.0 cm/s. The ratio between their vertical relative vorticity and the planetary vorticity exceeds 0.4. Further analysis suggests that similar submesoscale eddies can commonly occur in the northwestern Pacific. This study demonstrates the capability of SWOT to detect submesoscale eddies in the global ocean. Key Points: Two submesoscale cyclonic eddies (SCEs) were observed by SWOT and moorings in the northwestern PacificKinematic and dynamic features of the SCEs were revealedIt is feasible to use SWOT data to detect larger submesoscale eddies in the ocean [ABSTRACT FROM AUTHOR]

A new integrating model has been developed to couple tokamak edge multiscale magnetohydrodynamic (MHD) events and transport simulations, such as edge‐localized mode (ELM) cycles. As a proof of principle, we first start from a set of three‐field two‐fluid model equations, which includes the pressure, current, and vorticity. The equations are separated into the slowly evolving part of the axisymmetric component by taking a time average of the axisymmetric component. The time‐averaged fluxes, which are quadratic in fluctuating quantities, act as driven terms for the time‐averaged axisymmetric quantities that determine the plasma transport, and therefore the large‐scale evolution of the plasma profiles. Then the HL‐2A's ELM cycles are simulated using the model. Good agreements of ELM size and pedestal recovery time have been achieved for the solutions obtained from the coupled simulation compared with experiment. For one ELM cycle simulation, the coupled code can achieve a speedup of a factor of up to 30 over standalone code. [ABSTRACT FROM AUTHOR]

This study introduces new insights into the climatology of South Atlantic (SAt) cyclones by employing a novel cyclone life cycle detection method, the CycloPhaser. Utilizing the minimum relative vorticity series and its derivative at the cyclone centre, the program effectively identifies distinct phases in the cyclone life cycle. Cyclone tracks are obtained through the analysis of relative vorticity at 850 hPa, using the ERA5 dataset. The study identified six main cyclone life cycle patterns from the analysis of 28,458 systems. The predominant cyclone type, accounting for approximately 60% of the analysed systems, exhibited a four‐phase configuration: incipient, intensification, mature and decay. Detailed statistics for each developmental phase and the overall life cycle are presented, offering valuable comparisons and new insights while corroborating previous research findings. Key genesis regions in the SAt are identified, along with track density maps that reveal distinct preferences in cyclone developmental cycle. The main outcome of this study is the demonstration that the automated classification procedure enables the analysis of cyclones' life cycles to be conducted promptly and with low computing costs, facilitating the comprehensive study of cyclone behaviour with high efficiency. [ABSTRACT FROM AUTHOR]

In the internal parts of the Zagros collision zone, several deformation phases have been superimposed. The early deformation phase caused the development of a penetrative foliation. The late‐stage deformation phase was preferentially accommodated within shear zones and caused the generation of shear bands, implying a non‐coaxial component of deformation, the end of this stage deformation was marked by the development of kink‐bands. In the vicinity of Zagros suture zone, the kink angle increased from 40° to 60°, and the kink‐bands was converted to chevron folds. In this region, the external (α) and internal (β) angular ratio is α/β ≠ 1 and kink angle increased, and deformation occurred with 10% to 30% volume loss. Farther from the suture zone in the east, α/β = 1; and total volume was constant or increased by 5% to 10%. Kink‐bands kinematic analysis in the study area revealed this structures were sensitive to deformation conditions and components such that, with decreasing distance to the Zagros suture zone, shearing and rotation increased, a high kinematic vorticity dominated, and volume loss occurred during deformation. [ABSTRACT FROM AUTHOR]

As one kind of submesoscale instabilities, symmetric instability (SI) with spatiotemporal scales of O (100) m–O (1) km and O (1) hour exerts significant effects on vertical material transports and forward energy cascade in the ocean. The potential vorticity (PV) is an important conservative parameter controlling quasi‐geostrophic flows, whose budget can be modulated by SI. However, due to the small spatial scale of SI which is hardly resolved by most current observations and regional models, how SI affects the PV budget and how big the effect is remain unclear. In this work, the effect of SI on the PV budget in the surface mixed layer (SML) of the Kuroshio Extension region is quantitatively analyzed based on high‐resolution simulations by applying an existing SI parameterization scheme. Compared with the case without SI effects, negative PV is found to be eliminated in the SML in the SI‐parameterized case. The negative‐PV likelihood in the SI‐parameterized case is decreased by up to 12% due to SI. Analysis of the PV budget indicates that SI contributes to the PV budget mainly by modulating the friction term. The friction term tends to generate negative PV but its magnitude is decreased by 35% due to SI. Apart from the frictional term, both advection and non‐adiabatic terms are also found to be modulated by SI. This work sheds light on the contribution of SI in the PV budget in the ocean mixed layer and suggests a significant role of SI in quasi‐geostrophic PV dynamics. Plain Language Summary: Potential vorticity (PV) is a conservative but dynamically active tracer and an important indicator to characterize instability in the ocean. Traditionally, PV is applied to quasi‐geophysical dynamics, such as large‐scale circulation (O (1,000) km) and mesoscale currents (O (100) km). As the link between meso‐ and micro‐scales, submesoscale symmetric instability with spatial scales of O (100) m–O (1) km contribute to the PV budget, potentially modulating the quasi‐geostrophic dynamics. This work quantitatively evaluates the effect of SI on the PV budget by applying a parameterization scheme. Key Points: The effect of symmetric instability (SI) on potential vorticity is evaluated by applying a parameterization schemeElimination of negative potential vorticities is mainly caused by the friction effect with magnitude decreased by 35%The advection and non‐adiabatic effect are also found to be modulated by SI [ABSTRACT FROM AUTHOR]

The solar wind‐magnetosphere‐ionosphere interaction at Jupiter is reproduced numerically adopting the nine‐component magnetohydrodynamic simulation. Calculations take into account the magnetosphere‐ionosphere coupling, Jovian rotation, and Io plasma source. High‐speed rotating plasma inside restricted magnetospheric space causes expansion and contraction of magnetic field, forming super‐rotation at radial distance 20∼30 Rj and co‐rotation breakdown further outside. Field‐perpendicular current that restores co‐rotational delay beyond 30 Rj is connected via field‐aligned current to the main oval in the ionosphere. Inside 20 Rj, there is almost co‐rotation region (deviation from co‐rotation less than 20 km/s). Particularly within 10 Rj, the deviation from co‐rotation is less than 2 km/s. In the nearly co‐rotating region, the Io plasma forms a disk structure through field‐aligned redistribution. The interchange instability occurs near the outer wall of the Io plasma disk, and instability flow develops to vortex. Through this instability, a part of the centrifugal drift current supporting the Io plasma disk is connected to low‐latitude field‐aligned current that generates beads‐like spots on the lower latitude side of the main oval. Resulting interchange instability comes to satisfy the structure of convection and enables further development of vortex. The Coriolis force acting on eastward flow inside the developing vortex makes this flow protrude further outward, forming eastward bending fingers. Inside 10 Rj, Io plasma transport by the interchange instability becomes slower, despite the center of the disk. Io plasma escapes from the inner magnetosphere with a time constant of 20 days if this slow transport is taken into account. Key Points: We numerically reproduce the Jovian solar wind‐magnetosphere‐ionosphere interaction, considering planetary rotation and Io sourceOutward diffusion of Io plasma is facilitated by the interchange instability that occurs as vortex motion obeying the M‐I couplingFingers that develop in the Io plasma disk extend eastward in the region where the Coriolis force acts to accelerate the instability [ABSTRACT FROM AUTHOR]

Distinctive synoptic‐scale (∼1,500 km) flow features are identified within the core of the stratospheric polar‐night vortex at stratopause altitudes (∼50 km). Typically they comprise a train or a complex pattern of transient vortices, each characterized by enhanced values of potential vorticity (PV) and relative vorticity but with a weaker thermal signal. In the MERRA‐2 (and two other) reanalysis fields these cyclone‐like features persist for several days, occur episodically, and form essentially within the core of the polar‐night vortex itself. Their origin is plausibly linked to a form of barotropic instability associated with a radiatively‐induced annular ring of enhanced PV. Moreover, their ubiquity and dynamics carries possible implications for: ‐ the structure of the larger‐scale polar vortex and its preconditioning ahead of a Sudden Stratospheric Warming event; the distribution of trace‐constituents within the core; and the features representation in extended range/seasonal prediction and climate models. Plain Language Summary: In wintertime the earth's stratospheric polar vortex extends from a height of around 15 km to well above 50 km and equatorward to around 30° from the pole. At its edge, winds can be significantly in excess of 100 m s−1 whilst the vortex's core has been viewed as an enclosed containment vessel partially insulated from exterior influences. In contrast it is shown that, within the core, spatially rich patterns of synoptic‐scale (∼1,500 km) cyclone‐like features occur at stratopause altitudes (∼50 km). Their scale and structure indicates that their origin is linked to the large latitudinal temperature gradient that can develop across the polar‐night twilight zone. Their ubiquity suggests that they:‐ could contribute to the well‐mixed distribution of chemical constituents within the vortex's core; influence the overall structure of the polar vortex itself; impact upon the breakdown of the vortex during events of Sudden Stratospheric Warming; and need to be adequately represented in seasonal prediction and climate models. Key Points: Distinctive synoptic‐scale cyclone‐like features are identified within the core of the polar‐night vortex at stratopause altitudesAn account is given of their space‐time character and dynamics, and evidence adduced of their presence in three Reanalysis schemesTheir existence carries possible ramifications for seasonal and climate models and for the structure of the polar vortex itself [ABSTRACT FROM AUTHOR]

The Sonid Zuoqi ductile detachment zone is located at the southeastern margin of the Central Asian orogenic belt (CAOB), striking EW and dipping to the S. The major rock type of the Sonid Zuoqi ductile detachment zone is mylonite derived from granite. The sequence of mylonite features is: (1) S and C foliations of mylonite, and (2) extensional crenulation cleavage (ecc) or C and the kinematic vorticity (Wk) value changed from 0.70 to 0.95 and from 0.37 to 0.69, respectively; the strain type of the mylonites within the Sonid Zuoqi ductile detachment zone is compressional to planar strain. The strong deformation mylonite and Halatu plutons yielded a zircon U‐Pb age of 244 Ma and a zircon (U‐Th)/He age of 214 Ma, respectively. Based on the strain and kinematic vorticity analysis, together with the zircon U‐Pb and zircon (U‐Th)/He ages and the regional tectonic background, the study area experienced three stage evolution: tangential simple‐shear (244 Ma), simple‐shear‐dominated general shear represented by upper crustal extension (224 Ma) and pure–shear–dominated general shear represented by the Halatu pluton doming (214 Ma), which constrained the early Mesozoic NE–SW crustal extension at the southeastern margin of the CAOB. This NE–SW extension probably originated from the post‐orogenic extensional collapse of the CAOB, subsequent exhumation being controlled by the far afield effects of the closure of the Mongol–Okhotsk belt. [ABSTRACT FROM AUTHOR]

The paper combines experimental and numerical simulation methods to investigate the tip leakage vortex (TLV) in an oil–gas multiphase pump. The study aims to understand the evolution and dynamic characteristics of the TLV. The vorticity decomposition theory is used to analyze the spatial–temporal evolution, transient behavior, and rigid vorticity of the TLV. The findings reveal that the TLV is formed near the pressure surface when the tip clearance jet passes through the shear layer. In one impeller rotation period, transient fluctuations of the TLV are attributed to pressure differences and velocity changes across the tip clearance, and the TLV undergoes two split–dissipation–recurrence processes within one impeller rotation cycle. The presence of the gas phase enhances the scale and strength of the TLV while prolonging its existence in the flow channel. Analysis based on the rigid vorticity transport equation shows that the growth of the TLV and collapse are primarily governed by the rigid vortex generation term. The Coriolis force term contributes to stabilizing the TLV, while the rigid vorticity stretching term affects its shape. Furthermore, the gas phase significantly increases the value of the Rigid vorticity Curl of pseudo‐Lamb vector Term (RCT), which plays a crucial role in the prolonged existence of the TLV under gas–liquid two‐phase conditions. From an inlet gas void fraction of 0%–20%, the RCT value increases by 4.8 × 106/s2, the entropy production value increases by 75.55%, and the hydraulic efficiency decreases by 16.29%. [ABSTRACT FROM AUTHOR]

Using a high‐resolution numerical model, we investigate the influence of slope topography on the vertical tilted structure of mesoscale eddies in the northern South China Sea (NSCS). The model effectively captures key features including trajectories, intensities, and three‐dimensional tilted structures of these eddies. By compositing all NSCS eddies on the slope and in the basin, a more pronounced southwestward tilt in slope eddies is found from the sea surface down to the deep, compared to basin eddies. The tilt distance of slope eddies is approximately 1.8 times that of basin eddies, with the strongest eddy tilt near the Dongsha Islands. Variations in topography gradient induce noticeable changes in both the magnitude and direction of the eddy tilt. Due to potential vorticity conservation, the eddies' lower part follows isobaths, while the upper part drifts southwestward. This rapidly increases a southward eddy tilt during the upslope phase (USP) and a gradual transition to a southwestward tilt in the downslope phase (DSP). Moreover, the lower eddy part responds more significantly and earlier (about 20 days) to topography than the upper eddy part, moving faster and tilt‐developing more rapidly. The lower eddy part tilts larger during the USP, roughly 2.5 times than that of the upper eddy part. In the subsequent DSP, the tilt of lower eddy part decreases, about half of that in the upper eddy part. This study reveals the complex interactions between mesoscale eddies and steep slope topography, aiding further understanding the dynamics of eddy tilt and propagation. Plain Language Summary: Oceanic mesoscale eddies are ubiquitous and commonly exhibit vertical tilted structures, which may enhance the vertical transport of ocean heat, salt and energy. Previous research has shown that the sloping topography significantly influences the propagation and dissipation of eddies, yet most studies have treated the bottom slope as uniformly sloping terrain. However, whether the vertical tilting characteristics of eddies adjust with variations in the topography gradient during eddy propagation in real oceans remains insufficiently investigated. Through numerical simulations, we successfully reproduce the activity of eddies in the northern South China Sea, and elaborately explore the evolution of the vertical tilted structure of these eddies. It is suggested that potential vorticity conservation causes the lower part of eddies to move more rapidly along isobaths because they are more sensitive to the topography variations. This inconsistent speed of movement between the upper layer and lower layer of the eddy leads to changes in the vertical tilted structure when encountering a sloping topography. Overall, this study is significant to enhance our understanding of the spatiotemporal evolution and the interactions between three‐dimensional oceanic eddies and topography. Key Points: The model effectively captures key features of the mesoscale eddies in the northern South China SeaComposite slope eddies tilt southwestward from the sea surface to the deep, with the strongest tilt occurring near the Dongsha IslandsEddy tilt significantly varies with topography gradient, and the eddies' lower part responds more markedly and earlier than the upper part [ABSTRACT FROM AUTHOR]

The ability to understand and model ionospheric plasma flow on all spatial scales has important implications for operational space weather models. This study exploits a recently developed method to statistically separate large‐scale and meso‐scale contributions to probability density functions (PDFs) of ionospheric flow vorticity measured by the Super Dual Auroral Radar Network (SuperDARN). The SuperDARN vorticity data are first sub‐divided depending on the Interplanetary Magnetic Field (IMF) direction, and the separation method is applied to PDFs of vorticity compiled in spatial regions of size 1° of geomagnetic latitude by 1 hr of magnetic local time, covering much of the high‐latitude ionosphere in the northern hemisphere. The resulting PDFs are fit by model functions using maximum likelihood estimation (MLE) and the spatial variations of the MLE estimators for both the large‐scale and meso‐scale components are presented. The spatial variations of the large‐scale vorticity estimators are ordered by the average ionospheric convection flow, which is highly dependent on the IMF direction. The spatial variations of the meso‐scale vorticity estimators appear independent of the senses of vorticity and IMF direction, but have a different character in the polar cap, the cusp, the auroral region, and the sub‐auroral region. The paper concludes by discussing the sources of the vorticity components in the different regions, and the consequences for the fidelity of ionospheric plasma flow models. Plain Language Summary: The ability to accurately model the flow of ionized gases (plasma) in the Earth's ionosphere (the ionized region of the Earth's upper atmosphere) has important implications for operational space weather models. Large‐scale variations in this plasma flow are modeled well, but fluctuations on the meso‐scale and small scale are typically ignored in these models. This study uses measurements from a high‐latitude ground‐based radar network to measure the ionospheric plasma flow in terms of its vorticity (how straight or curved the flow is). The measured vorticity is separated into components related to both the large and meso‐scale fluctuations. The paper discusses the origins of the meso‐scale component, and what needs to be done before it can be confidently added to ionospheric plasma flow models. Key Points: The spatial variation of meso‐scale ionospheric flow vorticity is independent of the prevailing IMF By directionMeso‐scale ionospheric flow vorticity is strongest in the cusp and the auroral regionMeso‐scale ionospheric flow vorticity is most intermittent in the polar cap and the sub‐auroral region [ABSTRACT FROM AUTHOR]

The MMS satellites traversed a ∼6 di‐wide and ∼500 km/s southward reconnection exhaust at the dayside magnetopause on 6 December 2015 and ∼29 di from the associated X‐line region. A narrow ∼0.26–0.34 di layer of enhanced ±3.5 nW/m3 oscillating energy conversion perpendicular to the magnetic field resides in this exhaust. It contained two regions of diverging in‐plane electric fields in general agreement with two clockwise electron flow vortices and a proposed increase of the electron vorticity ∇ × Ve. The layer developed sunward of a unipolar Hall magnetic field for a duskward BM/BL ∼ 0.9 guide field. Each electron flow vortex supported a local ∆BM ∼ 10 nT strengthening of this Hall field. The presence of this electron‐scale layer in a southward exhaust for a duskward guide field is consistent with a two‐dimensional simulation of a similar structure that evolved from an X‐line into a northward exhaust for a similar strength dawnward guide field. Plain Language Summary: Magnetic reconnection is a critical process that drives large‐scale plasma convection in the Earth's magnetosphere. In this letter, we report new direct MMS observations for the presence of two electron flow vortices within a sub‐ion scale energy conversion channel that resides in a dayside magnetopause reconnection exhaust. Each of the two electron‐scale flow vortices is shown to contribute a significant fraction toward the large‐scale Hall magnetic field. Key Points: Electron‐scale 0.3 di layer of oscillating energy conversion and electron vorticity detected in 6 di wide reconnection jet 30 di from EDRTwo regions of in‐plane diverging electric field in energy conversion layer consistent with two measured clockwise electron flow vorticesOut‐of‐plane magnetic field increased ∼10 nT from each passing electron vortex immediately sunward of 50 nT unipolar Hall magnetic field [ABSTRACT FROM AUTHOR]

The present study considers tropical cyclogenesis as a multi‐stage process in which pre‐cursor disturbances develop first and a fraction of them further strengthen to become a tropical cyclone (TC). Using this framework, we analyze the impact of Madden‐Julian oscillation (MJO)‐ associated anomalous large‐scale environmental conditions on the triggering of tropical convective clusters (TCCs)—a type of pre‐cursor disturbance—and the TCC‐to‐TC transition in the western Pacific. We find that, within the MJO's lifecycle, the modulation of the TCC frequency by the MJO drives TC genesis frequency anomalies earlier than the TCC‐to‐TC transition rate. Also, the fluctuation of TCC occurrence frequency is most strongly associated with the MJO's large‐scale ascent and relative humidity anomalies, while that of the transition of TCCs to a TC is mainly associated with the MJO's vorticity anomalies. Our results suggest the distinct roles of large‐scale environmental variables in different stages of tropical cyclogenesis. Plain Language Summary: The frequency of tropical cyclones (TCs, also called hurricanes and typhoons) varies on many different timescales, including interannual (year to year) and subseasonal (weeks to months) timescales. The study of subseasonal variability in the frequency of TCs is often studied by attempting to understand why existing smaller‐scale storms organize into a TC. However, this approach does not consider the possibility that the frequency of the smaller‐scale storms may also vary. This study shows that the frequency of the smaller‐than‐TC storms is modulated on subseasonal timescales by a semi‐oscillatory phenomenon in the tropics known as the Madden‐Julian oscillation (MJO) in the western Pacific. The MJO does this by changing the amount of rising air and moisture throughout the region. This finding helps us better understand the processes that lead to the formation of a TC. Key Points: The Madden Julian oscillation (MJO) influences western Pacific tropical cyclogenesis in part through the modulation of the frequency of the tropical cloud clustersThe frequency of tropical cloud clusters varies most closely with large‐scale ascent and relative humidity anomalies of the MJOThe rate of transition from a tropical cloud cluster to a tropical cyclone is most correlated with large‐scale vorticity anomalies associated with the MJO [ABSTRACT FROM AUTHOR]

We investigate the global existence of classical solutions for two‐dimensional incompressible, inviscid, and resistive magnetohydrodynamics (MHD) system. Assuming that the initial magnetic field is close to an equilibrium state of constant magnetic vorticity, the global existence result could be obtained using a time‐weighted energy estimate. [ABSTRACT FROM AUTHOR]

The climatological mean barotropic vorticity budget is analyzed to investigate the relative importance of surface wind stress, topography, planetary vorticity advection, and nonlinear advection in dynamical balances in a global ocean simulation. In addition to a pronounced regional variability in vorticity balances, the relative magnitudes of vorticity budget terms strongly depend on the length‐scale of interest. To carry out a length‐scale dependent vorticity analysis in different ocean basins, vorticity budget terms are spatially coarse‐grained. At length‐scales greater than 1,000 km, the dynamics closely follow the Topographic‐Sverdrup balance in which bottom pressure torque, surface wind stress curl and planetary vorticity advection terms are in balance. In contrast, when including all length‐scales resolved by the model, bottom pressure torque and nonlinear advection terms dominate the vorticity budget (Topographic‐Nonlinear balance), which suggests a prominent role of oceanic eddies, which are of O(10–100) $\mathcal{O}(10\mbox{--}100)$ km in size, and the associated bottom pressure anomalies in local vorticity balances at length‐scales smaller than 1,000 km. Overall, there is a transition from the Topographic‐Nonlinear regime at scales smaller than 1,000 km to the Topographic‐Sverdrup regime at length‐scales greater than 1,000 km. These dynamical balances hold across all ocean basins; however, interpretations of the dominant vorticity balances depend on the level of spatial filtering or the effective model resolution. On the other hand, the contribution of bottom and lateral friction terms in the barotropic vorticity budget remains small and is significant only near sea‐land boundaries, where bottom stress and horizontal viscous friction generally peak. Plain Language Summary: Vorticity provides a measure of the local rotation and shear of fluid flow. The analysis of physical processes contributing to ocean vorticity has proven fundamental to our understanding of how those processes drive ocean flows, ranging from large‐scale ocean gyres to boundary currents such as the Gulf Stream, which is tens of km in width. Furthermore, a vorticity analysis can inform us about the relative importance of different physical processes in generating flow structures having different length scales. In the present work, we perform a length‐scale dependent vorticity budget analysis using a coarse‐graining method to remove signals finer than a fixed length scale. We coarse‐grain the climatological mean vorticity budget terms over a range of length scales, and then compare the relative magnitudes to identify the dominant vorticity balances as a function of length scale. We find that the spatial structure of the meridional transport is mainly controlled by atmospheric winds, variations in ocean depth and the momentum transport by ocean currents. However, the relative magnitudes of these factors change drastically at different length scales. We conclude that physical interpretations of the primary vorticity balances are fundamentally dependent on the chosen length scale of the analysis. Key Points: Relative magnitudes of barotropic vorticity budget terms display significant length‐scale dependenceBottom pressure torque and wind stress curl control the depth‐integrated meridional flow at length scales larger than 1,000 kmNonlinear advection and bottom pressure torque dominate the barotropic vorticity budget at smaller length scales [ABSTRACT FROM AUTHOR]

Polarization surrounding bias correction (BC) in creating climate projections arises from its lack of physicality. Here, we perform and analyze 18 dynamical downscaling simulations (with and without BC) to better understand the physical impacts of BC, applied before downscaling, on regional climate output across the western United States. Without BC, downscaled precipitation is systematically and unrealistically wet biased compared to a hierarchy of observationally based datasets over the 1980–2014 period due to cascading mean‐state Global Climate Model (GCM) biases: (a) overly strong lower‐tropospheric lapse rates (5 K/km), (b) overly cold (2 K) tropospheric temperatures, and (c) anomalous mid‐tropospheric cyclonic vorticity advection. With BC, downscaled precipitation (snow) biases are virtually eliminated (halved). Identified GCM biases are common to the broader Coupled Model Intercomparison Project ensemble. Physical effects of BC on the quality of the regionalized projections, pending an evaluation of BC's distortion of the downscaled climate response, may motivate its broader application by dynamical downscalers. Plain Language Summary: Global Climate Models (GCMs) are known to have biases that, when dynamically downscaled, damage the credibility of the e. A longstanding way around this problem is bias correction (BC) after downscaling, but this practice rarely involves physics and can mislead climate data users into overvaluing the quality of the downscaled data. Further, post‐downscaling BC techniques can over correct the higher‐order statistics, calling into question the faithful preservation of the original simulated signals. For the first time, we apply a minimally invasive BC procedure to a group of 9 GCMs in order to define physical relationships between mean GCM biases and their dynamically downscaled hydroclimate variables across the western United States. We find that native GCMs tend to exhibit surprisingly common mean biases that, when downscaled, effectuate an overly wet, cold, and snowy climate across the region. Key Points: Bias correction of Global Climate Models (GCMs) reduces biases in downscaled mean precipitation, snow, and temperature across the western United StatesCascading cold, thermodynamically unstable, and cyclonic vorticity biases from GCMs to regional climate models drive wet biases in dynamical downscalingCMIP6‐wide GCM biases are similar suggesting that biases in dynamically downscaled precipitation and temperature can be anticipated [ABSTRACT FROM AUTHOR]

In this paper, we are inspired by a famous result by Constantin and Fefferman who proved that a simple geometrical assumption on the direction of the vorticity leads to the regularity of weak solutions of the 3D Navier-Stokes equations. We show that the same result can be achieved if the vorticity direction is replaced by the velocity direction. We further strengthen this result and prove that in fact it is not necessary to consider the velocity direction in all close space points but only in the points whose distance equals to a small positive number dependant on the data. In the second part of the paper, we extend a result by Berselli and Córdoba concerning the role of the helicity for the regularity of the weak solutions of the Navier-Stokes equations. [ABSTRACT FROM AUTHOR]

For vortex particle methods relying on SPH‐based simulations, the direct approach of iterating all fluid particles to capture velocity from vorticity can lead to a significant computational overhead during the Biot‐Savart summation process. To address this challenge, we present a Monte Carlo vortical smoothed particle hydrodynamics (MCVSPH) method for efficiently simulating turbulent flows within an SPH framework. Our approach harnesses a Monte Carlo estimator and operates exclusively within a pre‐sampled particle subset, thus eliminating the need for costly global iterations over all fluid particles. Our algorithm is decoupled from various projection loops which enforce incompressibility, independently handles the recovery of turbulent details, and seamlessly integrates with state‐of‐the‐art SPH‐based incompressibility solvers. Our approach rectifies the velocity of all fluid particles based on vorticity loss to respect the evolution of vorticity, effectively enforcing vortex motions. We demonstrate, by several experiments, that our MCVSPH method effectively preserves vorticity and creates visually prominent vortical motions. [ABSTRACT FROM AUTHOR]

In this article, we propose a new formulation and a suitable finite element method for the steady coupling of viscous flow in deformable porous media using divergence‐conforming filtration fluxes. The proposed method is based on the use of parameter‐weighted spaces, which allows for a more accurate and robust analysis of the continuous and discrete problems. Furthermore, we conduct a solvability analysis of the proposed method and derive optimal error estimates in appropriate norms. These error estimates are shown to be robust in a variety of regimes, including the case of large Lamé parameters and small permeability and storativity coefficients. To illustrate the effectiveness of the proposed method, we provide a few representative numerical examples, including convergence verification and testing of robustness of block‐diagonal preconditioners with respect to model parameters. [ABSTRACT FROM AUTHOR]

We investigate the representation of individual supercells and intriguing tornado‐like vortices in a simplified, locally refined global atmosphere model. The model, featuring grid stretching, can locally enhance the model resolution and reach cloud‐resolving scales with modest computational resources. Given a conditionally unstable sheared environment, the model can simulate supercells realistically, with a near‐ground vortex and funnel cloud at the center of a rotating updraft reminiscent of a tornado. An analysis of the Eulerian vertical vorticity budget suggests that the updraft core of the supercell tilts horizontal vorticity into the tornado‐like vortex, which is then amplified through vertical stretching by the updraft. Results suggest that the simulated vortex is dynamically similar to observed tornadoes, as well as those simulated in modeling studies at much higher horizontal resolution. Lastly, we discuss the prospects for the study of cross‐scale interactions involving supercells. Plain Language Summary: We use a simplified global model to study individual supercells and intriguing cloudy rotating winds that behave like tornadoes. This model uses grid‐stretching techniques, making it a computationally efficient tool to study supercells on a real‐size Earth. Unlike most numerical models of tornadoes which simulate scales of a few tens of meters, our model can realistically simulate supercells and cloudy tornado‐like rotating winds even at kilometer scales, which appears unprecedented in the literature. We find that the physics behind the rotating winds is consistent with previous studies, including observations of tornado formation and simulations at much higher resolution. The findings of this study open the door to a better understanding of complex interaction between supercells, tornadoes, and their environment. Key Points: The FV3 dynamical core with simple microphysics can simulate individual supercells and cloudy tornado‐like vortices at kilometer scalesA stretched cubed‐sphere grid is used to economically reach cloud‐resolving scales locally on a real‐size EarthThe dynamics of the simulated tornado‐like vortices is consistent with previous studies on tornadogenesis [ABSTRACT FROM AUTHOR]

The southwest vortices (SWVs) are a unique type of mesoscale vortex that frequently induce torrential rainfall in China. In this study, we focused a long‐lived quasi‐stationary SWV, which was the primary system for producing an extremely heavy rainstorm within/around Sichuan (the maximum hourly precipitation was ~103.8 mm) in Mid July 2021. After reproduced the SWV's formation by using Weather Research and Forecasting model, we conducted trajectory analyses and topography sensitivity simulations to understand the effects of complicated topography on the vortex's formation. It is found that, the regions south and southwest of the SWV acted as the most important source regions for the air clusters that formed the SWV (proportion ≥ 65%), and the air clusters originated from the upper layer contributed the most (≥60%). Of these, the air clusters sourced from the upper layer southwest and south of the SWV played the most important role in the SWV's formation, as their increase in cyclonic vorticity and their contributions to trajectory number and vorticity were all much larger than those of the others. Sensitivity simulations indicated that, detailed topography features around the Sichuan Basin were crucial in determining the structure, intensity and precipitation of the SWV, whereas, the topography features were not a decisive factor for the SWV's formation. In summary, our findings are useful to enrich the current understanding of the SWVs' formation, which would be helpful to improve the related forecasts. [ABSTRACT FROM AUTHOR]

Various engineering applications commonly involve the flow of nanofluids over a porous 45° inclined square cylinder. Therefore, the current study is to assess the impact of the Darcy parameter (Da), nanoparticle volume fraction (ϕ), and Reynolds number (Re) on the momentum transport characteristics over the 45° inclined porous square cylinder. The governing equations were solved numerically using the Darcy–Brinkman–Forchheimer model for different values of Da (10−6≤Da≤10−2), nanoparticle volume fraction ϕ (0.01≤ϕ≤0.05), and Reynolds number Re (1≤Re≤40). The results for each parameter were visualized using streamline plots, velocity profiles within the porous cylinder, and vorticity contours. Complex flow behaviors were observed between Da = 10−3–10−2, flow separation detached and disappeared at the cylinder's downstream side at critical Darcy number. Drag and pressure coefficents are used to represent the global and local parameter of the flow fields. The pressure coefficient on the surface of the cylinder showed an inverse relationship with the nanoparticles volume fraction and Darcy number. The strength of the drag coefficient decreased with the addition of nanoparticles to the base fluid, with a decreasing trend observed for Da = 10−4–10−2 and no change observed for Da = 10−6–10−4. At last, the comparative analysis has been conducted between a porous square cylinder at 0° inclined and another 45° inclined. [ABSTRACT FROM AUTHOR]

The correlation between divergence and vorticity has traditionally served as a signature of convection in rotating fluids. While this correlation has been observed in the JIRAM brightness temperature data for Jupiter's polar vortices, it is notably absent in the JIRAM images. This discrepancy presents a new challenge in determining whether this correlation can serve as a reliable signature of convection in rapidly rotating atmospheres. In this study, we analyzed data from a three‐dimensional simulation of Jupiter's polar vortices using a deep convection model. Our findings confirm the theoretical prediction of a negative correlation between divergence and vorticity in the northern hemisphere. Interestingly, this correlation is weaker within the cyclones compared to outside them. The skewness of upflows and downflows plays an important role in this negative correlation. We also observed that the correlation varies with height, being strongest near the interface and decaying away from it. The correlation diminishes when the resolution is reduced. Furthermore, our findings suggest that the geostrophic approximation may not be suitable for the Jovian atmosphere, particularly in the stable layer. Both tilting and stretching effects contribute to the material derivative of vorticity, with the tilting effect dominating in the unstable layer and the stretching effect prevailing in the stable layer. This suggests a transfer of vorticity from the convectively unstable layer to the stable layer. Consistent with observations, we also noted an upscale energy transfer from smaller to larger scales. Plain Language Summary: Jupiter has fascinating polar vortices on its poles. But how do they form, how deep are they, and how do they survive? Answering these questions will not only enhance our understanding of Jupiter's weather patterns but also provide insights into the climatic conditions on our own planet, Earth. In this study, we employ a deep convection model to elucidate the formation of these vortices. By analyzing the simulation data, we can ascertain whether the observed data at the top of the atmosphere bear signatures from deep within. Divergence, which quantifies the tendency of fluid to accumulate or disperse at a point, and vorticity, which measures the tendency of fluid to swirl around a point, are key parameters in our analysis. The correlation between these two parameters can serve as a signature of convection. Indeed, our simulation identifies this signature. However, its strength varies with the depth of the atmosphere and the resolution of the measurement. Furthermore, our findings suggest that the spin of the polar vortices at the top of the atmosphere is likely maintained by the transfer of vorticity from the deeper layers of the atmosphere. Key Points: Deep convection model shows that the divergence and vorticity are correlated in the polar vortices of JupiterThe correlation varies with the depth of the atmosphere and the resolution of the measurementThe polar vortices at the top of atmosphere are likely sustained by the transfer of vorticity from deeper layers [ABSTRACT FROM AUTHOR]

In this study we have conducted a survey of westward‐propagating mixed Rossby–Gravity (MRG) wave events in the upper troposphere and quantified their association with the intrusions of extratropical disturbances for the period 1979–2019. MRG wave events are identified by imposing the meridional structure of theoretical MRG waves onto the equatorial meridional winds at 200 hPa. In all, 2390 MRG wave events are identified and the majority (61%) of them occurred during the months of May–October, and 65% of the total MRG wave events occurred over the central–east Pacific and Atlantic Ocean domains. Not only the frequency of occurrence but also the amplitude, wavenumber and trapping scale of the MRG wave events are found to exhibit a clear seasonality. MRG wave events associated with intrusions of extratropical disturbances are identified as when the potential vorticity on the 350‐K isentropic surface at 15° latitude exceeded 1 Potential Vorticity Unit (PVU) in the vicinity of the MRG wave events. We find that 37% of the MRG wave events are intrusion MRG wave events and a large majority (88%) of such events occurred over the central–east Pacific and Atlantic Ocean domains. It is also noteworthy that nearly 70% of such intrusions occurred in the winter hemisphere where the westerly wind ducts are well developed. Over the central–east Pacific during northern hemispheric (NH) winter, it is observed that the intrusion MRG wave events have a bigger amplitude and have a larger meridional extent compared to non‐intrusion MRG wave events. They also exhibit a similar spatial scale as the extratropical disturbances implying that resonant interactions may be a primary mechanism for the genesis of MRG wave events. During NH summer, on the other hand, MRG wave events are primarily triggered by convective processes and the extratropical disturbances may be instrumental in amplifying their amplitude. [ABSTRACT FROM AUTHOR]

Mixing along isopycnals plays an important role in the transport and uptake of oceanic tracers. Isopycnal mixing is commonly quantified by a tracer diffusivity. Previous studies have estimated the tracer diffusivity using the rate of dispersion of surface drifters, subsurface floats, or numerical particles advected by satellite‐derived velocity fields. This study shows that the diffusivity can be more efficiently estimated from the dispersion of coherent mesoscale eddies. Coherent eddies are identified and tracked as the persistent sea surface height extrema in both a two‐layer quasigeostrophic (QG) model and an idealized primitive equation (PE) model. The Lagrangian diffusivity is estimated using the tracks of these coherent eddies and compared to the diagnosed Eulerian diffusivity. It is found that the meridional coherent eddy diffusivity approaches a stable value within about 20–40 days in both models. In the QG model, the coherent eddy diffusivity is a good approximation to the upper‐layer tracer diffusivity in a broad range of flow regimes, except for small values of bottom friction or planetary vorticity gradient, where the motions of same‐sign eddies are correlated over long distances. In the PE model, the tracer diffusivity has a complicated vertical structure and the coherent eddy diffusivity is correlated with the tracer diffusivity at the e‐folding depth of the energy‐containing eddies where the intrinsic speed of the coherent eddies matches the rms eddy velocity. These results suggest that the oceanic tracer diffusivity at depth can be estimated from the movements of coherent mesoscale eddies, which are routinely tracked from satellite observations. Plain Language Summary: Ocean mesoscale eddies are swirling currents with size of 10–100 km. Mesoscale eddies mix heat, carbon, and other tracers along constant density surfaces, which impacts the ocean environment and global climate. Tracer mixing is commonly represented by an eddy diffusivity, which relates the eddy tracer mixing to the large‐scale properties in coarse‐resolution ocean models. Estimates of tracer diffusivity are important for evaluating and improving the representation of mesoscale eddies in models. Mesoscale eddies commonly take the form of individual swirls that move randomly over long distances and last for several months. This study finds that the tracer diffusivity can be accurately estimated from the movement of individual mesoscale eddies in highly idealized numerical simulations. Horizontal mixing is strong when eddies spread out quickly. In more realistic situations, the rate at which eddies spread is correlated with the tracer diffusivity at a depth where the eddy movement speed is close to the swirling velocity. This finding can be used to estimate the oceanic tracer diffusivity using the trajectories of mesoscale eddies from satellite observations. Key Points: Oceanic lateral diffusivity is estimated by the dispersion rate of coherent mesoscale eddiesDiffusivity of coherent eddies matches the upper‐layer tracer diffusivity in quasigeostrophic simulationsIn 3D simulations, the coherent diffusivity is correlated with the tracer diffusivity at the e‐folding depth of energy‐containing eddies [ABSTRACT FROM AUTHOR]

We parameterize sub‐grid scale (SGS) fluxes in sinusoidally forced two‐dimensional turbulence on the β‐plane at high Reynolds numbers (Re ∼25,000) using simple 2‐layer convolutional neural networks (CNN) having only O(1000) parameters, two orders of magnitude smaller than recent studies employing deeper CNNs with 8–10 layers; we obtain stable, accurate, and long‐term online or a posteriori solutions at 16× downscaling factors. Our methodology significantly improves training efficiency and speed of online large eddy simulations runs, while offering insights into the physics of closure in such turbulent flows. Our approach benefits from extensive hyperparameter searching in learning rate and weight decay coefficient space, as well as the use of cyclical learning rate annealing, which leads to more robust and accurate online solutions compared to fixed learning rates. Our CNNs use either the coarse velocity or the vorticity and strain fields as inputs, and output the two components of the deviatoric stress tensor, Sd. We minimize a loss between the SGS vorticity flux divergence (computed from the high‐resolution solver) and that obtained from the CNN‐modeled Sd, without requiring energy or enstrophy preserving constraints. The success of shallow CNNs in accurately parameterizing this class of turbulent flows implies that the SGS stresses have a weak non‐local dependence on coarse fields; it also aligns with our physical conception that small‐scales are locally controlled by larger scales such as vortices and their strained filaments. Furthermore, 2‐layer CNN‐parameterizations are more likely to be interpretable. Plain Language Summary: In this study, we demonstrate that simple, shallow neural networks can be used to effectively model complex turbulent flows in the atmosphere and oceans. By using these simpler NNs, we can improve the efficiency of our simulations and better understand the underlying physics of turbulent flows. We also explore different training techniques to make these models more accurate and robust. Our findings suggest that the stress in these turbulent flows has only a weak spatial dependence on larger‐scale features, which has important implications for our understanding of how turbulence behaves. Overall, our work can help improve climate and weather models by providing a more efficient and interpretable way to simulate turbulence. Key Points: Shallow convolutional neural networks (CNNs) accurately parameterize high Reynolds number forced2D turbulence, with efficient training and high online large eddy simulations accuracyExtensive hyperparameter searching and cyclical learning rates yield robust and accurate online solutions for CNN‐based turbulence modelsThe success of shallow CNNs implies nearly‐local dependence of SGS stresses providing insights into turbulent flow interactions [ABSTRACT FROM AUTHOR]

Mixing controls the fate of any solute entering porous media. Hence, an understanding of the involved processes is essential for assessing subsurface contamination and planning for its protection. However, the three‐dimensional mechanisms dominating solute mixing in the presence of several fluid phases in the pore space, and their dependency on phase saturation degree (fraction of the pore volume occupied by a phase) are unknown. Here, we analyze solute mixing in unsaturated porous media at the pore scale using X‐ray micro‐tomography performed with synchrotron radiation at unprecedented temporal and spatial resolutions for such an investigation. Transport experiments through a synthetic, sand‐like porous medium, followed in 4D using a contrast solution, are performed at different liquid phase saturation degrees. The results reveal larger solute's front deformation at lower saturation, which translates into an enhanced mixing with time. Using different topological indexes, defined based on a description of the liquid phase geometry and of the resulting hydrodynamics, we show an increase in the spatial convergence of flow streamlines at lower saturation, which, in turn, leads to a strengthened helical flow inside the liquid phase. Consequently, this increases the number of shear‐ and vorticity‐dominated deformation regions, as characterized by larger negative and positive Q‐criterion values, respectively. These findings represent a major step toward understanding the control of both saturation and the system's heterogeneity on solute mixing, essential, among others, to assess reactivity in porous media. Plain Language Summary: The fate of any solute spreading through porous media, as it is the case for nutrients or pollutants entering the subsoil, is controlled by liquid‐liquid mixing with the resident solution. However, it is still unknown which mechanisms control mixing in the presence of several fluid phases, as it occurs in the unsaturated region of soils. A combination of synchrotron 4D X‐ray micro‐tomography experiments with very high temporal and spatial resolutions, advanced 3D image analysis, and numerical simulations of flow, allowed to reveal an enhancement of the spatial convergence of flow streamlines at lower liquid phase content, that is, at a lower fraction of the entire pore volume that is occupied by the liquid phase. This increases the number of shear‐ and vorticity‐dominated flow regions, inducing an overall larger solute front deformation with time and rendering mixing more efficient. These findings can highly contribute to the assessment of mixing and reactions in natural porous media. Key Points: Lower liquid phase saturation induces stronger solute plume's front deformation, enhancing liquid‐liquid mixingHelical flow in the pore space is promoted by an increased convergence of flow streamlinesVorticity‐dominated deformation is enhanced as liquid phase saturation decreases [ABSTRACT FROM AUTHOR]

More and more researches evidence that hemodynamic factors play an important role in the occurrence and development of cardiovascular diseases. In this paper, a new mathematical model has been proposed to describe rogue waves in arterial vessels. Based on two‐dimensional Navier–Stokes (NS) equation and continuity equation, vorticity equation satisfied by blood flow is given. Further, by employing multiscale analysis and perturbation expansion method, the (2+1)‐dimensional nonlinear Schrödinger (NLS) equation is derived to describe the envelope solitary waves propagation of blood vessels. Different from the previous model, the (2+1)‐dimensional NLS model takes into account the propagation of blood flow along the vessel axis and radius. In order to further study, the integer‐order model is generalized to the time‐fractional nonlinear Schrödinger (TF‐NLS) equation by use of the semi‐inverse method and Agrawal's method, and the conservation laws are also investigated. Moreover, the rogue wave solution of the fractional model which can directly describe the behavior of the rogue waves in arterial vessels is obtained. Rogue wave and fractional parameter effect on blood flow volume is analyzed and discussed, which can provide some help for the study of cardiovascular diseases. [ABSTRACT FROM AUTHOR]

Tropical cyclone (TC) track forecasting provides essential guidance for coastal communities. However, track forecast errors still occur, highlighting the need for continued research into error sources. Piecewise potential vorticity (PV) inversion is used systematically to quantitatively diagnose errors in track forecasts in four models during the 2017 Atlantic hurricane season. The deep layer mean steering flow (DLMSF) provides a sufficient proxy for hurricane movement, and DLMSF errors are correlated with TC track errors. Analysis of track forecasts for Hurricanes Harvey, Irma, and Maria reveals that their track errors are attributed to steering errors caused by misrepresentations of specific pressure systems. Harvey's westward track error in the GFS resulted from zonal wind errors from the Continental High, while Irma's northward track error in the SHiELD gfsIC resulted from meridional wind errors in the Bermuda High and Continental High. Maria's southward track error in the IFS resulted from meridional wind errors in the Bermuda High and a misrepresentation of Jose to Maria's northwest. The mean absolute error of the DLMSF shows that the Bermuda High contributed the most to steering flow errors in the cases examined. Our results show that piecewise PV inversion can identify the sources of biases in TC track forecasts. The correction of these biases may lead to improved track forecasts. Quantitative diagnostics presented here provide useful information for future model development. Plain Language Summary: A tropical cyclone typically moves with the environmental wind, which is generated by several large‐scale pressure systems (e.g., Bermuda High, Continental High) in the atmosphere. Weather models can predict the path of tropical cyclones, but these forecasts have errors. Tropical cyclones often bring devastation along their path, so it is important to mitigate track errors to provide better warnings for impacted communities. Here, we use a diagnostic technique called "piecewise potential vorticity inversion" to understand how the environmental wind causes errors in tropical cyclone tracks. In three different examples of hurricane track forecasts, we show that errors in the predicted track are caused by errors in the environmental wind from specific pressure systems. By considering numerous cases, we can also identify model biases, or errors that are consistent throughout many forecasts. These errors are a result of errors in the models themselves. Overall, our results show that piecewise potential vorticity inversion is a useful diagnostic tool that has the potential to improve track forecasts through the identification of model biases. Key Points: Contributions to tropical cyclone movement from individual synoptic systems are quantified using piecewise potential vorticity inversionForecast errors of the deep layer mean steering flow are the main source of the track errors for Hurricanes Harvey, Irma, and Maria (2017)Forecast errors of the Bermuda High dominated the steering flow errors for the 2017 hurricane season [ABSTRACT FROM AUTHOR]

The windage loss in rotor‐stator gap has an important effect on rotating machinery, especially with higher rotational speed and fluid density. However, the mechanism of axial flow on windage loss in open shaft‐type gap is hardly studied in most literature. To clarify it, the influences of axial Reynolds number Reu and rotational Reynolds number Reω on skin friction coefficient Cf are investigated, and flow characteristics are analyzed with different gap geometry, radius ratio η. First, the results reveal that the Cf remains constant when Reu is less than 2.8 × 104 and increases rapidly as Reu when Reu ≥ 2.8 × 104, which indicates that the effect of axial velocity u on Cf is negligible for low Reu. The positive relative deviation Δ suggests that the axial flow makes windage loss and Cf rise. Besides, a larger number of Taylor vortexes fill with gap when the effect of the centrifugal force is larger than that of the inertial force, but they gradually disappear as Reu. Subsequently, the Cf and Δ increase as η, highlighting that the effect of u on windage loss and Cf is more prominent for larger η. The fact that vorticity near walls is larger than that at the center of gap reveals that windage loss arises from the interaction between walls and fluid rather than the dissipation with fluid itself. Finally, the model of Cf in shaft‐type gap is proposed in different Reω ranges based on numerical results, and the maximum sum of squares error of 1.02 × 10−5 and minimal R2 of 0.969 satisfy the requirement of fitting accuracy and indicate that the fitting model can accurately predict Cf. The conclusions significantly help predict windage loss in open shaft‐type gap with axial flow, and further improve the design for generators of supercritical CO2 turbine‐alternator‐compressor unit. [ABSTRACT FROM AUTHOR]

The windage loss in rotor‐stator gap has an important effect on rotating machinery, especially with higher rotational speed and fluid density. However, the mechanism of axial flow on windage loss in open shaft‐type gap is hardly studied in most literature. To clarify it, the influences of axial Reynolds number Reu and rotational Reynolds number Reω on skin friction coefficient Cf are investigated, and flow characteristics are analyzed with different gap geometry, radius ratio η. First, the results reveal that the Cf remains constant when Reu is less than 2.8 × 104 and increases rapidly as Reu when Reu ≥ 2.8 × 104, which indicates that the effect of axial velocity u on Cf is negligible for low Reu. The positive relative deviation Δ suggests that the axial flow makes windage loss and Cf rise. Besides, a larger number of Taylor vortexes fill with gap when the effect of the centrifugal force is larger than that of the inertial force, but they gradually disappear as Reu. Subsequently, the Cf and Δ increase as η, highlighting that the effect of u on windage loss and Cf is more prominent for larger η. The fact that vorticity near walls is larger than that at the center of gap reveals that windage loss arises from the interaction between walls and fluid rather than the dissipation with fluid itself. Finally, the model of Cf in shaft‐type gap is proposed in different Reω ranges based on numerical results, and the maximum sum of squares error of 1.02 × 10−5 and minimal R2 of 0.969 satisfy the requirement of fitting accuracy and indicate that the fitting model can accurately predict Cf. The conclusions significantly help predict windage loss in open shaft‐type gap with axial flow, and further improve the design for generators of supercritical CO2 turbine‐alternator‐compressor unit. [ABSTRACT FROM AUTHOR]

The Jitang metamorphic complex is key to studying the tectonic evolution of the Northern Lancangjiang zone. Through structural‐lithological mapping, structural analysis and laboratory testing, the composition of the Jitang metamorphic complex was determined. The macro‐ and microstructural analyses of the ductile detachment shear zone (Guoxuepu ductile shear zone, 2–4 km wide) between the metamorphic complex and the overlying sedimentary cap show that the shear sense of the ductile shear zones is top‐to‐the‐southeast. The presence of various deformation features and quartz C‐axis electron backscatter diffraction (EBSD) fabric analysis suggests multiple deformation events occurring at different temperatures. The average stress is 25.68 MPa, with the strain rates (έ) ranging from 9.77×10–14 s–1 to 6.52×10–16 s‐1. The finite strain of the Guoxuepu ductile shear zone indicates an elongated strain pattern. The average kinematic vorticity of the Guoxuepu ductile shear zone is 0.88, implying that the shear zone is dominated by simple shear. The muscovite selected from the protomylonite samples in the Guoxuepu ductile shear zone yields a 40Ar‐39Ar age of 60.09 ± 0.38 Ma. It is suggested that, coeval with the initial Indo–Eurasian collision, the development of strike‐slip faults led to a weak and unstable crust, upwelling of lower crust magma, then induced the detachment of the Jitang metamorphic complex in the Eocene. [ABSTRACT FROM AUTHOR]

Exploring methods to reconstruct the ocean interior from surface data is a crucial focus in the study of ocean processes and phenomena due to the shortage of subsurface and deep‐sea data. Nonetheless, the existing methods predominantly concentrate on either data‐driven or dynamical methodologies, with limited exploration of integrating the strengths of both approaches. To combine the advantages of these two methods for reconstructing the subsurface density field from surface data, a novel dynamics‐constrained deep operator learning network based on reduced‐order model is proposed. Encoding the mean‐squared residuals of the reduced‐order equation along with the mean‐squared error between the network outputs and targets into the loss function effectively merges the dynamical and data constraints during the training process. This integration makes the network outputs and inputs approximately satisfy a specific form of the equation, allowing for interpretability, and once the network is well‐trained, rapid reconstruction evaluation can be performed. The reduced‐order equation is established by the Galerkin projection of quasi‐geostrophic equation onto the low‐dimensional subspace identified via reduced‐basis, which explains the vertical variation of ocean density. The developed model can tackle the challenge of directly measuring subsurface potential vorticity and predicting subsurface density. Evaluation is conducted using simulation data from the Max‐Planck‐Institute ocean model, indicating that it can offer precise estimations, outperforms the purely data‐driven algorithm presented in the paper and the interior plus surface quasi‐geostrophic method, and enables model sharing across different regions. Plain Language Summary: Reconstructing the interior density of the ocean from surface data is a valuable way to make up for the lack of ocean observations. Most of the previous works are purely data‐driven or dynamics‐based methods. In order to employ the advantages of dynamic and data‐driven models at the same time, a physics‐informed deep operator learning algorithm is proposed to reconstruct the density field. The proposed method shows superior predictive performance and greater robustness when compared with the pure data‐driven and dynamics‐based methods presented in the paper. These findings underscore the potential of deep learning algorithms incorporating physical constraints for marine scientific research. Key Points: The deep operator learning algorithm based on physical constraints is proposed for density field inversionThe combination of deep learning and dynamics‐based methods provides interpretability while enabling fast density reconstructionThe proposed reconstruction framework outperforms proposed purely data‐driven algorithm and traditional dynamics algorithm [ABSTRACT FROM AUTHOR]

We prove the existence of small amplitude time quasi‐periodic solutions of the pure gravity water waves equations with constant vorticity, for a bidimensional fluid over a flat bottom delimited by a space periodic free interface. Using a Nash‐Moser implicit function iterative scheme we construct traveling nonlinear waves which pass through each other slightly deforming and retaining forever a quasiperiodic structure. These solutions exist for any fixed value of depth and gravity and restricting the vorticity parameter to a Borel set of asymptotically full Lebesgue measure. [ABSTRACT FROM AUTHOR]

The upper‐ocean relative vorticity has been found to be cyclonically skewed, but altimetry observations indicate that long‐lifespan mesoscale eddies tend to be anticyclonic. We are thus interested in whether cyclonic or anticyclonic eddies are more unstable under similar circumstances. Here we use submesoscale‐resolving simulations of idealized mesoscale eddies, incorporating theoretical analyses, to investigate asymmetries of submesoscale instabilities within the anticyclones and cyclones. It is found that submesoscale filaments initiate at regions with the largest horizontal buoyancy gradients for both anticyclones and cyclones, but these filaments subsequently rotate outward in anticyclones while inward in cyclones. Hence submesoscales are more vigorous at anticyclone peripheries and the cyclone center. Such differing distributions and evolutions of submesoscale processes are primarily caused by changes in the background stratification associated with the decaying of mesoscale eddies. The active submesoscales near the cyclone center eventually distort its core structure radically, whereas the anticyclone remains largely unaffected. Plain Language Summary: Previous studies found that flows with large anticyclonic vorticity, which is negative (positive) in the Northern (Southern) Hemisphere, tend to be suppressed from further growing due to developed instabilities. Hence large‐magnitude vorticity in the real ocean is more likely to be cyclonic than anticyclonic. However, satellite observations reveal that there are more anticyclonic than cyclonic eddies that live longer in time and also propagate farther in distance. It naturally raises a question whether cyclonic or anticyclonic eddies are more unstable to instabilities. In this study, by conducting high‐resolution numerical simulations of idealized mesoscale eddies, we find profound asymmetries in the spatial distributions and time evolutions of smaller‐scale features (mainly submesoscale filaments) within the simulated cyclonic and anticyclonic eddies. The submesoscale filaments are first generated at regions with the largest horizontal gradients of density for both eddies, but their subsequent evolutions are different. Submesoscale filaments migrate outward within anticyclonic eddies while inward within the cyclonic eddies. Because of this evolution asymmetry, the core structure of the cyclonic eddies is significantly distorted after a certain period whereas the anticyclonic eddies keep largely unaffected. This is perhaps the reason why anticyclonic eddies tend to live longer in time. Key Points: Distributions and evolutions of submesoscale features manifest prominent asymmetries in anticyclonic and cyclonic eddiesSubmesoscale filaments are generated in eddy‐front area for both types of eddies but migrate outward (inward) for anticyclones (cyclones)Submesoscale asymmetries in anticyclones and cyclones are mainly determined by changes in mesoscale (background) stratification [ABSTRACT FROM AUTHOR]

Blowups of vorticity for the three‐ and two‐dimensional homogeneous Euler equations are studied. Two regimes of approaching a blow‐up point, respectively, with variable or fixed time are analyzed. It is shown that in the n‐dimensional (n=2,3$n=2,3$) generic case the blowups of degrees 1,⋯,n$1,\text{\ensuremath{\cdots}},n$ at the variable time regime and of degrees 1/2,⋯,(n+1)/(n+2)$1/2,\text{\ensuremath{\cdots}},(n+1)/(n+2)$ at the fixed time regime may exist. Particular situations when the vorticity blows while the direction of the vorticity vector is concentrated in one or two directions are realizable. [ABSTRACT FROM AUTHOR]

This paper utilizes reanalysis data and statistical methods to elucidate the physical mechanisms of intraseasonal variations of precipitation over southern China during the boreal winter, as well as the two primary factors influencing these variations. Anomalous southerly (northerly) wind over southern China will result in the strong moisture convergence (divergence) in enhanced (suppressed) scenarios, and the stronger positive (negative) horizontal advection of absolute vorticity at upper troposphere induces the anomalous ascending (descending) motion in enhanced (suppressed) scenarios. The Madden–Julian oscillation (MJO) in the tropics and a wave train over the North Atlantic and Eurasia with four activity centres in the mid–high latitudes (referred as NAE‐wave train) are the two primary factors that modulate the intraseasoanl precipitation over southern China. The intraseasonal circulation induced by MJO and NAE‐wave train exhibits distinct features, resulting in different physical mechanisms of their influences. The moisture flux divergence anomalies over southern China associated with MJO mainly stem from the meridional moisture convergence, whereas the meridional moisture advection is the first contributor in the influence of NAE‐wave train. The anomalous vorticity advection at upper troposphere associated with MJO is primarily influenced by the meridional advection, but that associated with NAE‐wave train is dominated by the zonal advection. Anomalous precipitation induced by MJO is concentrated mainly over South China, while that caused by NAE‐wave train is primarily located in the mid–lower Yangtze River basin. Therefore, different phases locking of MJO and NAE‐wave train could lead to various precipitation anomalies over southern China. [ABSTRACT FROM AUTHOR]

In the process of natural gas extraction, the phenomenon of liquid loading will affect the efficiency of gas well extraction and reduce the life of the well. Compared with conventional drainage gas extraction technology, the jet pump can not only reduce the bottom back pressure and ensure the stable production of gas reservoirs but also promote the final recovery rate. Since the jet pump relies on the interaction between fluid particles to transfer energy, the energy loss is large and the efficiency is low. To maximize the advantages of the gas‐driven jet pump, this study innovatively combines a static mixer with an annular jet pump. Utilizing the cyclonic effect produced by the static mixer, the original gas‐liquid axial motion is transformed into a stronger vortex motion, and the liquid droplets are changed into a liquid film that is easier to carry, which significantly improves the discharge efficiency of the jet pump. This study uses a combination of numerical simulation and experimental analysis to compare the associated effects of the new annular jet pump (NAJP) and the conventional annular jet pump (CAJP) on the liquid‐carrying performance of gas wells in terms of cyclonic effect, droplet breakage ratio, and pump efficiency. The results show that, compared with CAJP, NAJP increases the mass flow rate of the sucked fluid. The droplet breakage ratio increases by 15.4% year‐on‐year, while the critical liquid‐carrying flow rate is reduced by about 10.7%, resulting in a maximum pumping efficiency of 37%, an increase of about 30.7% year‐on‐year. At the same time, the reduction of the energy coefficient means lower energy consumption. In summary, NAJP is better than CAJP in terms of liquid‐carrying effect and efficiency. [ABSTRACT FROM AUTHOR]

We study stability of a spherical vortex introduced by M. Hill in 1894, which is an explicit solution of the three‐dimensional incompressible Euler equations. The flow is axi‐symmetric with no swirl, the vortex core is simply a ball sliding on the axis of symmetry with a constant speed, and the vorticity in the core is proportional to the distance from the symmetry axis. We use the variational setting introduced by A. Friedman and B. Turkington (Trans. Amer. Math. Soc., 1981), which produced a maximizer of the kinetic energy under constraints on vortex strength, impulse, and circulation. We match the set of maximizers with the Hill's vortex via the uniqueness result of C. Amick and L. Fraenkel (Arch. Rational Mech. Anal., 1986). The matching process is done by an approximation near exceptional points (so‐called metrical boundary points) of the vortex core. As a consequence, the stability up to a translation is obtained by using a concentrated compactness method. [ABSTRACT FROM AUTHOR]

The responses of atmospheric kinetic energy (KE) spectra to three convective parameterizations (CPs) in global high‐resolution simulations are revealed. The results show that the KE spectra exhibit high sensitivity to the CPs, mainly at mesoscales in the middle and upper troposphere. The New Tiedtke scheme produces the steepest mesoscale slope, followed by the Kain‐Fritsch scheme and then the Grell‐Freitas scheme. In general, there is a compensating relationship between latent heat released by the CP and microphysics parameterization (MP). The less latent heat released by the CP is compensated by the more latent heat released by the MP. The shallowest mesoscale spectra for the Grell‐Freitas scheme are related to the strongest downscale cascade dominated by the rotational component of the flow, and this is attributed to more latent heat released from MP enhancing the intensity of vorticity in the troposphere and producing more gravity wave activities in the lower stratosphere. Plain Language Summary: At the current horizontal resolution level of the atmospheric models, convective parameterization (CP) is crucial for representing convective clouds unresolved by model mesh and thus is still an important model component. Exploring the impacts of different CP schemes on global high‐resolution simulations is an important subject of modeling. Energy spectra have become a useful diagnostic for validating and comparing atmospheric models. Their sensitivity to CP is an important and not‐well‐studied part of this subject. This paper investigates the impact of CPs on atmospheric mesoscale kinetic energy spectra with global simulations from the Model for Prediction Across Scales. We found that the energy spectral slope and energy cascade are sensitive to the CP schemes. This is related to the complementary relationship between CP and microphysical parameterization (MP), which is also important for moist convection development and evolution. The less latent heat released by the CP, the more released by the MP. This leads to stronger vertical motion, accompanied by stronger convergence/divergence in the troposphere, thereby enhancing vortex motion. As a result, more energy is transferred from the synoptic scale to the mesoscale and more gravity waves are vertically propagated into the lower stratosphere, leading to the shallower spectra at mesoscales. Key Points: The kinetic energy (KE) spectra exhibit high sensitivity to the convective parameterizations (CPs) mainly at mesoscalesThe more latent heat released from CP, the steeper KE spectra at mesoscalesThe shallowest mesoscale KE spectra generated by the Grell‐Freitas scheme are attributed to the strongest RKE downscale cascades [ABSTRACT FROM AUTHOR]

The summer precipitation in Northeast China (NEC) can usually be divided into two stages, namely the Northeast China cold vortex (NECV) influencing stage in early summer (May–June) and the monsoon influencing stage in midsummer (July–August). In this study, the influence of NECV on the precipitation at multi‐timescales during different summer periods is studied. The results show that even in midsummer, though the effect of the western Pacific subtropical high is strengthened, the NECV still has the major impact on the precipitation over NEC. High co‐variability could be found between the daily precipitation and the NECV index in each month. The running correlation with an 11‐day window between precipitation and the NECV index also proves that the NECV has large impact on the precipitation over NEC during the whole summer. Key linkage of NECVs and the precipitation in midsummer can still be detected in synoptic extreme rainfall events. The composite analysis shows that, for the heavy rainfall extremes in NEC, the dominant circulation is an obvious 'negative–positive–negative' vorticity pattern at high latitudes of Asia. The positive vorticity in the pattern corresponds to stronger and more active NECV. That means the NECV is still the most critical factor affecting the NEC precipitation in midsummer. [ABSTRACT FROM AUTHOR]

This paper presents a novel approach for generating structured light using a diffractive beam‐shaping element that can generate multiple beams with distinct spatial structures in the focal plane. The element is constructed by restructuring a spiral zone plate with fork gratings, providing a tunable and controllable means for generating structured light. The element can create linear and 2D arrays of various structured beams, including vortices with adjustable charge and vorticity, petallike beams, and ring‐lattice structures. To control the generation of these beams, it introduces several parameters of the fork gratings, enabling tailoring of the beam properties to specific applications. The proposed approach involves significant mathematical analysis, including the derivation of complex equations and expressions to understand the behavior of the proposed element and its impact on the generated beams. It conducts simulations and experiments to validate the mathematical analysis and demonstrate the feasibility of the proposed approach. [ABSTRACT FROM AUTHOR]

We investigate the long‐time properties of the two‐dimensional inviscid Boussinesq equations near a stably stratified Couette flow, for an initial Gevrey perturbation of size ε. Under the classical Miles‐Howard stability condition on the Richardson number, we prove that the system experiences a shear‐buoyancy instability: the density variation and velocity undergo an O(t−1/2)$O(t^{-1/2})$ inviscid damping while the vorticity and density gradient grow as O(t1/2)$O(t^{1/2})$. The result holds at least until the natural, nonlinear timescale t≈ε−2$t \approx \varepsilon ^{-2}$. Notice that the density behaves very differently from a passive scalar, as can be seen from the inviscid damping and slower gradient growth. The proof relies on several ingredients: (A) a suitable symmetrization that makes the linear terms amenable to energy methods and takes into account the classical Miles‐Howard spectral stability condition; (B) a variation of the Fourier time‐dependent energy method introduced for the inviscid, homogeneous Couette flow problem developed on a toy model adapted to the Boussinesq equations, that is, tracking the potential nonlinear echo chains in the symmetrized variables despite the vorticity growth. [ABSTRACT FROM AUTHOR]

In this paper, we show that a weak solution for unsteady flows of 3D shear‐thinning fluids is strong under certain integrability assumptions about two components of the vorticity. In particular, if two components of the vorticity belong to the marginal critical space L1(0,T;BMO)$$ {L}^1\left(0,T; BMO\right) $$, then the solution is strong. [ABSTRACT FROM AUTHOR]

This study investigates the asymmetric response of western North Pacific (WNP) tropical cyclone (TC) formation during August–November to the Pacific meridional mode (PMM) from 1961 to 2021. Basinwide WNP TC frequency significantly increases (slightly decreases) during positive (negative) PMM years, implying a nonlinear PMM–TC frequency relationship. Only small spatial changes in TC formation occur during negative PMM years, while there is nearly a basinwide enhancement of TC formation during positive PMM years, particularly over the region of 5°–30°N and 135°–155°E. This region is characterized by significantly enhanced low‐level vorticity, mid‐level updrafts and upper‐level divergence during positive PMM years, all favouring TC development. By contrast, environmental anomalies are of a smaller magnitude and mostly insignificant over the WNP during negative PMM years. These distinct environmental changes during different PMM phases can be explained by differences in PMM strength. Positive PMM events are of a greater strength and are associated with a stronger wind–evaporation–sea surface temperature feedback than negative PMM events, leading to a notable anomalous large‐scale low‐level cyclonic circulation over the WNP in positive PMM events. [ABSTRACT FROM AUTHOR]

"On‐the‐fly" molecule enrichment by micro/nanomotors obviously improves heterogeneous catalysis, trace detection, and environmental monitoring, yet faces challenges of the trade‐off between collection range and interaction time. Inspired by the versatile foraging process of predators, this work demonstrates that micromotors doing spontaneous multipattern motion with microvortex can greatly enhance "on‐the‐fly" enrichment, demonstrated by highly sensitive surface‐enhanced Raman scattering detection. It leverages an axis‐asymmetric bowl‐shaped structure and the nonlinear Ag–AgCl reaction, realizing alternating low‐velocity swinging forward and accelerated steering motions for prolonged interaction and large work area. Moreover, the bowl‐shaped microstructure bestows a micro‐vortex above the Ag side due to the competition of electric potential and pressure gradient, also extending interaction time during the acceleration. Consequently, it exhibits at least an order of magnitude larger enhancement of detection signals than the counterparts. This proof‐of‐concept study highlights the significance of motion mode and structure design in guiding flow field, offering substantial benefits for applications. [ABSTRACT FROM AUTHOR]