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Typhoon-induced storm tides can cause serious coastal disasters and considerable economic losses. Understanding the mechanisms controlling storm surges helps the prevention of coastal disasters. Hangzhou Bay (HZB), a typical macro-tidal estuary, is located on the east coast of China, where typhoons frequently occur. The funnel-shaped topography makes this macro-tidal bay even more sensitive to storm tides. Super Typhoon Chan-hom was used as an example to study the characteristics and dynamic mechanisms of storm surges using a well-validated numerical model. The model considers the two-way coupling of waves and tides. The wind strength for the model was reconstructed using multi-source wind data and was refined by considering different rotating and moving wind fields. The Holland–Miyazaki model was used to reconstruct the local wind-field data with a good performance. The model results show that the total water level of HZB during typhoon Chan-hom was mainly dominated by tides, and the storm surge was closely related to the wind field. Surface flow was mostly influenced by winds, followed by tides. The spatial and temporal distributions of the significant wave height were controlled by the wind and local terrain. Wind stress was the largest contributor to storm surges (91%), followed by the pressure effect (15%) and the wave effect (5%). Both wind and wave-induced surges occurred during low slack waters. The tide-surge interaction changes (enhance or suppress) the surge by approximately 0.5 m during the typhoon, comprising approximately 50% of the total surge. Tides interacted with surges through various mechanisms, from the bay mouth (local acceleration and friction) to the bay head (friction and advection). The Coriolis force had a relatively minor effect. The findings of this study provide useful information for studies on sediment dynamics and coastal structures under extreme weather conditions.

The main physical processes affecting the circulation variability in Halifax Harbour (HH), including the intense lateral intrusion of offshore sub-surface waters into Bedford Basin (BB), are studied using a nested-grid modelling system (NGMS). The annual and monthly mean circulation in HH are characterized by a typical two-layer estuarine circulation, with seaward currents in the upper layer and landward currents in the lower layer, both showing strong temporal and spatial variability. The intense lateral intrusion of offshore sub-surface waters into BB occurs at time scales of a few days. The intense intrusion, in combination with winter connection, is important for the renewal of deep waters in BB. The model sensitivity experiments suggest that the persistent northwesterly winds strengthen the near-surface seaward currents and the lateral intrusion of offshore sub-surface waters into BB. The persistent southwesterly winds can also trigger the lateral intrusion, but are less effective than the northwesterly winds. The southeasterly winds, on the contrary, reduce significantly the seaward currents in the surface layer and prevent the lateral intrusion. The accumulative effects of winds and tides on the 3D hydrodynamics in HH are also examined. Local winds have dominant effects on the 3D currents and temperature/salinity, through driving vertical mixing and coastal upwelling. By comparison, tides play a secondly role in affecting the currents and temperature/salinity in BB but are important in the Narrows. • The intense lateral intrusion of offshore sub-surface waters into Bedford Basin are studied using a nested-grid modelling system. • The persistent northwesterly winds strengthen the lateral intrusion of offshore sub-surface waters. • Local winds have dominant effects on the 3D currents and temperature/salinity. [ABSTRACT FROM AUTHOR]

While we have growing numbers of massive star observations, it remains unclear how efficient the key physical processes such as mass loss, convection and rotation are, or indeed how they impact each other. We reconcile this with detailed stellar evolution models, yet these models have their own drawbacks with necessary assumptions for 3-dimensional processes like rotation which need to be adapted into 1-dimensional models. The implementation of empirical mass-loss prescriptions in stellar evolution codes can lead to the extrapolation of base rates to unconstrained evolutionary stages leading to a range of uncertain fates. In short, there remain many free parameters and physical processes which need to be calibrated in order to align our theory better with upcoming observations. We have tested various processes such as mass loss and internal mixing, including rotational mixing and convective overshooting, against multiple observational constraints such as using eclipsing binaries, the Humphreys-Davidson limit, and the final masses of Wolf-Rayet stars, across a range of metallicities. In fact, we developed a method of disentangling the effects of mixing and mass loss in the 'Mass-Luminosity Plane' allowing direct calibration of these processes. In all cases, it is important to note that a combined appreciation for both stellar winds and internal mixing are important to reproduce observations. [ABSTRACT FROM AUTHOR]

Titan is a sedimentary world, with lakes, rivers, canyons, fans, dissected plateaux, and sand dunes. Sediments on Saturn's moon are thought to largely consist of mechanically weak organic grains, prone to rapid abrasion into dust. Yet, Titan's equatorial dunes have likely been active for 10s–100s kyr. Sustaining Titan's dunes over geologic timescales requires a mechanism that produces sand‐sized particles at equatorial latitudes. We explore the hypothesis that a combination of abrasion, when grains are transported by winds or methane rivers, and sintering, when they are at rest, could produce sand grains that maintain an equilibrium size. Our model demonstrates that seasonal sediment transport may produce sand under Titan's surface conditions and could explain the latitudinal zonation of Titan's landscapes. Our findings support the hypothesis of global, source‐to‐sink sedimentary pathways on Titan, driven by seasons, and mediated by episodic abrasion and sintering of organic sand by rivers and winds. Plain Language Summary: Like Earth, Saturn's moon Titan hosts lakes, rivers, canyons, fans, eroded plateaux, and sand dunes. On Titan, loose solid particles (or sediments) are likely made of soft hydrocarbon grains, prone to rapid breakdown into dust. Yet, Titan's equatorial dunes have been active for up to several hundreds of thousands of years, suggesting that some mechanism must produce sand‐sized particles at these latitudes. We explore the hypothesis that a combination of abrasion, when grains are transported by winds or methane rivers, and sintering, when they are at rest, could produce sand grains that maintain an equilibrium size. Our model demonstrates that seasonal sediment transport could produce sand on Titan and could explain the distribution of Titan's landscapes. Altogether, our findings support the hypothesis of global sedimentary pathways on Titan, driven by seasons, and mediated by episodic abrasion and sintering of organic sand by rivers and winds. Key Points: Long‐lived active dune fields are in apparent contradiction with the predicted rapid abrasion of windblown organic sediment on TitanEpisodic abrasion and sintering of organic sediment, driven by seasons, could generate sand with equilibrium sizes on TitanTitan's undifferentiated plains and labyrinth terrains could result from prolonged sintering and diagenesis where transport is infrequent [ABSTRACT FROM AUTHOR]

Accidental oil spills in the near-shore regions create severe impacts on coastal environments. The bulk carrier MV Wakashio ran aground off Southeastern Mauritius (SEM) on 25 July 2020, resulting in ~1000 tons of oil spillage into the Indian Ocean. The Sentinel-1 synthetic aperture radar (SAR) imagery is used to track and delineate the spilled oil and the affected coastal regions of Mauritius. The results depict that the spilled oil is primarily drifted towards the northwest, and beached along the SEM coastline, covering an area of ~24.42 km2 on 10 August. Within 6 days, the prevailing spill spreading has significantly reduced to ~5.1 km2 (on 16 August) and was almost the same even on 22 August. Subsequently, the spill spreading area has diminished further and more or less disappeared on 15 September. The assessment of SAR imagery corresponding to prevailed winds, tides, Stokes drift and currents illustrated that the spill has primarily drifted northwestwards owing to the force instigated by winds, Stokes drift and tides. This study recommends Sentinel-1 imagery to assess any such oil spill incidents in the future. Highlights: Sentinel-1 satellite imagery has successfully captured the spreading of the Wakashio spill. The northwestward drift of spill was primarily due to wind, Stokes drift and tides. The spill deposition is significant along 28 km of coastline from Pointe d'Esny. There was no significant evidence of the southward movement of the oil spill. Sentinel-1 provides a promising imagery results to study any oil spill event. [ABSTRACT FROM AUTHOR]

Wind information in urban areas is essential for many applications related to air pollution, urban climate and planning, safety of drone‐related operations, and assessment of urban wind energy potential. These applications require accurate wind forecasts, and obtaining this information in an urban environment is challenging as the morphology of a city varies from street to street, altering the wind flow. Remote sensing techniques such as Doppler lidars (light detection and ranging) provide a unique opportunity for wind forecast verification as they can provide both the vertical profile of the horizontal wind and the spatial variation in the horizontal domain at high resolution. In this study, the performance of numerical weather prediction (NWP) models, analysis systems, and large‐eddy simulation (LES) models have been analysed by comparing the modelled winds against Doppler lidar observations under various atmospheric conditions and from season to season, in the coastal environment of Helsinki, Finland. The long‐term mean vertical profile of the modelled horizontal wind shows good agreement with observations; the NWP model and the analysis systems selected here exhibit different strengths and weaknesses depending on the atmospheric conditions but no significant diurnal variation in performance. However, both the model and analysis systems show differences in their spatially‐averaged bias when investigating different wind directions. LES verification shows that these models can potentially provide winds down to street level, given pre‐computed scenarios of atmospheric conditions. For Helsinki, the observed winds are stronger during winter than summer, and, on average, higher wind speeds were observed at the urban site than the sub‐urban site. [ABSTRACT FROM AUTHOR]

Öz: 1588 yılında haftalarca süren şiddetli rüzgârlar, tarihin hiçbir döneminde ve yerinde olmadığı kadar bir ülkenin (İngiltere) kaderinde yön tayin edici olmuştur. İspanya Kralı II. Felipe’nin, İngiltere’yi işgal için Armada’yı gönderdiği sırada başlayan şiddetli rüzgârlar, bu iki ülke insanının zihnini haftalarca meşgul etmiştir. Bu durumun nedeni ise rüzgârların meydana getirdiği büyük tarihsel olaydır. Herhangi bir noktasının denize uzaklığı en fazla 120 km olan İngiltere, Avrupa’nın en büyük deniz gücü olarak bilinen İspanyol donanması Armada’ya karşı 1588 yılında çok az bir şansa sahip iken” güçlü bir müttefik” gibi ufakta beliren şiddetli rüzgârlar sayesinde “mucizevi bir zafer kazanmıştır.” 1588 yılının şiddetli rüzgârları II. Felipe’nin Armada’sını yok olmanın eşiğine getirirken İngiltere’ye de denizlerde üstünlük sağlayan en büyük güçlerden biri olmanın yolunu açmıştır. Bu sayede İngiltere bir dünya gücü haline gelmeye başlamıştır. Abstract: The severe winds that lasted for weeks in 1588 have never been in the direction of the destiny of a country (England) than at any time in history and in place. The winds that started when King Philip II of Spain sent Armada to occupy England occupied the minds of these two countries for weeks.The reason for this situation is the historical event caused by these winds.England, which hada maximum distance of 120 km from any point to the sea, has had a little chance against the Spanish navy Armada, known as the biggest sea power in Europe, in 1588, while gaining a miraculous victory thanks to the powerful winds that appear in the small like a strong ally.While the powerful winds of 1588 brought the Armada of Philip II to the brink of extinction, it paved the way to become one of the greatest powers that gave England superiority in the sea.In this way, England started to become a world power.

Abstract Wind information in urban areas is essential for many applications related to air pollution, urban climate and planning, safety of drone‐related operations, and assessment of urban wind energy potential. These applications require accurate wind forecasts, and obtaining this information in an urban environment is challenging as the morphology of a city varies from street to street, altering the wind flow. Remote sensing techniques such as Doppler lidars (light detection and ranging) provide a unique opportunity for wind forecast verification as they can provide both the vertical profile of the horizontal wind and the spatial variation in the horizontal domain at high resolution. In this study, the performance of numerical weather prediction (NWP) models, analysis systems, and large‐eddy simulation (LES) models have been analysed by comparing the modelled winds against Doppler lidar observations under various atmospheric conditions and from season to season, in the coastal environment of Helsinki, Finland. The long‐term mean vertical profile of the modelled horizontal wind shows good agreement with observations; the NWP model and the analysis systems selected here exhibit different strengths and weaknesses depending on the atmospheric conditions but no significant diurnal variation in performance. However, both the model and analysis systems show differences in their spatially‐averaged bias when investigating different wind directions. LES verification shows that these models can potentially provide winds down to street level, given pre‐computed scenarios of atmospheric conditions. For Helsinki, the observed winds are stronger during winter than summer, and, on average, higher wind speeds were observed at the urban site than the sub‐urban site.

The middle atmosphere over South America, particularly above the Andes mountain range, is known as one of the most dynamically active regions in the world. Previous studies have investigated wave dynamics at mesosphere and lower thermosphere (MLT) altitudes within this region, but only a handful of them have made use of continuous measurements provided by specular meteor radars (SMRs). Furthermore, it was only until recently that MLT horizontal wind gradients were estimated for the first time using Spread Spectrum Interferometric Multistatic meteor radar Observing Network (SIMONe) Argentina, a multistatic SMR network located in southern Patagonia. By observing larger amounts of meteors from different viewing angles, multistatic SMRs allow, among others, for more reliable momentum flux estimates. In this work, we explore and compare the summer and winter MLT momentum flux dynamics at low and middle latitude sectors over the Andes mountain range. We also investigate the intermittency of the total momentum flux over these sectors. For this purpose, we analyze measurements provided by four multistatic SMR networks: SIMONe Peru (12°S), Chilean observation network de Meteor radars (30°S), SIMONe Argentina (49°S) and multi‐frequency Agile radar for investigations of the atmosphere‐southern Argentina agile meteor radar (54°S). We find that the momentum flux dynamics can change considerably over distances of only a few hundred km (e.g., southern Argentina). On the other hand, the contributions of large momentum fluxes to the total flux can be similar between regions separated by thousands of km (e.g., between Peru and southern Argentina). Key Points: First latitudinal comparison of mesosphere and lower thermosphere momentum fluxes along the Andes mountain range28‐day mean momentum flux dynamics vary depending on the latitude and the seasonTotal momentum flux distributions are well represented by log‐normal functions, with parameters varying on location and season [ABSTRACT FROM AUTHOR]

Seasonal changes in wind regime have driven the formation and emergence of reversing dunes and crest reversal in the inland arid and coastal areas of Asia, but due to the strong prevailing winds, the reversing dunes or reversing crest can be flipped. Therefore, the transient reversing dunes or crest reversal will be ignored and unobserved. To investigate dune morphology and sedimentology concerning seasonal alternation of the wind regime, we reconstructed dune topographies using aerial drone photos and analyzed the grain‐size parameters and internal sedimentary structures of dunes. Morphological results show that wind‐blown sands from the lee side are transported and deposited on the upper stoss side because of the reversing winds. Then, the dune crestal area is flattened, surface sand compositions were reorganized from fining to coarsening at the dune crest. Combining these field surveys with numerical simulation results, we found that the internal sedimentary structures are composed of high‐angle cross‐strata and low‐angle bounding surfaces. The dip angles of the bounding surfaces gradually decrease from the bottom to the top because of the reversing wind erosion on the lee side. The increase in sand flux on the lee side plays a critical role in shaping the dip angle of the bounding surfaces due to the speed‐up effect. Plain Language Summary: Under the influence of the East Asian monsoon system, near‐surface wind strength and direction are characterized by strong northwest winds in spring and winter, and weak southeast winds in summer. The seasonal changes in wind regimes reshape the dune forms and reorganize the grain‐size characteristics and internal sedimentary structures of the dunes. After the influence of reversing wind, dune crestal areas are flattened, then dune crests are flipped, oriented in the opposite direction. The sands on the downwind side were transported and deposited on the upwind side by the reversing wind, causing the grain fining characteristics on the dune crest to change into coarsening characteristics. Moreover, field surveys show that internal layering structures in dune shift from a southeast dip in the lower part to a northwest dip in the upper part. It reveals that sand deposition on the downwind side caused by NW winds becomes sand deposition on the upwind side induced by SE winds. Numerical simulation results quantitatively illustrate that the internal sedimentary structures are composed of high‐angle cross‐strata and low‐angle bounding surfaces. The dip angles of the bounding surfaces gradually decrease from the bottom to the top because of the reversing wind erosion on the lee side. Key Points: Reversing winds produce reversing slip faces and rework sands on dune crestal areasHigh‐angle cross‐strata are truncated by low‐angle bounding surfaces in asymmetrical bidirectional wind regimesThe bounding surface angle decreases with height, which is caused by the reversing wind erosion due to the speed‐up effect [ABSTRACT FROM AUTHOR]

Observational records are more often than not influenced by residual non‐climatic factors which must be detected and adjusted for prior to their usage. In this work, we present a novel approach, named Radiosounding HARMonization (RHARM), providing a homogenized data set of temperature, humidity and wind profiles along with an estimation of the measurement uncertainties for 697 radiosounding stations globally. The RHARM method has been used to adjust twice daily (0000 and 1200 UTC) radiosonde data holdings at 16 pressure levels in the range 1,000–10 hPa, from 1978 to present, provided by the Integrated Global Radiosonde Archive. Relative humidity (RH) data are limited to 250 hPa. The applied adjustments are interpolated to all reported levels. RHARM is the first data set to provide homogenized time series with an estimation of the observational uncertainty at each sounding pressure level. By construction, RHARM adjusted fields are not affected by cross‐contamination of biases across stations and are fully independent of reanalysis data. Analysis of trends for temperature, RH and winds highlights increased geographical coherency of trends over 1978–2000 globally, but especially in the Northern Hemisphere and South America. RHARM shows warming trends of 0.39 K/decade at 300 hPa in the Northern Hemisphere and of 0.25 K/decade in the tropics. The RHARM adjustments also reduce differences with the European Centre for Medium‐Range Weather Forecast ERA5 reanalysis, with the strongest effect in the Northern Hemisphere for temperature and relative humidity. For wind speed, the comparison indicates a good agreement with ERA5 in the troposphere. Plain Language Summary: Systematic observations of atmospheric parameters by balloon soundings have been collected regularly across the globe since decades. However, changes in the instrumentation, calculation algorithms, station re‐locations and other factors can influence the measurement time series, making the identification of climate signals difficult. The availability of measurement metadata, cross‐comparison with (sparser) reference networks and the application of statistical methods allows to greatly improve the physical consistency of the records. We developed the Radiosounding HARMonization (RHARM) methodology to provide users with homogenized radiosonde profiles of temperature, humidity, and wind, along with measurement uncertainties, for 697 locations globally and twice daily based on the Integrated Global Radiosonde Archive. Key features of RHARM are the provision of multiple fundamental atmospheric parameters, adjusted for spurious biases and the inclusion of measurement uncertainties estimated following the standards of the metrological community when available metadata permits. The current version of the RHARM data set can be used to investigate tropospheric weather and climate for the last four decades. Key Points: The Radiosounding HARMonization (RHARM) data set provides homogenized time series of temperature, relative humidity and wind profiles for hundreds of radiosonde stationsMetrologically accurate estimates of the observational uncertainty are provided together with each observation and variableFor all variables, RHARM increases the geographical coherency of estimated trends and the agreement with a modern atmospheric reanalysis [ABSTRACT FROM AUTHOR]

Temperature and salinity data, obtained by two snapshot surveys during 19–20 May 2019 and 12–25 September 2019 across the East China Sea (ECS) shelf, revealed that the Kuroshio intrusion to the north of 28°N comprised the Nearshore Kuroshio Branch Current (NKBC) and the Offshore Kuroshio Branch Current (OKBC) at the bottom of the ECS during spring 2019, and that the NKBC was weak during autumn 2019. The Regional Ocean Model System was used to reproduce the distribution of water masses and the current structure over the continental shelf of the ECS during 2019. Analyses of the momentum balances indicated that the cross-shore range and the intensity of the NKBC were determined by the combination of the geostrophic flow and bottom Ekman current. In comparison with that in May 2019, a weakened shoreward bottom Ekman current and an increased offshoreward geostrophic flow caused the disappearance of cross-shore range of the NKBC in September 2019. Meanwhile, a diminished northeastward alongshore geostrophic flow in September 2019 also weakened the intensity of the NKBC. Sensitivity experiments indicated that a strong southwestward wind can push the western (eastern) boundary of the NKBC further offshoreward (shoreward) by increasing (decreasing) the offshore geostrophic flow (bottom Ekman current). A weak Taiwan Warm Current (TWC) can move the eastern boundary of the NKBC shoreward by decreasing the onshore bottom Ekman current. A weak Kuroshio Current (KC) can move the eastern boundary of the NKBC shoreward by increasing the offshoreward geostrophic flow. Furthermore, a strong (weak) southwestward wind, weak (strong) TWC, and strong (weak) KC can diminish (enhance) the intensity of the NKBC. Of the three factors, the wind plays the major role in influencing the NKBC. [ABSTRACT FROM AUTHOR]

Contemporary cities increasingly tend to relate to pedestrians in a more evident way, integrating bioclimatic design strategies to provide a more sustainable and livable city. The relationship between environment and built-in habitat in the history of humanity has been essential since natural resources were the only ones available, until the last century. The excessive urban cementification has once again placed a new challenge before the professionals of the sector: considering the environmental components in the urban planning and design steps. For this reason, sunlight, wind, humidity and vegetation are not simply ornaments and decorations of the city, but become the main factors in determining road axes, height of buildings, public spaces and green areas. The case study focuses on Lima, the capital of Peru which despite the great efforts made during the postpandemic period, turns out to be one of the cities with the greatest problems in considering bioclimatic design as a key instrument for its regeneration. The own characteristics of a site, such as the latitude and prevailing winds, among others, have been little considered in the decades, giving the population a city that lacks large parks, that is not protected from sunlight especially in summer and that does not eliminate high humidity, but it seems almost to raise the problem to an insoluble level. [ABSTRACT FROM AUTHOR]

To arrive in Aotearoa, we traversed thousands of miles. Waka hourua were our papakāinga and te ra filled with wind to carry us. Finding our way, we drew on knowledge of oceans, skies and winds. Creatures of the sea and air showed us the way and signs and signals of this world and between and across worlds guided us. We made our homes in Te Moana-nui-a-Kiwa, making lives for ourselves, drawing on long held matauranga. Our science, our scholarship is embedded in te tai ao and the survival and wellbeing of our people. We continue to find our way, drawing on long held matauranga and adapting and developing new knowledge. In this article, I attempt to centre being māori, exploring what it is to work and write with colonisation at the margin, rather than the defining determinant of who we are and how we differ. I face the challenge of writing as a Māori scholar, to claim rangatiratanga in our practice and representations of these practices. [ABSTRACT FROM AUTHOR]

A suite of satellite-derived data and high-resolution ocean model outputs were used to study the response of the upper ocean to Hurricane Dorian (2019), which impacted the Bahamas and the eastern coast of the United States in August and September of 2019. We observe enhanced upwelling that in conjunction with surface cooling from precipitation led to an approximate 4 °C drop in sea surface temperature (SST) along and slightly ahead of Dorian’s path. The upwelling also increased the local coastal chlorophyll-a levels. Soil Moisture Active Passive (SMAP) sea surface salinity (SSS) shows a clear eye and eye wall structure on September 4 (the day of peak intensity), which has never been seen due to the recency of the SMAP satellite’s launch and the strength of Hurricane Dorian (2019). The initial forecast path of Hurricane Dorian was set to travel northward through central Florida; however, we can see from satellite observations that a high-pressure system in the north Atlantic redirects the path of the hurricane offshore. We show a clear upper ocean response to Hurricane Dorian using satellite observations and hope that this multiparameter approach can improve the current quantification of air–sea interactions during Category 5 conditions. [ABSTRACT FROM AUTHOR]

This study documents the detailed features and processes of convection initiation (CI) at a coastal rainfall hotspot in South China, with emphasis on the typical meteorological conditions and effects of small‐scale orography. The CI occurrences are identified using high‐quality radar mosaics during 7‐year warm seasons. They tend to maximize in low‐lying areas adjacent to coastal small‐scale mountains rather than on the windward slopes of major mountains as previously expected. The genesis of the coastal convection exhibits a remarkable diurnal peak in the early afternoon and mostly occurs on the days of low‐level southwesterlies with a jet‐nose structure in offshore region. These onshore flows enhance the low‐level moistening and convergence on coasts. The characteristic synoptic patterns become common after the onset of summer monsoon, suggesting the key role of monsoonal flows in triggering coastal convection. Driven by the atmospheric conditions of the dominant synoptic pattern, quasi‐idealized numerical simulations demonstrate that the coastal small‐scale mountains disturb the low‐level onshore flow and produce multiple enhanced convergent zones downstream of the mountains. The induced local variations in upward motion and moisture pooling explain the CI occurrences that are located close to these small‐scale mountains. When these mountains are artificially removed in the simulation, convection preferentially initiates on the windward slopes of major mountains as expected. The findings suggest that the small‐scale orography can strongly regulate the local patterns of CI hotspot through disturbing low‐level onshore flow. An explicit resolving of the small‐scale coastal orography is warranted to improve the modeling of local severe weather. Key Points: The genesis of warm‐season convection at a rainfall hotspot in South China preferentially occurs near the coastal orographyThe characteristic low‐level onshore southwesterlies in monsoon flows are the dominant synoptic pattern favorable for the coastal CICoastal small mountains may generate substantial local variations in the lifting and moisture pooling, determining the detailed CI pattern [ABSTRACT FROM AUTHOR]

Future projections in austral winter characteristics of explosive extratropical cyclones (EECs) in three CORDEX Southern Hemisphere domains (Africa-AFR, Australia-AUS and South America-SAM) are investigated. The projections are obtained with a fine resolution (25 km) Regional Climate Model (RegCM4) within the CORDEX-CORE framework driven by three Global Climate Models (GCMs: HadGEM2-ES, MPI-ESM-MR and NorESM-1 M) under the RCP8.5 scenario. The cyclone database was obtained using a tracking scheme applied to 6-hourly mean sea level pressure fields and EECs are selected using the Sanders and Gyakum criterion. EECs represent ~ 13–17% of the total number of extratropical cyclones during austral winter in the ERA-Interim reanalysis (1995–2014), while both GCMs and RegCM4 ensembles underestimate this percentage. The frequency of EECs is projected to increase in AFR and in SAM domains at the end of the twenty-first century. However, the magnitude of the projected changes needs to be considered with caution because it is smaller than the underestimations in the frequency of EECs of both ensembles in the present climate. EECs in the future will be deeper and faster but with a shorter lifetime. Eady Growth Rate composites, when EECs reach the explosive phase, indicate a less baroclinic large-scale environment in the future. On the other hand, the intensification of precipitation associated with EECs in the future indicates an increase in the contribution of the diabatic processes acting to strengthen the local baroclinicity of the EECs. [ABSTRACT FROM AUTHOR]

Any tall building subjected to high-speed winds will tilt and crack unless precautionary measures are taken. Various active and passive control methods are proposed to control the wind induced responses of the tall buildings. These tall structures can be made aerodynamic by modifying the external geometry of the building. In the present study, minor geometrical modifications are rendered to the structures. G+30 storeys are considered for each model with constant plan layout. The location of the building is considered to be Bengaluru and corresponding wind load data is considered. Modeling and analysis is carried out using ETABS 2017 software. Wind load analysis is carried out to know the effect of these aerodynamic modifications. The parameters considered for the comparison are storey displacement, natural time period and overturning moment. On comparative analysis, it was observed that wind-induced responses of these geometrically modified buildings have reduced by 5% to 10%. It can also be concluded that minor modifications have shown significantly better performance than a conventional square-plan building in addition to an innovative architectural look. [ABSTRACT FROM AUTHOR]

In this paper, we examine the mechanism of middle‐ and low‐latitude sporadic‐E (Es) layer formation. Observations of ionosondes and meteor radars at stations of different latitudes show that Es layer also formed at low‐altitude nonwindshear points, which is distinct from prototypical windshear theory. The theoretical modeling results show that metallic ions can effectively accumulate by the combined effect of the zonal and meridional winds in the mesosphere and the lower thermosphere region. Numerical simulation results also demonstrate that metallic ions can accumulate without wind shear at lower height (90–105 km) as a consequence of the MLT winds leading to the ion drifting downward. We suggest that the turbopause at 90–105 km plays an important role in forming low‐altitude Es layer in the middle‐ and low‐latitude regions. Plain Language Summary: Sporadic‐E layer is an enhanced ionization patch, which can reflect radio wave signals, and plays a significant role in the telecommunication and navigation system. The occurrence of Es layer is inconsecutive and influenced by many factors, such as wind, electric field, and meteor input, which makes the prediction of Es layer very difficult. In this study, we try to investigate the process of the formation of Es layer from electrodynamic theory of ionosphere. Our simulation results demonstrate that the wind shear, a classical theory for the Es layer formation at midlatitude, is not the only mechanism leading to the generation of Es layer, and turbopause at 90–105 km height can provide the concentration location for metallic ions. Key Points: Windshear Theory of sporadic‐E (Es) formation is reexaminedMeteor radar and ionosonde observations show that Es can form at nonwindshear pointsSimulation results show that Es formation can be affected by the turbopause [ABSTRACT FROM AUTHOR]

We combined observations of ocean surface winds from Indian SCATterometer SATellite-1 (SCATSAT-1) with a background wind field from a numerical weather prediction (NWP) model available at National Centre for Medium-Range Weather Forecast (NCMRWF) to generate a 6-hourly gridded hybrid wind product. A distinctive feature of the study is to produce a global gridded wind field from SCATSAT-1 scatterometer passes with spatio-temporal data gaps at regular synoptic hours relevant for forcing models and other NWP studies. We are following the concept from the modern particle filter technique, which does not represent the model probability density function (PDF) as Gaussian. We generated the 6-hourly hybrid winds for 2018 and validated them using the wind speed from daily gridded level-4 SCATSAT-1 winds (L4AW), Cross Calibrated Multi-Platform (CCMP) dataset and global buoy data from National Data Buoy Centre (NDBC). The results suggest the potential of the technique to produce scatterometer winds at the desired temporal frequency with significantly less noise and bias along the swath. The study shows that the generated hybrid winds are of prime quality compared with the already existing daily products available from Indian Space Research Organization (ISRO).

A significant haze event occurred in northern China from 16 to 21 November 2022. This study analyzed the haze spatial evolution, and meteorological influences by integrating ground and satellite measurements. Most data were obtained using aerosol lidar and wind lidar observations in suburban (Nanjiao Observation Station, NJOS) and urban Beijing (Haidian Observation Station, HDOS). The observations at NJOS and HDOS indicate the presence of a distinct layer of haze restricted to a height of up to 1500 m above the surface. However, the aerosol intensity at HDOS was comparatively lower (aerosol extinction coefficient: 1.39 ± 0.27 km ^−1 ) than at NJOS (1.77 ± 0.38 km ^−1 ), with approximately one day of time lag in response to the southerly winds. Though NJOS and HDOS presented a similar wind stratification structure, the downdraft under 1000 m influenced the surface air quality were significantly different. The intense downdraft at the lower height at HDOS prevented the vertical upward diffusion of accumulated ground pollutants, whose effect was similar to that of the inversion layer. That led to a more stable increasing trend of PM _2.5 at HDOS, with the shallowest planet boundary layer height of 242 m on 20 November. By contrast, NJOS in the transportation path was more regularly influenced by the southerly flow and presented cyclical PM _2.5 concentration. This study shows downdraft in urban environments acting as an accelerator for urban episodic PM _2.5 pollution, suggesting the complicated contribution from meteorological factors.