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The Tibetan Plateau vortices (TPVs) are mesoscale weather systems active at the near-surface of the Tibetan Plateau (TP), which are one of the major precipitation-producing systems over the TP and its surrounding areas. TPVs mainly occur in the warm season from May to September. In this paper, we investigated the interdecadal change of TPVs in the warm seasons of 1979–2020 with the six widely used reanalysis datasets. A significant change of the TPVs frequency appears around the mid-1990s, associated with less TPVs during 1979–1995 and more TPVs during 1996–2020, which is constant among the multiple reanalysis datasets. The abrupt change of TPVs is caused by a transition of the Atlantic Multi-decadal Oscillation (AMO) from a cold phase to a warm phase in the mid-1990s. The shift of AMO leads to a silk-road pattern-like wave train and a spatially asymmetric change of tropospheric temperature. It modifies the intensity of the subtropical westerly jet and the TP heating, leading to the interdecadal change of TPV activities. [ABSTRACT FROM AUTHOR]

Tibetan Plateau (TP) snow cover is featured by sub‐seasonal changes, affecting weather and climate in surrounding and downstream areas. Previous studies emphasize the effect of background atmospheric circulation on rapid changes of TP snow cover as a whole. However, spatial discrepant changes of snow cover over the TP with complex topography and uneven snowfall remain unaddressed. Our research indicates that snow cover fraction dominates the rapid changes of surface albedo across the TP, and snow depth also significantly influences surface albedo changes through modulating snow albedo in central and eastern TP with shallow snow. However, the excessive snow amount and empirical snow cover fraction schemes introduce spatially divergent biases of surface albedo changes in simulations. Our research highlights the instant response of TP surface albedo to both snow coverage and depth in snow season, and provides a promising perspective for improving TP snow and surface albedo simulations. Plain Language Summary: Tibetan Plateau (TP) snow cover is characterized not only by obvious seasonal changes, but also by rapid sub‐seasonal changes, which has a significant impact on the weather and climate of the downstream areas by affecting the surface albedo over the TP. Previous studies have generally concluded that the background atmospheric circulation dominates rapid changes of overall TP snow cover. However, rapid changes of snow cover exhibit spatial discrepancies over the TP with complex topography and uneven snowfall. Our study finds that snow coverage and depth both contribute to rapid changes of surface albedo and energy budget over the TP, which further lead to rapid changes of snow cover. However, current numerical models tend to overestimate the snow and fail to simulate spatial different changes of snow coverage and depth, leading to spatially divergent simulation biases in surface albedo, surface energy balance and local atmospheric circulation over the TP. Therefore, there is an urgent need to improve the snow parameterization in models to enhance the intra‐seasonal simulation of snow cover and surface albedo over the TP. Key Points: Observed surface albedo over the Tibetan Plateau (TP) has significant weekly scale fluctuations during winterSnow cover fraction and snow depth jointly dominate observed rapid changes of surface albedo over the TPExcessive snow amount and empirical snow cover fraction schemes lead to spatially divergent bias of surface albedo change [ABSTRACT FROM AUTHOR]

The suspension of a single cylindrical particle in a square stirred tank was investigated by detailed visualization experiments. The flow pattern in the tank generated by a spinning disk is laminar (Reynolds numbers based on the disk diameter are less than 50). The cylinder's motion and orientation were recorded by two cameras at 100 frames per second and then quantitatively analyzed. The length over diameter aspect ratio of the cylinders was varied in the range 1 – 8. The angular speed of the spinning disk at which incipient lift-off of the cylinder occurs depends on the cylinder's diameter and its aspect ratio. Beyond an aspect ratio of about 5, this critical disk speed only weakly depends on the aspect ratio indicating that then the hydrodynamic force on the cylinder approximately scales with its length. The self-rolling as well as the azimuth sliding over the tank bottom were quantitatively identified when the cylinder approached being lifted off. The suspension phenomenon of the cylinder with aspect ratio 1 is different from other cylinders. We obtained highly reproducible results for the trajectory and orientation of the cylinder during the suspension process that can serve as benchmark data for critical evaluation of computational approaches. • Suspension motion of one cylinder in a stirred tank was quantitatively analyzed. • Reproducible trajectories and orientations of cylinders at three suspension stages. • Off-center sliding and self-rolling are precursors for cylinder lift-off. • Effect of aspect ratio on cylinders' motion was investigated. [ABSTRACT FROM AUTHOR]

The Tibetan Plateau (TP) is the highest land in the world and has a very complex topography. However, the influence of topography on TP snow cover simulations has not been adequately addressed in most land surface models. The analysis of satellite observations indicates that snow cover fraction (SCF) simulation biases increase with the topography complexity, and this increasing trend slows down when the standard deviation of topography is greater than 200 m. The result also shows that using the SCF schemes without consideration of topography leads to a consistent overestimation in winter. To account for the topographic effects, we introduce a modified topographic factor to the SCF schemes. Then we conduct regional simulations using the Simplified Simple Biosphere Model version 3 (SSiB3) and evaluate the results at the location of observation sites to reduce the uncertainty induced by forcing data. Compared with the default SCF scheme, the mean winter SCF bias is reduced from 3.83% to −0.10%. The optimization of SCF simulations further improves the winter surface albedo and land surface temperature (LST) simulations. The winter surface albedo bias over the TP is reduced from 0.020 to 0.007, with a maximum reduction by −0.133. The winter LST bias is reduced from −3.33 to −3.04 K, with a maximum reduction by 3.60 K. This study highlights the importance of topographic effects in simulating snow cover distribution and land surface energy budget for reducing the "cold bias" in winter climate simulations over the TP. Plain Language Summary: The Tibetan Plateau (TP) has a very complex topography, which greatly influences the snow cover distribution in winter. However, the influence of topography on snow cover simulations has not been adequately addressed in most land surface models. Based on the satellite data, we find that ignoring topography leads to a significant overestimation of the simulated snow cover distribution over the TP in winter, and the overestimation increases with the topographic complexity until the terrain complexity reaches a certain level. By applying this relationship, the winter snow cover distribution simulations are greatly improved over the TP, and this improvement further leads to the improvement of land surface energy budget simulations in winter. Taking the topographic effect on snow cover distribution into account contributes to reducing the "cold bias" in winter climate simulations over the TP. Key Points: The complex topography over the Tibetan Plateau greatly influences the snow cover distribution in winterUsing the snow cover fraction (SCF) schemes without topography leads to a consistent positive bias of SCF simulations in winterBy adding a topographic factor, the simulations of winter SCF and surface albedo are significantly improved [ABSTRACT FROM AUTHOR]

This paper investigates the throughput performance of an incremental virtual full-duplex non-orthogonal multiple access (I-VFD-NOMA) communication system, where two energy harvesting (EH) enabled near users are willing to forward message for far user using decode-and-forward (DF) protocol. If the direct link between the source and the far user exists, I-VFD-NOMA scheme is used to save the channel resources. If the direct link between the source and the far user does not exist, I-VFD-NOMA can not be used and only VFD-NOMA can be used. With this structure, The analytical expressions of the system throughput considering imperfect successive interference cancellation (I-SIC) and selection combining (SC) are derived when the direct link exists or not. With the aim of maximizing the throughput, the expression for the optimal power splitting factor at near users is also derived when the direct link does not exist. All theoretical results are validated by numerical simulations which demonstrate that the proposed I-VFD-NOMA scheme is superior to existing NOMA systems. [ABSTRACT FROM AUTHOR]

The Tibetan Plateau (TP) is known as the Asian water tower that supplies fresh water for millions of people in Asia. The Tibetan Plateau vortices (TPVs) are one of the major precipitation‐producing weather systems over the TP. The characteristics of TPV‐associated precipitation from 1979 to 2017 are quantitatively analysed based on three daily precipitation datasets. The influence of TPVs on precipitation is more significant in the warm season (May–September) because the precipitation and TPV activities both peak in the warm season. The TPV‐associated precipitation (VAP) dominates the total precipitation over most of the TP in the warm season. The VAP contributes more than 50% of the total precipitation in the warm season over 30% of the area over the TP, particularly in the central TP, while the VAP accounts for more than 25% of the total precipitation in the cold season over about 20% of the area over the TP. Therefore, TPVs are the major systems to produce precipitation on the TP in the warm season, and they are also important in the cold season in certain regions. The interannual variation of VAP is mainly determined by the number, rather than the precipitation intensity, of TPVs. Furthermore, the heating anomaly caused by the TP thermodynamic effect is an influential factor of VAP. Stronger (weaker) TP heating and resulting ascending motion strengthen (attenuate) the convergence near the TP surface and the divergence in the upper troposphere. The thermal adaption‐associated circulation generates more (less) TPVs and VAP. [ABSTRACT FROM AUTHOR]

Oceanic absorption of heat generated by greenhouse gas emissions has resulted in warming of the dark ocean (>200 m) that contains a large refractory DOM (RDOM) pool. However, changes in microbially mediated production and degradation dynamics for RDOM components in response to warming of dark marginal basins remain unclear. Herein, we integrated data from the dark South China, Mediterranean and Japan Seas (temperature range: 0.09–15.1°C) to demonstrate that in situ production efficiency of two ubiquitous humic‐like fluorophores increased at higher dark ocean temperature, whereas chromophores at a wavelength of 325 nm (aCDOM(325)) changed from production to degradation at higher temperature. Increased oxygen consumption and a reduction of labile substrates in future warmer dark ocean environments may initiate the final degradation of some semi‐refractory components, thereby increasing the recalcitrance of RDOM, but decreasing the DOM inventory in dark basins and creating a positive feedback to rising atmospheric CO2. Plain Language Summary: Marine refractory dissolved organic matter (RDOM) in the dark ocean is primarily formed during heterotrophic degradation of labile organic matter, which has a pronounced sensitivity to temperature variation. Since the 1960s, the global dark ocean has exhibited an accelerated warming with a discernable temperature increase. Thus, determining the importance of temperature on microbial regulation of the oceanic RDOM pool is of great significance. This study utilized the ocean interior of the marginal South China, Mediterranean and Japan Seas as natural basin‐scale enclosed incubators along with optical DOM characterization methods to reveal a production‐degradation reaction series for RDOM components. A decrease in the DOM inventory by enhanced microbial mineralization (producing CO2) in a warmer dark ocean may create a positive feedback in response to global climate change. Key Points: Faster turnover for optical components of dissolved organic matter (DOM) was observed in dark marginal basins than in the open oceanIn situ production efficiency of two ubiquitous humic‐like fluorophores increased at higher dark ocean temperaturesAn increase of DOM recalcitrance and decrease of the bulk dissolved organic carbon pool may occur due to a future warming of dark basins [ABSTRACT FROM AUTHOR]

Land surface processes are vital to the performance of regional climate models in dynamic downscaling application. In this study, we investigate the sensitivity of the simulation by using the weather research and forecasting (WRF) model at 10-km resolution to the land surface schemes over Central Asia. The WRF model was run for 19 summers from 2000 to 2018 configured with four different land surface schemes including CLM4, Noah-MP, Pleim-Xiu and SSiB, hereafter referred as Exp-CLM4, Exp-Noah-MP, Exp-PX and Exp-SSiB respectively. The initial and boundary conditions for the WRF model simulations were provided by the National Centers for Environmental Prediction Final (NCEP-FNL) Operational Global Analysis data. The ERA-Interim reanalysis (ERAI), the GHCN-CAMS and the CRU gridded data were used to comprehensively evaluate the WRF simulations. Compared with the reanalysis and observational data, the WRF model can reasonably reproduce the spatial patterns of summer mean 2-m temperature, precipitation, and large- scale atmospheric circulation. The simulations, however, are sensitive to the option of land surface scheme. The performance of Exp-CLM4 and Exp-SSiB are better than that of Exp-Noah-MP and Exp-PX assessed by Multivariable Integrated Evaluation (MVIE) method. To comprehensively understand the dynamic and physical mechanisms for the WRF model's sensitivity to land surface schemes, the differences in the surface energy balance between Ave-CLM4-SSiB (the ensemble average of Exp-CLM4 and Exp-SSiB) and Ave-NoanMP-PX (the ensemble average of Exp-Noah-MP and Exp-PX) are analyzed in detail. The results demonstrate that the sensible and latent heat fluxes are respectively lower by 30.42 W·m−2 and higher by 14.86 W·m−2 in Ave-CLM4-SSiB than that in Ave-NoahMP-PX. As a result, large differences in geopotential height occur over the simulation domain. The simulated wind fields are subsequently influenced by the geostrophic adjustment process, thus the simulations of 2-m temperature, surface skin temperature and precipitation are respectively lower by about 2.08 ℃, 2.23 ℃ and 18.56 mm·month−1 in Ave-CLM4-SSiB than that in Ave-NoahMP-PX over Central Asia continent. [ABSTRACT FROM AUTHOR]

Oceanic absorption of heat generated by greenhouse gas emissions has resulted in warming of the dark ocean (>200 m) that contains a large refractory DOM (RDOM) pool. However, changes in microbially mediated production and degradation dynamics for RDOM components in response to warming of dark marginal basins remain unclear. Herein, we integrated data from the dark South China, Mediterranean and Japan Seas (temperature range: 0.09–15.1°C) to demonstrate that in situ production efficiency of two ubiquitous humic‐like fluorophores increased at higher dark ocean temperature, whereas chromophores at a wavelength of 325 nm (aCDOM(325)) changed from production to degradation at higher temperature. Increased oxygen consumption and a reduction of labile substrates in future warmer dark ocean environments may initiate the final degradation of some semi‐refractory components, thereby increasing the recalcitrance of RDOM, but decreasing the DOM inventory in dark basins and creating a positive feedback to rising atmospheric CO2. Plain Language Summary: Marine refractory dissolved organic matter (RDOM) in the dark ocean is primarily formed during heterotrophic degradation of labile organic matter, which has a pronounced sensitivity to temperature variation. Since the 1960s, the global dark ocean has exhibited an accelerated warming with a discernable temperature increase. Thus, determining the importance of temperature on microbial regulation of the oceanic RDOM pool is of great significance. This study utilized the ocean interior of the marginal South China, Mediterranean and Japan Seas as natural basin‐scale enclosed incubators along with optical DOM characterization methods to reveal a production‐degradation reaction series for RDOM components. A decrease in the DOM inventory by enhanced microbial mineralization (producing CO2) in a warmer dark ocean may create a positive feedback in response to global climate change. Key Points: Faster turnover for optical components of dissolved organic matter (DOM) was observed in dark marginal basins than in the open oceanIn situ production efficiency of two ubiquitous humic‐like fluorophores increased at higher dark ocean temperaturesAn increase of DOM recalcitrance and decrease of the bulk dissolved organic carbon pool may occur due to a future warming of dark basins [ABSTRACT FROM AUTHOR]

This paper investigates physical layer security analysis of cooperative non-orthogonal multiple access (NOMA) communication system. A virtual full-duplex (VFD) relaying scheme with an untrusted amplify-and-forward (AF) half-duplex (HD) relay and a trusted decode-and-forward (DF) HD relay is used in this system to improve the spectral efficiency. In order to prevent the untrusted relay from eavesdropping, a simple and practical cooperative jamming scheme is designed to confuse the untrusted relay. The exact expressions of effective secrecy throughput (EST) for NOMA users and approximate expression of EST for non-NOMA user are derived. All theoretical results are validated by numerical simulations which demonstrate that the proposed VFD-NOMA scheme is superior to existing HD-NOMA scheme in cooperative system and jamming plays an important role for obtaining acceptable EST. In addition, simulation results shows that the best secrecy performance highly depends on the system parameters such as transmit powers and jamming signal power. [ABSTRACT FROM AUTHOR]

The Tibetan Plateau vortex (TPV) is a mesoscale weather system active in the near-surface layer, which is one of the major systems for the generation of precipitation in the Tibetan Plateau (TP). However, no long-term observations of the TPVs are available due to the scarcity of observations in the TP. Thereby, long-term, high-accuracy reanalysis products are a reliable source for the analysis of characteristic TPV activities and possible mechanisms behind. In the present study, an objective analysis method is implemented to obtain a complete dataset of TPV based on several reanalysis products, including the ERA-Interim, ERA40, JRA55, NCEP CFSR, and NASA MERRA2. The TPVs are detected and tracked by the minima in geopotential height at 500 hPa. Results indicate that the TPVs derived from multiple reanalysis products have quite similar spatial patterns and temporal variability. The characteristic parameters of the TPVs derived from a given reanalysis data are related to the resolution of this reanalysis product. Higher-resolution reanalysis products can yield more low-pressure systems, which explains why the TPVs derived from high-resolution reanalysis datasets generally have longer lifetime, stronger and larger vortex scale than those from low-resolution reanalysis products, although the total number of TPVs are similar. The annual average number of TPVs generated in the TP is 63.5, and these TPVs largely originate in the mountainous area of the central western TP around (34° N, 78–95° E) and a belt zone (30° N, 80–84° E) in the southern TP, where the elevation is around 5500 m. The TPVs often dissipate in low valleys and the lee side of mountains. They mainly occur in the warm season during May–September, most active in the summer and least active in the winter. More TPVs form in the daytime than in the nighttime. Those TPVs that move out of the TP account for less than 10–14% of all TPVs, and they usually follow three moving paths: eastward (6.9–7.8%), northeastward (2.3–3.4%) and southward (2.3–3.5%). [ABSTRACT FROM AUTHOR]

China is several decades into large-scale afforestation programs to help address significant ecological and environmental degradation, with further afforestation planned for the future. However, the biophysical impact of afforestation on local surface temperature remains poorly understood, particularly in midlatitude regions where the importance of the radiative effect driven by albedo and the nonradiative effect driven by energy partitioning is uncertain. To examine this issue, we investigated the local impact of afforestation by comparing adjacent forest and open land pixels using satellite observations between 2001 and 2012. We attributed local surface temperature change between adjacent forest and open land to radiative and nonradiative effects over China based on the Intrinsic Biophysical Mechanism (IBM) method. Our results reveal that forest causes warming of 0.23°C (±0.21°C) through the radiative effect and cooling of −0.74°C (±0.50°C) through the nonradiative effect on local surface temperature compared with open land. The nonradiative effect explains about 79% (±16%) of local surface temperature change between adjacent forest and open land. The contribution of the nonradiative effect varies with forest and open land types. The largest cooling is achieved by replacing grasslands or rain-fed croplands with evergreen tree types. Conversely, converting irrigated croplands to deciduous broadleaf forest leads to warming. This provides new guidance on afforestation strategies, including how these should be informed by local conditions to avoid amplifying climate-related warming. [ABSTRACT FROM AUTHOR]

[Display omitted] • The random deterministic three-dimensional fracture coupling model is constructed. • A new fracture search algorithm: full space parallel search algorithm is proposed. • Based on this, the accurate prediction of water inflow of the tunnel is realized. With the rapid development of national infrastructure construction, the water inrush disaster of "strong burst, high water pressure and large flow" is more and more frequent in the construction process. To achieve high-precision prediction of tunnel water inflow, based on the Yue Longmen Tunnel, according to the structural plane detection data in the study area, combined with the Monte Carlo algorithm and using "parent-daughter" and "step–structure" correction mode, this paper constructs a random deterministic three-dimensional fracture network seepage model. Based on the three-dimensional fracture network seepage model and the principle of flow balance, the water inflow of each mileage section of the Yue Longmen Tunnel is solved by numerical calculation method, and good results are obtained through comparison and verification. The research results have important theoretical significance and engineering application value for tunnel water inflow prediction. [ABSTRACT FROM AUTHOR]

The removal of rare earth elements in mineral processing wastewater is highly desirable but still challenging. In this study, three bimetallic Prussian blue analogues (PBA) and six corresponding oxides are prepared by co-precipitation and calcination methods, and then utilized to adsorb aqueous Yb(III) solution. The results of XRD, SEM, BET, and XPS indicate the successful synthesis of all the adsorbents. Among them, three PBA-oxide samples (PBO-800) exhibit the superior adsorption capacities (˃250 mg/g). The adsorption processes of Yb(III) are in accordance with the pseudo-second-order kinetic model and Langmuir model, simultaneously showing the spontaneous and endothermic thermodynamics. Moreover, PBO-800 can be reused after alkaline solution regeneration with less than 10% degradation after five consecutive adsorption-desorption cycles. More importantly, PBO-800 exhibits the impressive separation selectivity of Yb(III) and most light rare earth ions (e.g., 5.51 of Yb/La, 4.03 of Yb/Pr), as well as the selectivity of Yb(III) and alkali metal ions (e.g., 300.5 of Yb/Na, 256.2 of Yb/Ca). According to the characterization analysis and DFT calculation, the adsorption mechanism of Yb(III) by PBO-800 is mainly attributed to the strong interaction between the abundant active-oxygen sites and Yb(III), and the significant electrostatic attraction. [Display omitted] • PBA-derived adsorbents with abundant active-oxygen sites are designed and fabricated. • Comparative study of PBA and PBA-oxides for adsorption of REEs is reported. • Mechanism reveals adsorption of Yb via surface complexation and electrostatic attraction. • Different affinity of Yb, light REEs and alkali metals benefits the selective separation. • Regenerated adsorbent is successfully reused for 5 times with less than 10% degradation. [ABSTRACT FROM AUTHOR]

In this paper, a novel metasurface with shared perforating holes is proposed. The metasurface consists of two types of meta-surface units. The shared perforating holes of adjacent units are realized on the covering layer using the periodic property of the metasurface unit which contributes to widening the operating bandwidth of the unit. To satisfy the periodicity condition, 4 × 4 units are formed into a subarray. Then, for the first time, Genetic Simulated Annealing Algorithm (GSAA) and Convolutional Operation (CO) are used simultaneously to optimize the distribution of the subarray. The optimized meta-surface leads to a wider radar cross section (RCS) reduction bandwidth and more dispersed scattering patterns. The measured result shows a 10 dB RCS reduction observed for 126% of the relative bandwidth (8.2–36.4 GHz). The proposed strategy provides a new idea for the meta-surface to realize ultra-wideband RCS reduction. [ABSTRACT FROM AUTHOR]

Land surface processes play an important role in the East Asian Summer Monsoon (EASM) system. Parameterization schemes of land surface processes may cause uncertainties in regional climate model (RCM) studies for the EASM. In this paper, we investigate the sensitivity of a RCM to land surface parameterization (LSP) schemes for long-term simulation of the EASM. The Weather Research and Forecasting (WRF) Model coupled with four different LSP schemes (Noah-MP, CLM4, Pleim-Xiu and SSiB), hereafter referred to as Sim-Noah, Sim-CLM, Sim-PX and Sim-SSiB respectively, have been applied for 22-summer EASM simulations. The 22-summer averaged spatial distributions and strengths of downscaled large-scale circulation, 2-m temperature and precipitation are comprehensively compared with ERA-Interim reanalysis and dense station observations in China. Results show that the downscaling ability of RCM for the EASM is sensitive to LSP schemes. Furthermore, this study confirms that RCM does add more information to the EASM compared to reanalysis that imposes the lateral boundary conditions (LBC) because it provides 2-m temperature and precipitation that are with higher resolution and more realistic compared to LBC. For 2-m temperature and monsoon precipitation, Sim-PX and Sim-SSiB simulations are more consistent with observation than simulations of Sim-Noah and Sim-CLM. To further explore the physical and dynamic mechanisms behind the RCM sensitivity to LSP schemes, differences in the surface energy budget between simulations of Ens-Noah-CLM (ensemble mean averaging Sim-Noah and Sim-CLM) and Ens-PX-SSiB (ensemble mean averaging Sim-PX and Sim-SSiB) are investigated and their subsequent impacts on the atmospheric circulation are analyzed. It is found that the intensity of simulated sensible heat flux over Asian continent in Ens-Noah-CLM is stronger than that in Ens-PX-SSiB, which induces a higher tropospheric temperature in Ens-Noah-CLM than in Ens-PX-SSiB over land. The adaptive modulation of geopotential height gradients affects wind field (through geostrophic balance) simulation especially at lower levels, which subsequently affects the simulation of large-scale circulation, 2-m temperature and monsoon precipitation as well as RCM's downscaling ability. [ABSTRACT FROM AUTHOR]

Uncertainties in some key parameters in land surface models severely restrict the improvement of model capacity for successful simulation of surface-atmosphere interaction. These key parameters are related to soil moisture and heat transfer and physical processes in the vegetation canopy as well as other important aerodynamic processes. In the present study, measurements of surface-atmosphere interaction at two observation stations that are located in the typical semi-arid region of China, Tongyu Station in Jilin Province and Yuzhong Station in Gansu Province, are combined with the planetary boundary layer theory to estimate the value of two key aerodynamic parameters, i.e., surface roughness length z and excess resistance κB. Multiple parameterization schemes have been used in the study to obtain values for surface roughness length and excess resistance κB at the two stations. Results indicate that z has distinct seasonal and inter-annual variability. For the type of surface with low-height vegetation, there is a large difference between the default value of z in the land surface model and that obtained from this study. κB demonstrates a significant diurnal variation and seasonal variability. Using the modified scheme for the estimation of z and κB in the land surface model, it is found that simulations of sensible heat flux over the semi-arid region have been greatly improved. These results suggest that it is necessary to further evaluate the default values of various parameters used in land surface models based on field measurements. The approach to combine field measurements with atmospheric boundary layer theory to retrieve realistic values for key parameters in land surface models presents a great potential in the improvement of modeling studies of surface-atmosphere interaction. [ABSTRACT FROM AUTHOR]

The Loess Plateau of China has witnessed a remarkable greening trend due to vegetation restoration in recent decades. However, the precipitation response to greening remains unclear, and the hydrological effect of greening is controversial. Here, we revisited biophysical effects of greening on precipitation over the plateau during 2002–2015 using the state‐of‐the‐art water vapor tracer embedded in a regional coupled model. We find that greening can promote the growing season precipitation (0.45 mm·day−1), with 15% and 85% of the precipitation increment resulting from increases in the local evapotranspiration and the water vapor inflow from outside the plateau, respectively. As a consequence, the enhanced precipitation can compensate for the terrestrial water loss driven by the increased evapotranspiration, leading to a slight increase in the water yield. This study highlights the dominant role of the nonlocal effect in precipitation responses to greening in this region. Plain Language Summary: In recent decades, the Loess Plateau of China has shown a significant greening trend due to vegetation restoration. In the meantime, greening tends to accelerate the terrestrial water loss via the enhanced evapotranspiration, leading to a decline in the terrestrial water storage. However, such an impact remains controversial because of large uncertainties in precipitation responses to greening. It remains unclear whether the precipitation response can alleviate or aggravate the surface water deficit due to the enhanced evapotranspiration following greening. In this study, we examine impacts of greening on precipitation over the plateau during 2002–2015 using a water vapor tracer embedded in a regional coupled model. The results show that greening can enhance precipitation, which can compensate for evapotranspiration‐driven water loss and consequently increase the water yield in the growing season. 85% of the precipitation increment results from the enhanced water vapor inflow outside the plateau due to responses of large‐scale circulations to greening. The water vapor originating from the enhanced evapotranspiration within the plateau only accounts for 15% of the precipitation increment. This study provides new insight into precipitation responses to greening and the mechanism over the plateau using water vapor tracing. Key Points: Biophysical impacts of greening on precipitation over the Loess Plateau are investigated based on WRF‐WVTGreening can promote the growing season precipitation, which can compensate for the evapotranspiration‐driven terrestrial water lossThe enhanced precipitation mainly results from enhanced water vapor inflow outside the plateau due to responses of circulations to greening [ABSTRACT FROM AUTHOR]

The Tibetan Plateau is the world’s largest and highest plateau and holds the largest mass of ice on Earth outside the ice-sheets of Greenland and Antarctica, as well as abundant lakes. This study examined the molecular and isotopic signatures of dissolved organic matter (DOM) along with its biolability in glacier ice, glacier-fed streams, and alpine lakes on the Tibetan Plateau. The aim was to assess the sources of DOM and the potential of DOM to provide a carbon subsidy to downstream ecosystems. Tibetan glaciers and glacier streams exhibited low dissolved organic carbon (DOC) concentrations (17.7–27.9 μM) and ancient DOC radiocarbon ages (749–2350 ybp). The optical properties, stable carbon isotope ratios (δ 13 C-DOC) and the molecular composition (Fourier transform ion cyclotron resonance mass spectrometry) of Tibetan glacier DOM are consistent with data from other glacier systems around the world. The geochemical signatures and the ancient apparent ages of Tibetan glacier DOM suggest a significant fraction is derived from the atmospheric deposition of pre-aged, possibly fossil fuel derived organics. Within the Tibetan alpine lakes, DOC was also ancient (525–675 ybp), due to either inputs of pre-aged organics from glacier runoff, direct deposition, or due to the aging of organics in situ (i.e. a radiocarbon reservoir effect). The glacier ice and glacier stream sites exhibited high biolability of DOC and so provide a carbon subsidy to downstream environments that will change as glaciers on the Tibetan Plateau recede. [ABSTRACT FROM AUTHOR]

In this study, a novel broadband and low profile magnetoelectric dipole (MED) antenna with a low radar cross section (RCS) is proposed. The 10 dB RCS reduction is achieved by shifting the reflected energy to six directions, which is an efficient optimization method based on convolutional operations. Specifically, the polarization conversion metasurface (PCM) unit with high polarization conversion rate is constructed and employed in the MED antenna for RCS reduction. The proposed antenna is fabricated and measured. Measured results depict that the low RCS antenna offers good impedance matching in 12–15.6 GHz (relative bandwidth 26%). Compared with the reference antenna, the RCS of the proposed antenna is reduced by more than 10 dB from 9.9 to 16 GHz. It is proved that the proposed antenna has broadband and stable radiation performance and outstanding specular reflecting suppression capabilities. [ABSTRACT FROM AUTHOR]

Abstract: Chromophoric dissolved organic matter (CDOM) may show notable non-conservative behaviors in many estuaries due to a variety of biogeochemical processes. The partition between CDOM and chromophoric particulate organic matter (CPOM) was examined in the Jiulong Estuary (China) using absorption and fluorescence spectroscopy, which was also compared with microbial and photochemical degradations. The absorption coefficient of water-soluble CPOM (a CPOM(280)) at ambient Milli-Q water pH (6.1) ranged from 0.11 to 7.94 m−1 in the estuary and was equivalent to 5–101% of CDOM absorption coefficient. The a CPOM(280) correlated significantly with the concentration of suspended particulate matter and was highest in the bottom water of turbidity maximum zone. Absorption spectral slope (S 275–295) and slope ratio (S R ) correlated positively with salinity for both CPOM and CDOM, suggesting decreases in the average molecular weight with increasing salinity. The adsorption of CDOM to re-suspended sediments (at 500 mg L−1) within 2 h was equivalent to 4–26% of the initial a CDOM(280). The adsorption of CDOM to particles was less selective with respect to various CDOM constituents, while the microbial degradation resulted decreases in S 275–295 and S R of CDOM and preferential removal of protein-like components. The partition between CPOM and CDOM represented a rapid and important process for the non-conservative behavior of CDOM in turbid estuaries. [Copyright &y& Elsevier]

SUMMARY This paper advocates the capacity analysis of an amplify-and-forward cooperative communication system model in multi-relay multiuser networks. A two-step selection scheme is adopted, and both relay and user selection are based on the outdated channel state information. Exact expression of channel capacity for independent, but not necessarily identically distributed, Rayleigh fading channels is derived. Finally, simulations are carried out to verify the correctness of theoretical analysis and illustrate the effect of parameters on the performance. Results show that although the performance of our scheme is inferior to the optimal joint selection scheme, it is still a practical scheme because its complexity is much lower than that of the optimal scheme. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Abstract: Dissolved organic matter (DOM) has not been studied fully for tropical and subtropical rivers, in particular during storm events. DOM dynamics during a summer storm event in June, 2011 were examined in a subtropical river (the North Jiulong River, China). Stormwater runoff was sampled for measurement of dissolved organic C (DOC), absorption spectroscopy and fluorescence excitation emission matrix spectroscopy (EEMs). Three different fluorescent components were identified using parallel factor analysis (PARAFAC), including humic-like C1 and C3, and C2 as a combination of humic-like and protein-like fluorophores. The flux of DOC increased fivefold from 0.4kgs−1 at baseflow to 2.0kgs−1 at peak flow. Chromophoric DOM (CDOM) and fluorescent components also showed large increases with stormflow. The flux of DOC was similar during the rising and falling hydrographs at equal water discharge, while those of CDOM and fluorescent components were much higher during the falling-hydrograph. Carbon specific CDOM absorption coefficient at UV (SUVA254) and the fraction of C3 which fluoresced at long emission wavelength correlated positively to each other but negatively to absorption spectral slope ratio (S R) and C2%. They showed notable temporal variations indicative of increases in aromaticity, C3% and average molecular weight of DOM during the storm event. Changes in DOM composition lagged behind those in DOM flux. Changes in the flux and quality of DOM during the storm event, which were monitored effectively by absorption spectroscopy and EEMs–PARAFAC, could affect biogeochemical processes in the river and receiving coastal waters. [Copyright &y& Elsevier]

Human activity have caused significant increase in greenhouse gas (GHG) concentration and land use and land cover change (LULCC), which can in turn affect regional and global climate. We investigate the relative contributions of increased GHG concentration and LULCC to the precipitation and surface air temperature (SAT) in Asia through three dynamical downscaling simulations with different land cover maps and GHG concentrations. The results suggest that the increased GHG concentration leads to an increase (decrease) in precipitation over East Asia and Southeast Asia (South Asia) in spring and winter. Over Southeast Asia and the Bay of Bengal, LULCC induced a significant decrease in precipitation in autumn and winter, and the change is greater than that induced by GHG. Moreover, the enhanced GHG concentration generally leads to a decrease in dry days or light rain days and an increase in heavy rain days over the land area. However, LULCC‐induced changes in extreme precipitation are generally weak. The increased GHG concentration induces a significant increase of 1–3°C in the SAT throughout the year. LULCC plays a more important role than the increased GHG concentration in modulating the SAT over South Asia, Southeast Asia, and East Asia throughout the year. The increased GHG concentration and LULCC cause a broader range of changes in the daily temperature frequency. The anomalous warm event of 8–10°C increases by 1–1.5 days per season in the middle latitude regions in boreal spring due to the increased GHG concentration. LULCC also leads to an increase in high‐temperature events except central Asia. [ABSTRACT FROM AUTHOR]

Afforestation can impact surface temperature through local and nonlocal biophysical effects. However, the local and nonlocal effects of afforestation in China have rarely been explicitly investigated. In this study, we separate the local and nonlocal effects of idealized afforestation in China based on a checkerboard method and the regional Weather Research and Forecasting (WRF) Model. Two checkerboard pattern–like afforestation simulations (AFF1/4 and AFF3/4) with regularly spaced afforested and unaltered grid cells are performed; afforestation is implemented in one out of every four grid cells in AFF1/4 and in three out of every four grid cells in AFF3/4. The mechanisms for the local and nonlocal effects are examined through the decomposition of the surface energy balance. The results show that the local effects dominate surface temperature responses to afforestation in China, with a cooling effect of approximately −1.00°C for AFF1/4 and AFF3/4. In contrast, the nonlocal effects warm the land surface by 0.14°C for AFF1/4 and 0.41°C for AFF3/4. The local cooling effects mainly result from 1) enhanced sensible and latent heat fluxes and 2) decreases in downward shortwave radiation due to increased low cloud cover fractions. The nonlocal warming effects mainly result from atmospheric feedbacks, including 1) increases in downward shortwave radiation due to decreased low cloud cover fractions and 2) increases in downward longwave radiation due to increased middle and high cloud cover fractions. This study highlights that, despite the unexpected nonlocal warming effect, afforestation in China still has great potential in mitigating climate warming through biophysical processes. [ABSTRACT FROM AUTHOR]

In this study, a new parameter optimization method was used to investigate the expansion of conditional nonlinear optimal perturbation (CNOP) in a land surface model (LSM) using long-term enhanced field observations at Tongyu station in Jilin Province, China, combined with a sophisticated LSM (common land model, CoLM). Tongyu station is a reference site of the international Coordinated Energy and Water Cycle Observations Project (CEOP) that has studied semiarid regions that have undergone desertification, salination, and degradation since late 1960s. In this study, three key land-surface parameters, namely, soil color, proportion of sand or clay in soil, and leaf-area index were chosen as parameters to be optimized. Our study comprised three experiments: First, a single-parameter optimization was performed, while the second and third experiments performed triple- and six-parameter optimizations, respectively. Notable improvements in simulating sensible heat flux (SH), latent heat flux (LH), soil temperature (TS), and moisture (MS) at shallow layers were achieved using the optimized parameters. The multiple-parameter optimization experiments performed better than the single-parameter experminent. All results demonstrate that the CNOP method can be used to optimize expanded parameters in an LSM. Moreover, clear mathematical meaning, simple design structure, and rapid computability give this method great potential for further application to parameter optimization in LSMs. [ABSTRACT FROM AUTHOR]

Abstract: The spatial and temporal dynamics of chromophoric dissolved organic matter (CDOM) were studied using excitation emission matrix fluorescence spectroscopy (EEMs) and parallel factor analysis (PARAFAC) during five cruises in the subtropical Jiulong Estuary from August 2008 to June 2009. Two humic-like (C1 and C3), one tryptophan-like (C4) and one possible protein-like (C2) component was identified by PARAFAC and their behavior in the river–estuary–coastal interface was evaluated. The spatial distributions of the maximum fluorescence (F max) for the fluorescent components showed a remarkable loss in the upper estuary. The following significant addition of all components in the low salinity turbidity maximum zone suggested the inputs from riverine source, sediment resuspension and the surrounding mangrove ecosystem. C1, C2 and C3 showed conservative behavior in the middle and lower estuary indicated by the linear relationship between their fluorescence intensities and salinity in the five cruises. However, the tryptophan-like C4 received widespread additions (likely from autochthonous production) in the estuary. Although the humic-like C1 and C3 showed no significant variation in the estuary–coastal interface, C2 and C4 decreased more rapidly beyond this interface, indicating the significant influence of coastal current to this estuarine environment. The seasonal variation of tryptophan-like C4 was characterized by higher F max values in the upper to middle estuary in the dry season, which is in contrast to that of the humic-like C3. Correlation analysis with DOC showed that the fluorescence intensity of C1 (or C2 and C3) was suitable for tracing DOC dynamics in this estuary. These results indicated different mixing behavior and temporal variability for different fluorescent components in this dynamic estuarine environment. [Copyright &y& Elsevier]

The bulk surface properties, including canopy height (h), zero-plane displacement height (d), roughness length (z 0), and aerodynamic resistance (r b and r d), are crucial biophysical parameters that influence momentum, energy and mass exchanges at the land-atmosphere interface. The variabilities of these parameters are important for understanding possible impacts of the ecosystem on climate change, yet they have not been systematically evaluated due to the lack of large-scale, long-term observations. Here we provide global estimates of these bulk aerodynamic parameters, including d , z 0 , r b , and r d , for the period 1982–2017 based on remote-sensed leaf area index (LAI), h , and plant functional type dependent canopy morphological characteristics. The global h estimate is acquired from LAI using a semi-empirical relation in which the coefficients have been optimized based on the canopy height product from the Geoscience Laser Altimeter System (GLAS) onboard the Ice, Cloud, and land Elevation Satellite (ICESat). Two LAI products, Global Land Surface Satellite (GLASS) and Global Inventory Modeling and Mapping Studies (GIMMS), are used to calculate canopy height and parameters separately. The products derived from the above two LAI datasets agree very well (spatial correlation coefficient, SCC = 0.99, relative root-mean-square-error, rRMSE = 8.28% for h , SCC = 0.99, rRMSE = 12.15% for d , and SCC = 0.98, rRMSE = 13.78% for z 0). Verification of the products against in-situ canopy height records from the FLUXNET and eddy-covariance (EC)-based d and z 0 estimates shows that the estimates can reproduce the annual means and seasonal variations of the bulk surface properties. We found significant positive trends in global h (0.04–0.05% year−1), d (0.07% year−1) and z 0 (0.07% year−1) associated with the Earth greening, but they are different from the trend in LAI (0.14–0.25% year−1). The differences between the trends in LAI and the trends in derived parameters are also found in different latitudes. For instance, in the Northern Hemisphere Polar region, the GLASS LAI increases by 0.48% year−1, leading to positive trends of 0.03% year−1 in h , 0.18% in d , and 0.20% year−1 in z 0. The above results highlight the importance of comprehensively considering changes in LAI, canopy height, and aerodynamic parameters when evaluating the effects of ecosystem change on climate. This long-term dataset can be used in climate models to assess the response of bulk aerodynamic parameters to climate changes and the impact of vegetation dynamics on regional and global climate. • Long-term global estimates of canopy height and roughness parameters for 1982–2017. • Evaluate the global bulk aerodynamic parameters products with in-situ observations. • Long-term trends of the aerodynamic parameters in response to Earth's greening. [ABSTRACT FROM AUTHOR]

Abstract: The spectral absorption properties of chromophoric dissolved organic matter (CDOM) and their distributions in two Chinese estuaries, the Yangtze River Estuary and the Jiulong River Estuary, were studied during August 2003 (wet season) and during different seasons between 2003−2005, respectively. The CDOM concentrations (a 355) of fresh end members in the Jiulong River Estuary varied seasonally, while its quality remained relatively stable. However, the a 355 of the marine end members exhibited less variability. Application of a conservative mixing model indicated that CDOM behaved conservatively in the Yangtze River Estuary. No photobleaching removal was observed at high salinity region of this estuary. Although CDOM showed conservative behavior for many cruises in the Jiulong River Estuary, there was evidence for removal in the low salinity regions during some cruises. Laboratory mixing experiments and a salt addition experiment suggested that particle sorption of CDOM maybe the possible reason for the removal. These results showed that absorption properties of CDOM can be used as a tool to observe the quantitative and qualitative dynamics of DOM during estuarine mixing. [Copyright &y& Elsevier]

Abstract: The onset of Rayleigh–Marangoni convection in a vertical annulus heated from below is investigated using linear stability analysis. The results of the present study also show the pattern transitions as a function of scaled gap width and aspect ratio. It is concluded that Marangoni convection can change the fluid pattern in an otherwise pure Rayleigh problem. It is also concluded that the gap width cannot significantly change the Marangoni effect as it is essentially the depth of liquid and Biot number that play a dominant role. [Copyright &y& Elsevier]

This paper investigates the effect of anisotropic interfacial energy on nanoscale pattern formation during the electropolishing of aluminum. We have derived the anisotropic evolution equation of the aluminum interface by including the effects of interfacial energy with cubic anisotropy. The special cases of [1 1 1], [1 1 0], and [1 0 0] directions are considered. A linear stability analysis was used to predict the growth rate at the maximum wave number, and a weakly nonlinear analysis was used to predict the type and stability of the patterns (i.e. hexagons or stripes). We find that increasing the interfacial energy can extend the stability range of hexagons. When the interfacial energy is high enough, only stable hexagons exist for the [1 1 1] and [1 0 0] directions. Previous studies have shown that electropolished [1 1 1] aluminum exhibits stable hexagons and stripes, depending on the alignment of the hexagonal array with respect to the crystal axes while [1 1 0] produces only striped patterns. For the [1 0 0] direction, anisotropy has no effect and an isotropic solution result. Our theoretical predictions agree qualitatively with the existing experiments. [Copyright &y& Elsevier]

Recent studies suggest that hypolimnetic respiration may be responsible for greenhouse gas (GHG) emissions from deep reservoirs. Currently, quantitative evaluation of aerobic vs. anaerobic processes and priming (enhanced processing of organic matter due to the addition of labile carbon) in regulating GHG production and emissions across the reservoir‐downstream continuum remains largely unknown. High‐resolution, annual time‐series observations in a large, subtropical reservoir (Shuikou) experiencing seasonal hypoxia in southeast China indicate that aerobic hypolimnetic CO2 production dominated in most periods of the stratified spring/summer with higher rates at higher temperatures. In addition, anaerobic production of hypolimnetic CO2 occurred in the late stratified spring/summer period, which stimulated hypolimnetic production of CH4 and N2O. Incubation experiments showed that priming in spring enhanced both aerobic and anaerobic production of excess GHGs. A late spring flood event generated the highest daily efflux of CO2 through the flushing of GHG‐enriched hypolimnion waters. Turbine degassing contributed 59%, 93%, and 63% of annual CO2, CH4, and N2O effluxes, respectively. Moreover, annual downstream GHG emissions were similar to those in the transition/lacustrine zone of the Shuikou reservoir. Diurnal variation observations revealed net CO2 emissions even during algal bloom seasons. The reservoir‐downstream river continuum was a year‐round source of GHGs (218.5 ± 18.9 Gg CO2‐equivalent yr−1; CO2 contributed 91%). However, the loss of oxygen also leads to increased production and storage of recalcitrant dissolved organic carbon (RDOC). Thus, identifying mechanisms controlling both GHG emissions and RDOC production is crucial to constrain the carbon neutrality issue of hydroelectric reservoirs in the context of climate change mitigation strategies. [ABSTRACT FROM AUTHOR]

Results from eight regional climate models (RCMs) participating in the Impact of Initialized Land Temperature and Snowpack on Sub-seasonal to Seasonal Prediction (LS4P) initiative of the Global Energy and Water Exchanges (GEWEX) are examined and compared with observations over the Tibetan Plateau (TP). The RCM common domain covers most areas of East Asia with a horizontal resolution of 20–30 km. The model simulation covers a period from April to September in each year between 1991 and 2015. This study explores the RCMs' ability for seasonal climate simulation over the TP, focusing on the summer monsoon climate as part of the LS4P initiative. An intercomparison is made among eight RCMs for precipitation, surface air temperature, mid-troposphere atmospheric circulation, moisture conditions, and surface energy fluxes. It shows that the downscaling characteristics differ significantly between two major RCM types. The RegCM4 models show positive precipitation biases over the entire TP, especially over the south and southeast TP, while the WRF models mostly show both positive and negative precipitation biases over the TP with relatively high spatial correlation between simulated and observed precipitation. The multi-model ensemble mean produces overall smaller precipitation biases than most individual RCMs, with the largest biases over the southeastern TP, and smaller surface air temperature biases over most areas of the TP, especially over the central and southwestern TP. Moreover, the ensemble mean can better reproduce the inter-annual variation of precipitation and surface air temperature than most RCMs with proper magnitude. Sensitivity analyses using RegCM4 with different physics parameterizations show that varying land and cumulus schemes may induce large precipitation differences over the TP by affecting moisture and atmospheric circulation conditions in the lower and upper troposphere, respectively. Moreover, turbulent heat and radiation fluxes differences are associated with the temperature differences between different RegCM4 models. [ABSTRACT FROM AUTHOR]

Recent observational and modeling studies have demonstrated the substantial influence of the Tibetan Plateau (TP) spring land surface temperature (LST) and subsurface temperature (SUBT) on downstream summer droughts/floods events in East Asia, highlighting the potential application of LST/SUBT on sub-seasonal to seasonal prediction (S2S). In this study, we employ the National Centers for Environment Prediction—Global Forecast System/Simplified Simple Biosphere model version 2 (GFS/SSiB2) to investigate the potential role of the late spring warm LST anomaly over the TP on the extraordinary June 1998 flood in the south of the Yangtze River region. Numerical experiments indicate that the warmer (above normal) May LST over the TP may contribute to the extreme flood of 1998 over the south of the Yangtze River region, with the LST reproducing about 57% and 64% of observed above-normal rainfall anomaly over the south of the Yangtze River region and southeastern China, respectively. Further analyses reveal a possible effect of springtime TP's LST on summer southern and eastern Asian rainfall and identify some hot spots, suggesting that the TP's spring LST effect is not only limited to the Yangtze River region, but to a much larger scale. The imposed warm LST/SUBT over the TP triggers a strong wave activities propagating eastward along the upper-level westerly jet, associated with an increase of the atmospheric baroclinic instability as well as a strengthening and southeastward movement of the South Asian high, leading to intensified moisture convergence and convective instability favorable to the excessive rainfall in the downstream region of East Asia. The results of the 1998 case have also been compared with the results from year of 2003, which had a very cold spring LST anomaly over the TP and a severe downstream June 2003 drought (flood) in southern (northern) of the Yangtze River Basin area. Simulation results provide further evidence of the great importance of the TP spring land surface temperature anomaly in regulating summer extreme hydroclimatic events (e.g. droughts and floods) in South and East Asia. The present study suggests that consideration of LST/SUBT anomalies has a strong potential for more skillful S2S prediction of extreme hydroclimatic events such as floods, droughts and heatwaves over both Southern and Eastern Asia. [ABSTRACT FROM AUTHOR]

Deforestation can impact precipitation through biophysical processes and such effects are commonly examined by models. However, previous studies mostly conduct deforestation experiments with a single model and the simulated precipitation responses to deforestation diverge across studies. In this study, 11 Earth system models are used to robustly examine the biophysical impacts of deforestation on precipitation, precipitation extremes, and the seasonal pattern of the rainy season through a comparison of a control simulation and an idealized global deforestation simulation with clearings of 20 million km2 of forests. The multimodel mean suggests decreased precipitation, reduced frequency and intensity of heavy precipitation, and shortened duration of rainy seasons over deforested areas. The deforestation effects can even propagate to some regions that are remote from deforested areas (e.g., the tropical and subtropical oceans and the Arctic Ocean). Nevertheless, the 11 models do not fully agree on the precipitation changes almost everywhere. In general, the models exhibit higher consistency over the deforested areas and a few regions outside the deforested areas (e.g., the subtropical oceans) but lower consistency over other regions. Such intermodel spread mostly results from divergent responses of evapotranspiration and atmospheric moisture convergence to deforestation across the models. One of the models that has multiple simulation members also reveals considerable spread of the precipitation responses to deforestation across the members due to internal model variability. This study highlights the necessity of robustly examining precipitation responses to deforestation based on multiple models and each model with multiple simulation members. [ABSTRACT FROM AUTHOR]

• A novel framework is proposed for coal geographical origin identification via NIRS. • PCA combined with an improved LDA technique is proposed for feature extraction. • Different types of classifiers are employed to identify the coal geographical origin. Coal geographical origin information provides powerful proof for evaluating coal quality and boosting the inspections of import and export coal. Since traditional identification methods depend on a series of instruments which induce considerable time and economic cost, it is crucial to employ an efficient and effective method to discriminate coal origin. As a rapid, non-destructive, and reagent-free analytical method, near-infrared spectroscopy (NIRS) enables rapid qualitative and quantitative characterization of a wide variety of materials, such as food and fuel. In this work, different multivariate data analysis approaches based on NIRS data are investigated to identify the geographical origin of coal. Considering that raw spectra are in high-dimensional spaces, principle component analysis (PCA), isometric mapping (Isomap) and linear discriminant analysis (LDA) are introduced to extract features. However, given the classes with similar centers, it is difficult to separate them via the standard LDA because it overvalues the contributions of the edge classes to the between-class scatter matrix. To address this concern, we propose an improved LDA (iLDA) in consideration of the contribution of each class, and enhance the impact of the classes with similar centers. In addition, we combine PCA and iLDA to solve the small sample size problem. The experimental results show that nonlinear approaches outperform linear approaches generally, and kernel partial least squares discriminant analysis combined with PCA-iLDA provides the best performance with the accuracy of 97.21%. The obtained results indicate that NIRS in tandem with different machine learning algorithms are promising for the rapid and accurate identification of coal geographical origin. [ABSTRACT FROM AUTHOR]

The Tibetan Plateau vortex (TPV) is a major rain-producing system over the Tibetan Plateau (TP) in summer. The vertical structure of TPV is critical in understanding the generation and development of TPV. In this paper, the ERA-Interim reanalysis data and an objective TPV detection and vertical tracing method are used to investigate the vertical structure of TPV in boreal summer (June–August). Most TPVs are shallow, with only 1/5 of them can reach 400 hPa. Among the TPVs that move off the TP, more than half are deep vortices. The tilting direction of TPV is related to its baroclinic structure. In general, TPVs tilt to the direction of the cold air from low to high isobaric levels, and the tilting direction depends on the relative positions of the warm pool and the cold air intruding into TPV. Deep TPVs inside the TP and those moving off the TP have different vertical structures. On the plateau, TPVs have convergence at the low levels (400–500 hPa) and divergence at the high levels (above 400 hPa), which can cause updrafts in the vortex and a tropical cyclone-like structure. For the TPVs moving off the TP, the updrafts are significantly weak due to the relatively low low-level convergence and the relatively low high-level divergence. These TPVs almost have positive vertical vorticity and present an extratropical cyclone-like structure. The vertical thickness of TPV is important in determining whether the TPV could move off the TP. The results show that the deep TPVs are more likely to move out than the shallow ones. Therefore, the vertical structure is a better predictor on the movement of TPV than its other properties. [ABSTRACT FROM AUTHOR]

Tibetan Plateau snow cover (TPSC) has subseasonal variations and rapidly influences the atmosphere. In this study, we present the rapid response of the East Asian trough (EAT) within a week to subseasonal variations in TPSC during the boreal winter. Using snow cover analysis obtained from the daily interactive multisensor snow and ice mapping system and the ERA‐Interim reanalysis, a considerable relationship between TPSC and 500‐hPa geopotential height anomalies over the downstream EAT region is found. Significant negative (positive) 500‐hPa geopotential height anomalies originating from the Tibetan Plateau and moving into the EAT region appear within a week following anomalous positive (negative) TPSC events, which lead to changes in EAT strength. Thus, a significantly enhanced (reduced) intensity of the EAT occurs approximately 5–6 days after increased (decreased) TPSC. Numerical experiments confirm the causality of this relationship. Further analysis of the quasi‐geostrophic geopotential height tendency equations in numerical experiments indicates that such EAT variations result from anomalous thermal advection from the Tibetan Plateau forced by TPSC. [ABSTRACT FROM AUTHOR]

Using the daily snow cover data at 24‐km resolution from the Interactive Multi‐sensor Snow and Ice Mapping System snow cover analysis, this study describes the variability in Tibetan Plateau (TP) snow cover (TPSC) at multiple time scales with a focus on the intraseasonal time scale (10–90 days). TPSC demonstrates variability over a wide range of temporal scales, but the annual cycle is generally dominant. Synoptic‐scale variability, seasonal variability and interannual and long‐term changes make small contributions to the total daily variability in TPSC. Intraseasonal variability (ISV) is dominant over most of the central and eastern TP and explains 22–40% of the total variability and leads to obvious variations in TPSC over periods shorter than a season. The ISV of TPSC is more active in the cold season than in the warm season. Specifically, the ISV over the Changtang Plateau explains approximately 50% of the total variability of snow cover in the cold season and is even more dominant than the annual cycle. Possible influences of regional atmospheric circulations on TPSC are also examined. TPSC variability is highly correlated with regional surface air temperature (SAT) and precipitation at an intraseasonal time scale. TPSC and SAT tend to have a simultaneous relationship, while anomalous precipitation leads to subsequent TPSC variations with a lag of approximately 5 days and a positive relationship. Such relationships are the result of intraseasonal variations in regional atmospheric circulation. The anomalous adiabatic heating induced by vertical ascending motion leads to tropospheric temperature variations. Furthermore, the horizontal advection of moisture and apparent moisture sink, which are induced by anomalous moisture supply and snow evaporation anomalies, respectively, lead to anomalous moisture associated with changes in the TPSC. [ABSTRACT FROM AUTHOR]

Precipitation is one of the major challenges in climate modeling. Among various factors, the large-scale atmospheric circulation plays an important role in modulating regional precipitation through dynamic processes that has been widely discussed in previous studies. However, few efforts have been made to investigate the relationship of model abilities to simulate precipitation and vector winds. Such an investigation may help to understand the source of uncertainty of precipitation simulation. Here, we examined the relationship between model performances in simulating precipitation with that in simulating vector winds by using the Coupled Model Intercomparison Project Phase 5 (CMIP5) models. Our results suggest that the model biases/uncertainties in simulating climatological mean precipitation often accompanied by the biases/uncertainties in vector wind fields. Model ability to simulate precipitation is closely related to the ability to simulate vector winds, especially over monsoon regions and the regions with warm and moist advection or high terrains, such as the South Asian and East Asian summer monsoon region, the Alaskan region, the Rocky Mountain, etc. Over these regions, the models with higher horizontal resolution tends to generate improved simulations in both the vector winds and precipitation relative to the models with coarse horizontal resolution. Besides, the model's ability to simulate vector winds, compared to simulate the zonal wind, meridional wind, and skin temperature, is more closely related to the ability to simulate precipitation. This indicates that it is more meaningful to evaluate the vector winds than the zonal or meridional wind from the perspective of improving regional precipitation simulation. [ABSTRACT FROM AUTHOR]

Satellite solar‐induced chlorophyll fluorescence (SIF) products from the Global Ozone Monitoring Experiment 2 (GOME‐2) and Orbiting Carbon Observatory 2 (OCO‐2) are used to investigate the responses of vegetation growth to the 2019 heat wave in Australia. Both satellite SIF data sets are more sensitive to water and heat stress than is the greenness‐based vegetation index (enhanced vegetation index). Moreover, the OCO‐2 SIF observations show a more significant reduction and earlier response to the heat stress than does GOME‐2 SIF, indicating that the two satellite SIF data sets differ in how they monitor the drought and heat wave event due to the different timing of observations. Eddy covariance measurements confirm the different responses of dryland vegetation to the 2019 heat wave at a subdaily time scale. The differences in the timing of the satellite SIF products can be used to assess different elements of the impact of heat and water stress on Australian dryland ecosystems. Plain Language Summary: An extreme heat wave occurred across Australia during the summer of 2019, and the high air temperatures and low precipitation affected the vegetation. We used two satellite solar‐induced chlorophyll fluorescence (SIF) data sets to investigate the response of vegetation growth to the extremely high temperatures in Australia. Vegetation growth was reduced during the 2019 summer, but SIF measurements allowed us to separate the impact of the heat wave on the vegetation in the morning and in the afternoon. Our work illustrates how the timing of satellite observations provides different information on how dryland vegetation responds to heat waves in Australia. Key Points: The impact of the 2019 heat wave on Australian dryland ecosystems is examinedSolar‐induced fluorescence (SIF) shows stronger reductions to heat and water stress than does vegetation indexSIF observed at noon responds to the heat stress earlier than does that measured in the morning in Australia [ABSTRACT FROM AUTHOR]

Satellite solar‐induced chlorophyll fluorescence (SIF) products from the Global Ozone Monitoring Experiment 2 (GOME‐2) and Orbiting Carbon Observatory 2 (OCO‐2) are used to investigate the responses of vegetation growth to the 2019 heat wave in Australia. Both satellite SIF data sets are more sensitive to water and heat stress than is the greenness‐based vegetation index (enhanced vegetation index). Moreover, the OCO‐2 SIF observations show a more significant reduction and earlier response to the heat stress than does GOME‐2 SIF, indicating that the two satellite SIF data sets differ in how they monitor the drought and heat wave event due to the different timing of observations. Eddy covariance measurements confirm the different responses of dryland vegetation to the 2019 heat wave at a subdaily time scale. The differences in the timing of the satellite SIF products can be used to assess different elements of the impact of heat and water stress on Australian dryland ecosystems. Plain Language Summary: An extreme heat wave occurred across Australia during the summer of 2019, and the high air temperatures and low precipitation affected the vegetation. We used two satellite solar‐induced chlorophyll fluorescence (SIF) data sets to investigate the response of vegetation growth to the extremely high temperatures in Australia. Vegetation growth was reduced during the 2019 summer, but SIF measurements allowed us to separate the impact of the heat wave on the vegetation in the morning and in the afternoon. Our work illustrates how the timing of satellite observations provides different information on how dryland vegetation responds to heat waves in Australia. Key Points: The impact of the 2019 heat wave on Australian dryland ecosystems is examinedSolar‐induced fluorescence (SIF) shows stronger reductions to heat and water stress than does vegetation indexSIF observed at noon responds to the heat stress earlier than does that measured in the morning in Australia [ABSTRACT FROM AUTHOR]

Vector wind plays a crucial role in shaping regional climate through transferring energy and moisture. In this study, we evaluate 37 Coupled Model Intercomparison Project Phase 5 (CMIP5) models and multi-model ensembles (MME) in terms of the climatological mean state, annual cycle, and interannual variability of vector winds in the Asian-Australian monsoon (A-AM) region. Unlike most previous studies those assessed meridional and zonal wind separately, we treat vector wind as a whole by employing a recently developed vector field evaluation method. The results are summarized as follows: (1) MME exhibits the best performance in reproducing the climatological mean of vector winds, followed by CESM1-CAM5 and three MPI-ESM models. However, models still show significant biases characterized by overestimated lower level vector winds and its spatial variation. The biases are mainly rooted in the anomaly components of vector winds and are observed in the regions with complex topography. (2) CMIP5 models can well simulate the annual cycle of upper-tropospheric vector winds, especially in the extratropical regions, but show large biases and dispersion over complex terrains in the lower troposphere. (3) MME still outperforms individual model for the simulation of interannual variance of vector winds, although most CMIP5 models overestimate the strength of vector wind variability in the lower troposphere. (4) Model skills in simulating climatological means, annual cycle, and interannual variability are positively correlated with each other to a certain degree over the A-AM region, suggesting an improvement in climatological mean may lead to a better simulation in the annual cycle or interannual variability of vector winds. [ABSTRACT FROM AUTHOR]

Blueberry (Vaccinium spp.) rhizosphere microorganisms can significantly increase the absorption area and improve the efficiency of rhizospheric nutrient uptake. However, there has been little research on blueberry rhizosphere microorganisms, especially those that can complement root function deficiency. In this study, we analyzed the rhizosphere fungi of 'O'Neal,' 'Sharpblue,' and 'Premier' blueberry cultivars and found that 'Premier' blueberries showed strong growth potential and relatively high root regulation ability. The dominant symbiotic fungus Sistotrema was correlated with the strong growth of 'Premier' and was directionally screened and isolated based on conserved gene structures and COG function analysis. This fungus was reinoculated onto the roots of 'Gulfcoast' and 'Star' blueberry cultivars. Sistotrema promoted the growth of blueberries and improved their ability to resist stress and grow under adverse conditions, as indicated by maintained or increased chlorophyll content under such conditions. Further analyses showed that Sistotrema has certain functional characteristics such as the ability to dissolve iron in its insoluble form and then release it, to fix nitrogen, and to inhibit nitrification in soil. Thus, it effectively doubled the soil nitrogen content and increased the soluble iron content in soil by 50%. This investigation indicates sistotrema inoculation as an approach to increase blueberry stress tolerance and complete their root nutrition deficiency. [ABSTRACT FROM AUTHOR]

A scaled boundary finite element method is developed for the analysis of hydrodynamic pressures acting on arch dam faces with a reservoir of irregular geometry. Water compressibility and reservoir boundary absorption are considered simultaneously. The reservoir is idealized as composed of finite and infinite subdomains. Governing equations for evaluating hydrodynamic pressures of finite fluid domain have been established and the solution procedures are presented. In addition, the boundary conditions at the interface between finite and infinite subdomains are decided. Numerical examples validate the present method with high accuracy and show that the fairly irregular geometry of a reservoir has an important influence on the hydrodynamic pressures acting on the arch dam face. Frequency response functions of the hydrodynamic pressures in the stream and cross-stream directions are evidently influenced by reservoir geometry, while hydrodynamic pressures in the vertical direction are relatively less influenced. Another feature of the frequency response function of hydrodynamic pressures is that the amplitude of resonant peaks is affected much more by reservoir geometry as compared to the resonant frequency. Besides, peak value of hydrodynamic pressures in the arch direction and cantilever direction is also significantly influenced by reservoir geometry. Based on these facts, it can be concluded that the effect of reservoir geometry on hydrodynamic pressure should be considered for seismic design of arch dams. [ABSTRACT FROM AUTHOR]

HBV-integrated local genomic alterations reveal multicentric independent occurrences of multifocal HCC As such, the HBV-integrated local haplotype would be specific to each tumour clone and could discriminate between the IM and MO.[2] IM implies that all tumour cells develop from the first cancer cell, thus having at least one shared HBV integration event. Dear Editor, We sampled two different HCC tumours from a patient with HBV infection and found different HBV integration events, suggesting multicentric occurrence (MO) rather than intrahepatic metastasis (IM). So we sequenced one more tumour sample (T2) from another lesion of this patient and finally obtained short and long-read sequencing data from T1 and T2. [Extracted from the article]

Precise, rapid, and reliable prediction of rock strength parameters is of great significance for underground engineering. This paper presents a method for predicting rock strength parameters including the Poisson's ratio (P), elastic modulus (E), and uniaxial compressive strength (UCS) based on computer drilling jumbo measurement while drilling (MWD) data. First, the distribution characteristics and correlation of MWD data are studied; second, a filtering method of MWD data is proposed, which reduces the influence of operational and mechanical factors; finally, an intelligent prediction model of rock mechanics parameters was established, 30 groups of test data were used for application, and the mean absolute percentage error (MAPE) of prediction results for P, E and UCS are 2.11%, 3.11%, and 2.9%, the determination coefficients (R2) are 0.4346, 0.8241, and 0.6616. Compared with the data before optimization, the accuracy of prediction results is improved significantly, it shows that the deep neural network model can accurately predict rock mass parameters. [ABSTRACT FROM AUTHOR]

Two novel N -rich triazine-based COFs with the well-designed abundant active-nitrogen sites and ultralight weight nature, manipulating the as-prepared materials as the excellent adsorbent for La(III) with high capacity and selectivity via the complexation interaction mechanism. [Display omitted] • Two less-precious nitrogen-rich COFs are designed and fabricated via a facile method. • Isotherm and kinetic study of two COFs for adsorption of La(III) is comparatively reported. • Mechanism reveals adsorption of La(III) occurs via complexation interaction. • Higher affinity to light REEs endows COFs with giant potential in further REE separation. • Regenerated adsorbent is repeatedly used for 5 times with less than 4.5% degradation. The development of stable and inexpensive adsorbents for La(III) recovery from wastewater is of great importance for rare earth industries. In this work, two novel N -rich covalent organic frameworks (COFs) synthesized via a one-step solvothermal method were termed as COF-PA-CC and COF-ML-CC, and employed as the adsorbents for removal of rare earth (RE) ions from aqueous solution. The structures and properties of COFs were characterized with X-ray diffractometer, total reflection infrared spectrometer, field-emission scanning electron microscopy, X-ray photoelectron spectroscopy, nitrogen adsorption–desorption instrument and thermogravimetric analyzer. The results revealed that COF-PA-CC composed of nanowires with the average length of 500 nm, whereas COF-ML-CC displayed the spherical morphology with the diameter of 100 ∼ 300 nm. Specific surface areas of COF-PA-CC and COF-ML-CC were calculated to be 82.13 and 191.08 m2/g, respectively. The adsorption process of La(III) was well-fitted with pseudo-second-order kinetic model and Langmuir isotherm model, exhibiting the high adsorption capacities of 150.88 and 168.19 mg/g for COF-PA-CC and COF-ML-CC after 120 min. Moreover, the influences of pH, temperature, different RE ions on adsorption performances were comprehensively tested, yielding an optimal adsorption condition (pH = 5.5, 65 °C and 120 min) and a better affinity for some light RE ions. Importantly, the fabricated COFs possess the excellent reusability after five adsorption-regeneration cycles, remaining 97.84 % and 95.51 % of initial capacities for COF-PA-CC and COF-ML-CC, respectively. The adsorption mechanism revealed that the complexation interaction between La(III) and the unoccupied N sites of N -rich COFs was recommended to interpret the remarkable adsorption performance of La(III) on the basis of the characterization analysis after the adsorption with elemental mapping, EDS and XPS. Consequently, these low-cost and robust COFs with abundant active N sites supplied a promising strategy for the recovery of RE ions from wastewater. [ABSTRACT FROM AUTHOR]

Soil organic matter (SOM) is enriched on the eastern Tibetan Plateau, but its effects on the hydrothermal state of the coupled land–atmosphere system remain unclear. This study comprehensively investigates these effects during summer from multiple perspectives based on regional climate modeling, land surface modeling, and observations. Using a regional climate model, we show that accounting for SOM effects lowers cold and wet biases in simulations of this region. SOM increases 2-m air temperature, decreases 2-m specific/relative humidity, and reduces precipitation in coupled simulations. Inclusion of SOM also warms the shallow soil while cooling the deep soil, which may help to preserve frozen soil in this region. This cooling effect is captured by both observations and offline land surface simulations, but it is overestimated in the offline simulations due to no feedback from the atmosphere compared to the coupled ones. Including SOM in coupled climate models could therefore not only imrove their representations of atmospheric energy and water cycles, but also help to simulate the past, present, and future evolution of frozen soil with increased confidence and reliability. Note that these findings are from one regional climate model and do not apply to wetlands. Significance Statement: The eastern Tibetan Plateau is rich in soil organic matter (SOM), which increases the amount of water the soil can hold while decreasing the rate at which heat moves through it. Although SOM is expected to preserve frozen soil by insulating it from atmospheric warming, researchers have not yet tested the effects of coupled land–atmosphere interactions on this relationship. Using a regional climate model, we show that SOM typically warms and dries the near-surface air, warms the shallow soil, and cools the deep soil by modifying both soil properties and energy exchanges at the land–atmosphere interface. The results suggest that the cooling effect of SOM on deep soil is overestimated when atmospheric feedbacks are excluded. [ABSTRACT FROM AUTHOR]