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The physicochemical properties and origins of atmospheric aerosols in the Tibetan Plateau (TP) region are a research topic of great interest, but an in‐depth understanding of this topic is challenging, partially due to a lack of intensive in situ observations. Thus, a field campaign was conducted over Yadong, a remote area on the south slope of the TP from June 11 to 31 August 2021. The aerosol loading was low, with a black carbon mass concentration of 147.4 ± 98.4 ng·m−3. Aerosol single‐scattering albedo was low (0.73 ± 0.11 at 550 nm) and increased from 450 to 700 nm wavelength. Organic matter (OM) accounting for 69.6% of the total aerosol mass and relatively high secondary organic carbon ratios, highlighting the importance of secondary formation. An interesting phenomenon observed was that the evolution of aerosols was mainly characterized by diurnal variation, which could not be explained by large‐scale atmospheric processes such as Indian summer monsoon. Instead, it was found that regional mountain‐valley winds between the Himalayas and South Asia transported polluted air masses toward the TP, especially in the afternoon when regional valley wind are expected to be the strongest and the boundary layer in South Asia is deepest. Additionally, daytime local valley wind further elevated these aerosols to higher altitudes on the TP. This paper provides insights into the transport mechanisms of aerosols from South Asia to the TP. These findings are of great importance since aerosols exhibit significant diurnal variations in the TP region. Plain Language Summary: Previous studies focused on the analysis of the physical or chemical properties of aerosols on the Tibetan Plateau, but this study provides a comprehensive examination of both. The findings reveal that aerosols on the southern slope of the Tibetan Plateau exhibit strong absorption efficiency. Aerosol single‐scattering albedo was low (0.73 ± 0.11 at 550 nm), which may be attributed to aerosol secondary generation and coating. Finally, the mechanism of pollutant transport from South Asia to the Tibetan Plateau was analyzed relies on site observations, satellite, and reanalysis data to highlight the link between diurnal variations of pollutants and transport mechanism. The specific transport mechanism be understood uniformly across different scales, including Indian summer monsoon, regional mountain‐valley winds between the Himalayas and South Asia, and local mountain‐valley winds circulation. Key Points: Aerosol single‐scattering albedo was low (0.73 ± 0.11 at 550 nm) and secondary organic matter was the major aerosol componentThe evolution of aerosols was mainly characterized by diurnal variation that was related to transport mechanism over YadongThe Himalayas‐South Asia regional mountain‐valley winds combined with local mountain‐valley winds transport aerosols to the Tibetan Plateau [ABSTRACT FROM AUTHOR]

Accurate quantification of the absorption properties of brown carbon (BrC) aerosols is crucial to assess the Earth‐atmosphere radiative impacts of BrC. However, the BrC absorption properties were often misestimated in field observations, due to neglecting the contribution of dust absorption. This study solved this problem by coupling a method for calculating the dust concentration into the traditional model for quantifying BrC absorption. The results show that dust absorption was up to 16.8% of the sum of BrC and dust absorption in northwestern China. The potential contribution of dust to the sum of BrC and dust absorption was significantly higher in the Asia‐located studies (0.4%–16.8%) than in the Americas‐located (<1.2%) and Europe‐located (<2.3%) studies. This work underscores the necessity of eliminating the negative effect of dust in BrC quantitative model. It prompts us to revisit the BrC absorption properties resolved by previous studies, especially in dust‐influenced areas such as Asia. Plain Language Summary: Organic components in aerosols that can absorb light are collectively referred to as brown carbon (BrC), and dust aerosols can also absorb light. Their ability to change weather and climate by absorbing solar radiation has received a lot of attention from the academic community. Previous studies have often misestimated the BrC absorption properties because of the difficulty in separating BrC and dust absorption. To solve this difficulty, we proposed a new method to separate the BrC and dust absorption properties, which was successfully applied at a northwestern Chinese site. Subsequently, we found that the contribution of dust to absorption was generally high in the Asia‐located studies, not only in this study, emphasizing the necessity of applying the new method proposed in this study in dust‐affected regions such as Asia. Key Points: A method was developed to remove dust effect when quantifying light absorption properties of brown carbon (BrC)Dust absorption was up to 16.8% of the sum of BrC and dust absorption at a typical site in northwest ChinaAbsorption properties of BrC in dust‐affected areas such as Asia need to be reassessed due to high dust absorption contribution [ABSTRACT FROM AUTHOR]

Coastal nitrogen enrichment significantly contributes to the decline of seagrass health and habitat, thereby diminishing its capacity to capture and sequester carbon (i.e., Blue Carbon). However, the consequences to blue carbon stocks due to sublethal changes in chemical recalcitrance of seagrass organic matter (OM) caused by nitrogen enrichment is unknown. In this study, we investigated the effects of nitrogen‐loading on the chemical composition of meadow‐forming Thalassia hemprichii. We found that the amino acid content in seagrass leaves and rhizomes increased with nitrogen loading, while the total labile OM and refractory OM (i.e., cellulose and lignin) content in seagrass leaves, sheaths, and roots generally decreased with nitrogen loading. Additionally, cellulose and lignin within sheath tissues showed a threshold response whereby refractory OM dropped when leaf nitrogen content (i.e., indicator of nitrogen loading) exceeded 2.2%. The rhizome labile OM and cellulose content also peaked at 2.2% leaf nitrogen content but subsequently reduced to a minimum at ~2.9% leaf nitrogen. The threshold of 2.2% leaf nitrogen content, equivalent to 43~72 μM dissolved inorganic nitrogen concentration in sediment pore water, may be utilized to forecast the contribution of seagrass refractory OM to sediments. It was estimated that high nitrogen loading could result in a loss of 309–645 kg ha−1 of refractory OM inputs in this study sites. The findings underscore that nitrogen enrichment has sublethal but significant negative impacts on carbon cycling via the reduction of refractory OM in seagrass biomass, consequently weakening the autochthonous contribution of seagrass to long‐term carbon sequestration. [ABSTRACT FROM AUTHOR]

The region surrounding the Tibetan Plateau (TP) is widely considered a primary global dust source, with mineral dust comprising a significant proportion of aerosols over the TP. Current research on TP dust has mainly focused on transport from the surrounding deserts, with little focus on dust emissions from the TP's interior. The erodibility factor used by the WRF‐Chem (ERODDEF) is 0 for the TP, so the model cannot simulate the dust emissions inside the plateau. Thus, we constructed a high‐resolution erodibility data set (ERODSDS) based on a reliable dust source distribution and intensity map. Based on the modified EROD map, the WRF‐Chem model was used to simulate dust emissions and direct radiative forcing on the TP in 2018. With the modified EROD map, WRF‐Chem can well simulate the temporal variation and spatial pattern of mineral dust on the plateau, which greatly improves the model's dust emissions simulation accuracy on the TP. Plain Language Summary: Due to certain limitations of the ERODDEF, the previous WRF‐Chem model was unable to accurately simulate dust emissions from the TP's interior. Thus, we constructed a more realistic ERODSDS and improved simulations of dust emissions and dust direct radiative forcing within the plateau. The west‐central part of the plateau is also an important source of dust emissions, and the amount of dust emitted within the plateau should not be neglected. Key Points: The WRF‐Chem model seriously underestimates local dust emissions on the Tibetan PlateauHigh‐precision erodibility data on the Tibetan Plateau is constructed to accurately describe the surface dust emission potentialThe temporal and spatial distribution of the local dust emission on the Tibetan Plateau was estimated [ABSTRACT FROM AUTHOR]

To better understand aerosol vertical distribution and radiation effects, the seasonal variation and vertical distribution characteristics of aerosol optical properties were analyzed based on the aerosol extinction coefficient, depolarization ratio and backscatter Ångström exponent derived from the dual-wavelength polarization lidar at the Semi-Arid Climate and Environment Observatory of Lanzhou University (SACOL) from December 2009 to November 2012. Combining the CE-318 sun photometer, the microphysical, optical and vertical distribution characteristics of aerosol during a dust process were discussed comprehensively. The results revealed that the vertical profiles of the aerosol extinction coefficient and depolarization ratio clearly had seasonal variation characteristics. The aerosol optical depth (AOD) integrating with the aerosol extinction coefficient within 0–2 km in the spring, summer, autumn and winter accounted for 48%, 45%, 56% and 58% of the total AOD, respectively. The non-spherical feature was most distinctive in the spring, followed by the winter, autumn and summer. The particle size of aerosol in the lower layer was larger than that in the upper layer according to the vertical profile of the backscatter Ångström exponent. The cluster analysis of backward trajectory showed SACOL is dominated by dust aerosol in the spring and the mixtures of dust with anthropogenic pollution in the winter. A dust event in April 2010 was selected and the analysis showed that it mainly came from the high-altitude and long-range transportation from the Taklamakan Desert. During this period, the extinction coefficient increased up to 0.9 km−1, the maximum AOD was 2.21 and the SSA ranged from 0.92 to 0.99. The radiation force in the atmosphere reached 126.15 W/m2. It can be found that the influence of aerosol on the atmospheric radiation effect cannot be ignored. [ABSTRACT FROM AUTHOR]

Turbulence intermittency driven by submeso motions limits the progress of turbulence theory. Field observations from the Horqin Atmospheric Boundary‐Layer and Environment Experimental Station, China were used to investigate turbulence intermittency. An automated algorithm to Separate and reconstruct Submeso and Turbulent motions (SST) was improved for more accurately extraction and quantitative characterization of submeso motions. The existing intermittency intensity indexes, the local intermittency strength of turbulence (LIST) and intermittency strength (IS), which are based on kinetic energy only, are revised by considering the potential energy of submeso and turbulent motions to quantify intermittency intensity more comprehensively. The analysis of eight cases revealed that turbulent intermittency events are characterized by quiescent (pulsation, material, and energy transportation are weak) and burst (pulsation, material, and energy transportation fluctuate violently) periods. The conversion of both the kinetic and potential energy of submeso to turbulent motion contributes to the transition from quiescent to burst periods. The transition always occurs after ∆TE$$ \Delta \mathrm{TE} $$ <0 (the total energy difference between the submeso motion and turbulence), followed by a significant increase in ∆TE$$ \Delta \mathrm{TE} $$. Atmospheric stability decreases during the transition from quiescent to burst periods in most cases. In a totally intermittent night, the burst periods take up most of the material and energy transport, and the amount transported is not smaller than that during a totally turbulent night. The weaker the intermittency at night, the greater the capacity of turbulent transport. A comparison of five types of turbulence intermittency intensity indexes highlights the consistency and advantages between LIST (IS) and indexes in the literature. Finally, we found that turbulent intermittency events tended to occur more easily in the atmospheric boundary layer (ABL) with small winds (U < 2 m s−1) or stable stratification (Rib > 1), although they can also occur in ABL with unstable stratification and in the non‐stationary state of the day–night transition. [ABSTRACT FROM AUTHOR]

Because of the unique geographical location of the Tibetan Plateau and its important role in global climate change, aerosol variability over the plateau has been of wide interest to the academic community. Most studies have focused on the influence of external aerosols; however, a few studies have been conducted on dust aerosols within the plateau. In this study, the plateau was divided into three regions, west, south, and north based on surface vegetation and climatic characteristics, and the Weather Research and Forecasting model with Chemistry was used to simulate the Tibetan Plateau from 2004 to 2006 to quantify the spatial and temporal variability of dust within the plateau with high resolution. The dust sources of the plateau are located in the northern part of the Qiangtang Plateau, the Yarlung Tsangpo River basin, the Namucuo and Lhasa regions, the Qaidam Basin, the source areas of the Yellow and Yangtze Rivers, and the Qinghai Lake and its surrounding areas. Owing to windy weather and arid soil conditions, the dust emissions of the three regions reached 11.00 × 107 (west), 3.30 × 107 (south) and 4.50 × 107 (north) μg·m-2, during winter, and remained at a low level from May to October. Although the annual variation in dust emissions was relatively consistent across the three regions, there were substantial differences in dust loading, with almost no dust present in the atmosphere in the south, a peak dust loading of 94.00 × 105 μg·m-2 in January in the west, and a bimodal structure in the north with peaks in April and October and a maximum value of 13.00 × 1010 μg·m-2, which was primarily influenced by the temperature 2 m above the ground. In summer 10 % of the dust that starts in the interior of the plateau can be transported to the upper troposphere (above 8 km). [ABSTRACT FROM AUTHOR]

Surface-based inversions (SBIs) are significant and common natural phenomena in the planetary boundary layer, and they play essential roles in weather and climate. This study used radiosonde data from 493 radiosonde stations worldwide from the Integrated Global Radiosonde Archive during 1989–2019 to investigate the variations in surface-based inversions from a global perspective. The results indicated that, from 1989 to 2019, the SBI frequency increased and the SBI strength variations with fluctuations and SBI depth decreased over the study period. However, the spatial distribution of frequency, strength, and depth did not have consistent trends. In comparison with the Southern Hemisphere, SBIs in the Northern Hemisphere occurred more frequently and were stronger and deeper. In terms of stations over land and the ocean, we found that the SBI frequency over the ocean has increased faster than that over land in the past 15 years and that the SBI strength over land was almost 2 times that of the ocean. The amplitudes of the annual cycle of SBI characteristics over land were greater than over the ocean in both hemispheres, and the frequency, strength, and depth were greater over land. This study investigated surface-based inversions from a global perspective and filled a gap in the current research on SBIs. [ABSTRACT FROM AUTHOR]

Surface layer turbulence has an important influence on land-air interactions and pollutant dispersion, and studying the characteristics of surface layer turbulence in complex terrain can contribute to understanding land-air interactions, improving model surface layer parameterization, and enhancing pollution prediction capabilities. The surface layer turbulence observations from the Semi-Arid Climate and Environment Observatory (SACOL) of Lanzhou University in 2008 were processed in this study. High-quality turbulence parameters were calculated, the statistical and transfer characteristics of turbulence were analyzed, and the formation of turbulence was assessed in terms of dynamics and thermodynamics. The atmospheric stability in the semiarid region of the Loess Plateau is basically dominated by neutral/near-neutral and weakly unstable/weakly stable conditions; this pattern is significantly different from the preponderance of unstable and stable layers at other sites. The turbulence intensity differs significantly in both the horizontal and vertical directions and basically shows the relationship I u ≈ I v > I w . The mean values of I u and I v are 0.42 and 0.40, respectively, and the mean value of I w is 0.14, which is different from the general pattern of I u > I v > I w , indicating that the turbulence intensity at SACOL is characterized by a large lateral wind contribution. The dimensionless standard deviations of the nonneutral wind velocity components satisfy the "1/3rd law," and the dimensionless standard deviations of u, v , and w components are 3.35, 2.98, and 1.26, respectively, in the semiarid Loess Plateau. These values are larger than those over flat terrain. The contribution of the shear term to the formation of turbulence is greater than that of the buoyancy term, and the mean annual values of the shear term and the buoyancy in the kinetic energy budget equation in SACOL are 47.94 × 10−4 m2·s−3 and 11.32 × 10−4 m2·s−3, respectively. The annual mean values of the momentum transfer coefficient C D and the heat transfer coefficient C H under near-neutral conditions are 8.54 × 10−3 and 2.52 × 10−3, respectively. [ABSTRACT FROM AUTHOR]

B-cell lymphoma 2 (Bcl-2) is a regulator protein involved in apoptosis. In the past few decades, this protein has been demonstrated to have high efficacy in cancer therapy, and several approaches targeting Bcl-2 have been tested clinically (e.g., oblimersen, ABT-737, ABT-263, obatoclax mesylate, and AT-101). This review reports potential Bcl-2 inhibitors according to current information on their underlying mechanism and the results of clinical trials. In addition, the function and mechanisms of other potentially valuable Bcl-2 inhibitors that did not show efficacy in clinical studies are also discussed. This summary of the development of Bcl-2 inhibitors provides worthwhile viewpoints on the use of biomedical approaches in future cancer therapy. [ABSTRACT FROM AUTHOR]

The particle mixing state plays a significant yet poorly quantified role in aerosol radiative forcing, especially for the mixing of dust (mineral absorbing) and anthropogenic pollution (black carbon absorbing) over East Asia. We have investigated the absorption enhancement of mixed-type aerosols over East Asia by using the Aerosol Robotic Network observations and radiative transfer model calculations. The mixed-type aerosols exhibit significantly enhanced absorbing ability than the corresponding unmixed dust and anthropogenic aerosols, as revealed in the spectral behavior of absorbing aerosol optical depth, single scattering albedo, and imaginary refractive index. The aerosol radiative efficiencies for the dust, mixed-type, and anthropogenic aerosols are -101.0, -112.9, and -98.3Wm-2 τ-1 at the bottom of the atmosphere (BOA); -42.3, -22.5, and -39.8-2 τ-1 at the top of the atmosphere (TOA); and 58.7, 90.3, and 58.5Wm-2 τ-1 in the atmosphere (ATM), respectively. The BOA cooling and ATM heating efficiencies of the mixed-type aerosols are significantly higher than those of the unmixed aerosol types over the East Asia region, resulting in atmospheric stabilization. In addition, the mixed-type aerosols correspond to a lower TOA cooling efficiency, indicating that the cooling effect by the corresponding individual aerosol components is partially counteracted. We conclude that the interaction between dust and anthropogenic pollution not only represents a viable aerosol formation pathway but also results in unfavorable dispersion conditions, both exacerbating the regional air pollution in East Asia. Our results highlight the necessity to accurately account for the mixing state of aerosols in atmospheric models over East Asia in order to better understand the formation mechanism for regional air pollution and to assess its impacts on human health, weather, and climate. [ABSTRACT FROM AUTHOR]

The current understanding of the climate effects of mixed-type aerosols is an open question. The optical and radiative properties of the anthropogenic, mixed-type, and dust aerosols were studied using simultaneous observations of a sun photometer and a depolarization lidar over the Semi-Arid Climate and Environment Observatory of Lanzhou University (SACOL), northwestern China. The aerosol radiative effect was calculated using the Santa Barbara DISORT Atmospheric Radiative Transfer (SBDART) model and was in good agreement with the Aerosol Robotic Network (AERONET) product. The anthropogenic, mixed-type, and dust aerosols were identified mainly based on the lidar-measured depolarization ratio, which was supported by the airmass back trajectories. The mixed-type aerosols exhibit lower (higher) extinctions below (above) 1.5 km above the ground, indicating anthropogenic pollution from the atmospheric boundary layer and dust aerosols above. The dust aerosols exhibit the highest absolute radiative effect because of the highest aerosol loading. However, the mixed-type aerosols are effective in both scattering and absorbing solar radiation, leading to the highest cooling efficiency at the bottom of the atmosphere (BOA), 7.4% and 6.5% higher than those of the anthropogenic and dust aerosols, respectively. The mixed-type aerosols exhibit the highest warming efficiency in the atmosphere (ATM), 20.8% and 28.2% higher than the anthropogenic and dust aerosols, respectively. The mixed-type aerosols also show the lowest cooling efficiency at the top of the atmosphere (TOA). The results suggest the necessity of carefully characterizing the mixed-type aerosols in atmospheric numerical models to more precisely assess the energy budget of the Earth--atmosphere system. [ABSTRACT FROM AUTHOR]

To assess the impacts of initial soil moisture (SMOIS) and the vegetation fraction (Fg) on the diurnal temperature range (DTR) in arid and semiarid regions in China, three simulations using the weather research and forecasting (WRF) model are conducted by modifying the SMOIS, surface emissivity and Fg. SMOIS affects the daily maximum temperature (Tmax) and daily minimum temperature (Tmin) by altering the distribution of available energy between sensible and latent heat fluxes during the day and by altering the surface emissivity at night. Reduced soil wetness can increase both the Tmax and Tmin, but the effect on the DTR is determined by the relative strength of the effects on Tmax and Tmin. Observational data from the Semi-Arid Climate and Environment Observatory of Lanzhou University (SACOL) and the Shapotou Desert Research and Experimental Station (SPD) suggest that the magnitude of the SMOIS effect on the distribution of available energy during the day is larger than that on surface emissivity at night. In other words, SMOIS has a negative effect on the DTR. Changes in Fg modify the surface radiation and the energy budget. Due to the depth of the daytime convective boundary layer, the temperature in daytime is affected less than in nighttime by the radiation and energy budget. Increases in surface emissivity and decreases in soil heating resulting from increased Fg mainly decrease Tmin, thereby increasing the DTR. The effects of SMOIS and Fg on both Tmax and Tmin are the same, but the effects on DTR are the opposite. [ABSTRACT FROM AUTHOR]

Variation of the turbulence barrier effect caused by the turbulence intermittency have a strong impact on the vertical distribution and variation of pollutants, which limits the accuracy of pollution process simulation. Turbulence observation data from the five layers of the 255 m meteorological tower in Tianjin during two severe haze pollution periods were used to discuss energy changes during the enhancement and break of the turbulence barrier. Results showed that a sharp decrease in turbulence kinetic energy contributed to barrier enhancement and the kinetic energy transfer from sub-mesoscale motion to turbulence triggered the barrier break. The barrier break point tends to occur after Δ KE < 0 (the kinetic energy difference between turbulence and sub-mesoscale motion), subsequently followed by a significant increase in Δ KE. Due to the significant reduction in wind speed during severe haze pollution, type-B intermittency events occurred more frequently and existed at five heights. Type-A intermittency events were more likely to occur at the heights of 40 and 80 m, and type-C intermittency events were more likely to occur at heights above 80 m. Wind speed thresholds at different heights (2.5 m s−1 for 40 m, 4 m s−1 for 80 m, 4 m s−1 for 120 m, 4 m s−1 for 160 m, 4.5 m s−1 for 200 m) can be used to determine whether turbulent barrier effects occurred. This study provides an important research basis for solving the theoretical problem of the stable boundary layer that currently limits the accurate prediction of severe haze pollution processes. [Display omitted] • The sharp decrease of turbulence kinetic energy contributes to barrier enhancement. • Energy transition from sub-mesoscale to turbulent motion triggers barrier break. • Barrier break point tends to occur after Δ KE < 0 following significant increase. • Type-B intermittency occurs more frequently and exists at all levels in haze events. • Wind speed thresholds for whether turbulence barrier effect occur was determined. [ABSTRACT FROM AUTHOR]

Schistosoma japonicum insulin receptors (SjIRs) have been identified as encouraging vaccine candidates. Interrupting or blocking the binding between host insulin and the schistosome insulin receptors (IRs) may result in reduced glucose uptake leading to starvation and stunting of worms with a reduction in egg output. To further understand how schistosomes are able to exploit host insulin for development and growth, and whether these parasites and their mammalian hosts compete for the same insulin source, we identified insulin binding sites on the SjIRs. Based on sequence analysis and the predicted antigenic structure of the primary sequences of the SjIRs, we designed nine and eleven peptide analogues from SjIR-1 and SjIR-2, respectively. Using the Octet RED system, we identified analogues derived from SjIR-1 (10) and SjIR-2 (20, 21 and 22) with insulin-binding sequences specific for S. japonicum. Nevertheless, the human insulin receptor (HIR) may compete with the SjIRs in binding human insulin in other positions which are important for HIR binding to insulin. However, no binding occurred between insulin and parasite analogues derived from SjIR-1 (2, 7 and 8) and SjIR-2 (14, 16 and 18) at the same locations as HIR sequences which have been shown to have strong insulin binding affinities. Importantly, we found two analogues (1 and 3), derived from SjIR-1, and two analogues (13 and 15) derived from SjIR-2, were responsible for the major insulin binding affinity in S. japonicum. These peptide analogues were shown to have more than 10 times (in KD value) stronger binding capacity for human insulin compared with peptides derived from the HIR in the same sequence positions. Paradoxically, analogues 1, 3, 13 and 15 do not appear to contain major antigenic determinants which resulted in poor antibody responses to native S. japonicum protein. This argues against their future development as peptide-vaccine candidates. [ABSTRACT FROM AUTHOR]

High-precision and -resolution atmospheric boundary layer height (BLH) has received increasing attention in air pollution research in recent years. The low time resolution of sounding data is the main challenge to validate BLH retrieval from lidar observations. To resolve this issue, we conducted simultaneous tethered balloon sounding and lidar observations at the Semi-Arid Climate and Environment Observatory of Lanzhou University (SACOL) during winter 2019–2020. The BLHs derived from the tethered balloon sounding data were 170, 210, 393, 676, 423, and 190 m at 02:00, 08:00, 11:00, 14:00, 17:00, and 20:00 (Beijing time), respectively. The diurnal evolution of BLH was reasonably captured by lidar observation-based wavelet covariance transform and ideal profile fitting methods, which exhibited correlation coefficients of 0.91 and 0.89, respectively, with the BLHs determined from tethered balloon sounding data. The lidar results slightly overestimated the BLHs, though all results were acceptable when considering both the absolute and relative errors with respect to BLHs from the tethered balloon data. Our results revealed high-precision and -resolution diurnal variations in BLH at SACOL in Northwest China and suggest the importance of validating lidar-based BLHs using simultaneous sounding data. [ABSTRACT FROM AUTHOR]

Cloud water is an important geophysical quantity that connects the hydrological and radiation characteristics of climate systems and plays an essential role in the global circulation of the atmosphere, water, and energy. However, compared to the contribution of water vapor to precipitation, the understanding of cloud-precipitation transformation and its climate feedback mechanism remains limited. Based on precipitation and temperature datasets of the National Meteorological Observatory and MODIS (Moderate Resolution Imaging Spectroradiometer) satellite remote sensing products, the evolution characteristics of cloud water resources in China over the last twenty years of the 21st century were evaluated. Significant decreasing trends of −3.3 and −4.89 g/m2 decade−1 were found for both the liquid and ice water path. In humid areas with high precipitation, the cloud water path decreased fast. In semiarid areas with an annual precipitation ranging from 500–800 mm, the decreasing trend of the cloud water path was the lowest. The cloud-water period was calculated to represent the relative changes in clouds and precipitation. The national average cloud-water period in China is approximately 12.4 h, with obvious seasonal changes. Over the last 20 years, the cloud water path in dry regions decreased more slowly than that in wet regions, and the cloud-precipitation efficiency significantly increased, which narrowed the climate difference between the dry and wet regions. Finally, the mechanism of the cloud-water period evolution in the different regions were examined from the perspectives of the dynamic and thermal contributions, respectively. Due to the overall low upward moisture flux (UMF) in the dry region, the response of the cloud-water period to the lower tropospheric stability (LTS) mainly first increased and then decreased, which was the opposite in the wet region. The increase in cloud-precipitation efficiency in the dry region of Northwest China is accompanied by a continuous decrease in LTS. The different configurations of regional UMF and LTS play a crucial role in the evolution of cloud-precipitation, which can be used as a diagnostic basis to predict changes in the precipitation intensity to a certain extent. [ABSTRACT FROM AUTHOR]

Changes in water circulation and uneven distributions of water resources caused by global warming are prominent problems facing the world at present. It is important to understand the influencing factors, and evapotranspiration (ET) is a key parameter for measuring the water cycle. However, understanding of spatiotemporal changes in actual evapotranspiration and its mechanism is still limited by a lack of long-term and large-scale in situ datasets. Here, the evolution of evapotranspiration in typical East Asian monsoon areas in China from 1989 to 2005 was analyzed with global land ET synthesis products. Evapotranspiration in China showed evident interdecadal variations around 1998; it decreased before 1998 and subsequently increased, which is inversely related to global ET changes. We further divided China into water-control and energy-control regions to discuss the factors influencing ET changes in each region. The interdecadal variations in increasing ET after 1998 in China were dominated by increasing potential evaporation in the energy-control region. An analysis using the empirical orthogonal function (EOF) method found that this occurred because ET is mainly manifested as decadal changes controlled by climate warming in the energy-control region and as interannual variations in the water-control region. The different feedbacks of ET on climate change in the two regions were also reflected in the difference in energy partition. The change in the Bowen rate (BR) did not increase climatic differences between energy- and water-control zones, but increases in the BR in arid summers significantly affected local weather and climate. [ABSTRACT FROM AUTHOR]

To study the influence of complex terrain with different scales on the structure of near-surface turbulence, the turbulence observational data from Semi-Arid Climate and Environment Observatory of Lanzhou University (SACOL) were analyzed. SACOL is located in typical Loess Plateau topography. The terrain around the site varies greatly with the direction. Representative data from the Northeast, Southeast, Southwest, and Northwest were selected to study the structure characteristics of the near surface turbulence. The complex topography within the flux footprint enhances the vertical scale of turbulence σw and thereby increases the vertical–longitudinal ratio of turbulence Ar. While the turbulent horizontal scale σu is also significantly affected by the distant terrain beyond the flux footprint. The upwind terrain undulation increases σu and reduces Ar. Affected by the complex terrain, the ratio of the spectrum of the vertical velocity to that of the longitudinal velocity, Sw(n)/Su(n), is far less than 4/3 in the southwest direction, and the turbulence is significantly anisotropic. [ABSTRACT FROM AUTHOR]

Precipitable water vapor (PWV) was retrieved using direct solar irradiance at 938 nm measured by a multifilter rotating shadowband radiometer (MFRSR) at the Semi-Arid Climate and Environment Observatory of Lanzhou University (SACOL) located in the semi-arid area of northwest China from August 2007 to June 2010. Measurement also occurred at Zhangye, China, at the Atmosphere Radiation Measurements (ARM) Program's Ancillary Facility during the dust period from April to June 2008. The line-by-line radiative transfer model (LBLRTM) code combined with the HITRAN 2004 spectral database is used to model the water vapor spectral transmittance throughout the 938-nm spectral response of MFRSR in the retrieval algorithm. Gaussian fitting is proposed to determine the daily calibration constant at the top of atmosphere for a long-term series under an obvious annual change in solar radiation. PWV retrieved by MFRSR over SACOL shows that 90% of PWV values are smaller than 1.52 cm, and PWV distribution has a seasonal variation, with maximum in summer and minimum in winter. The comparisons between MFRSR and other measurements show a better agreement between MFRSR and sunphotometer (AERONET's Cimel) PWV retrievals with relative bias of 2.9% and RMS difference of 9.1% than between MFRSR and microwave radiometer (MWR) with relative bias of 10% and RMS difference of 23% over SACOL, and an excellent agreement between MFRSR and sunphotometer with relative bias of 0.56% and RMS difference of 6.1% over Zhangye. To verify satellite PWV products over the semi-arid area of northwest China, the comparisons of PWV from MODIS and AIRS with MFRSR suggest that the agreement between satellite and MFRSR PWV retrievals is not as good as that between MFRSR and other ground-based instruments. MODIS appears to slightly underestimate PWV in a dry atmosphere but overestimate PWV in a moist atmosphere against MFRSR. A method is proposed to correct MODIS PWV products. AIRS PWV products relative to MFRSR show a systematic underestimation. [ABSTRACT FROM AUTHOR]