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In this study, the long-term characteristics of the dust weather frequency (DWF) in the ensuing spring (March–April–May, MAM) in northern China (NC) and the association with sea ice concentration in the Barents Sea (SICBS) and Arctic Oscillation (AO) in the preceding winter (December–January–February, DJF) during 1979–2021 are investigated. The results show that the dust weather in NC is mainly associated with decreased SICBS during 1982–2008 and linked with a negative AO phase during 2009–2021. Due to the decreased SICBS in the preceding winter during 1982–2008, the surface adiabatic heating excites Rossby waves to spread southward and eastward, resulting in decreased snow cover over Eurasia and more dust weather by anomalous northerly wind in the ensuing spring over NC. On the other hand, with a negative AO phase in the preceding winter during 2009–2021, the increased meridional temperature gradient at mid-latitudes tends to enhance westerly wind and cyclogenesis over NC, leading to more dust weather in the ensuing spring. Consequently, both the negative AO phase and decreased SICBS in the preceding winter correspond to strong wind and dry soil in the dust source region, which favor an increase in the DWF in the ensuing spring over NC. Studying the characteristics of the SICBS and AO could provide some clues to predict the dust weather in NC. [ABSTRACT FROM AUTHOR]

Anthropogenic aerosols play an important role in altering the radiation budget and Earth's climate. In this study, the association of anthropogenic aerosols with subtropical drought in East Asia is investigated with multisource data and simulations of Coupled Model Intercomparison Project Phase 5 (CMIP5) models. The result shows that the increase in anthropogenic aerosols partially contributes to the zonal drought at subtropical latitudes in East Asia from 1970. In East Asia, sulphate is the dominant type of anthropogenic aerosol and is mainly distributed over the southeastern China. Due to the sulphate aerosols, the geopotential height decreases/increases significantly at the upper‐/lower‐level atmosphere in the subtropical region, with a maximum variation at approximately 30°N. Consequently, the downward motion of air is intensified in the subtropical region. Ultimately, the precipitation amount in the vicinity of the subtropical region is significantly diminished, with a maximum decrease at approximately 30°N. In contrast, the sulphate aerosols could induce more precipitation over the tropical region. In conclusion, the anthropogenic aerosols have an important impact on precipitation in East Asia. In the future, with the intensification of human activities, the contribution of anthropogenic aerosols to aridification is an inevitable question. [ABSTRACT FROM AUTHOR]

The Tibetan Plateau (TP), known as the "Third Pole," profoundly affects weather and climate at regional and global scales. In this study, we investigate the characteristics of heat waves in China and their association with the TP heat source. The results show that during the summertime from 1980 to 2020, the frequency of heat wave days that hit eastern China and northwest China increased at rates of 0.09 and 0.24 days yr−1, respectively, accompanied by an increase in the atmospheric heat source (AHS) over the TP by over 2 W m−2 yr−1 under the background of global warming. The enhanced TP heat source induces an anomalous upper-tropospheric anticyclone, which caused the western Pacific subtropical high and South Asia high to be stronger and closer to each other, causing descending motions over eastern China and consequently more heat waves. At the same time, the enhanced TP heat source weakened the westerlies, thereby favoring the occurrence and maintenance of the anticyclone centered in northwest China and creating more heat waves due to strong descending motions. Therefore, the association between the TP heat source and heat waves in China provides relevant information for studying the mechanism and future changes of heat waves. Significance Statement: The Tibetan Plateau significantly affects the surrounding weather and climate. We find that there are some linkages between the Tibetan heat source and heat waves in China. The stronger the Tibetan heat source is, the more heat waves hit China. The enhancement of the Tibetan heat source could induce an anomalous upper-tropospheric anticyclone by affecting the western Pacific subtropical high and South Asia high, consequently causing descending motions over eastern China and the resulting heat waves. The weaker westerly due to the enhanced Tibetan heat source favors the occurrence of the anticyclone centered in northwest China, leading to more heat waves by descending motions. This study reveals a potential contributor to heat waves in China, providing some clues for better prediction in the future. [ABSTRACT FROM AUTHOR]

Previous study of the tropopause aerosol layer is focused on the region surrounding the Tibetan Plateau. However, other transport pathways of the tropopause aerosol layer remain unclear. In this study, by simulating the dusts from different dust sources individually, we detected the Ethiopian Plateau and the Rocky Mountains are two new transport pathways of the global tropopause dust layer (GTDL). In addition, the contributions of different dust sources to the GTDL were quantified, the mass concentration percentage of dusts originating from Indian Peninsula in the GTDL at 100 hPa is 31.5%, which is the largest, followed by those of dusts from Middle East and Northwestern East Asia, dusts from North Africa contribute 17.3% to the GTDL at 100 hPa, which is the smallest. Our results demonstrate the existence of multiple transport pathways of the tropopause aerosol layer and clearly provide the contributions of each dust source to the GTDL. Plain Language Summary: Tropospheric aerosols can be transported through specific regions to the stratosphere. The current studies indicate the TP as a key region for aerosol transport. Through model simulations, in this study, we found that the Ethiopian Plateau in Africa and the Rocky Mountains in North America are also the pathways for aerosol transport. We also found the contribution of dusts originating from Indian Peninsula to the GTDL is the largest, followed by dusts originating from Middle East and Northwestern East Asia, and the contribution of dusts originating from North Africa to the GTDL is the smallest. Key Points: The tropopause dust layer covers a full circuit around the globeaThe Ethiopian Plateau and the Rocky Mountains are two new transport pathways of the GTDLThe contribution of dusts from IND to GTDL is the largest and the one from NAF to GTDL is the smallest [ABSTRACT FROM AUTHOR]

Drylands occupy about 41% of land surface and feed 38% of the world's population, where understanding drylands' water‐cycle is in urgent need. In this study, response of water‐cycle over the drylands to global warming from 1980 to 2015 and its mechanisms have been investigated in detail. The results show that, with the global surface air temperature (SAT) increasing at a rate of 0.03 K⋅year−1 over the drylands, an increased evaporation is found; however, the net water vapour transport over the global drylands appears an overall decreased rate of −0.24 mm⋅year−1. Due to global warming and atmospheric circulation anomalies, the evaporation increases by 1.1 mm⋅year−1, while the precipitation and runoff decrease by −2.32 and −0.8 mm⋅year−1, respectively. In addition, the precipitation conversion rate (PCR) tends to decrease during this period, while the precipitation recycling rate (PRR) shows slightly increasing trend, implying a more dependence of the precipitation on the local evaporation over the drylands. Overall, except the drylands of Africa, it indicates a weakened water‐cycle over the global drylands from 1980 to 2015. Though some findings have been revealed, there still remains some uncertainties due to the observation limitation on the water‐cycle components. Therefore, a comprehensive study including multi‐sourced data and model simulation is expected in the future. [ABSTRACT FROM AUTHOR]

The Tibetan Plateau (TP), the so-called water tower of Asia, plays an important role in the water cycle. However, few studies have linked the TP's water vapor supply with the climate over North China. In this study, we found that changes in the subtropical westerly jet (SWJ) dynamically induce drought in North China, and the TP plays an important role in this relationship. During July–August for the period of 1981–2019, the SWJ center between 75° and 105°E obviously shifted northward at a rate of 0.04° per year. Correspondingly, the zonal winds in the southern subtropics were incredibly weakened, causing the outflow of water vapor from the TP to decrease dramatically. Combined with numerical simulations, we discovered that a reduction in water vapor transport from the TP can obviously decrease the precipitation over North China. Sensitivity experiments demonstrated that if the water vapor outflow from the eastern border of the TP decreases by 52.74%, the precipitation in North China will decrease by 12.69% due to a decrease in the local cloud fraction caused by a diminished water vapor content in the atmosphere. Therefore, although less water vapor transport occurs in the upper troposphere than in the lower troposphere, the impact of transport from the TP in the former on the downstream precipitation cannot be ignored. [ABSTRACT FROM AUTHOR]

The effects of anthropogenic factors on the water cycle in drylands of the Northern Hemisphere (NH) are unclear. Here, we used the Community Earth System Model (CESM2.1.0) to quantify the influences of greenhouse gases (GHGs) and anthropogenic aerosols (AAs) on the water cycle and precipitation recycling rate (PRR) over drylands from 1980 to 2014. The corresponding mechanisms are also revealed in this study. The results show that GHGs can intensify the water cycle over drylands by increasing precipitation (P; 0.023 mm day−1) and evapotranspiration (ET; 0.037 mm day−1). Consequently, the negative P − ET (−0.014 mm day−1) is induced because infiltration (I; −0.014 mm day−1) and total water storage (S; −0.011 mm day−1) are decreased, implying a loss of soil water. The PRR is reduced by approximately −0.18% because of the GHG-induced extra water vapor export, which originated from ET. In contrast, AAs can weaken the water cycle over drylands by decreasing P (−0.03 mm day−1) and ET (−0.039 mm day−1). Correspondingly, positive P − ET (0.009 mm day−1) is induced, reflecting an input of soil water. Because of the AA-induced persistent ET from a wetter land and the reduced export water vapor from ET, the PRR increases by approximately 0.15%. Mechanistically, GHGs and AAs can affect the water cycle over drylands by perturbing the descending branches of Hadley circulation in midlatitude regions. Quantifying the climate effects of GHGs and AAs on the regional water cycle improves our understanding of the regional water cycle; the results of this study could also be conducive to the climate predictions for drylands. [ABSTRACT FROM AUTHOR]

Extensive observational and numerical simulations have been performed to better characterize the role of aerosols in affecting the clouds and precipitation. However, due to the large uncertainties of aerosol property, the effect of aerosols on clouds and precipitation over the arid and semiarid region (briefly called 'drylands') of East Asia (EA) is still unclear. Basing on observations and model simulations from the Coupled Model Intercomparison Project Phase 5 (CMIP5), we investigated the aerosol's effects on the cloud properties and precipitation over the drylands of EA from 1850 to the present and projected forward to 2,300. It is found that, during 1850–2005, with the mean aerosol optical depth (AOD) over the drylands of EA increasing, the cloud droplet number concentration (CDNC) increases, while the cloud effective droplet radius (CEDR) decreases significantly at a rate of −0.40 μm·century−1. Besides, the cloud water path (CWP) and precipitation show slightly increasing trends with the AOD increasing. Additionally, the effect of aerosols on cloud properties is saturated when the AODs reach 0.21 and 0.15 over the arid region (AR) and semiarid region (SR), respectively. According to the prediction for the period 2006–2300, the AOD and CDNC tend to decline over the drylands of EA, while the CWP, CEDR and precipitation show increasing trends. Particularly, the aerosol, clouds and precipitation indicate more significant changes over the SR in EA during 2006–2300. In future research, there is an urgent need to quantify the contribution of aerosol‐cloud interaction to the precipitation change over the drylands of EA. [ABSTRACT FROM AUTHOR]

Dust aerosols have been generally regarded as efficient ice nuclei (IN), but their influences on mixed-phase clouds and precipitation are poorly quantified. In this study, combining satellite observations, reanalysis data and the Weather Research and Forecasting (WRF) model, we investigate the impacts of dust aerosols on mixed-phase clouds and precipitation during a super dust storm over northern China. The Suomi National Polar-Orbiting Partnership (S-NPP) satellite observed a super dust storm from March 15–19, 2021 in northern China, followed by heavy precipitation between March 17 and 19. The results showed that the occurrence of super dust storms may play an important role in cloud formation and precipitation processes. Furthermore, numerical modeling revealed that dust aerosols can increase the ice crystal number concentration (QN i) and decrease the cloud droplet number concentration (QN c) in mixed-phase clouds through the Wegener–Bergeron–Findeisen (WBF) process, in which the maximum increase in QN i can reach 21%. Simultaneously, the mass mixing ratios of rain, graupel and snow increased due to dust aerosols. Consequently, precipitation could increase by up to 9.8% in northern China. This study could provide evidence for understanding the mechanisms of dust effects on mixed-phase clouds over northern China. Time series of the domain–averaged (a) dust AOD (black) and cloud fraction (red), (b) liquid/ice water path (black/blue, unit: g·m−2) and cloud optical depth (red) over the study region from 15–19 March. The dust AOD and cloud parameters are derived from MERRA-2 and CERES products, respectively. (c) Effects of dust on precipitation, QN c , QN i , RE c and RE i from 17 to 19 March 2021 derived from model simulations (units: %). [Display omitted] • The occurrence of heavy dust storms may play an important role in cloud formation and precipitation processes. • Dust aerosols can enhance rainfall by increasing the number of ice crystals in mixed-phase clouds. • Dust aerosols can induce a maximum increase in the daily precipitation up to 9.8%. [ABSTRACT FROM AUTHOR]

Recent efforts reported that the aerosols even can be transported from a long distance to the Pacific Ocean (PO) and potentially influence the marine primary productivity. In this study, based on the multi-source satellite observations and meteorological reanalysis data, the source and transport of aerosols from Asia to the PO region are investigated. The result shows that the satellites capture 104 aerosol events during 2007–2016, which occur in Asia, and can further influence the PO region. The Asian source regions of aerosol over the PO region mainly include eastern and central China (ECC), eastern and central Russia (ECR), Inner Mongolia and Gansu of China and Mongolia (IMGM), and Southeast Asia (SEA), corresponding to sulfate, organic carbon, dust, and organic carbon aerosol sources, respectively. Among the aerosol events detected over the PO region, most of them are sourced from ECC region, accounting for 54.8% of the total aerosol events, followed by ECR region (accounting for 22.1%). Statistical analyses show that, during 2007–2016, the aerosol events observed over the PO region mainly occur in the spring (47 times), followed by the autumn (25 times); and the least of them occur in the winter (14 times). Correspondingly, the months with the most and least aerosol events are March and February, respectively. When the aerosols enter the PO region, the average optical depths of aerosols sourcing from ECC, ECR, IMGM and SEA are 0.24, 0.38, 0.29 and 0.19, respectively. Besides, the transport of aerosols from Asia to the PO region is mainly influenced by westerly winds and troughs of low-pressure system. This study can provide some evidence of understanding the aerosol type, physical and optical properties over the PO region. • The source, frequency and strength of Asian aerosols transport to the Pacific Ocean are counted. • The dominant meteorological conditions for Asian aerosols transport to the Pacific Ocean are analyzed. • The dominant aerosol types in different source regions are analyzed. [ABSTRACT FROM AUTHOR]

Recently, satellites have observed that dust events are occurring more frequently over the Tibetan Plateau (TP), which implies a new issue of aerosols influencing cloud properties and presents a new challenge in research on the role of the TP in climate change. In this study, combining satellite observations with Climate Model Intercomparison Project Phase 5 (CMIP5) model simulations, the inconsistent aerosol indirect effects on the properties of water clouds and ice clouds over the TP are compared and quantified. Analyses of satellite observations show that, compared with water clouds, ice clouds are observed more frequently and are more significantly correlated with aerosols over the TP. Correspondingly, the aerosol effect on the radiative forcing of ice clouds is more significant than that on the forcing of water clouds, in which the aerosol indirect effect is dominated by the effect on the shortwave radiative forcing of ice clouds. Both observations and CMIP5 model simulation results show that, due to the variation of aerosols, changes in the ice cloud radiative forcing cover most of the TP, while changes in the water cloud radiative forcing mainly appear over the southern edge of the TP. The CMIP5 simulation results suggest that the aerosol indirect effect on the total radiative forcing of water clouds over the TP is −0.34 (±0.03) W⋅m−2, while that on the forcing of ice clouds is −0.73 (±0.03) W⋅m−2. Overall, both the model simulations and satellite results show that the indirect effect of aerosols on ice clouds is more pronounced than that on water clouds. [ABSTRACT FROM AUTHOR]

In this study, a combination of satellite observations and reanalysis datasets is used to analyze the spatiotemporal distribution, classification and source of pollutants over the eastern slope of the Tibetan Plateau (ESTP). The aerosol optical depth (AOD) over the ESTP is extremely large and even larger than some important industrialized regions and deserts. The main aerosol component over the ESTP is sulfate, followed by carbonaceous and dust aerosols. Local emissions related to human activity directly contribute to the accumulation of sulfate and carbonaceous aerosols over the Sichuan Basin. In addition, in spring, abundant carbonaceous aerosols emitted from forest, grassland and savanna fires in Southeast Asia can be transported by the prevailing southwesterly wind to southern China and the ESTP. The dust AOD over the ESTP peaks in spring because of the transport from the Taklimakan and Gobi deserts. Additionally, the high aerosol loading over the ESTP is also directly related to the meteorological background. Due to the special topography, the terrain-driven circulation can trap aerosols in the Sichuan Basin and these aerosols can climb along the ESTP due to the perennial updraft. The aerosol loading is lowest in summer because of effective wet deposition induced by the strong precipitation and better dispersion conditions due to the larger vertical temperature gradients and ascending air movement enhanced by the plateau heat pump effect. In contrast, the aerosol loading is greatest in winter. Abundant anthropogenic aerosols over the ESTP may generate some climatic and environmental risks and consequently greatly influence the downstream regions. [ABSTRACT FROM AUTHOR]

With the global warming slowdown in the twenty‐first century, a huge discrepancy in regional climate warming has been identified over the main region of the Tibetan Plateau (TP). Compared with the +0.04 °C/decade warming from 1961 to 1999, the warming greatly accelerated for the period 2000–2015 at a rate of +0.30 °C/decade. During the same period, warming in the cold season (November to March) was more pronounced than in the warm season (May to September) over the TP. The results also indicated that the middle‐level cloud (middle cloud) decreased (−0.359%/year), while the high‐level cloud (high cloud) increased (+0.241%/year) over almost all the TP during the cold season. Further analysis showed positive net cloud radiative forcing over the western TP from 2000–2015, that is, a heating effect of clouds, especially in the cold season. Combining the trends of the increase in high cloud and the decrease in middle cloud over most parts of the TP, the decreased albedo effect of middle cloud and the increased longwave greenhouse effect of high cloud may have partially contributed to the sustained warming, especially in the cold season from 2000 to 2015. Meanwhile, the results showed that the warming rate and cloud area fraction changes were significantly amplified with elevation. The analysis based on a model of Coupled Model Intercomparison Project Phase 5 shows that the decreased middle cloud plays more important role than the increased high cloud in modulating the enhanced warming over the TP, especially in the cold season. The percentage of SAT caused by longwave CRF (red bar) and shortwave CRF (blue bar) to total SAT derived from CNRM‐CM5 model of CMIP5 over the TP for cold season in the period of 2000–2005. [ABSTRACT FROM AUTHOR]

Serious forest fires were observed over Siberia, particularly in the vast area between Lake Baikal and the Gulf of Ob, during the period of 18–27 July 2016 using Moderate Resolution Imaging Spectroradiometer (MODIS) data. The Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite simultaneously detected a multitude of smoke aerosols surrounding the same area. Combing a Lagrangian Flexible Particle dispersion model (FLEXPART) executed using the Weather Research and Forecasting (WRF) model output, the transport of smoke aerosols and the quantification of impact of Russian forest fires on the Asia were investigated. From model simulations, two transport paths were determined for the smoke plumes from the Russian forest fires. The first path was directed southwestward from Russia to Central Asia and eventually Xinjiang Province of China, furthermore, the second path was directed southeastward through Mongolia to Northeast China. The FLEXPART-WRF model simulations also revealed that the smoke aerosol concentrations entering the Central Asia, Mongolia and Northern China were approximately 60–300 μg m −3 , 40–250 μg m −3 and 5–140 μg m −3 , respectively. Meanwhile, the aerosol particles from these forest fires have an impact on the air quality in Asia. With the arrival of smoke aerosols from the Russian forest fires, the near-surface PM10 concentrations over Altay, Hulunbuir and Harbin increased to 61, 146 and 42 μg m −3 , respectively. In conclusion, smoke aerosols from Russian forest fires can variably influence the air quality over Central Asia, Mongolia and Northern China. [ABSTRACT FROM AUTHOR]

The Tibetan Plateau (TP), the most massive topographic feature in the world, is located at the crossroads of the Asian dust cycle and plays an important role in dust transport via topography. However, the difference in the Tibetan Plateau's topographical effect on and mechanism of dust transport from the northern and southern TP are not clear. Here, through the Tibetan topography experiments by a model, we propose a mechanism for the differential impact of the TP on the dust cycle sourced from northern and southern deserts neighboring the TP. Dust emitted from the southwestern Taklimakan Desert (TD), which is located on the north side of the TP, is mainly transported by the strong upslope winds caused by Tibetan topography to the upper layers. Consequently, it results in less dust suspended in low layers but more dust suspended in upper layers. In addition, the "narrow pipe effect" caused by massive Tibetan topography in the Hexi Corridor induces stronger dust activity in the Gobi Desert. In addition, on the southern side of the TP, more intensive dust emissions in the Great Indian Desert (GID) are induced by Tibetan topography; simultaneously, whole layers are lifted to the upper troposphere through the "heat pump effect" of the TP where the Tibetan topography acts as a "ladder". Essentially, the existence of Tibetan topography can change the near-surface wind speeds by adjusting the atmospheric circulations, which changes the dust emission location in the TD and strengthens dust emissions in GID and Gobi Desert. This study can provide clues for a better understanding of the impact of TP topography on the dust cycle. • Topography has a great impact on dust emissions and transport around Tibetan Plateau. • Tibetan topography changes wind field by adjusting the atmospheric circulations. • Topography has different effects on the dust cycle around the Tibetan Plateau. [ABSTRACT FROM AUTHOR]