Xinjiang is located in inner Eurasia and is characterized by a typical mountain-basin system composed of "Three Mountains and Two Basins" (Figure 1). Its unique geographic location and topographic features result in a typical arid and semiarid climate that is highly sensitive to global climate change (Wu et al., 2010;Zhao et al., 2010). From the mid-1980s to 2000, the average annual air temperature increased by 0.7°C compared to that measured from 1961 to the mid-1980s in northwest China (Shi et al., 2006;Yao, Chen, Yu, et al., 2020); this increase is much higher than the global average increase of approximately 0.2°C (Shi et al., 2006;L. Wang et al., 2020). In an interesting phenomenon observed in northwest China, the regional climate changed from warm-dry to warm-wet conditions in the mid-1980s under the background of global warming (B.
The amount, frequency and intensity of extreme precipitation over Xinjiang have increased dramatically under the wetting trend in Northwest China, but long‐term trends in the precipitation‐recycling process remain largely unexplored. Based on dynamic recycling model and MERRA2 reanalysis, we revealed a mean recycling ratio for extreme precipitation in Xinjiang of 42.3% with a growth rate of 2.3% decade−1 during 1982–2019. The increasing trend of extreme precipitation was almost equally attributed to increased recycling precipitation (49%) and external precipitation (51%). The extreme precipitation in Xinjiang exhibited two peak centers, the Tianshan Mountains region (TS) and Kunlun Mountains region (KL), highlighting variations in the water cycle. Specifically, the external cycle predominated the increased extreme precipitation in TS (61%), while the recycling process mainly influenced the increase in KL (67%) due to markedly enhanced evapotranspiration. Moisture source attribution further proved the crucial role of evapotranspiration from Xinjiang and its vicinity in extreme precipitation.
The tropopause aerosol layer (TAL) represents the increase of aerosols
in tropopause. It was first discovered over Asia but was found in this
study to also occur over South America and Africa owing to the combined
effects of monsoon dynamics and pollutant emissions. Over Asia, the TAL
has the highest altitude and widest spread due to strong deep convection
and the upper troposphere anticyclonic system there. TAL intensity is
highest in South America due to heavy pollutant emissions. Anthropogenic
pollution from India and western China produces two Asian TAL centers,
whereas widespread wildfires result in single centers over South America
and Africa. TAL radiative forcing induced by carbonaceous aerosols at
the top of the atmosphere has warming effects over Asia (+0.21 W m−2),
whereas cooling effects occur over South America (−0.47 W m−2) and
Africa (−0.12 W m−2) owing to the divergent strengths of black-carbon
absorption and organic-carbon scattering.
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