Why does a decrease in cloud amount increase terrestrial evapotranspiration in a monsoon transition zone?

Terrestrial evapotranspiration plays a critical role in drought monitoring and water resource management. Changes in evapotranspiration are significantly influenced by cloud-related precipitation and radiation effects. However, the impact of cloud amount (CA) on evapotranspiration through its influe...

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Bibliographic Details
Published in:Environmental research letters 2024-04, Vol.19 (4), p.44047
Main Authors: Liu, Wenhui, Yue, Ping, Wu, Xianghua, Li, Junjun, Shao, Naifu, Zhu, Bin, Lu, Chunsong
Format: Article
Language:English
Subjects:
Arid regions
Arid zones
Aridity
Climate change
cloud amount
cloud type
Convective clouds
Drought
East Asian summer monsoon
Enthalpy
Environmental monitoring
Evapotranspiration
Global warming
Hydrologic cycle
Monsoons
Precipitation
Radiation
Radiation effects
Resource management
Semi arid areas
Semiarid lands
Sensible heat
Short wave radiation
the semi-arid region
Transition zone
Water resources management
Wind
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Summary:Terrestrial evapotranspiration plays a critical role in drought monitoring and water resource management. Changes in evapotranspiration are significantly influenced by cloud-related precipitation and radiation effects. However, the impact of cloud amount (CA) on evapotranspiration through its influence on precipitation remains uncertain, especially in the transition zone affected by the East Asian summer monsoon (EASM), which limits the understanding of the water cycle. Therefore, this study deeply explores the impact of CA on evapotranspiration and its potential physical mechanisms in Northwest China. The results show that the correlation between 31-year average evapotranspiration and CA is negative only in the semi-arid region and is positive in other climatic regions of Northwest China. This unique negative correlation is related to the change of precipitation pattern in the semi-arid region caused by the weak EASM. Smaller CA in weak monsoons results in more short-wave radiation reaching the surface, larger sensible heat, and weaker convective inhibition. Consequently, the proportion of convective clouds (CCs) increases and precipitation from these CCs enhances evapotranspiration. Less CA increases evapotranspiration and potentially exacerbates aridity in the semi-arid region of Northwest China. These results emphasize the role of cloud type in evapotranspiration. It is well known that global warming can change cloud type with more CCs. Therefore, this study sheds new light on evapotranspiration change under global warming.
ISSN:1748-9326
1748-9326
DOI:10.1088/1748-9326/ad3569