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Intensification and Expansion of Soil Moisture Drying in Warm Season Over Eurasia Under Global Warming
Author(s) -
Gu Xihui,
Zhang Qiang,
Li Jianfeng,
Singh Vijay P.,
Liu Jianyu,
Sun Peng,
He Chunyang,
Wu Jianjun
Publication year - 2019
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1029/2018jd029776
Subject(s) - environmental science , precipitation , climatology , arid , monsoon , climate change , global warming , aridity index , water content , representative concentration pathways , ecosystem , atmospheric sciences , population , geography , climate model , ecology , geology , oceanography , geotechnical engineering , meteorology , demography , sociology , biology
Abstract Soil moisture (SM) is a key hydrological component regulating the net ecosystem energy exchange at the land‐atmosphere boundary layer over the continents via heat fluxes and relevant feedback on precipitation. Due to its ecological and meteor‐hydrological implications, SM change is of great significance in Eurasia that has the highest population density and fragile ecological environment. Using monthly data from the Global Land Data Assimilation System, this study investigated SM changes over Eurasia during the warm season (May–September). It was found that recent 63 years witnessed widespread decreasing SM across Eurasia during the warm season. Regions with a drying SM tendency kept expanding till the 1990s. Specifically, the largest decreasing magnitude of SM with the aridity index ranging 0.5–0.6 and 1.0–1.1 was found along the semi‐arid and dry‐humid transition regions, respectively. In addition, more significant drying SM was observed in Sahel, northern Asia, northeastern Asia, and western Europe. Weakening West African monsoon (WAM)/East Asia summer monsoon did not benefit the propagation of water vapor flux to the Sahel regions/northeastern and northern Asia, and hence decreased SM in these regions. Besides, results by the maximum covariance analysis highlighted the roles of warming climate in SM variations over Eurasia during the warm season. Global climate models also indicate decreased SM due to global warming and projects continuously decreasing SM in the warm season over the 21st century under Representative Concentration Pathway (RCP)2.6, RCP4.5, RCP6.0, and RCP8.5 scenarios. Decreasing SM across the Eurasia and related ecological and environmental implications should cause international concern.