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Arid Land Geography ›› 2024, Vol. 47 ›› Issue (1): 38-47.doi: 10.12118/j.issn.1000-6060.2023.287

• Climatology and Hydrology • Previous Articles     Next Articles

Influences of soil moisture anomalies in May on June precipitation in Central Asia

LIU Wenli(),CHEN Zhang(),ZHAO Yong,LIANG Yuxin   

  1. School of Atmospheric Sciences, Chengdu University of Information Technology, Chengdu 610225, Sichuan, China
  • Received:2023-06-14 Revised:2023-07-18 Online:2024-01-25 Published:2024-01-26

Abstract:

Using RA5 monthly reanalysis data from the European Centre for Medium-Range Weather Forecasts and monthly precipitation records from the Global Precipitation Climatology Centre spanning 1980 to 2019, this study examines the influence of May soil moisture anomalies on subsequent June precipitation variability in Central Asia. The findings unveil the following key insights: (1) The spatial distribution of springtime soil moisture exhibited elevated levels in Central Asia’s northern and central regions and lower levels in the southwest and southeast. Maximum standard deviations occurred in southwest Central Asia during March and April. In the north of Central Asia, soil moisture experiences a noteworthy increasing trend in March but displays a declining trend from April to May. Conversely, southwest Central Asia witnessed substantial decreases in March. (2) June precipitation in Central Asia positively correlates with local soil moisture in May. Persistent wet soil moisture anomalies from May to June contribute to increased atmospheric precipitable water, modifying regional evaporation patterns in June. Heightened evaporation leads to increased latent heat flux and reduced sensible heat flux. A small Bowen ratio indicates a relatively shallow boundary layer that promotes low-layer moist entropy and a heightened potential for convective activity. Consequently, June rainfall over the central regions of Central Asia increased. (3) A notable positive correlation exists between soil moisture in May and precipitation in June over middle Central Asia and the preceding winter Niño3.4 index. The influence of the preceding El Nino-Southern Oscillation (ENSO) on June precipitation in middle Central Asia is mediated by May soil moisture. Nonetheless, soil moisture anomalies can independently impact the variability of June precipitation, separate from the influence of ENSO.

Key words: Central Asia, soil moisture, precipitation, evaporation, ENSO