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<p>Precipitation is a primary factor affecting drought variability in West Asia, and is crucial for monitoring local climate change. Analysis of observational data for cold-season (DJFM) precipitation in West Asia (20°–40°&#xa0;N, 40°–70°&#xa0;E) (WACP) from 1970 to 2021 reveals a significant interdecadal decrease in the late 1990s. This period coincides with a northward shift in the Middle East jet stream (MEJS) in the upper troposphere and the strengthening of the anticyclone system in the lower troposphere over West Asia, reflecting the interdecadal changes in WACP. Concurrently, cold-season sea ice in the Barents Sea (70°–80°&#xa0;N, 30°–70°&#xa0;E) (BSIC) and Atlantic Multidecadal Oscillation (AMO) exhibited significant interdecadal variability. Granger causality analysis indicates that the interdecadal change in WACP is associated with the shift of the AMO from a cold to a warm phase and the interdecadal decline in BSIC. The loss of BSIC typically results in enhanced sea surface upward turbulent heat flux and net upward longwave radiation, leading to increased sea ice surface temperature. The anomalous heating in the Barents Sea triggers quasi-barotropic anomalous anticyclonic circulation and anomalous ascent. Through the modulation of the meridional circulation anomalies, the atmospheric circulation associated with WACP is further affected, ultimately favoring a decrease in WACP. Additionally, the transition of the AMO from its cold phase to warm phase affects the atmospheric circulation linked to WACP via the downstream propagation of Rossby wave train that emanates from the Atlantic Ocean to the arid West Asia. The Community Earth System Model (CESM2) sensitivity experiments reproduced the observed precipitation anomalies and confirmed that the warm-phase AMO and reduced BSIC jointly suppress moisture transport, contributing to decreased WACP.</p>

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Interdecadal change of cold season precipitation in West Asia in the late twentieth century: impact of Arctic sea ice and AMO

  • 期刊论文

  • 发表日期：

    2026年3月24日

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  • Jiarong He,
  • Siguang Zhu,
  • Haishan Chen,
  • Zehua Qiao

摘要

Precipitation is a primary factor affecting drought variability in West Asia, and is crucial for monitoring local climate change. Analysis of observational data for cold-season (DJFM) precipitation in West Asia (20°–40° N, 40°–70° E) (WACP) from 1970 to 2021 reveals a significant interdecadal decrease in the late 1990s. This period coincides with a northward shift in the Middle East jet stream (MEJS) in the upper troposphere and the strengthening of the anticyclone system in the lower troposphere over West Asia, reflecting the interdecadal changes in WACP. Concurrently, cold-season sea ice in the Barents Sea (70°–80° N, 30°–70° E) (BSIC) and Atlantic Multidecadal Oscillation (AMO) exhibited significant interdecadal variability. Granger causality analysis indicates that the interdecadal change in WACP is associated with the shift of the AMO from a cold to a warm phase and the interdecadal decline in BSIC. The loss of BSIC typically results in enhanced sea surface upward turbulent heat flux and net upward longwave radiation, leading to increased sea ice surface temperature. The anomalous heating in the Barents Sea triggers quasi-barotropic anomalous anticyclonic circulation and anomalous ascent. Through the modulation of the meridional circulation anomalies, the atmospheric circulation associated with WACP is further affected, ultimately favoring a decrease in WACP. Additionally, the transition of the AMO from its cold phase to warm phase affects the atmospheric circulation linked to WACP via the downstream propagation of Rossby wave train that emanates from the Atlantic Ocean to the arid West Asia. The Community Earth System Model (CESM2) sensitivity experiments reproduced the observed precipitation anomalies and confirmed that the warm-phase AMO and reduced BSIC jointly suppress moisture transport, contributing to decreased WACP.