气候变化研究进展

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我国西北降水变化趋势和预估

张诗妍,胡永云,李智博   

  1. 北京大学物理学院大气与海洋科学系气候与海–气实验室,北京 100871
  • 收稿日期:2021-12-27 修回日期:2022-02-18 出版日期:2022-06-06 发布日期:2022-06-06
  • 通讯作者: 胡永云
  • 基金资助:
    大陆演化与季风系统演变

Recent changes and future projection of precipitation in Northwest China

ZHANG Shi-Yan, HU Yong-Yun, LI Zhi-Bo   

  1. Laboratory for Climate and Ocean-Atmosphere Studies, Department of Atmospheric and Oceanic Sciences, School of Physics, Peking University, Beijing 100871, China
  • Received:2021-12-27 Revised:2022-02-18 Online:2022-06-06 Published:2022-06-06
  • Contact: Yongyun Hu

摘要: 利用观测资料、GPCC再分析资料和第六次耦合模式比较计划(CMIP6)模拟结果,研究了我国西北地区近几十年及未来降水变化趋势。结果表明,1979—2019年我国西北干旱半干旱区降水在全年各季节均有显著增加,其中秋季增加最多。CMIP6模拟结果显示,随着全球变暖,我国西北地区降水在2015—2100年将继续增加。至21世纪末,在SSP2-4.5和SSP5-8.5情景下,我国西北地区年平均降水量将分别增加约13.7 %(37 mm)和25.8 %(78 mm),其中降水量增加最多的季节分别为夏季和春季。考虑到西北地区蒸发量也将随全球变暖而增加,模式平均的结果显示西北地区年平均净降水量在两种情景下的增幅分别约1.4%和4.9%,表明我国西北地区未来气候呈现显著的变湿趋势。进一步分析表明,西北地区未来降水增加可能与局地大气低层位势高度降低和上升运动加强有关。

关键词: 西北变湿, 降水, 全球变暖, 土壤湿度, 未来预估

Abstract: Using the observational data and simulation results from the Coupled Model Intercomparison Project Phase 6 (CMIP6), precipitation changes in Northwest China during 1979―2019 and under future global warming conditions are studied. Observations show that annual mean precipitation increased significantly in the arid and semi-arid areas of Northwest China over 1979―2019. Precipitation increased significantly in all seasons, with the largest increase in autumn. CMIP6 projection simulations show that precipitation in Northwest China will continue to increase from 2015 to 2100 along with global warming. Compared with that of the other regions in China, the increase of precipitation percentage is the largest in Northwest China. According to the projection of multi-mode ensemble mean, under the SSP2-4.5 and SSP5-8.5 scenarios, the increasing rates of annual mean precipitation in Northwest China are about 1.6%/(10 a) and 3.0%/(10 a), respectively. By the end of the 21st century, the annual mean precipitation in Northwest China will increase by ~13.7 % (37 mm) for SSP2-4.5 and ~25.8 % (78 mm) for SSP5-8.5. The seasons with the largest increase in precipitation are summer for SSP2-4.5 and spring for SSP5-8.5. Considering that evaporation in Northwest China will also increase with global warming, the annual mean net precipitation in Northwest China will increase by ~1.4% for SSP2-4.5 and ~4.9% for SSP5-8.5 at the end of the 21st century. Consequently, the increase of near surface soil moisture in Northwest China are ~10% for SSP2-4.5 and ~20% for SSP5-8.5. These results indicate that there is a significant wetting trend in Northwest China in the future. Further analysis also shows that future precipitation increasing in Northwest China are due to decreases of geopotential heights at the lower troposphere, which enhances upward motions.

Key words: Wetting in Northwest China, Precipitation, Global warming, Soil moisture, Future projection

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