Effects of spring Tibetan Plateau land temperature anomalies on early summer floods/droughts over the monsoon regions of South East Asia
Effects of spring Tibetan Plateau land temperature anomalies on early summer floods/droughts over the monsoon regions of South East Asia
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DOI：
10.1007/s00382-021-06053-8
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发表时间：
2022-01
期刊：
影响因子：
4.6
通讯作者：
I. Diallo;Y. Xue;Qiu-shi Chen;X. Ren;W. Guo
中科院分区：
文献类型：
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作者：
I. Diallo;Y. Xue;Qiu-shi Chen;X. Ren;W. Guo
最近的观测和模拟研究表明，青藏高原（TP）春季地表温度（LST）和次表层温度（SUBT）对东亚下游夏季干旱/洪水事件的重大影响，突出了LST/SUBT在亚季节到季节预测（S2 S）中的潜在应用。本文利用国家环境预报中心-全球预报系统/简化生物圈模式（GFS/SSiB 2），研究了1998年6月长江以南特大洪水中，春季末暖LST异常对TP的潜在影响。数值试验结果表明，5月长江三角洲上空LST偏暖可能是造成1998年长江以南地区特大洪水的重要原因，LST对长江以南地区和中国东南部地区降水异常的重现率分别为57%和64%。进一步的分析揭示了春季TP的LST对夏季南亚和东亚降水的可能影响，并确定了一些热点，这表明TP的春季LST效应不仅限于长江流域，但要大得多的规模。青藏高原暖LST/SUBT触发了一场强波动活动，沿高空西风急流沿着向东传播，导致大气斜压不稳定增强，南亚高压加强并东移，导致水汽辐合和对流不稳定增强，有利于东亚下游地区的暴雨。2003年6月长江流域南部（北方）发生了严重的干旱（洪涝），而2003年6月长江流域南部（北部）发生了严重的干旱（洪涝）。模拟结果进一步证明了TP春季地表温度异常在调节南亚和东亚夏季极端水文气候事件（如干旱和洪水）中的重要性。本研究表明，考虑LST/SUBT异常有很强的潜力，更熟练的S2 S预测极端水文气候事件，如洪水，干旱和热浪在南亚和东亚。
Recent observational and modeling studies have demonstrated the substantial influence of the Tibetan Plateau (TP) spring land surface temperature (LST) and subsurface temperature (SUBT) on downstream summer droughts/floods events in East Asia, highlighting the potential application of LST/SUBT on sub-seasonal to seasonal prediction (S2S). In this study, we employ the National Centers for Environment Prediction—Global Forecast System/Simplified Simple Biosphere model version 2 (GFS/SSiB2) to investigate the potential role of the late spring warm LST anomaly over the TP on the extraordinary June 1998 flood in the south of the Yangtze River region. Numerical experiments indicate that the warmer (above normal) May LST over the TP may contribute to the extreme flood of 1998 over the south of the Yangtze River region, with the LST reproducing about 57% and 64% of observed above-normal rainfall anomaly over the south of the Yangtze River region and southeastern China, respectively. Further analyses reveal a possible effect of springtime TP’s LST on summer southern and eastern Asian rainfall and identify some hot spots, suggesting that the TP’s spring LST effect is not only limited to the Yangtze River region, but to a much larger scale. The imposed warm LST/SUBT over the TP triggers a strong wave activities propagating eastward along the upper-level westerly jet, associated with an increase of the atmospheric baroclinic instability as well as a strengthening and southeastward movement of the South Asian high, leading to intensified moisture convergence and convective instability favorable to the excessive rainfall in the downstream region of East Asia. The results of the 1998 case have also been compared with the results from year of 2003, which had a very cold spring LST anomaly over the TP and a severe downstream June 2003 drought (flood) in southern (northern) of the Yangtze River Basin area. Simulation results provide further evidence of the great importance of the TP spring land surface temperature anomaly in regulating summer extreme hydroclimatic events (e.g. droughts and floods) in South and East Asia. The present study suggests that consideration of LST/SUBT anomalies has a strong potential for more skillful S2S prediction of extreme hydroclimatic events such as floods, droughts and heatwaves over both Southern and Eastern Asia.