基於HadGEM3-GC2模式的中國東部夏季降水變率在全球增暖下的可能變化

Citation:

Duan, Y. W., P. L. Wu, X. L. Chen, and Z. G. Ma, 2018: Assessing global warming induced changes in summer rainfall variability over eastern China using the latest Hadley Centre climate model HadGEM3-GC2. Adv. Atmos. Sci., 35(8), 1077-1093，doi: 10.1007/s00376-018-7264-x.

基於HadGEM3-GC2模式的中國東部夏季降水變率在全球增暖下的可能變化

段亞雯，Peili Wu, 陳曉龍，馬柱國

在年際和年代際尺度上，中國東部的夏季降水異常通常表現為明顯的經向型特徵，對區域性旱澇產生影響。在氣候變化影響下，除了長期趨勢外，降水變率尤其是空間分布特徵的變化對該地區的農業生產、水資源調度等具有重要意義。通過對比分析英國氣象局Hadley中心最新氣候模式HadGEM3-GC2的驟增4倍CO2及工業革命前控制試驗，本文研究了增暖背景下該地區夏季降水模態的可能變化。基於EOF分析的結果表明，在該模式的控制實驗中，前兩個降水模態佔總降水變率的20%。EOF1是一個單極型，與ENSO事件的發展位相相關；而EOF2為偶極型，與ENSO事件的衰減位相相關。驟增4倍CO2強迫下，年際尺度上，偶極型變為了主導模態，這主要是由於印度洋的作用增強所致。而年代際尺度上，降水模態受到更多來自高緯度的影響，增暖下主導模態與控制實驗差距較大，表現出更強的東-西向分布特徵。

關鍵詞：降水變率，全球增暖，ENSO，HadGEM3-GC2

Abstract

Summer precipitation anomalies over eastern China are characterized spatially by meridionally banded structures fluctuating on interannual and interdecadal timescales, leading to regional droughts and floods. In addition to long-term trends, how these patterns may change under global warming has important implications for agricultural planning and water resources over this densely populated area. Using the latest Hadley Centre climate model, HadGEM3-GC2, this paper investigates the potential response of summer precipitation patterns over this region, by comparing the leading modes between a 4×CO2 simulation and the model』s pre-industrial control simulation. Empirical Orthogonal Function (EOF) analyses show that the first two leading modes account for about 20% of summer rainfall variability. EOF1 is a monopole mode associated with the developing phase of ENSO events and EOF2 is a dipole mode associated with the decaying phase of ENSO. Under 4×CO2 forcing, the dipole mode with a south–north orientation becomes dominant because of a strengthened influence from excessive warming of the Indian Ocean. On interdecadal time scales, the first EOF looks very different from the control simulation, showing a dipole mode of east–west contrast with enhanced influence from high latitudes.

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