江淮流域夏季强降水事件的主导模态（英文）

Dominant variation modes associated with Yangtze–Huai River Basin summer heavy rainfall events

基于29年夏季平均的日降水率及降水标准偏差的空间分布,本文将江淮流域分为南、北两个子区域。谱分析结果显示,3–7天高频天气尺度模态是江淮流域北部夏季降水的主导模态,10–20、15–40天的变化模态次之。相比之下,3–7、10–20天变化模态在江淮流域南部均很显著,7–14、15–40、20–60天的低频模态次之。高频天气尺度扰动在江淮流域北部强降水事件形成过程中起绝对主导作用,而在江淮流域南部,高频、中等频次、低频扰动的作用相当。

The Yangtze–Huai River Basin(YHRB)always suffers from anomalously heavy rainfall during the warm season,and has been well explored as a whole area during the past several decades.In this study,the YHRB is divided into two core regions-the northern YHRB(nYHRB)and southern YHRB(sYHRB)-based on 29-year(1979–2007)June–July–August(JJA)temporally averaged daily rainfall rates and the standard deviation of rainfall.A spectral analysis of JJA daily rainfall data over these 29 years reveals that a 3–7-day synoptic-timescale high-frequency mode is absolutely dominant over the nYHRB,with 10–20-day and 15–40-day modes playing a secondary role.By contrast,3–7-day and 10–20-day modes are both significant over the sYHRB,with 7–14-day,15–40-day,and 20–60-day modes playing secondary roles.Based on a comparison between bandpass-filtered rainfall anomalies and original rainfall series,a total of 42,1,5,and 3 heavy rainfall events(daily rainfall amounts in the top 5%of rainy days)are detected over the nYHRB,corresponding to 3–7-day,7–14-day,10–20-day,and 15–40-day variation disturbances.Meanwhile,a total of 28,8,12,and 6 heavy rainfall events are detected over the sYHRB,corresponding to 3–7-day,7–14-day,10–20-day,and 20–60-day variation disturbances.The results have important implications for understanding the duration of summer heavy rainfall events over both regions.