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YANG Xiu-Qun 1 , XIE Yi-Jun 1 , and XIE Qian 2 School of Atmospheric Sciences, Nanjing University

Winter-to-summer transition of atmospheric circulation over subtropical East Asia: Does it indicate the earliest onset of summer monsoon?. YANG Xiu-Qun 1 , XIE Yi-Jun 1 , and XIE Qian 2 School of Atmospheric Sciences, Nanjing University

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YANG Xiu-Qun 1 , XIE Yi-Jun 1 , and XIE Qian 2 School of Atmospheric Sciences, Nanjing University

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  1. Winter-to-summer transition of atmospheric circulation over subtropical East Asia: Does it indicate the earliest onset of summer monsoon? • YANG Xiu-Qun1, XIE Yi-Jun1, and XIE Qian2 • School of Atmospheric Sciences, Nanjing University • Institute of Meteorology, PLA University of Science & Technology

  2. 东亚副热带大气环流型季节转换的三维特征 • 东亚副热带大气环流型季节转换的机理 • - 江南春雨的潜热反馈作用

  3. Regionality of Asian summer monsoon (ASM) (Wang and Lin, 2002)

  4. Onset timing of ASM （Qian and Lee）

  5. Issues under debate （1）What is the attribute of rain before pentad 28? （2）If can the onset timing of ASM be earlier than pentad 28? Rain rate 850hPa wind Pentad 28

  6. Persistent 850hPa southwesterly

  7. Persistent southern China rain

  8. Land-sea thermal contrast for 500-200hPa atmospheric temperature Meridional land-sea thermal contrast Zonal land-sea thermal contrast

  9. 东亚副热带大气环流的季节演变 经向环流反转 V200-V850反转 降水率持续 500~200hPa纬向 海陆热力差反转 22候(4月16-20日)

  10. 850hPa 低层风场的 季节演变 925hPa 纬度 1000hPa 候

  11. 反转前后 1000hPa环流的比较 22候前(a)的 1000hPa流场 22候后(b)的 1000hPa流场

  12. 反转前后 200hPa环流的比较 22候前(a)的 200hPa流场 22候后(b)的 200hPa流场

  13. 反转前后降水场的比较 China 22候前 China 22候后 CMAP 22候前 CMAP 22候后

  14. 东亚副热带大气环流逐候的季节演变 (H vs T) 冬季 正压结构 夏季 斜压结构

  15. 东亚副热带大气环流的季节转换 冬季： 68, 69, 70, 71, 72, 1, 2, 3, 4, 5, 6 候 夏季：31, 32, 33, 34, 35, 36, 37, 38 候 空间型相关性 22候 22候

  16. 东亚副热带大气环流逐候的季节演变 局地季风环流的建立

  17. 大气非绝热加热率和垂直速度的季节演变 第22候

  18. 大气非绝热加热率和垂直速度的季节演变 第22候

  19. 江南春雨释放的凝结潜热加热对夏季环流型触发作用的概念图江南春雨释放的凝结潜热加热对夏季环流型触发作用的概念图 Z A C 凝结潜热加热 Warm Cool N C A E S 热力强迫的准地转位涡平衡关系式：

  20. CCM3 experiments with and without Feedback of Released Latent Heat (FRLH) from Jan 1 With FLH Without FLH

  21. With FLH Without FLH

  22. With FLH Without FLH

  23. 主要结论 • 东亚副热带大气环流型从冬季型到夏季型的季节转换发生于22候（4月16~20日），这可标志着副热带夏季风的最早建立。 开始于3月份的江南地区持续性降水在22候之前为“春雨”属性，22候之后归属“夏季风雨季降水”。 • 在亚洲季风区大的环流背景尚未发生季节转换、大尺度经向海陆热力梯度尚未反转的情况下，高原特殊地形形成的江南春雨的凝结潜热加热可以触发夏季风在东亚副热带地区率先建立。

  24. 谢 谢！

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