This article examined the meteorological features of the second Meiyu/Baiu episode(hereafter Meiyu Ⅱ)in 1998 and the results are summarized as follows:(1)The Meiyu Ⅱ period in 1998 has been the longest and the most ...This article examined the meteorological features of the second Meiyu/Baiu episode(hereafter Meiyu Ⅱ)in 1998 and the results are summarized as follows:(1)The Meiyu Ⅱ period in 1998 has been the longest and the most delayed ending one since 1885,which caused the great flood around the Yangtze River Basin.The circulation situation in Meiyu Ⅱ is so typical that the average geopotential height and wind fields at 500 hPa and 850 hPa are very similar to monthly mean in June.The abnormal circulation in Meiyu Ⅱ is associated with an adjusting of the Okhotsk high and short period south-north oscillation of the subtropical high.(2)The heavy rainfall around the Yangtze River during Meiyu Ⅱ period is closely related to a persistent shear line,a clear eastward moving vortex structure and a very strong jet flow at lower levels.It is very clear that the strong divergence at higher levels and convergence at lower levels occurred in situ during Meiyu Ⅱ period. (3)It is very clear that the convective activity propagates eastward quickly with a period about 7 days during Meiyu Ⅱ period.展开更多
基金National Natural Science Foundation of China under Grant No.49794030.
文摘This article examined the meteorological features of the second Meiyu/Baiu episode(hereafter Meiyu Ⅱ)in 1998 and the results are summarized as follows:(1)The Meiyu Ⅱ period in 1998 has been the longest and the most delayed ending one since 1885,which caused the great flood around the Yangtze River Basin.The circulation situation in Meiyu Ⅱ is so typical that the average geopotential height and wind fields at 500 hPa and 850 hPa are very similar to monthly mean in June.The abnormal circulation in Meiyu Ⅱ is associated with an adjusting of the Okhotsk high and short period south-north oscillation of the subtropical high.(2)The heavy rainfall around the Yangtze River during Meiyu Ⅱ period is closely related to a persistent shear line,a clear eastward moving vortex structure and a very strong jet flow at lower levels.It is very clear that the strong divergence at higher levels and convergence at lower levels occurred in situ during Meiyu Ⅱ period. (3)It is very clear that the convective activity propagates eastward quickly with a period about 7 days during Meiyu Ⅱ period.
