Meteorological characteristics during the second Meiyu episode in 1998

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 occured 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.