The Start Date And End Date Of The Definition And Diagnosis Research

Meiyu periods is an important period of the precipitation per year at the middle and lower reaches of Yangtze River basin in China from May to August, at the end spring and the beginning of summer.Due to different understanding of the rainy season, the variety standard of the date division of Meiyu, it is hard to reach a unified. The traditional diagnostic of Meiyu partition method is mainly based on the continuous precipitation days, sunshine hours, temperature, and the subtropical high position. But because of the changeable climate, the discontinuity rainy days and temperature,the diagnosis of the start date of Meiyu have disagreed. And there are a lot of index for this classification standard. For this reason,the diagnosis of Meiyu periods has been a hot issue of academic interest.This paper uses the NPEC reanalysis data from2000to2011.Draw the θse changes in Zhejiang province from May to August by meteorological software grads (Ose sequence diagram and θse diagram field).Select the sequence diagram in mid Zhejiang Province in Jinhua area as an example.Make5days moving average variation with the Jinhua station from2000to2011, during May to July of daily precipitation data for diagnosis of division of Meiyu time.Use the θse field map changes as the delineation of the Meiyu time basis.Research and analysis the division standard of Meiyu time.Study on the division standard of the Meiyu in Zhejiang Province. The start date of Meiyu standard:When the continuous five days moving average value of a reached340, and in the five selected rainfall more than5mm a day as the start date of Meiyu. If five days without a daily rainfall reached5mm, Should choose the rain day and on the next day after2consecutive days rain that day as the start date of Meiyu. The end of the rainy season standard:The θsefield in the A340contour for5consecutive days in the north of Zhejiang province, and a wide range of mid China and Southern China region for high values of closed curve or a wide range of high value θse, Should choose one day after three consecutive days did not appear that day as the end date of Meiyu.The start date and the end date of the division results from the research that the Meiyu in Zhejiang Province,θse combined with rainfall as the diagnosis of Meiyu beginning date and the ending index of Meiyu can good resolution start date and end date of Meiyu This method compared with the traditional diagnostic method, index, data is easy to access and judgment method is simple.