The isotopic data(δ~18O and δD) in precipitation at New Delhi,the IAEA/WMO station in southwest monsoon region,were collected and analyzed.A few absentδD records were predicated based on the monsoonal water meteoric line,and finally the 36-year deuterium excess series was constructed by the isotopic data.The NCEP/NCAR Reanalysis Data,the relative humidity and zonal wind speed at 1000 hPa level over the western Arabian Sea,as well as the monsoon rainfall data in the northwest of India,have been used in order...