Wind variations at the Nanyue Mountain Observatory as indicators for two different kinds of heavy precipitation in Hunan

Based on the wind field observations of Nanyue Mountain station during 1954-2011, observational data of the meteorological elements in Hunan from April to September during 2005-2011, NCEP/NCAR global reanalysis data (2.5°×2.5°) during 1954-2011 and NECP analysis data (1.0°×1.0°), the representativeness of data from Nanyue Mountain station in relation to lower tropospheric circulation was discussed in terms of the seasonal and interannual variability. And then the indicative function of the wind field evolution characteristics for two cases of different types of torrential rain in Hunan was analyzed. The results show that Hunan is near the center of interannual and intraseasonal maximum correlation between the data from Nanyue Mountain station and the data of global reanalysis wind field, the correlation area is at the downstream of seasonal prevailing winds through the year, with the best correlation observed in the summer half year, especially from June to August. There are also positive correlations between the temperature, depression of the dew point, wind direction and speed observed at Nanyue Mountain station with that observed at many sounding stations in Hunan at the corresponding 850 hPa, in which the temperature correlations are the best, the correlations of depression dew point, wind direction and wind speed are well-matched with the correlation coefficient between 0.49-0.74.