Estimation and Analysis of Precipitation Cloud Base Height in China
Based on daily data of precipitation, air pressure, temperature, average vapor pressure and average relative humidity in 622 stations released by the National Meteorological Information Centre of China during 1960-2013 and the data collected at 02:00, 08:00, 14:00 and 20:00 BT from 25 August to 25 September 2013 by 249 stations, the algorithms of China Meteorological Administration, Barnes and Georgakakos are applied to calculate the height of lifting condensation level to approximate height of precipitation cloud base, and then the spatiotemporal distribution characteristics of cloud base height in China are analyzed. The results indicate that (1) the spatial distribution of precipitation cloud base heights on the annual, seasonally and hourly bases show consistent with precipitation levels Ⅰ and Ⅱ. The cloud base height gradually increases from southeast to northwest, and the interannual difference is not significant. (2) The regional difference is significant. In term of four nature zones in China (North, South, Northwest and the Tibetan Plateau), the precipitation cloud base heights of the Northwest and the Tibetan Plateau are higher than the national mean. The base height decreases gradually year by year except the Tibetan Plateau. (3) Seasonally, the precipitation cloud base height in spring and summer is higher, and the lowest is in winter. (4) Diurnal variation of the precipitation cloud base height is significant and the lowest at 08:00 and the highest is at 14:00. (5) By using the three algorithms, the correlation coefficients between the cloud base height and precipitation are -0.47, -0.46 and -0.44, and between the cloud base height and relative humidity are -0.81, -0.81 and -0.79, respectively.