1.College of Atmospheric Physics,Nanjing University of Information Science and Technology;2.Yunnan Meteorological Bureau,Kunming
In this paper, the coupling Noah/Single Layer Urban Canopy scheme coupled with WRF (V3.9.1) model is used as a control case to study the effects of land use type (Md04 scheme), land surface process (NoUCM scheme) and lake (Nolake scheme) on the intensity of urban heat island and the horizontal and vertical spatial distribution characteristics of urban meteorological elements in Kunming. The main conclusions are as follows: (1) The average daily variation of urban heat island intensity in four cases is basically the same. The UHI intensity is weak in the daytime and strong at night, and reaches the maximum at about 2000 BT. In the case of Control-NoUCM (Nolake), the average daily maximum difference is -0.79oc (+1.07oc). (2) From the energy balance equation analysis of Control-Md04 case, the difference of sensible heat (latent heat) energy is +46.18 (-79.71) w/m2，and the release of latent energy is greater than the absolute value of sensible energy. In the case of Control-NoUCM,the difference of sensible heat (latent heat) energy is -40.88 (+29.60) w/m2. NoUCM scheme does not consider the heat storage and shielding of geometric buildings, and most of them are absorbed by the surface, resulting in a large absolute value of sensible heat flux. (3) In the four cases, the boundary layer height reaches the maximum (minimum) value at 1500(0700) BT. The height of urban boundary layer in NoUCM (Nolake) decreased by about 103m (32m), while that in Md04 case increased by about 102m. (4) The experimental results of the influence of lakes on the circulation of urban heat island show that the vertical movement over the lake is weak, while the horizontal lake land wind is strong, which is conducive to the transportation of water vapor to the city, increasing the humidity of dry air and making the water vapor content higher, thus increasing the release of latent heat energy, reducing the sensible heat flux and reducing the temperature gradient.