Chinese Academy of Meteorological Sciences
As an important feature in the macroscopic characteristics of clouds, the vertical structure characteristics of clouds determines different cloud types, and further affects the energy budget balance of earth atmosphere system through absorbing and emitting radiation. Therefore, the research about the vertical structure characteristics of clouds is always an important subject of cloud physics. As an instrument for observing the vertical structure characteristics of clouds, sounding balloon can penetrate clouds to achieve temperature and humidity profiles in high resolution. And based on this information, the vertical structure of clouds can be precisely identified by some method. In this paper, observation data of our national operational radiosonde sites are used to identify the vertical structure of clouds by relative humidity threshold method, and cloud boundary are further tested by comparing with ceilometer and “FengYun-4” satellite. It is on this basis that mean vertical distribution of one-, two-, and three-layer clouds is obtained from 2015 to 2017 and analyzed in daily, seasonal and regional variations. The results indicate that (1) one-layer clouds are generally located at altitudes that fall somewhere between the altitudes of the two- and three-layer cloud configurations, and with the increase of the number of cloud layers, the uppermost layer is more higher and the lowest layer is more lower. (2) In diurnal variation, the lowest cloud base height of single and multilayer clouds at noon is higher than those at morning, and the uppermost cloud top height of single and multilayer clouds at evening is higher than those at morning and noon, the variation of the mid layer in multilayer clouds is less than the uppermost layer and lowest layer. (3) In seasonal variation, there are a greater number of clouds with more vertically developed during summer than other seasons, suggesting that development of cloud is favorable under warm atmospheric conditions. (4) The regional variation of cloud vertical distribution in China shows obvious latitudinal variation trend. Thin clouds with higher cloud base centered on the Tibetan Plateau in southwest gradually transform to thick clouds but lower cloud base in coastal area of southeast, which indicates that different cloud type directly affected by the difference of the geographical condition and climate zone.