关键词: 大气水汽, 大气液态水, 祁连山东段, 时空分布, 微波辐射计

Abstract:

Under the background of climate warming, the global drought risk increases, especially in the arid and semi-arid region of northwestern China, which is highly sensitive to climate change, and the drought seriously restricts the sustainable development of regional economy. The scientific development of cloud water resources is an effective way to solve the shortage of water resources in this region. Based on the ground-based multi-channel microwave radiometer data and conventional meteorological observation data at Yongdeng national meteorological observation station in Gansu, the spatial and temporal distributions of atmospheric water vapor and liquid water in eastern section of the Qilian Mountains were analyzed, and their evolution characteristics before rainfalls with different properties were discussed. The results are as follows: (1) Under the influences of atmospheric circulation, topography, boundary layer and local and regional weather and climate conditions, etc., the atmospheric water vapor more than 98% in eastern section of the Qilian Mountains concentrated below 6.0 km, and the water vapor density decreased with height, while the liquid water content firstly increased and then decreased with height. The water vapor density and liquid water content increased significantly on rainy days, and the height with the maximum liquid water content decreased. (2) The seasonal variations of water vapor and liquid water were obvious. The atmospheric precipitable water in summer was much more than that in winter, and the vertical extension of liquid water and the height with maximum content in summer were higher than those in winter. (3) The diurnal variations of water vapor and liquid water were obvious, and they had seasonal differences. The diurnal peak value of water vapor appeared from afternoon to nightfall, and the trough value appeared from morning to noon. The occurring time of peak and trough values of water vapor in summer half year were later than those in winter half year, and the variation range was larger. The vertical extension of liquid water in the daytime was higher than that in the nighttime, and the distribution of liquid water in summer half year was deeper than that in winter half year. (4) There were main periodic changes with about 10-20 days and 8 days of precipitable water vapor in eastern section of the Qilian Mountains, and the periods with 4-7 days and 21-32 days were obvious in summer and autumn. (5) The water vapor and liquid water jumpily increased before precipitation with different properties, but there were differences about jumping increment, time and height. The time of jumping increase was the earliest before cumulus-stratus mixed cloud precipitation from July to August in eastern section of the Qilian Mountains, and the increment was the maximum and the jumping height was the highest before cumulus precipitation, while the jumping height was lower significantly before the precipitation of warm cloud.

Key words: atmospheric water vapor, atmospheric liquid water, eastern section of the Qilian Mountains, temporal and spatial distribution, microwave radiometer