应用气象学报 (Mar 2024)
Distribution Characteristics of Water Vapor and Liquid Water in the Warm Zone of a Stratiform Cloud in North China
Abstract
The water vapor content is a crucial factor in assessing cloud water resources, and the content and distribution of cloud liquid water are important reference indicators for determining the quantity and location of catalysts in weather modification operations. Based on inversion results of G-band water vapor radiometer, ground-based microwave radiometer and cloud radar, combined with FY-4A measurements, meteorological observations, radar products and reanalysis data, distribution characteristics of water vapor and liquid water in the warm zone of a stratiform cloud is studied in North China on 15 May 2021, in order to provide some reference for the study of macro-micro structure and precipitation mechanism of the warm zone of precipitable stratiform clouds and weather modification operations.The horizontal distribution of the warm zone is not uniform, and there is also clear horizontal inhomogeneity in the distribution of water vapor and liquid water. The integrated water vapor content and liquid water path, detected by G-band water vapor radiometer, fluctuate during the level flight of aircraft, with maximum values of 4.00 cm and 1.87 mm, respectively. As the cloud top height and cloud thickness decrease in the warm zone, the integrated water vapor content and liquid water path also decrease to 0.89 cm and 0.13 mm. The liquid water path detected by G-band water vapor radiometer is primarily derived from low-level clouds in the warm zone and is also influenced by high-level supercooled water clouds or mixed clouds. With the onset of precipitation, the ground-based microwave radiometer detected a surge in integrated water vapor content and liquid water path, reaching peaks of 8.62 cm and 3.85 mm, respectively. The thickness of liquid water content accumulation zone, as well as its maximum value and height in the vertical direction, initially increase and then decrease with precipitation. The temporal and spatial evolution of liquid water is highly significant for understanding the occurrence and development of precipitation, as well as for identifying the timing and location of precipitation enhancement in warm zones. The liquid water content retrieved by the cloud radar also exhibits a jump phenomenon. When the reflectivity factor of the cloud radar is high and the falling velocity and velocity dispersion of particles are high below 1 km, the liquid water content is abundant, leading to significant rainfall on the ground. Particle collision is the primary mechanism of precipitation in the warm zone.
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