ISSN 1000-0526
CN 11-2282/P
CN 11-2282/P
Archive > Volume 50 Issue 10 > 2024,50(10):1175-1186. DOI:10.7519/j.issn.1000-0526.2024.040801 Prev Next
Microphysical Characteristics and Regional Differences of Summer Severe Convective Cloud in Xinjiang Based on NPP/VIIRS Data
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Abstract:
Hail disaster is one of the main disastrous weather events in Xinjiang, with strong regional characteristics, multiple occurrences, and severe disasters. It is of great significance to conduct research on the microphysical characteristics of hail clouds in different regions of Xinjiang. This article uses severe convective weather processes in Xinjiang from 2015 to 2021 and corresponding NPP/VIIRS satellite data as well as satellite cloud microphysical inversion technology and quantitatively analyzes the microphysical characteristics of hail clouds and deep convective clouds. A comparative study is conducted on the differences in microphysical parameters of hail clouds in northern and southern Xinjiang. The results show that the crystallization temperature of hail cloud (-34.0℃) is lower than that of deep convective cloud (-30.5℃), the height of deep convective cloud top is higher, and the hail cloud top has anvil structure. Hail mostly occurs in June-July in northern Xinjiang, and in May-July in southern Xinjiang. Hail time is mainly distributed from 15:00 BT to 20:00 BT. Hail in southern Xinjiang occurs in the wee hours and morning, with higher frequency than in northern Xinjiang. The mean durations of hail in northern and southern Xinjiang are 12.60 min and 12.27 min, and the mean maximum diameters of hail are 13.53 mm and 12.80 mm, respectively. The hail cloud top in northern Xinjiang is higher, the duration of hail is longer, the diameter of hail is larger, and the freezing temperature is lower than that in southern Xinjiang. The mean cloud bottom temperature and cloud bottom height of hail in northern and southern Xinjiang are 5.15℃, 1.96 km and 4.85℃, 2.19 km, respectively. The cloud bottom temperature in northern Xinjiang is warmer than that in southern Xinjiang, and the cloud bottom height is lower than that in southern Xinjiang. The mean rising speed of cloud base in southern Xinjiang (2.07 m·s-1) is 1.13 times that in northern Xinjiang (1.84 m·s-1), and the average thickness of hail cloud in northern Xinjiang (8.90 km) is 1.25% greater than that in southern Xinjiang (8.79 km). Influenced by human activities, industrial pollution and other factors, the mean concentration of condensation nuclei at the bottom of hail cloud in northern Xinjiang (396 cm-3) is 65% higher than that in southern Xinjiang (240 cm-3) where agriculture is dominant. The mean maximum supersaturations of hail cloud bottom are 0.55% and 0.85%, respectively. Affected by the strong updraft, the growth time of hail cloud particles is short, each growth zone develops slowly, and there is no rain embryo formation zone. Targeted seeding of hygroscopic nuclei in the middle and lower layers of the cloud in advance can promote the formation of precipitation at the bottom of the cloud as soon as possible, and excessive seeding of AgI ice nuclei near the 0℃ layer will compete for the supercooled water in the cloud, which can achieve the goal of increasing rain and preventing hail.
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