ISSN 1000-0526
CN 11-2282/P
CN 11-2282/P
Archive > Volume 47 Issue 2 > 2021,47(2):192-204. DOI:10.7519/j.issn.1000-0526.2021.02.006 Prev Next
Forecast on Convective Cloud Condition and Analysis on Seeding Plan of an Artificial Rainfall Mitigation Case
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Abstract:
In order to do well artificial rainfall mitigation on specific target period and area, cloud seeding condition such as cloud properties and structure, moving speed and direction, cloud evolution, precipitation mechanism and so on was forecast by using Cloud Precipitation Explicit Forecast System (CPEFS). The results showed that on 8 August 2017 in Hohhot there were scattering convective clouds, with coldwarm mixed vertical structure and strong updrafts. Horizontal scale of single convective cloud was about tens of kilometers, and lifetime was about 1.5-3.0 hours. 〖JP2〗Cloud top (bottom) height of 10 (3) km, 〖JP〗and 0℃ layer height of 4.3 km. Cloud microphysics aspects were with high content of snow and graupel, low cloud water content in warm regions, maximum content of supercooled water of 0.7 g·kg-1, less ice crystals in areas with rich supercooled water, mainly with cold precipitation mechanism. Convective clouds first appeared in the northwest direction of the core zone in Hohhot, rapidly developing and moving eastward and southward gradually to the core zone at the speed about 30-40 km·h-1. Satellite and radar observations also showed there were convective clouds. The forecasted generation time of convective clouds was 1-2 hours later than observation, but moving direction was consistent with observation. Moving speed was 10-20 km·h-1 slower. The maximum liquid water content was 0.6 g·m-3 at the 5 〖KG-*5〗400 m height (-8℃) by airborne cloud physical detection. The forecasted cloud water content was consistent with detection. The seeding plan was made based on cloud condition forecast. The area 30-50 km northwest of the core zone was chosen as key defense zone. AgI overseeding would be suitable to be implemented in the 5.1-7.0 km height. In the morning of 8 August the aircraft would carry out detection in weak echo areas of the first defense line. Ground operations would focus on the implementation of overseeding in the initial stage of convective clouds in the third defense line to achieve the goal of rainfall mitigation. Based on the plan, additional five sets of ground mobile seeding equipment were added to reinforce the capability of rainfall mitigation ahead of 24 hours of target time. Rainfall mitigation was carried out with the 5 sets equipment. In summary, the cloud seeding condition forecast was proper, and the seeding plan was reasonable, which provided strong support for field rainfall mitigation action.
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Clc Number:
P481
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