ISSN 1000-0526
CN 11-2282/P
CN 11-2282/P
Archive > Volume 51 Issue 10 > 2025,51(10):1171-1181. DOI:10.7519/j.issn.1000-0526.2025.011603 Prev Next
Causes and Nowcasting Focus of Local Severe Convective Weather in an Afternoon in Shanghai Under the Control of Subtropical High
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Abstract:
On the afternoon of 13 August 2022, a local severe convection occurred near the coast of Shanghai under the control of Western Pacific subtropical high. This event displayed characteristics of a short life span, strong local manifestation, and high intensity. Using the data from minute-level surface automatic weather stations, FY-4A geostationary meteorological satellite cloud images, and dual-polarization radar data, this paper studies the nowcasting focus and causes of this local severe convection. The findings are as follows. The beginning of precipitation at the surface was identified as the accurrence sign of local severe convective events. By analyzing radar reflectivity factor, satellite visible light cloud images, and Q vector divergence, combined with perturbation dew point temperature and perturbation temperature data from surface automatic weather stations, we find the early warning of the convective event could be issued 23, 70 and 100 min in advance, respectively. This integrated monitoring and mutual verification of the atmospheric, satellite, and sruface observations not only improved the lead time of early warning for local severe convection, but also reduced missed detections. Under the control of the Western Pacific subtropical high, temperatures exceeding 35℃, combined with the perturbations in temperature and dew point temperature near the urban area, provided favorable thermodynamic conditions for the initiation of deep convection. Simultaneously, differences in land-water underlying characteristics led to higher temperatures on urban land compared to the temperature of adjacent Yangtze River water, thus, onshore winds were formed. On one hand, this process experienced abrupt changes in land-water underlying characteristics and complex urban land surfaces, causing convergence of wind direction and speed. On the other hand, the convergence of warm and cold air caused the enhanced instability of atmosphere. Further analysis reveals that the convergence of significant Q vector divergence at the surface persisted until surface precipitation occurred, indicating the generation of vertical upward motion due to the dynamic and thermodynamic forcings at the surface. Furthermore, the interaction between the sea breeze front and the convergence-induced updrafts from the urban heat island resulted in the local severe convection.
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Clc Number:
P458，P456
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