Characteristics of convective clouds producing heavy precipitation in northwest Russia
A.A. Sin’kevich, Yu.P. Mikhailovskii, A.B. Kurov, I.A. Tarabukin, N.E. Veremei, O.A. Dmitrieva, R.E. Torgunakov, M.L. Toropova
The Voeikov Main Geophysical Observatory, St Petersburg, Russia
Keywords: radar, precipitation, thunder, microphysics
Abstract
Characteristics of clouds which produced heavy precipitation in St. Petersburg and Leningrad region on June 18, 2020 are considered based on measurements with C-band Doppler radar, Pluvio2 200 weight precipitation gauges, and Blitzortung lightning detection system. To assess the intensity of precipitation, different values of the coefficients in the Marshall-Palmer Z - R ratio are studied. We show that it is reasonable to use the specific differential phase to calculate the precipitation intensity when it exceeds 30 mm/hour and precipitation consists of raindrops and hail. The top of the clouds exceeded 12 km, the maximal reflectivity was higher than 52 dBZ, the maximal precipitation intensity could exceed 160 mm/hr. A significant volume of a cloud was occupied by hail particles, which were recorded from the earth's surface up to an altitude of 10 km. The highest reflectance was recorded in the precipitation zone, as well as in the hydrometeors melting area. All the clouds under study were thunderstorm. A sufficiently high correlation between the frequency of lightning and the intensity of precipitation is noted. Spearman's correlation coefficient exceeds 0.7.
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