Basic characteristics of post-frontal shower precipitation rates

Publisher： E. Schweizerbart'sche Verlagsbuchhandlung

ISSN： 0941-2948

Source： Meteorologische Zeitschrift, Vol.17, Iss.6, 2008-12, pp. : 793-805

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Abstract

For the post-frontal precipitation field, a rain rate analysis was carried out based on the radar composite RZ of the German Weather Service. Two different approaches were followed: an Eulerian- and a Lagrangian-type analysis. Rain rate distributions and their diurnal cycle were investigated and the instantaneous rain rates per individual cell, embedded in an enclosed rain area, were determined. The rain amount per individual cell within a rain area increases with the total cell number. A comparison of the tracks of the rain areas with the 925 hPa wind field revealed a movement with the mean wind direction. Furthermore, the life cycle of the rain areas was investigated with respect to related rain amounts as well as to the area. For single-cell-tracks the mean temporal development of the area integrated rain rate (AIRR) shows a parabola shape, while the area time series is better represented by a sine function. The resulting functions only depend on the life time of the track. This result reveals a simple underlying law for an apparently chaotic precipitation process.