Extended Abstract

By multiply ing calibrated echo intensities by the calibration factor as determinedabove, an estimated precipitation at the grid g is obtained.3.3 COMPOSITION OF CALIBRATED DATA ON EACH RADAR FIELDAfter the above calibration, we produce a composite precipitation map using thecalibrated echo intensities from 46 radar s by transforming the coordination fromzenithal projection into latitude-longitude gr id with equidistant cyli ndrical projection. Ifmultiple radars observe the same grid, the largest value is selected.3.4 ACCURACY OF R/ATo assess the accuracy of R/A, about 200 raingauge data were excluded forverification. Then, R/A data were produced without these raingauge data. R/A datawere compared with excluded raingauge dat a. Here we compared a raingauge valuewith the R /A values at 9 gr ids including 8 neighboring grid s, considering locationerrors about by one grid (i.e. 1 km) due to advection of raindrops by wind beforereaching the ground, and/or ones resulting from the coordinate transform.Fig. 2 shows a scatter pl ot for comparisons between hour ly R/A values andcorresponding raingauge measurements for 4 months in a warm season (from Augustto November in 2009). Here, only best R/A values among ones at the 9 grids areplotted. This figure shows a good agreement between raingauge data and R/A values.120R/A(mm)8040Fig. 2 Scatter plot of R/A andraingage with a regressedline(red)(R/A=0.96 x Raingauge)40 80Raingauge(mm)1204 ALGORITHMS AND ACCURACY OF VSRFVSRF is a 6-hour forecast of pr ecipitation with a spatial resolution of 1km. V SRF ismade up to 6 hours ahead by merging the for ecast precipitation with MSM and thosewith the extrapolation method. Here, we introduce details of the procedures forproducing VSRF4.1 EXTRAPOLATION METHOD4.1.1 MOVEMENT VECTORS-109-