Extended Abstract

QPE and QPF of Japan Meteorological AgencyKazuhiko NAGATAForecast Division, Japan Meteorological Agency1 INTRODUCTIONThe Japan Meteorological Agency (JMA ) has been producing analyzed hourlyprecipitation called “Radar/R aingauge-Analyzed Prec ipitation (here after call “R/A”)since 1983, and precipitation nowcasting (Very-Short-Range Forecast of precipitation,here after call “VSRF ”) since 1988, in orde r to mitigate disasters caused by heavyrainfall, such as landslides, flash floods, and debris flows.R/A and VSRF are disseminated to local met eorological offices, local gover nments,TV stations, as well as private weather companies. When disasters caused by heavyrain are likely to occur, JMA issues warnings and advisories based on R/A and VSRFand indices of possibilities of landslides and flood produced with them.2 DATAR/A and VSRF are produced with rain gau ge data, radar data, and NWP outputs.Raingauge data are collected, every ten minutes or every one hour, from10000-raingauge net work operated by JMA, Mi nistry of Land, Infrastructure,Transport and Tourism (here after call “MLIT”) and local governments (raingauges arelocated ev ery 7km grid square on averag e). 46 C-band radars data with a spatialresolution of 1 km are collect ed, every five minutes, from the radar network operatedby JMA and MLIT. A radar of the network covers a 500km×500 km square domain.Mesoscale model (here after call “MSM”) outputs used for V SRF are wind fromsurface to 700hPa, temperat ure and relativ e humidity fr om surface to 850hPa, andhourly precipitation. MSM produces 15 or 33-hour forecast at 5km of spatial resolutionevery 3hours.3 ALGORITHM AND ACCURACY OF R/A3.1 ACCUMURATION OF RADAR INTENSITY DATAIn this section, we introduce the procedure for calculating one hour accumulated echointensity. One hour accumula ted echo intensity is calculated as sum of echointensities obtained every five minutes. Howeve r, if some echo intensities move fast,one hour accumulated echo intensities sometimes show unnatural stripe pattern (Seethe left image of Fig.1). To avoid such unnat ural patterns, the accumulation must beconducted taking the movement of the echoes into consideration (See the right imageof Fig.1). In this process, we first divi de observed echo intensities into some piecesand trace them every five minutes. Then, by summing up the echo intensities passinga grid, the one hour accumulated echo intensity of the grid is estimated. Here, quality-107-