THE STUDY OF PRELIMINARY APPLICATION OF SATELLITE-DERIVED RELATIVE HUMI-DITY IN RAINSTORM FORECAST

The feasibility of improving rainstorm precipitation forecast by making an attempt to augment high resolution satellite-derived relative humidity to initial conditions is studied.In forecast contrast experiments,total five rainstorm cases were tested with two relative humidity initial condition sources respectively.(1) CNMC T63L16 model-generated global large-scale assimilated forecast data with resolution 1.875 latitude×1.875 longitude;(2) GMS-5 four-spectrum-derived data with high resolution 0.052 latitude×0.0633 longitude.The result indicates:(1) satellite-derived relative humidity could better depict real relative humidity horizontal mesoscale structures,significantly it could enhance the analysis of high humidity regions where precipitation is sensible to and it agrees better with radiosonde observations;(2) the introduction of satellite-derived relative humidity to initial conditions usually could improve 24h precipitation forecast scores,specifically,in earlier forecast stage (0-6h),it could nudge model-generated precipitation field to observational field,nevertheless,in later forecast stage (6-24h) its effect on precipitation is not clear.