Impact of the CHAMP Occultation Data on the Rainfall Forecast
Impacts of the occultation data observed by CHAMP were investigated using the mesoscale four-dimensional data assimilation system of the Japan Meteorological Agency. We assimilated refractivity data provided from GFZ by using the method of Chen et al., in which the vertical correlation of the observation error was considered. This method was extended to apply the refractivity average along the path from a GPS satellite to a LEO satellite. When this extended method was applied to predict a rainfall system that developed in northern Japan, the rainfall system, which could not be developed without the assimilation of the occultation data, was reproduced. This result demonstrated that occultation data is useful for improving heavy rainfall forecasts.
KeywordsGlobal Position System Japan Meteorological Agency Observation Error Path Data Tangent Point
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