Operational use of satellite radiance in JMA mesoscale analysis

In Japan Meteorological Agency´s mesoscale Numerical Weather Prediction system, a radiance assimilation scheme was introduced on 13 December 2010. The radiance assimilation enables us to use the satellite radiance data directly without any error contamination from the retrieval process. From data denial experiments, it was confirmed that the radiance assimilation brought considerable improvements, especially in tropospheric geopotential height analysis and short-range precipitation forecasts. And the radiance data constrained the temperature and moisture fields strongly over the ocean in clear and non-precipitation areas. On the other hand, the contribution in thick cloud and rainy area and over the land was relatively weak in the analysis. Assimilation of cloud- and rain- affected radiances and surface sensitive radiances is expected to bring further improvement of the analysis and precipitation forecast score.