Early results of the evaluation of the JRA-3Q Reanalysis

Abstract:

The Japan Meteorological Agency (JMA) is conducting the third Japanese global atmospheric reanalysis named Japanese Reanalysis for Three Quarters of a Century (JRA-3Q). JMA’s operational data assimilation system has been developed and improved since the Japanese 55-year Reanalysis (JRA-55). Provisional specifications of the forecast model that is used in JRA-3Q system are as follows: Vertical levels are increased up to 100 layers (60 layers in JRA-55 system); The top level of the numerical model used in JRA-3Q system is 0.01 hPa (0.1 hPa in JRA-55 system); Inner model for 4D-Var also increases horizontal resolution up to TL319 (T106 in JRA-55 system); Various parameterization schemes have been improved and several new schemes have been implemented. In addition, we use observations newly rescued and digitized by the ERA-CLIM and other projects as well as newly reprocessed and improved satellite observations. As for GNSS radio occultation, bending angle is assimilated up to 60 km (refractivity up to 30 km in JRA-55). The early results show that both over estimation of precipitation in the tropics and dry bias in the middle troposphere are diminished compared with those in JRA-55, and the vertical profile of diabatic heating rate is also improved. In addition, biases of surface heat fluxes and radiation fluxes at the top of the atmosphere are also reduced.