Satellite Radiance Assimilation in the JMA Operational Mesoscale 4DVAR System

Abstract

The direct radiance assimilation scheme used in the Japan Meteorological Agency (JMA) global analysis system is applied to the JMA mesoscale four-dimensional variational data assimilation (4DVAR) system with two modifications. First, the data-thinning distance is shortened, and, second, the atmospheric profiles are extrapolated from the mesoscale model top to the radiative transfer model top using the U.S. Standard Atmosphere lapse rate. Although the variational bias correction method is widely used in many numerical weather prediction centers for global radiance assimilations, a radiance bias correction method for regional models has not been established because of difficulties in estimating the biases within limited regions and times. This paper examined the use of the bias correction coefficients estimated in the global system for the mesoscale system when the radiance data were introduced instead of the retrievals. It was found that the profile extrapolation was necessary to reduce the biases. Moreover, the use of common bias coefficients enables the use of the radiance data in the same way as the global system. The radiance data assimilation experiments in the mesoscale system demonstrated considerable improvements to the tropospheric geopotential height forecasts and precipitation forecasts. The improvements resulted from the introduction of radiance data from multiple satellites into data-sparse regions and times. However, the major effect of the radiance assimilation on the precipitation forecasts was limited to weak precipitation areas over oceans; the effects on deep convective areas and over land were relatively small.

Assimilating Every‐10‐minute Himawari‐8 Infrared Radiances to Improve Convective Predictability

“…This important issue was investigated in recent studies (e.g., Okamoto et al, ). Removing the biases between model forecast and observations would contribute to effectively assimilating satellite radiances and improving the analysis in the operational systems (e.g., Kazumori, ; Otkin et al, ).…”

Operational use of satellite radiance in JMA mesoscale analysis

“…Detail of the experimental result was described in our other paper [2]. The important results were that the direct radiance assimilation improved the temperature and moisture analysis.…”

“…In advance of the operational implementation of the radiance assimilation, the experiments for the comparison between radiance assimilation and the retrieval assimilation were conducted by using JMA mesoscale NWP system. The detail results were described in our other paper [2]. In this paper, we investigated the impacts of individual radiance components on the mesoscale forecasts with several data denial experiments for a typhoon case by using the JMA mesoscale NWP system.…”

Impact of assimilating GOES imager clear‐sky radiance with a rapid refresh assimilation system for convection‐permitting forecast over Mexico

“…It provides 90–95% of the actively assimilated data [ Bauer et al , ]. As the development of fast radiative transfer models and their adjoint models, a number of clear‐sky or all‐sky infrared and microwave channel radiance observations from satellite instruments have been assimilated directly into most operational centers, such as the National Centers for Environmental Prediction (NCEP), European Centre for Medium‐Range Weather Forecasts (ECMWF), Met Office, Japan Meteorological Agency, Météo‐France, and Environment Canada [ Greenwald et al , ; Heilliette and Garand , ; Pavelin et al , ; McNally , ; Pangaud et al , ; Heilliette , ; Bauer et al , ; Geer et al , ; Geer and Bauer , ; Guidard et al , ; Lupu and McNally , ; Okamoto , ; Zhu et al , ; Kazumori , ; Yang et al , ]. These infrared and microwave instruments are carried on different geostationary and polar‐orbiting satellites.…”