UPGRADED USAGE OF ATMOSPHERIC MOTION VECTORS FROM ALL GEOSTATIONARY SATELLITES IN THE OPERATIONAL GLOBAL AND MESO-SCALE 4D-VAR ASSIMILATION SYSTEM AT JMA

The usage of Atmospheric Motion Vectors (AMVs) in the BUFR-encoded dataset (BUFR AMVs) generated from all geostationary satellites was revised in the JMA operational global 4D-Var assimilation system on 18 October 2006, and in the JMA operational mesoscale 4D-Var assimilation system on 7 December 2007. This revision included the replacement of SATOB AMVs with BUFR AMVs, the introduction of hourly MTSAT-1R AMVs and improvement of the pre-processing method in both assimilation systems. Before the revision, BUFR AMVs generated from only METEOSAT satellites and SATOB AMVs from MTSAT-1R and GOES satellites had been assimilated in both systems. BUFR AMVs have a great advantage over SATOB AMVs in their high-density distribution and the availability of quality information known as Quality Indicator (QI). For this reason, all SATOB AMVs were replaced with corresponding BUFR AMVs in both assimilation systems. We also made several revisions to the pre-processing method in both systems in order to use BUFR AMVs efficiently. Firstly, the usage of data is limited more strictly, reflecting error characteristics according to height. Secondly, fewer but more reliable data selected through a more rigorous Q