Recent activities on utilization of microwave imager data in the JMA NWP system - Preparation for AMSR2 data assimilation - Masahiro Kazumori Japan Meteorological Agency AMSR-E Joint Science Team Meeting, Portland, OR, U.S.A. 11 & 12 September 2012

Introduction Microwave imager data has been assimilating in JMA Global Data Assimilation (DA) system and Meso scale DA system. The radiance assimilation provides atmospheric moisture information for initial state of NWP models. The assimilated Microwave imager data Clear Sky radiance data for Global DA system Radiance and Retrieved Rain Rate for Meso scale DA system In Use TMI/TRMM AMSR-E/Aqua (by Oct. 6, 2011) SSMIS/DMSP F-16, F-17, F-18 In Preparation Windsat/Coriolis AMSR2/GCOM-W1 V-pol. channels (19, 23, 37 and 89) are assimilated in JMA NWP system. 1 (since Dec. 6, 2011)

Impact of microwave imager data in JMA NWP MW imager data is one of the essential data to produce realistic moisture fields as initial conditions of NWP. The initial fields are updated (four times per day for Global DA, eight times for Meso scale DA) to capture change of weather conditions. Use of multiple MW imager data is necessary for the frequent update of the initial field. New MW imager data should be used. Operational Short-range precipitation forecast Without Microwave Imager data TRMM observed rain JAXA 2

Recent updates of MW radiance assimilation in JMA Stop of AMSR-E observation (Oct. 6) Start of TMI ver. 7 (Dec. 1) Introduction of F-18 SSMIS (Dec. 6 ) Oct. 6, 2011 Stop of AMSR-E observation Dec. 1, 2011 Start of TMI ver. 7 Tb data use Dec. 6, 2011 Start of DMSP F-18 SSMIS Tb use Time sequence of O-B statistics [K] 3

Used MW radiance data in Global DA Decrease of DMSP F-17 SSMIS data Time sequence of Data Counts Available data number of DMSP F-17 SSMIS is decreasing since June [Counts] 4

In the data assimilation, satellite data are thinned spatially and temporally (e.g., 200km and hourly). Satellite data in separate orbit are preferred because they increase the data coverage in six-hour analysis time window. The orbit of SSMIS (F-16 and F-17) are becoming very close. F-16 F-17 F-18 Aqua Equator crossing time 12UTC Jun. 10, UTC Sep. 4, 2012 Both F-16 and F-17 data can be used because they are in the different thinning box. One satellite (F-16) data can be used because they are in the same thinning box. 5

Cal/Val collaboration with JMA and JAXA JAXA successfully launched GCOM-W1. And AMSR2 is working in very good condition. For early use of satellite data in operational NWP, Space agency and NWP center are collaborating in Cal/Val activities (e.g., AMSU-A/Metop- A, ECMWF and EUMETSAT, SSMIS/DMSP F-16, UK Met Office, NESDIS and NRL, ATMS/Suomi-NPP, NCEP, NESDIS, and NASA ) Comparison of observed Tb and NWP model’s calculated Tb reveals Tb calibration issues. For early use of AMSR2 data in JMA NWP, JMA and JAXA started Cal/Val collaboration. Preliminary un-calibrated AMSR2 L1B product has been delivering to JMA since Sep. 3, O-B Monitoring of AMSR2 is ongoing. A pre- processor for the data assimilation is being developed. 6

Microwave Imager data’s coverage in JMA NWP AMSR2 is a unique Microwave Imager in PM Orbit. The data fill the gap in the 6-houly global data coverage. In Meso scale DA system, 06UTC and 18 UTC analysis has little microwave imager data. The data cut-off time for the receiving is 50 min. after the analysis time. Direct receiving AMSR2 data by JAXA can be used in real time. Global DAMeso scale DA 06UTC18UTC Light blue: AMSR2 7

Development of pre-processor for AMSR2 radiance assimilation Main function –Data thinning and ocean data selection –Removal of cloud and rain affected data →Clear sky radiance assimilation –QC with TPW and CLW retrievals TPW: Consistency check of retrieval and NWP model CLW: Cloud and rain screening. Used as one of predictors of variational bias correction –Scan position dependent bias correction (static) –Radiative transfer calculation with NWP model’s profiles (RTM: RTTOV-10.2) Monitoring of AMSR2 data quality with O-B. The biases in O-B are corrected by variational bias correction scheme (VarBC). The biases are estimated using a linear function with some predictors and those coefficients are optimized in the analysis and updated every analysis cycle. Bias correction term is in the observation operator Predictors : TPW, SST, SST^2, SSW, CLW, ORBIT,CONST 8

Preliminary O-B Comparison with other MW imagers TMI and AMSR-E (ocean and clear sky condition) AMSR2 TMI Ver.7 AMSR-E 19V23V37V89V Red: W BC Green: WO BC July 2011 July 2012 [K] 9 ME STD ME STD ME STD ME STD ME STD ME STD ME STD ME STD ME STD ME STD ME STD ME STD

Preliminary O-B Comparison with other MW imagers SSMIS (ocean and clear sky condition) AMSR2 SSMIS F-18 SSMIS F-16 19V23V37V89V Red: W BC Green: WO BC [K] July ME STD ME STD ME STD ME STD ME STD ME STD ME STD ME STD ME STD ME STD ME STD ME STD

Preliminary L1B Comparison between AMSR2 and AMSR-E Ascending Descending Local Time Latitude [K] One month O-B orbit dependent bias AMSR2 AMSR-E July 2012 July V23V37V89V 19V23V37V89V 11

Preliminary assimilation experiment (single case) AMSR-2 data assimilation experiments are in preparation. AMSR2 19GHz V-pol. O-B Q925 Q925 analysis increment 12

Summary Microwave imagers data have large positive impacts in JMA NWP system. The data are essential for accurate humidity analyses and precipitation forecasts for Japan. Current satellite microwave observing configuration is not optimal for NWP. Due to no PM orbit microwave imager, the data sparse area and period exist. AMSR2 can fill the gap. JMA and JAXA started collaboration in Cal/Val activities for the early use of AMSR2 data in JMA NWP system. Preliminary un-calibrated AMSR2 L1B data show positive biases in the comparison with calculated Tb. And our bias correction scheme can correct the bias globally. AMSR2 bias corrected O-B departure are comparable with other MW imager data (F16, F18 SSMIS and TMI). AMSR2 orbit dependent bias looks different from AMSR-E. Preliminary assimilation experiment (single case) was performed. Global and Meso scale data assimilation experiments are planned to confirm the impacts of AMSR2 data assimilation for the weather forecast. 13