Recent activities on microwave radiance data assimilation at JMA
Masahiro Kazumori
Numerical Prediction Division, Forecast department, Japan Meteorological Agency
JMA global NWP system and satellite radiance data
Forecast model and data assimilation
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Outer model: TL959L100 (horizontal reso. 20km, top 0.01hPa)
Inner model: TL319L100 (horizontal reso. 55km, top 0.01hPa)
6-hr assimilation window, incremental 4D-Var
Analysis variables (Wind, surface pressure, specific humidity and temperature)
11 day forecast from 00, 06, 12, 18 UTC initials.
Radiative Transfer Model
RTTOV-10.2 (planned to use RTTOV-11 in the next year)
• Bias correction Method
VarBC for radiance data
Satellite radiance data for operational use (clear-sky)
Development of all-sky microwave imager radiance
assimilation in JMA global DA system
All-sky assimilation of AMSR2, GMI, SSMIS F16, F17, F18
Clear-sky MW imager radiance assimilation
All-sky MW imager radiance assimilation
RTM: RTTOV-10 (rttov_scatt, rttov_scatt_ad)
Input profile: Temperature, Water vapor, cloud
liquid water, cloud ice water, cloud fraction, rain,
snow
Data thinning: Averaging with 80 km grid-box and
200 km distance thinning
Used MW imager: AMSR2, SSMIS (F16,17,18), TMI,
GMI
Inner model moist physics update: little impacts for
Data assimilation experiment for comparison clear-sky assimilation
DA system: JMA global 4D-Var DA system
Used channels: 19V, 23V, 37V over ocean
Period: From 10 June to 11 August, 2014
11-day forecast from 12 UTC initial every day
RTM: RTTOV-10 (rttov_direct, rttov_k)
Input profile: Temperature, Water vapor
Data thinning: 200 km grid-box thinning
Used MW imager: AMSR2, SSMIS (F16, F17, F18),
TMI
Used channels: 19V, 23V, 37V, 89V clear-sky
oceanic data
• Microwave radiance： AMSR2/GCOM-W, AMSU/Aqua ,
AMSU/Metop, MHS/NOAA, MHS/Metop, SSMIS/DMSP,
SAPHIR/Megha-Tropiques
• Infrared radiance： AIRS/Aqua, IASI/Metop, CSR/GOES,
CSR/MTSAT, CSR/Meteosat
AMSR2 37V
AMSR2 19V FG departure mean bias
FG departure
AMSR2 37V FG departure mean bias
Monitored and evaluated radiance data
• CSR/Himawari-8, GMI/GPM, ATMS/S-NPP, CrIS/S-NPP
Under preparation for monitoring
• SSMIS/DMSP F19, MWHS/FY-3B, MWHS2/FY-3C, MWRI/FY-3B
Assimilation of SAPHIR Tb data in JMA global DA system
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21 UTC
23
00
01
02
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Assimilation Window
for 00UTC ANL
22 UTC
00 UTC, 2 August, 2014
23 UTC
00 UTC
GOES-W IR
00UTC 10 June 2014
C37: Mean cloud amount, C37o: Obs. cloud amount, C37b: Background cloud amount
Biased data rejection: C37>0.4 for 23V and 37V
Results
Improved fits in FG departure
Changes in Std. of FG departure
IR-Imager
MW-Sounder
IASI
AMV
• Consistent improvement
NH
in various observations
• Big impacts on Tropics
• Improved fits to AMV TR
01 UTC
02 UTC
Used data coverage of MHS and SAPHIR
Negative value indicates
improvement
SH
In operational use since 25 June 2015
• Clear-sky and oceanic data assimilation (6 channels)
• Cloud-screening is based on adjacent channel’s FG departure
• High frequent observation in Tropics
e.g. 4 time observation for TC in 6-hr assimilation window
Assimilation experiment
• Control: Same as JMA operational global DA system as of Sep. 2014
• Test: Control + SAPHIR radiance (clear-sky and oceanic data, 6 ch.)
Results
• Positive impacts for typhoon track prediction
• Improved waver vapor field in AN and FG in Tropics (not shown here)
(a)
(b)
Realistic analyzed TPW in cloudy condition
All-sky
Improved TC prediction
Clear-sky
Central
pressure
Max surface
wind
Test: All-sky
Cntl: Clear-sky
Best track
GOES-W IR
GSMaP
12UTC 06 Aug. 2014
00-06UTC 06 Aug. 2014
Initial 6-hr precipitation forecast
All-sky
Clear-sky
diff: Test-Cntl
00-06UTC 06 Aug. 2014
(c)
Summary and plans
Figures (a) Typhoon track forecast errors
averaged for equalized samples (Test,
Control), (b) Difference of Typhoon track
forecast error between Test and Control,
(c) An example case of improved track
forecast in Test run.
12UTC 06 Aug. 2014 Initial.
Operational use of clear-sky SAPHIR radiance since 25 June 2015
• Positive for moisture analysis in Tropics and TC track prediction
Development of all-sky microwave radiance assimilation
• Promising results from the initial experiment
• Need to study forecast model biases related to cloud physics
and precipitation process
Preparation for new radiance (GMI, ATMS, CrIS, Himawari-8)
The 20th International TOVS Study Conference (ITSC-20), Lake Geneva, Wisconsin, USA 28 October – 3 November 2015