recent activities on utilization of microwave imager data in the jma nwp system - preparation for...
TRANSCRIPT
Recent activities on utilization of microwave imager data
in the JMA NWP system
- Preparation for AMSR2 data assimilation -
Masahiro KazumoriJapan 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.
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(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 3
Recent updates of MW radiance assimilation in JMA
Stop of AMSR-Eobservation (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]
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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 2011.
[Counts]
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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, 2011
12UTC 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.
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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, 2012. O-B Monitoring of AMSR2 is ongoing. A pre-processor for the data assimilation is being developed.
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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 DA Meso scale DA06UTC 18UTC
Light blue: AMSR2
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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.
xxβxz bphh~
yBias correction term is in the observation operator
Predictors : TPW, SST, SST^2, SSW, CLW, ORBIT,CONST9
Preliminary O-B Comparison with other MW imagersTMI and AMSR-E
(ocean and clear sky condition)AMSR2
TMI Ver.7
AMSR-E
19V 23V 37V 89V
Red: W BCGreen: WO BC
July 2011
July 2012
[K]
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ME 5.02 0.03STD 1.65 1.61
ME 5.62 0.09STD 2.43 2.45
ME 3.63 0.02STD 1.69 1.55
ME 2.95 0.05STD 2.34 2.20
ME 1.22 -0.10STD 1.55 1.48
ME -0.31 -0.15STD 2.27 2.20
ME -0.63 -0.09STD 1.29 1.27
ME 0.47 -0.12STD 1.76 1.71
ME 1.67 -0.06STD 1.43 1.38
ME 1.44 -0.11STD 2.12 2.14
ME 0.14 -0.06STD 1.33 1.31
ME -0.67 -0.1STD 2.15 2.11
Preliminary O-B Comparison with other MW imagersSSMIS
(ocean and clear sky condition)AMSR2
SSMISF-18
SSMISF-16
19V 23V 37V 89V
Red: W BCGreen: WO BC
[K]
July 2012
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ME 5.02 0.03STD 1.65 1.61
ME 5.62 0.09STD 2.43 2.45
ME 3.63 0.02STD 1.69 1.55
ME 2.95 0.05STD 2.36 2.20
ME -0.29 0.01STD 1.43 1.36
ME 0.64 0.02STD 2.27 2.14
ME -0.71 0.01STD 1.29 1.28
ME -2.08 -0.01STD 1.98 1.50
ME 1.03 -0.06STD 1.52 1.41
ME 1.80 -0.10STD 2.39 2.20
ME 0.36 -0.06STD 1.29 1.26
ME -0.55 -0.10STD 1.95 1.53
Preliminary L1B Comparison between AMSR2 and AMSR-E
Ascending
Descending
Local Time
Latitude
[K]
One month O-B orbit dependent biasAMSR2
AMSR-E
July 2012
July 2010
19V 23V 37V 89V
19V 23V 37V 89V
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Preliminary assimilation experiment (single case)
AMSR-2 data assimilation experiments are in preparation.
AMSR2 19GHz V-pol. O-B
Q925
Q925 analysis increment
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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.
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