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Aim of the Study• Evaluate the benefit of adding microwave (MW) channels to the
measurement vector of EUMETSAT’s optimal estimation method (OEM) scheme for retrieving temperature, humidity and ozone from the infra-red (IR) sounder IASI
• Extend EUMETSAT’s baseline (IR-only) OEM scheme to:- Fit surface spectral emissivity (IR and MW)- Work in the presence of (some) cloud (but not precipitation)
MethodologyWP1000 Assess measurement errors of AMSU+MHS
(Input via consultancy from UK Met Office)WP2000 Set up EUMETSAT OEM in RAL code; test retrievals (IR and MWIR) over clear sea WP3000 OEM(MWIR/Metop-B) repeat over clear landWP4000 OEM(MWIR/Metop-B) repeat over land; emissivity added to stateWP5000 OEM(MWIR/Metop-B) repeat, but test also cloud scenes and add cloud to the state-vector WP6000 Test impact of missing AMSU channels Throughout, modifications to scheme are assessed via i. Statistical comparisons to ECMWF analyses for 3 days of global data ii. OE diagnostics (estimated errors, information content etc.)
EUMETSAT ODV Scheme• EUMETSAT’s operational OE scheme for IASI (temperature, humidity, O3)• A priori the result of a piece-wise linear regression scheme applied to
IASI+AMSU/MHS radiances (trained using ECMWF analyses)- Prior errors based on comparison of results to analyses
Results shown don’t include MW channels yet, but retrieving surface emissivity already benefits IR window channels
ImprovementsTemperature
(MWIR with fitted emissivity and cloud vs. standard OEM)
ImprovementsHumidity
(MWIR with fitted emissivity and cloud vs. standard OEM)
Mid-Lat Land Retrieval (PWLR)
Mid-Lat Land Retrieval (Clim.)
Task 4: Retrieval Simulations• Large set of retrievals conducted to asses benefit MW/IR and performance of emissivity retrieval:
– standard: IR only, RAL retrieval ~ EUMETSAT OEM. – IR+MW: IR+MW retrieval (no emissivity, no cloud retrieval). – MW: MW only retrieval (no emissivity, no cloud retrieval). – IR+MW; Cloud: IR+MW retrieval with cloud fraction and height also retrieved. – Emis:[10/20/30]n: IR only retrieval, with 10/20/30 spectral emissivity patterns retrieved (no emissivity
correlations between IR and MW). – IR+MW; Emis:20: IR+MW retrieval, with 20 spectral emissivity patterns retrieved. Spectral
correlations assumed between IR and MW. – IR+MW; Emis:20n: As above, no spectral correlations IR/MW– MW; Emis:20: MW only retrieval, with 20 spectral emissivity patterns – IR+MW; Emis:20; Cloud: As above, also with cloud retrieved
• Two versions of each; with PWLR as a priori and a new “climatological constraint”