Status of the operational IASI L2 version 5 products

GlobVapour, Workshop 08-10 March 2011Status of the operational IASI L2 products

Thomas August (EUMETSAT)

Tim Hultberg, Dorothée Coppens, Arlindo Arriaga, Lars Fiedler, Xavier Calbet, Dieter Klaes, Peter Schlüssel, Rose Munro, Marc Crapeau

Status of the operationalIASI L2 version 5 products

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Outline

I. Overview of the IASI mission

II. The IASI L2 processor (PPF) version 5

III. Discussion on T, q validation

IV. Summary


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I. The IASI mission The instrument

COCH4O3 H2OCO2CO2N2O

SurfaceClouds Surface

Clouds

T profiles

Infrared Fourier transform interferometer

Spectral range: 645 to 2760 cm-1 (15.5-3.62 µm)

Spectral sampling: 0.25 cm-1

Footprint: 12 km (Nadir)

Swath: ±1000km (± 48.3°)


I. The IASI mission Metop and the EPS program

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Prime objective: provide continuous, long-term data sets in support of operational meteorological and environmental forecasting and global climate monitoring.

Lifetime: 3 satellites, more than 14 years operation from October 2006.

Imager (AVHRR) and MW (AMSU,MHS) companions

European contribution to The Initial Joint Polar-orbiting System (IJPS)

Satellites in complementary orbits designed to ensure global data coverage at intervals of no more than 6 hours.


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Vertical profiles: TemperatureVertical profiles: HumidityLand & Sea Surface TemperatureCloud detection and characterisation

Ozone: total & partial (0-6, 0-12, 0-16 km) columns

Surface emissivity

TWT

EMS

CLD

OZO

TRG

I. The IASI mission The operational L2 products

Disseminated in NRT (sensing +3h)

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II. IASI L2 PPF version 5 Why upgrade ?

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bias σ

Processing chain version 5 operational since 14 September 2010 !

rmse

σ

bias

v4

v5

IASI – ECMWF @ 500 hPa

-1

0

1

2


1. Input data pre-processing

2. Cloud detection and characterisation

3. Statistical retrievals: T, q, Ts, ε, trace gases

4. Optimal Estimation Method (OEM): T, q, Ts, O3

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Conf. dataStatic db

IASI L1CNWPAux.

meas.IASIL2

productEOF cloudy

EOFANN

cloud-free

OEM

II. IASI L2 PPF version 5 The main steps


Data type Origin ResolutionLand/Sea mask AAPP quadtree

Surface elevationGTOPO 30

(US Geological Survey)

30” x 30” (~1 km)

Emissivity Atlas

Global land surface IR

emissivity databaseUW-Madison

(Borbas et al., 2007)

0.05° x 0.05° lat/lon

10 wavelengthsMonthly means

Emissivity Atlas

Global land surface climatology from

IASI measurements(Zhou et al.,

submitted to IEEE TGRS )

0.5°x0.5°Full spectrum (via

PCs)Monthly means

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II. IASI L2 PPF version 5 The static databases


IASI L1C radiances• Noise-filtering via PC reconstruction ECMWF 6h-forecasts: 00, 06, 12, 18 UTC• Up to 3h difference with sensing-time• Time-interpolation AVHRR• L1B used if IASI L1C format < 11.0• Cloud-fraction embedded in IASI 1C used for cloud

screening AMSU & MHS 1B• Not used yet.“Potential for the use of reconstructed IASI radiances in the detection of atmospheric trace gases”, N. C. Atkinson, F. I. Hilton, S. M. Illingworth, J. R. Eyre, and T. Hultberg, AMT 2010

Raw L1C Ammonia Reconstructed

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II. IASI L2 PPF version 5 Measurements & aux. products


II. IASI L2 PPF version 5 Cloud detection

NWP cloud test• OBS – CALC(NWP, ems, … ) @ chans 751 & 1023• Cloudy if |OBS-CALC| > 1K• Relies on accurate forecasts and surface ems

AVHRR integrated cloud-fraction• IASI PSF weighted count of AVHRR cloudy pixels• Cloudy if CFR > 2%

Cloud optical depth test• EOF retrieval, D. Zhou et al., GRL 2005• Triggers final acceptance of cloudy retrievals

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NWP test

AVHRR test

Opt. depth test

18/11/2009 White: clear


II. IASI L2 PPF version 5Statistical retrievals: T, q profiles

EOF retrieval (D. Zhou et al., 2005, GRL)

Regression with different coefficients for different viewing angles

Full profiles available under clear and partly cloudy conditions

Clear sky: first-guess in the final iterative retrieval

Clear sky: q profiles enters final L2 products

Cloudy IFOVs: after users request, the cloudy T,q profiles retrievals were added to the final IASI L2 products. Distributed since 02/12/2010.

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II. IASI L2 PPF version 5 Statistical retrievals: SST

NWP cloud testANN cloud testNo dust - ANN cloud test

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AVHRR cloud test

Impact of the cloud & aerosol detectionon the product quality

(AATSR – IASI) SST

Global figuresCold bias: 0.4 K

σ ~ 0.4 K

Outside aerosol areas

Cold bias: 0.25 Kσ < 0.3 K

IASI L2P GHRSST

Global figuresCold bias: 0.4 K

σ ~ 0.4 K

Outside aerosol areas

Cold bias: 0.25 Kσ < 0.3 K

IASI L2P GHRSST


II. IASI L2 PPF version 5 Statistical retrievals: LST

10 K-10

Bias

5 K0

σ

19-24 March 2010 :: NightLANDSAF_MSG – IASI

Global figures(excluding deserts)

ρ ~ 0.99Warm bias

~ 1 Kσ < 2 K

Global figures(excluding deserts)

ρ ~ 0.99Warm bias

~ 1 Kσ < 2 K

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II. IASI L2 PPF version 5The iterative retrieval: OEM

Standard Optimal Estimation Method (OEM) after Rodgers: J = (x - xa)T . B-1 . (x - xa) + (F(x) – y)T . R-1 . (F(x) – y)

Marquardt-Levenberg minimisation (5 iterations max.) Active parameters: Tskin and T, q & O3 profiles

Background term computed in the EOF space of the atmospheric parameters: T -> 28 PCs, q -> 18 PCs, O3 -> 9 PCs

One unique global a priori and covariance matrix 316 channels after Collard (Collard et al., QJRMS 2007) global radiance tuning and measurement error

covariance matrix: prior clear sky OBS-CALC Forward model: RTIASI-4 optimised for faster computations First guess: statistical retrievals

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II. IASI L2 PPF version 5T, q profiles: non-regression check

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• Non-regression check and validation result from comparisons against ECMWF analyses.

• 3 datasets:- “One Year” orbits centred on analyses synoptic

times- “Focus days” (8 Sep 2007, 5 March and 9 May

2008)- 19-24 March 2010, with latest L1c products

• Detailed results presented in EUM/MET/TEN/09/0448


II. IASI L2 PPF version 5T, q profiles: non-regression check

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Ps < 900 hPa


II. IASI L2 PPF version 5Temp. profiles: non-regression check

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- v5- v4

rms ~ 0.7 K !!! rms ~ 0.7 K !!! rms ~ 0.7 K !!!

19-24 March 2010IASI - ECMWF

Yield increased x1.7

rms ≤ 1K [200-800hPa]


II. IASI L2 PPF version 5WV profiles: non-regression check

EOF FG

19-24 March 2010

(IASI - ECMWF)

Bias reduced in BDL

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OEM

- v5- v4


Include covariance Tskin – T – WV and possibly O3 in BG Synergistic use of MW measurements: AMSU, MHS Add physical constraints (super-saturation and

adabiatic lapse rate) to restrict solution space More channels needed for humidity retrievals:

external study for MTG-IRS by C. Serio (Univ. Basilicata), paper by Rodgers in Adv. Space Res. 1998

Migration to RTTOV-10:• Upgraded spectroscopy• MW instruments => residual cloud contamination effect• PCRTM => use more channels in retrievals• Simulation of clouds & aerosols

All channelsAll channels

300 PCs300 PCs

300 channels

300 channels

Credits: C.Serio (Univ. Basilicata)

Credits: C.Serio (Univ. Basilicata)

II. IASI L2 PPF version 5OEM: Future developements

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III. Discussion on T,q validationT @ NOAA/NPROVS

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http://www.star.nesdis.noaa.gov/smcd/opdb/poes/NPROVS.php

IASI L2PPFv5.0

T @ 500 hPaT @ 700 hPaT @ 850 hPa

PPFv4PPFv5

Credits: NOAA / NESDIS Center for

Satellite Applications and Research.

AIRS AQUACOSMIC UCARIASI NOAAIASI EUM


III. Discussion on T,q validation WV @ NOAA/NPROVS

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PPFv5

WV @ 500 hPaWV @ 700 hPaWV @ 850 hPa

Credits: NOAA / NESDIS Center for

Satellite Applications and Research.

AIRS AQUACOSMIC UCARIASI NOAAIASI EUM


III. Discussion on T,q validation Sondes @ Sodankylä

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Humidity profiles: High variability, model vs sondes differences

Credits: X. Calbet (EUM) and R. Kivi (FMI)

3σnoise


3 main field experiments during Austral springs 2008, 2009 and 2010

In 2010, 19 super-pressure balloons (CNES) launched from McMurdo, 6 with a scientific payload sounding the stratosphere, and 13 of the driftsonde type developed at NCAR.

From the 13 driftsondes flying at around 20km altitude, ~640 dropsondes were dropped over Antarctica and the surrounding seas, coincident with Metop overpasses.

Additional measurements performed at other stations in Antarctica: Dumont d’Urville, Concordia and Rothera.

Drop-ondes coincident with Metop and A-Train overpasses

IAS

I/A

VH

RR

CTP @

CM

FCredits: Lydie Lavanant

CALIOP CTP (hPa)

IAS

I C

TP @

EU

M

III. Discussion on T,q validation ConcordIasi

Co-operation with F. Rabier and L. Lavanant (Meteo-France)

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Summary

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PPFv5 operational since 14/09/2010 ! Significant improvements: T, LST, clouds (O3, CO) Products further characterised: SST, LST Some cloudy retrievals Validation documentation available on-line: www.eumetsat.int

Improve/characterise further T and q in bottom layers Reduce use of NWP forecasts

¿ Seasonal variations in long-term monitoring: origins ? How to account for it in CDRs ?

¿ clouds/aerosol detection/simulation impact on WV profiles quality ?

¿ What WV products references for the validation of satellite retrieved profiles with ground resolution of 12-30 km ?


Thank you for your attention !

[email protected]

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Status of the operational IASI L2 version 5 products

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