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Status of the operational IASI L2 version 5 products. Thomas August (EUMETSAT) Tim Hultberg, Dorothée Coppens, Arlindo Arriaga, Lars Fiedler, Xavier Calbet, Dieter Klaes, Peter Schlüssel, Rose Munro, Marc Crapeau. Outline. Overview of the IASI mission The IASI L2 processor (PPF) version 5

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status of the operational iasi l2 version 5 products

Status of the operationalIASI L2 version 5 products

Thomas August (EUMETSAT)

Tim Hultberg, Dorothée Coppens, Arlindo Arriaga, Lars Fiedler,

Xavier Calbet, Dieter Klaes, Peter Schlüssel, Rose Munro, Marc Crapeau

outline
Outline
  • Overview of the IASI mission
  • The IASI L2 processor (PPF) version 5
  • Discussion on T, q validation
  • Summary
i the iasi mission the instrument
I. The IASI mission The instrument

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°)

Surface

Clouds

Surface

Clouds

N2O

CO2

CO

CO2

O3

CH4

H2O

T profiles

i the iasi mission metop and the eps program
I. The IASI mission Metop and the EPS program
  • 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.
  • 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
i the iasi mission the operational l2 products
I. The IASI mission The operational L2 products

Disseminated in NRT (sensing +3h)

Vertical profiles: Temperature

Vertical profiles: Humidity

Land & Sea Surface Temperature

TWT

EMS

Surface emissivity

CLD

Cloud detection and characterisation

OZO

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

CO

N2O

CH4

CO2

Total columns

TRG

Slide: 5

slide6

II. IASI L2 PPF version 5 Why upgrade ?

IASI – ECMWF @ 500 hPa

2

rmse

Processing chain version 5

operational since 14 September 2010 !

v4

σ

1

σ

bias

Error [K]

v5

0

-1

bias

ii iasi l2 ppf version 5 the main steps
II. IASI L2 PPF version 5 The main steps
  • Input data pre-processing
  • Cloud detection and characterisation
  • Statistical retrievals: T, q, Ts, ε, trace gases
  • Optimal Estimation Method (OEM): T, q, Ts, O3

IASI L1C

EOF

ANN

cloud-free

OEM

IASI

L2

product

NWP

Aux. meas.

EOFcloudy

Conf. data

Static db

ii iasi l2 ppf version 5 measurements aux products
II. IASI L2 PPF version 5 Measurements & aux. products

Raw L1C Ammonia Reconstructed

  • 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

slide10

II. IASI L2 PPF version 5 Cloud detection

Opt. depth test

AVHRR test

NWP test

  • 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

18/11/2009 White: clear

slide11

II. IASI L2 PPF version 5 Statisticalretrievals: 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.
slide12

II. IASI L2 PPF version 5 Statisticalretrievals: SST

Impact of the cloud & aerosol detection

on the product quality

AVHRR cloud test

ANN cloud test

No dust - ANN cloud test

NWP cloud test

Global figures

Cold bias: 0.4 K

σ ~ 0.4 K

Outside aerosol areas

Cold bias: 0.25 K

σ < 0.3 K

IASI L2P GHRSST

(AATSR – IASI) SST

slide13

II. IASI L2 PPF version 5 Statisticalretrievals: LST

  • 19-24 March 2010 :: Night
  • LANDSAF_MSG – IASI

10 K

-10

Global figures

(excluding deserts)

ρ ~ 0.99

Warm bias ~ 1 K

σ < 2 K

Bias

0

5 K

σ

Slide: 13

slide14

II. IASI L2 PPF version 5 The iterativeretrieval: 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
slide15

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

  • 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
slide17

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

  • 19-24 March 2010
  • IASI - ECMWF
  • Yield increased x1.7
  • rms ≤ 1K [200-800hPa]

rms ~ 0.7 K !!!

rms ~ 0.7 K !!!

- v5

- v4

slide18

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

  • 19-24 March 2010
  • (IASI - ECMWF)
  • Bias reduced in BDL

EOF FG

OEM

- v5

- v4

slide19

II. IASI L2 PPF version 5 OEM: Future developements

  • Includecovariance Tskin – T – WV and possiblyO3in BG
  • Synergistic use of MW measurements: AMSU, MHS
  • Addphysicalconstraints(super-saturation and adabiatic lapse rate) to restrict solution space
  • More channelsneeded for humidityretrievals: externalstudy for MTG-IRS by C. Serio (Univ. Basilicata), paper by Rodgers in Adv. SpaceRes. 1998
  • Migration to RTTOV-10:
  • Upgradedspectroscopy
  • MW instruments => residualcloud contamination effect
  • PCRTM => use more channels in retrievals
  • Simulation of clouds & aerosols

All channels

300 channels

300 PCs

Credits: C.Serio (Univ. Basilicata)

slide20

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

T @ 500 hPa

T @ 700 hPa

T @ 850 hPa

IASI L2

PPFv5.0

PPFv4

PPFv5

IASI EUM

IASI NOAA

COSMIC UCAR

AIRS AQUA

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

Credits: NOAA / NESDIS Center for

Satellite Applications and Research.

slide21

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

WV @ 500 hPa

WV @ 700 hPa

WV @ 850 hPa

PPFv5

IASI EUM

IASI NOAA

COSMIC UCAR

AIRS AQUA

Credits: NOAA / NESDIS Center for

Satellite Applications and Research.

slide22

III. Discussion on T,q validation Sondes @ Sodankylä

  • Humidity profiles: High variability, model vs sondes differences
  • Credits: X. Calbet (EUM) and R. Kivi (FMI)

13/07/2007

noise

Calbet et al., AMTD 2010

slide23

III. Discussion on T,q validation ConcordIasi

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

IASI/AVHRR CTP @ CMF

IASI CTP @ EUM

Credits: Lydie Lavanant

CALIOP CTP (hPa)

summary
Summary
  • 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 ?
slide25

Thank you for your attention !

  • thomas.august@eumetsat.int