Transcript II. IASI L2 PPF version 5 Statistical retrievals

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
GlobVapour, Workshop 08-10 March 2011
Status of the operational IASI L2 products
Slide: 1
Outline
I.
Overview of the IASI mission
II. The IASI L2 processor (PPF) version 5
III. Discussion on T, q validation
IV. Summary
GlobVapour, Workshop 08-10 March 2011
Status of the operational IASI L2 products
Slide: 2
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
CO2
O3
T profiles
GlobVapour, Workshop 08-10 March 2011
Status of the operational IASI L2 products
CH4
H 2O
CO N2O CO2
Slide: 3
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
GlobVapour, Workshop 08-10 March 2011
Status of the operational IASI L2 products
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I. The IASI mission
The operational L2 products
Disseminated in NRT (sensing +3h)
TWT
Vertical profiles: Temperature
Vertical profiles: Humidity
Land & Sea Surface Temperature
EMS
Surface emissivity
CLD
Cloud detection and characterisation
OZO
Ozone: total & partial (0-6, 0-12, 0-16 km) columns
TRG
CO
N2O
CH4
CO2
Total columns
GlobVapour, Workshop
08-10
March 2011
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5
Status of the operational IASI L2 products
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II. IASI L2 PPF version 5
IASI – ECMWF @ 500 hPa
2
Why upgrade ?
rmse
v4
Error [K]
Processing chain version 5 σ
1
operational
since 14 September 2010 !
bias
σ
v5
0
-1
GlobVapour, Workshop 08-10 March 2011
Status of the operational IASI L2 products
bias
Slide: 6
II. IASI L2 PPF version 5
The main steps
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
IASI L1C
EOF
ANN
NWP
Aux. meas.
cloud-free
Conf. data
Static db
EOF cloudy
GlobVapour, Workshop 08-10 March 2011
Status of the operational IASI L2 products
OEM
IASI
L2
product
Slide: 7
II. IASI L2 PPF version 5
The static databases
Data type
Origin
Resolution
Land/Sea mask
AAPP
quadtree
Surface elevation
GTOPO 30
(US Geological Survey)
30” x 30” (~1 km)
Emissivity Atlas
Global land surface IR
emissivity database
UW-Madison
(Borbas et al., 2007)
0.05° x 0.05° lat/lon
10 wavelengths
Monthly 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
GlobVapour, Workshop 08-10 March 2011
Status of the operational IASI L2 products
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II. IASI L2 PPF version 5
Raw
L1C L1C radiances
 IASI
Measurements & aux. products
Ammonia
Reconstructed
• 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
GlobVapour, Workshop 08-10 March 2011
Status of the operational IASI L2 products
Slide: 9
II. IASI L2 PPF version 5
Cloud detection
Opt.AVHRR
depth
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
GlobVapour, Workshop 08-10 March 2011
Status of the operational IASI L2 products
18/11/2009 White: clear
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II. IASI L2 PPF version 5
Statistical 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.
GlobVapour, Workshop 08-10 March 2011
Status of the operational IASI L2 products
Slide: 11
II. IASI L2 PPF version 5
Statistical retrievals: SST
Impact of the cloud & aerosol detection
on the product quality
cloud test
test
No dustAVHRR
-NWP
ANN cloud
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
GlobVapour, Workshop 08-10 March 2011
Status of the operational IASI L2 products
Slide: 12
II. IASI L2 PPF version 5
Statistical retrievals: LST
19-24 March 2010 :: Night
LANDSAF_MSG – IASI
-10
10 K
Global figures
(excluding deserts)
0
ρ ~ 0.99
Bias
Warm bias ~ 1 K
5K
σ<2K
σ
GlobVapour, Workshop 08-10 March 2011
Status of the operational IASI L2 products
Slide: 13
II. IASI L2 PPF version 5
The 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
GlobVapour, Workshop 08-10 March 2011
Status of the operational IASI L2 products
Slide: 14
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
GlobVapour, Workshop 08-10 March 2011
Status of the operational IASI L2 products
Slide: 15
II. IASI L2 PPF version 5
T, q profiles: non-regression check
Ps < 900 hPa
GlobVapour, Workshop 08-10 March 2011
Status of the operational IASI L2 products
Slide: 16
II. IASI L2 PPF version 5 Temp. profiles: non-regression check
19-24 March 2010
IASI - ECMWF
rms ~ 0.7 K !!!
rms ~ 0.7 K !!!
 Yield increased x1.7
 rms ≤ 1K [200-800hPa]
GlobVapour, Workshop 08-10 March 2011
Status of the operational IASI L2 products
- v5
- v4
Slide: 17
II. IASI L2 PPF version 5
WV profiles: non-regression check
19-24 March 2010
(IASI - ECMWF)
EOF
OEMFG
 Bias reduced in
BDL
GlobVapour, Workshop 08-10 March 2011
Status of the operational IASI L2 products
- v5
- v4
Slide: 18
II. IASI L2 PPF version 5
OEM: Future developements
 Include covariance Tskin – T – WV and possibly O3 in BG
 Synergistic use of MW measurements: AMSU, MHS
All channels
300 channels
 Add
physical constraints
(super-saturation 300
andPCs
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 => residualCredits:
cloud C.Serio
contamination
effect
(Univ. Basilicata)
• PCRTM => use more channels in retrievals
• Simulation of clouds & aerosols
GlobVapour, Workshop 08-10 March 2011
Status of the operational IASI L2 products
Slide: 19
III. Discussion on T,q validation
T @ 850
500 hPa
700
PPFv5
PPFv4
T @ NOAA/NPROVS
IASI L2
PPFv5.0
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.
GlobVapour, Workshop 08-10 March 2011
Status of the operational IASI L2 products
Slide: 20
III. Discussion on T,q validation
WV @ NOAA/NPROVS
IASI EUM
IASI NOAA
COSMIC UCAR
AIRS AQUA
WV @ 850
500 hPa
700
PPFv5
Credits: NOAA / NESDIS Center for
Satellite Applications and Research.
GlobVapour, Workshop 08-10 March 2011
Status of the operational IASI L2 products
Slide: 21
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
3σ
noise
GlobVapour, Workshop 08-10 March 2011
Status of the operational IASI L2 products
Calbet et al., AMTD 2010
Slide: 22
III. Discussion on T,q validation
ConcordIasi
Co-operation with F. Rabier and L. Lavanant (Meteo-France)
IASI/AVHRR CTP @ CMF
 3 main field experiments during Austral springs 2008, 2009 and 2010
IASI CTP @ EUM
 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.
Credits: Lydie Lavanant
Drop-ondes coincident with Metop and A-Train overpasses
CALIOP CTP (hPa)
GlobVapour, Workshop 08-10 March 2011
Status of the operational IASI L2 products
Slide: 23
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 ?
GlobVapour, Workshop 08-10 March 2011
Status of the operational IASI L2 products
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Thank you for your attention !
[email protected]
GlobVapour, Workshop 08-10 March 2011
Status of the operational IASI L2 products
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