Recent Advances in Land Surface Albedo Generation from European Satellite Sensors (POLDER, MSG,...
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Recent Advances in Land Surface Albedo Generation from Recent Advances in Land Surface Albedo Generation from
European Satellite Sensors (POLDER, MSG, VEGETATION)European Satellite Sensors (POLDER, MSG, VEGETATION)
O. HAUTECOEUR, D. CARRER, O. HAUTECOEUR, D. CARRER, J.-L. ROUJEANJ.-L. ROUJEAN, B. GEIGER, C. MEUREY, B. GEIGER, C. MEUREY
Centre National de Recherches Météorologiques (CNRM) / GAME
Météo-France / CNRS
A global analysisA global analysis
Comparison with other land surface albedos according following Comparison with other land surface albedos according following criteria: criteria: globalglobal, , routinely disseminatedroutinely disseminated, , free accessfree access. .
2 classes of products are analysed:2 classes of products are analysed:
a)a) Albedos issued from radiation transfer codes and GCMsAlbedos issued from radiation transfer codes and GCMs
(ISCCP, ECMWF, ARPEGE)(ISCCP, ECMWF, ARPEGE)
b) Albedos issued from a Ground Segment of remote sensing b) Albedos issued from a Ground Segment of remote sensing data processingdata processing
(MISR, MODIS, MSA)(MISR, MODIS, MSA)
A local analysisA local analysis
Comparison with ground-based pyranometers:Comparison with ground-based pyranometers:
BSRN, ARM, SURFRAD, CarboEurope, AsiaFluxBSRN, ARM, SURFRAD, CarboEurope, AsiaFluxObjective criteriaObjective criteria: seasonal trend, spatial coherence, gap filling, % of erroneous data, : seasonal trend, spatial coherence, gap filling, % of erroneous data, quality assessment, attempt of error explanation by other means.quality assessment, attempt of error explanation by other means.
Validation plan - Overview
Peculiarities of observing systemsPeculiarities of observing systems
Reflectance of woody and herbacious vegetation (Asner),
soil and snow reflectance (ASTER); Solar Irradiance (E/2000,W/m2/nm)
0
0,2
0,4
0,6
0,8
1
1,2
0 500 1000 1500 2000 2500 3000 3500 4000
WAVELENGTH (nm)
RE
FLE
CT
AN
CE
, E
Woody Veg.
Herbaciuous
Alfisol
Mollisol
snow
Irrad. (E)
AlbedoAVHRR-3
MSG
Spectral response functionsSpectral response functions
Kernel-driven BRDF modelsKernel-driven BRDF models
BRDF algorithmBRDF algorithm
),,(),,(),,( vsvolvolvsgeogeoisovs fkfkkR
s s s s s s n n s s1 10 2 2ρ θ ,θ ,φ =k +k.f θ ,θ ,φ +k .f θ ,θ ,φ +...+k .f θ ,θ ,φ
+ …+
0
1
2
n
k : Lambertian coefficient
k : roughness coefficientk : volume scattering coefficient...k : specular coefficient
IsoGeo
Vol
1 pixel
BRD F
IsotropicIsotropic geomericgeomeric volumetricvolumetric
CPP distributes 2 products:
-Directional Parameters productsDirectional Parameters products : spectral BRDF model coefficients.
-AlbedoAlbedo : spectral Directional Hemispherical Reflectance (DHR) for median solar zenith angle (to be changed for solar noon for PARASOL/POLDER-3)
Synthesis period : 30 joursComposite period : 10 jours
[enhanced weight is given to the data near central date]
DQXDQX (Data Quality indeX) : includes ‘level of noise’ and quality of BRDF model inversion.
Centre de Production POLDER (CPP)Centre de Production POLDER (CPP)
ISCCP
POLDER
ISCCP
POLDER
-0.25 0.25
-0.25 0.25
15 April 2003 15 June 2003
[ISCCP - POLDER] - range of variations [-0.25 ; 0.25 ]
1° degree (spatial resolution)
-diffuse / direct albedos
( ECOCLIMAP)
Characteristics of GCMs albedo products
0.5 ° degree (spatial resolution)
-climatology ISLSCP Initiative II updated with soil reflectance, biophysical parameters [Los et al., 2000].
- vegetation albedo = 0.07
- snow albedo exposed = [ 0.5 , 0.85 ]
- snow albedo shaded = 0.2
- diffuse / direct albedos
solar product (0.4 - 3.0 µm)
- global
- monthly (snow-free)
- tri-hourly (snow)
ECMWF (forecast ECMWF (forecast product)product)
ARPEGE (forecast ARPEGE (forecast product)product)
ARPEGE
POLDER
ARPEGE
POLDER
-0.25 0.25
-0.25 0.25
15 April 2003 15 October 2003
[ARPEGE - POLDER] - range of variations [-0.25 ; 0.25 ]
ECMWF
POLDER
ECMWF
POLDER
-0.25 0.25
15 Avril 2003 15 Octobre 2003
-0.25 0.25
[ECMWF - POLDER] - range of variations [-0.25 ; 0.25 ]
MSA
POLDER
MODIS
POLDER
-0.25 0.25
-0.25 0.25
15 April 2003 15 June 2003
[MSA - POLDER] - range of variations [-0.25 ; 0.25 ]
MSA
Meteosat Surface Albedo < JRC + EUMETSAT
-0.25 0.25
-0.25 0.25
MISR
POLDER
MODIS
POLDER
-0.25 0.25
15 April 2003 15 June 2003
[MISR - POLDER] - range of variations [-0.25 ; 0.25 ]
MISR
-0.25 0.25
-0.25 0.25
MODIS
POLDER
MODIS
POLDER
-0.25 0.25
-0.25 0.25
15 April 2003 15 June 2003
[MODIS - POLDER] - range of variations [-0.25 ; 0.25 ]
MODIS
-0.25 0.25
-0.25 0.25
SURFRAD
POLDER
MODIS
CarboEurope & AsiaFlux
PAR albedo
PAR albedo
Shortwave albedo
Shortwave albedo
POLDER
MODIS
The main purpose of the Land SAF is to increase the benefits from The main purpose of the Land SAF is to increase the benefits from MSG/SEVIRIMSG/SEVIRI and and EPS/AVHRR-3EPS/AVHRR-3 data related to data related to landland, , land-atmosphere interactionsland-atmosphere interactions and and biophysical biophysical applicationsapplications, namely by , namely by developing techniquesdeveloping techniques, that will allow a more effective use of , that will allow a more effective use of data from the two planned EUMETSAT satellites (MSG and EPS)data from the two planned EUMETSAT satellites (MSG and EPS)
SAF on Land Surface AnalysisSAF on Land Surface Analysis
THE LSA SAF PRODUCTS
N_Africa
S_Africa
Europe
S_America
Data processing chain
SAF NowCastingSAF NowCasting
ECMWF
(H20, 03, aerosols ?)
MSG vs MODIS
MSGMSG MODISMODIS
Bias of VIS = 0.015(due to aerosols ?)
Standard deviation :0.015 (VIS)0.030 (NIR)
period August 13 – 28, 2006
June 1rst, 2005 October 1rst, 2006
[ MSG – MODIS ]
Broadband - BHRBroadband - BHR Broadband - DHRBroadband - DHR
Near Infrared - DHRNear Infrared - DHR Visible - DHRVisible - DHR
EuropeEurope
Short-wave broadband albedo
November 17 - December 2, 2005
MSG vs MODIS vs ECMWF
BSRN station – TORAVERE (Estonia)
MSG
BSRN
BHR
DHR
Ground measurement (orange).
Land SAF albedo (black).
Daily AOT from AERONET at 440nm (blue).
[values on y-axis need to be multiplied by 10 ]
Rainfall estimates from TRMM (in mm) (green).
AMMA sites – Agoufou (Mali) & Niamey (Niger)
ARM station
CESBIO station
DSSF flux
Comparison of DSSF productsComparison of DSSF products
Network RADOME of Météo-Network RADOME of Météo-FranceFrance
EUROPEEUROPE AFRICAAFRICA
Ground-based validation of DSSF
http://landsaf.meteo.pt/
CYCLOPES Project Meeting Paris 28 July 200612
SpectralSpectral AlbedoAlbedo (France…, Summer)(France…, Summer)
VEGETATION / SPOT – 1 km
blue red
NIR SWIR
VEGETATION <-> MODIS
Assimilation – Kalman filterAssimilation – Kalman filter
i
s si ialbédo= k.f θ ,θ ,φ
11/14
(Samain, Roujean and Geiger, RSE, 2007)
CATCH zone CATCH zone (West Africa)(West Africa)
K0
K1
K2
ECOCLIMAP-II land cover map
(305 classes)
Questions about snow albedo …
Overview of Land surface albedo
- Essential climate variableEssential climate variable to assess energy budget (via net absorbed radiation) in Numerical Weather Prediction (NWP) and climate modeling
- SpecificationsSpecifications required by end-users community for a snow-free albedo product is assessed around 0.03 (absolute units)
- ValidationValidation is the process of determination by which a model provides a representation of the truth. Typically, it yields an analysis of the spatial variability ( i.e. the representation of the gradients at the continental scale ), plus the temporal evolution, typically over an annual cycle.
Spectral responses of sensor channelsSpectral responses of sensor channels