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