Recent Advances in Land Surface Albedo Generation from European Satellite Sensors (POLDER, MSG, VEGETATION) O. HAUTECOEUR, D. CARRER, J.-L. ROUJEAN, B. GEIGER, C. MEUREY Centre National de Recherches Météorologiques (CNRM) / GAME Météo-France / CNRS

A global analysis Comparison with other land surface albedos according following criteria: global, routinely disseminated, free access. 2 classes of products are analysed: a)Albedos issued from radiation transfer codes and GCMs (ISCCP, ECMWF, ARPEGE) b) Albedos issued from a Ground Segment of remote sensing data processing (MISR, MODIS, MSA) A local analysis Comparison with ground-based pyranometers: BSRN, ARM, SURFRAD, CarboEurope, AsiaFlux Objective criteria: seasonal trend, spatial coherence, gap filling, % of erroneous data, quality assessment, attempt of error explanation by other means. Validation plan - Overview

Peculiarities of observing systems

Albedo AVHRR-3MSG Spectral response functions

Kernel-driven BRDF models BRDF algorithm + …+ IsoGeo Vol 1 pixel BRDFBRDF Isotropicgeomericvolumetric

CPP distributes 2 products: -Directional Parameters products -Directional Parameters products : spectral BRDF model coefficients. -Albedo -Albedo : spectral Directional Hemispherical Reflectance (DHR) for median solar zenith angle (to be changed for solar noon for PARASOL/POLDER-3) Synthesis period : 30 jours Composite period : 10 jours [enhanced weight is given to the data near central date] DQX DQX (Data Quality indeX) : includes ‘ level of noise ’ and quality of BRDF model inversion. Centre de Production POLDER (CPP)

ISCCP POLDER ISCCP POLDER April 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 = snow albedo exposed = [ 0.5, 0.85 ] - snow albedo shaded = diffuse / direct albedos solar product ( µ m) - global - monthly (snow-free) - tri-hourly (snow) ECMWF (forecast product) ARPEGE (forecast product)

ARPEGE POLDER ARPEGE POLDER April October 2003 [ARPEGE - POLDER] - range of variations [-0.25 ; 0.25 ]

ECMWF POLDER ECMWF POLDER Avril Octobre [ECMWF - POLDER] - range of variations [-0.25 ; 0.25 ]

MSA POLDER MODIS POLDER April June 2003 [MSA - POLDER] - range of variations [-0.25 ; 0.25 ] MSA Meteosat Surface Albedo < JRC + EUMETSAT

MISR POLDER MODIS POLDER April June 2003 [MISR - POLDER] - range of variations [-0.25 ; 0.25 ] MISR

MODIS POLDER MODIS POLDER April June 2003 [MODIS - POLDER] - range of variations [-0.25 ; 0.25 ] MODIS

SURFRAD POLDER MODIS

CarboEurope & AsiaFlux PAR albedo Shortwave albedo POLDER MODIS

The main purpose of the Land SAF is to increase the benefits from MSG/SEVIRI and EPS/AVHRR-3 data related to land, land-atmosphere interactions and biophysical applications, namely by developing techniques, that will allow a more effective use of data from the two planned EUMETSAT satellites (MSG and EPS) SAF on Land Surface Analysis

THE LSA SAF PRODUCTS

Data processing chain SAF NowCasting ECMWF (H20, 03, aerosols ?)

MSG vs MODIS MSG MODIS Bias of VIS = (due to aerosols ?) Standard deviation : (VIS) (NIR) period August 13 – 28, 2006

June 1rst, 2005 October 1rst, 2006 [ MSG – MODIS ] Broadband - BHR Broadband - DHR Near Infrared - DHR Visible - DHR Europe

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 products Network RADOME of Météo-France

EUROPEAFRICA Ground-based validation of DSSF

VEGETATION / SPOT – 1 km bluered NIR SWIR

VEGETATION MODIS

Assimilation – Kalman filter 11/14 (Samain, Roujean and Geiger, RSE, 2007) CATCH zone (West Africa) K0 K1 K2 ECOCLIMAP-II land cover map (305 classes)

Questions about snow albedo …

Overview of Land surface albedo Essential climate variable - Essential climate variable to assess energy budget (via net absorbed radiation) in Numerical Weather Prediction (NWP) and climate modeling -Specifications -Specifications required by end-users community for a snow-free albedo product is assessed around 0.03 (absolute units) -Validation -Validation 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 channels