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1. LAND SURFACE ALBEDO AND
DOWNWELLING SHORTWAVE RADIATION
FROM MSG GEOSTATIONARY SATELLITE
(METHOD FOR RETRIEVAL, VALIDATION,
AND APPLICATION)
Dominique Carrer, Jean-Louis Roujean, Olivier Hautecoeur,
Jean-Christophe Calvet, Jure Cedilnik, Laurent Franchistéguy, Bernhard Geiger,
Sebastien Lafont, Jean-François Mahfouf , Catherine Meurey ,
and Isabel Trigo
2. 2
OUTLINE
LSA SAF project
Surface Albedo Products
method for retrieval
evaluation
application for weather forecast
DSSF
evaluation
impact on the modelled land water and energy budget
Perspectives
IGARSS Conference 2011, Vancouver
3. 3
OUTLINE
LSA-SAF project
Surface Albedo Products
method for retrieval
evaluation
application for weather forecast
DSSF
evaluation
impact on the modelled land water and energy budget
Perspectives
IGARSS Conference 2011, Vancouver
4. 4
LSA-SAF CHRONOGRAM
LSA-SAF: Satellite Application Facility on Land Surface Analysis
IGARSS Conference 2011, Vancouver
7. 7
THE PRODUCTS
Product Acronym Type Institution
Surface Albedo AL OP MF
Bi-directional Reflectance
BRDF OP-Int MF
Distribution Function
Land Surface Temperature LST OP IM
POC-
Thermal Surface Parameter TSP IMK
Int
Emissivity EM OP-Int ICAT
Downwelling Surface Short-wave
DSSF OP MF
Fluxes
Downwelling Surface Long-wave
DSLF OP IM
Fluxes
Snow Cover SC OP SMHI
Evapotranspiration ET OP RMI
Fractional Vegetation Cover FVC OP UV
Leaf Area Index LAI OP UV
Risk Fire Manager RFM DEM IDL
Fire Radiative Power & Energy FRP&FRE OP
Fraction of Absorbed
fAPAR OP UV
Photosynthetic Active Radiation
IGARSS Conference 2011, Vancouver
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THE PRODUCTS
IGARSS Conference 2011, Vancouver
17. 17
OUTLINE
LSA-SAF project
Surface Albedo Products
method for retrieval
evaluation
application for weather forecast
DSSF
evaluation
impact on the modelled land water and energy budget
Perspectives
IGARSS Conference 2011, Vancouver
18. 18
PRODUCT CHARACTERISTICS (AL)
Spatial Resolution: 3km at the Sub-Satellite
Point
Projection: native MSG/SEVIRI Projection
Production Frequency: Daily
Effective Temporal Resolution: 5 Days
(in the near future also monthly)
Format: HDF5
Colour Composite Of Timeliness: 3 hours
Spectral Albedo Dissemination: EUMETSAT broadcast system
(EUMETCast), and project website
(http://landsaf.meteo.pt)
Spectral Albedo (6): 0.6µm, 0.8µm, and 1.6µm
(DH&BH)
BroandBand Albedo (4): VIS-DH ([0.4µm, 0.7µm]
), NIR-DH ([0.7µm, 4.0µm]), SW-DH ([0.3µm,
4.0µm]), SW-BH ([0.3µm, 4.0µm])
IGARSS Conference 2011, Vancouver
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METHOD FOR RETRIEVAL
TOA Reflectance Factor
for each slot
∆t=15min
Atmospheric
AL1
Geometry Atmosphere
Correction
TOC Reflectance Factor
BRDF Model
Geometry Previous Model Estimate
Inversion
for each day
∆t=1day
AL2
Model Parameters k, Ck
Geometry Integration
Albedo
IGARSS Conference 2011, Vancouver
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ALBEDO INPUT DATA
• MSG Data: 0.6µm, 0.8µm, 1.6µm
• Solar and View Angles
• Land/Sea Mask
• Cloud Mask (SAF-NWC software)
• Total Column Water Vapour, and Pressure (ECMWF)
• Ozone Content (Climatology)
• Aerosol Optical Thickness (Climatology)
IGARSS Conference 2011, Vancouver
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COMPARISON WITH MODIS ALBEDO (1/2)
[0.4µm,0.7µm]
over Europe (from 2005-06-01 to 2006-10-01)
16-day average MSG Albedo [0.7µm,4µm]
–
MODIS albedo projected
on SEVIRI grid
[0.3µm,4µm]
10-25 of June 2006
IGARSS Conference 2011, Vancouver
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ALBEDO TIME SERIES (snowfall episodes)
(Estonia)
Modis SW-BH albedo (boreal forest)
MSG albedo ground measurements
(Germany)
(mixed shrub/tree)
IGARSS Conference 2011, Vancouver
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ALBEDO TIME SERIES (aerosol events)
X10 for AOT
Modis SW-DH albedo
SAF-Land albedo
ground measurements
Rainfall
The temporal evolution of the albedo estimate is related to the evolution of surface
properties (typically rainfall). The spurious fluctuations appear to be caused by
aerosol effects.
IGARSS Conference 2011, Vancouver
25. 25
SUMMARY OF PERFORMANCES (AL)
Accuracy
Over mid-latitude region:
bias: 5% in relative units for SW and NIR broadband albedo (except for
snow/ice pixels) – bellow 0.01 in absolute unit
20% for VIS broadband albedo (potentially due to the use of
different BRDF models and aerosol products)
stdev: 0.015 for VIS and 0.030 for NIR and SW (or BB)
Over brightening surfaces (North Africa): no degradation in relative units
Publications:
Geiger, B., Carrer D., Franchistéguy L., Roujean J.-L., Meurey C., 2008, “Land Surface Albedo derived on a
daily basis from Meteosat Second Generation Observations”, IEEE Transactions on Geoscience and Remote
Sensing, 46, 3841–3856, doi:10.1109/TGRS.2008.2001798.
Carrer, D., Roujean J.-L., Meurey C., “Evaluating operational MSG/SEVIRI land surface albedo products from
LSA-SAF with ground measurements and MODIS”, IEEE Transactions on Geoscience and Remote Sensing,
doi:10.1109/TGRS.2009.2034530.
(Product User Manual, and Validation Report, internal documents)
IGARSS Conference 2011, Vancouver
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APPLICATION FOR WEATHER FORECAST
Weather forcast model: ALADIN (~9.5km)
Two experiments: with ALADIN albedo and with LSA-SAF albedo analysis
Run every day at 00h (2007) - 54h forcast
Surface albedo 15022007 00UTC+12 2m temperature 15022007 00UTC+12
LandSAF-reference LandSAF-reference
no assimilation
of
LandSAF albedo
snow/ice pixels
is lower than
Aladin albedo
a lower albedo
induced warmer
atmospheric T2m
Conclusion of Score Study: weather model has a significant cold bias in
winter. Satellite data permit to reduce this bais.
(J. Cedilnik, D. Carrer, J.-L. Roujean and J.-F. Mahfouf, “Analysis of satellite derived surface albedo
for numerical weather prediction”, to submit)
IGARSS Conference 2011, Vancouver
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OUTLINE
LSA-SAF project
Surface Albedo Products
method for retrieval
evaluation
application for weather forecast
DSSF
evaluation
impact on the modelled land water and energy budget
Perspectives
IGARSS Conference 2011, Vancouver
28. 28
PRODUCT CHARACTERISTICS (DSSF)
Spatial Resolution: 3km at the Sub-Satellite
Point
Projection: native MSG/SEVIRI Projection
Production Frequency: 30 Minutes
Instantaneous Flux Estimate
DSSF Format: HDF5
Estimate Timeliness: 3 hours
Dissemination: EUMETSAT broadcast system
(EUMETCast), and project website
(http://landsaf.meteo.pt)
Wavelength interval: [0.3µm, 4.0µm]
Processing
Flag
IGARSS Conference 2011, Vancouver
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EVALUATION OF DAILY DOWNWELLING
SHORTWAVE SURFACE FLUXES (DIDSSF)
LSA-SAF product DIDSSF
ECMWF (DSR) product
(Geiger, B, C. Meurey, D. Lajas, L. Franchistéguy, D. Carrer, and J.-L. Roujean, 2008: Near real-time
provision of downwelling shortwave radiation estimates derived from satellite observations, Royal
Meteorological Society, 15, 411-420.)
IGARSS Conference 2011, Vancouver
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DSSF: IMPACT ON THE MODELLED LAND
WATER AND ENERGY BUDGET
land surface model: ISBA 4 experiments: SAFRAN atmospheric analysis (Ref)
or LSA-SAF DSSF and DSLF
Difference statistics of Net Radiation (RN) over Aurade station based on ISBA
simulations in using various forcing
• When satellite data are considered, the standard deviation of net radiation simulated with ISBA
model can decease by 20 W.m-2 in comparison with ground-measurements.
• As many areas lack a high resolution meteorological forcing, the LSA-SAF radiative products
provide new and valuable information.
(D. Carrer, S. Lafont, J.-L. Roujean, J.-C. Calvet, C. Meurey, P. Le Moigne, and I. Trigo, 2011: Incoming
solar and infrared radiation derived from METEOSAT: impact on the modelled land water and energy
budget over France, Submitted to J. Of Hydrometeorology.)
IGARSS Conference 2011, Vancouver
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OUTLINE
LSA-SAF project
Surface Albedo Products
method for retrieval
evaluation
application for weather forecast
DSSF
evaluation
impact on the modelled land water and energy budget
Perspectives
IGARSS Conference 2011, Vancouver
32. 32
OPEN ISSUES AND FURTHER DEVELOPMENTS
•2011-2012:
1/ tuning of algorithms
2/ high latitude coverage: extension achieved due to the merging of
MSG and MetOp data.
3/ to strengthen validation: over Africa & snow covered areas
4/ use in NWP models:
- radiative forcing (DSSF & DSLF).
- surface analysis (albedo).
5/ aerosols:
- operational algorithm under development.
(Carrer, D., J.-L. Roujean, O. Hautecoeur, and T. Elias (2010), Daily estimates of aerosol optical
thickness over land surface based on a directional and temporal analysis of SEVIRI MSG visible
observations, J. Geophys. Res., 115, D10208, doi:10.1029/2009JD012272.)
•Until 2019:
=> The LSA-SAF program provides a mean to constrain the climate trend
in Europe, Africa, and South America thanks to the insurance of a
constant production foreseen until at least 2019.
IGARSS Conference 2011, Vancouver
