LAND SURFACE ALBEDO AND DOWNWELLING SHORTWAVE RADIATION FROM MSG GEOSTATIONARY SATELLITE (METHOD FOR RETRIEVAL, VALIDATION, AND APPLICATION)

Transcription

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

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

4 4 LSA-SAF CHRONOGRAM LSA-SAF: Satellite Application Facility on Land Surface Analysis

5 5 OPERATIONAL SYSTEM (

6 6 THE Land-SAF CONSORTIUM

7 7 THE PRODUCTS Product Acronym Type Institution Surface Albedo AL OP MF Bi-directional Reflectance Distribution Function BRDF OP-Int MF Land Surface Temperature LST OP IM Thermal Surface Parameter TSP POC- Int IMK Emissivity EM OP-Int ICAT Downwelling Surface Short-wave Fluxes DSSF OP MF 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 Photosynthetic Active Radiation fapar OP UV

8 8 SNOW COVER

9 9 SURFACE ALBEDO

10 10 LAND SURFACE TEMPERATURE

11 11 SHORT-WAVE RADIANCE

12 12 LONG-WAVE RADIANCE

13 13 FRACTIONAL VEGETATION COVER

14 14 LEAF AREA INDEX

15 15 fapar

16 16 THE PRODUCTS

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

18 18 PRODUCT CHARACTERISTICS (AL) Colour Composite Of Spectral Albedo 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 Timeliness: 3 hours Dissemination: EUMETSAT broadcast system (EUMETCast), and project website ( 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])

19 19 METHOD FOR RETRIEVAL TOA Reflectance Factor AL1 for each slot t=15min Geometry Atmospheric Correction Atmosphere TOC Reflectance Factor AL2 for each day t=1day Geometry BRDF Model Inversion Model Parameters k, C k Previous Model Estimate Geometry Integration Albedo

20 20 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)

21 21 COMPARISON WITH MODIS ALBEDO (1/2) [0.4µm,0.7µm] 16-day average MSG Albedo MODIS albedo projected on SEVIRI grid of June 2006 over Europe (from to ) [0.7µm,4µm] [0.3µm,4µm]

22 22 COMPARISON WITH MODIS ALBEDO (2/2) of July 2006

23 ALBEDO TIME SERIES (snowfall episodes) 23 Modis SW-BH albedo MSG albedo (Estonia) (boreal forest) ground measurements (Germany) (mixed shrub/tree)

24 24 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.

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: for VIS and 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, , doi: /tgrs 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: /tgrs (Product User Manual, and Validation Report, internal documents)

26 26 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 UTC+12 LandSAF-reference 2m temperature UTC+12 LandSAF-reference no assimilation of snow/ice pixels LandSAF albedo 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)

27 27 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

28 28 PRODUCT CHARACTERISTICS (DSSF) DSSF Estimate Spatial Resolution: 3km at the Sub-Satellite Point Projection: native MSG/SEVIRI Projection Production Frequency: 30 Minutes Instantaneous Flux Estimate Format: HDF5 Timeliness: 3 hours Dissemination: EUMETSAT broadcast system (EUMETCast), and project website ( Wavelength interval: [0.3µm, 4.0µm] Processing Flag

29 EVALUATION OF DAILY DOWNWELLING SHORTWAVE SURFACE FLUXES (DIDSSF) 29 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, )

30 DSSF: IMPACT ON THE MODELLED LAND WATER AND ENERGY BUDGET 30 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.)

31 31 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

32 OPEN ISSUES AND FURTHER DEVELOPMENTS : 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: /2009jd ) 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

33 33

34 MANY THANKS 34