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Some preliminary tests on VGT data over France J-L CHAMPEAUX, L FRANCHISTEGUY, S. GARRIGUES CNRM/GMME/MATIS.

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Presentation on theme: "Some preliminary tests on VGT data over France J-L CHAMPEAUX, L FRANCHISTEGUY, S. GARRIGUES CNRM/GMME/MATIS."— Presentation transcript:

1 Some preliminary tests on VGT data over France J-L CHAMPEAUX, L FRANCHISTEGUY, S. GARRIGUES CNRM/GMME/MATIS

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3 Cloud mask evaluation Status map cloud mask. New VITO cloud mask (Lissens and al, Belgirate 2000) with thresholds tuned over the world applied to TOA reflectance: a pixel is declared clear if B0<493 OR SWIR<180. New tuned cloud mask with thresholds tuned over France for surface reflectance (S1 data): a pixel is declared cloudy if B0>=220 AND SWIR>=180 Comparison between:

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12 What strategy for the cloud mask? use the status map (poor quality) use the VITO thresholds Must be applied to TOA reflectances determine new thresholds on B0 for specific window

13 Work on bidirectional effects: Evaluation of bidirectional effects in different solar-target-sensor configurations over homogeneous landcover areas Implementation and test of BDC method (B.Duchemin, CESBIO) Proposal VEGA2000: Determination of global albedo from VGT products

14 VEGA2000 proposal : Determination of global albedo products from VGT instrument data for use in numerical weather forecast and climate models. L. FRANCHISTEGUY(CNRM/GMME) Preliminary study with a data set of VGT-P products (April 1998 – March 1999) a) Atmospheric corrections : SMAC TOA reflectances  surface reflectances b) BRDF kernel-driven model inversion : correction of bidirectional effects (30 days compositing period with a sliding period of 10 days). c) Retrieval of land surface albedo (directional albedo) for a 100*100 km domain located in southeast part of France.

15 Method for retrieval of surface properties  Inversion of a BRDF model :  s,  v,  = k 0 + k 1  f 1  s,  v,  + k 2  f 2  s,  v,  (model of Roujean et al., 1992) K0: Normalized reflectance for  s =0 and  v =0

16 DECIDUOUS PIXELS ( South of France)A

17 Unsupervised classification using 10 days MVC ( from 1/1/2000 to 31/09/2000 over SO France Corine Land Cover dataset at 1km resolution

18 Unsupervised classification using 10 days MVC from 1/1/2000 to 31/09/2000 over SO France


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