Comparison of Green Vegetation Fraction Retrievals from SPOT-VEGETATION and MSG-SEVIRI Sensors<br /> <br />Bernard LACAZE ...
Outline<br /><ul><li>SPOT-VEGETATION and MSG-SEVIRI NDVI data
SPOT-VEGETATION : deriving Green Vegetation Fraction (GVF) from  scaled NDVI
MSG-SEVIRI : deriving GVF from spectral unmixing or scaled NDVI
Results  : Comparison of dekadal NDVI and GVF data (MSG-SEVIRI and SPOT-VEGETATION)
Conclusion</li></ul>IGARSS 2011 24-29 July, Vancouver, Canada<br />2<br />
SPOT-VEGETATION sensor (since 1998)<br />SPOT-4 and SPOT-5<br />sun synchronous orbit<br /> altitude 822 km<br />return in...
SPOT-VEGETATION 10-daily NDVI<br />S10 :Maximum Value Compositing<br />IGARSS 2011 24-29 July, Vancouver, Canada<br />4<br />
SPOT-VEGETATION 10-daily NDVI<br />NDVI data : HDF format, 1 byte/pixel<br />Real NDVI = 0.004 * Digital Number -0.1<br />...
MSG-SEVIRI sensor (since 2004)<br />MSG-1 and MSG-2<br />SEVIRI one image every 15mn                                      ...
MSG-SEVIRI daily NDVI products<br /><ul><li>Land surface monitoring products are elaborated by EUMETSAT Land Surface Analy...
daily NDVI derived from LSA-SAF spectral albedos is available from  AMMASAT data base (area= West Africa, spatial resoluti...
daily experimental NDVI data available from EUMETSAT, since February 2011 (+ pre-operational data from 2010 : 176 days, el...
MSG – SEVIRI NDVI   daily data           since sept. 2005 AMMASAT database <br /><ul><li>covered area:       West Africa25...
resolution 0.05°  1000 samples x 500 lines
daily data since septembre 2005
 NDVI calculatedfrom spectral albedosproduced by LSA-SAF (BRDF model Roujeanet al., 1992, k0parameter), 		model fitted ove...
NetCDF format, integer, NDVI*10000, NDVI≥0,    -1 = ocean</li></ul>8<br />
MSG – SEVIRI NDVI   monthly synthesis january 2010 AMMASAT database <br />9<br />
MSG – SEVIRI NDVI   daily data<br />Turkish  State Met. Service pre-operational data (2010) <br /><ul><li>covered area:   ...
 MSG native projection  3712 samples x 3712 lines
176 days (February-August 2010)
NDVI calculatedfrom top of atmospherereflectances, with BRDF correction (dailymean, maximum and minimum NDVI, number of ob...
HDF5 format, byte, NDVI*100, NDVI≥0</li></ul>10<br />
MSG-SEVIRI NDVI 10-daily synthesis<br />0<br />0.7<br />Maximum NDVI 20-30 March 2010<br />IGARSS 2011 24-29 July Vancouve...
MSG-SEVIRI NDVI 10-daily synthesis<br />21-31 May 2007<br />0<br />0.7<br />Maximum NDVI 20-30 March 2010<br />IGARSS 2011...
MSG – SEVIRI NDVI   daily data<br />NDVE :Eumetsat experimental data (2011) <br /><ul><li>covered area:                   ...
 MSG native projection  3712 samples x 3712 lines
daily data sinceFebruary 2011
 NDVI calculatedfrom top of atmospherereflectances, with BRDF correction
HDF5 format, with 899 bytes header</li></ul>13<br />
MSG – SEVIRI  NDVI   daily data<br />Eumetsat experimental data (2011) <br />surface type = IGBP land cover classification...
From NDVI to Green Vegetation Fraction<br />GVF is the fraction of green vegetation covering a unit area of horizontal soi...
Availability of Green Vegetation Fraction data<br />SPOT-VEGETATION : GVF is named fCover and available since October 2009...
Deriving Green Vegetation Fraction (Fcover) from SPOT-VEGETATION data<br />scaled NDVI<br />BioPar Product User Manual  (2...
Deriving Green Vegetation Fraction (Fcover) from SPOT-VEGETATION data<br />NDVIsoil = min (NDVImin, 0.14)<br />NDVImax = 0...
Green Vegetation Fraction (FCover) from SPOT-VEGETATION data<br />Fcover : 30-days composite, updated every 10 days using ...
Green Vegetation Fraction (FCover) from SPOT-VEGETATION data<br />10° x 10°     tiles<br />GVF data available since oct. 2...
Green Vegetation Fraction (FCover)     from SPOT-VEGETATION : West Africa, July 1-10, 2010<br />DN 0-250 = FVC*250<br />DN...
Deriving Green Vegetation Fraction (FVC) from MSG-SEVIRI data<br />EUMETSAT<br /><ul><li>The operational daily product FVC...
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COMPARISONOFGREENVEGETATIONFRACTIONRETRIEVALSFROMSPOT-VEGETATIONANDMSG-SEVIRISENSORS.pptx

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COMPARISONOFGREENVEGETATIONFRACTIONRETRIEVALSFROMSPOT-VEGETATIONANDMSG-SEVIRISENSORS.pptx

  1. 1. Comparison of Green Vegetation Fraction Retrievals from SPOT-VEGETATION and MSG-SEVIRI Sensors<br /> <br />Bernard LACAZE (1) and Aydin ERTÜRK (2)<br /> CNRS UMR 8586 PRODIG Pôle de Recherche pour l’Organisation et la Diffusion de l’Information Géographique, Paris, France<br />Turkish State Meteorological Service, Remote Sensing Division, Ankara, Turkey<br />1<br />
  2. 2. Outline<br /><ul><li>SPOT-VEGETATION and MSG-SEVIRI NDVI data
  3. 3. SPOT-VEGETATION : deriving Green Vegetation Fraction (GVF) from scaled NDVI
  4. 4. MSG-SEVIRI : deriving GVF from spectral unmixing or scaled NDVI
  5. 5. Results : Comparison of dekadal NDVI and GVF data (MSG-SEVIRI and SPOT-VEGETATION)
  6. 6. Conclusion</li></ul>IGARSS 2011 24-29 July, Vancouver, Canada<br />2<br />
  7. 7. SPOT-VEGETATION sensor (since 1998)<br />SPOT-4 and SPOT-5<br />sun synchronous orbit<br /> altitude 822 km<br />return interval 1 day<br /> swath width 2250km<br />IGARSS 2011 24-29 July, Vancouver, Canada<br />3<br />
  8. 8. SPOT-VEGETATION 10-daily NDVI<br />S10 :Maximum Value Compositing<br />IGARSS 2011 24-29 July, Vancouver, Canada<br />4<br />
  9. 9. SPOT-VEGETATION 10-daily NDVI<br />NDVI data : HDF format, 1 byte/pixel<br />Real NDVI = 0.004 * Digital Number -0.1<br />Status map : HDF format, 1 byte /pixel<br />IGARSS 2011 24-29 July, Vancouver, Canada<br />5<br />
  10. 10. MSG-SEVIRI sensor (since 2004)<br />MSG-1 and MSG-2<br />SEVIRI one image every 15mn Spinning Enhanced Visible and Infrared Imager<br />resolution at nadir 3km (1km for channel 12)<br />IGARSS 2011 24-29 July, Vancouver, Canada<br />6<br />
  11. 11. MSG-SEVIRI daily NDVI products<br /><ul><li>Land surface monitoring products are elaborated by EUMETSAT Land Surface Analysis Satellite Application Facility (LSA SAF) Lisbon, Portugal : NDVI is not a standard product of LSA SAF (vegetation parameters = FVC, LAI, FAPAR)
  12. 12. daily NDVI derived from LSA-SAF spectral albedos is available from AMMASAT data base (area= West Africa, spatial resolution 0.05°, daily since september 2005)
  13. 13. daily experimental NDVI data available from EUMETSAT, since February 2011 (+ pre-operational data from 2010 : 176 days, elaborated with Turkish State Metorological Service)</li></ul>IGARSS 2011 24-29 July, Vancouver, Canada<br />7<br />
  14. 14. MSG – SEVIRI NDVI daily data since sept. 2005 AMMASAT database <br /><ul><li>covered area: West Africa25° W to 25° E, 20° N to 5° S
  15. 15. resolution 0.05°  1000 samples x 500 lines
  16. 16. daily data since septembre 2005
  17. 17. NDVI calculatedfrom spectral albedosproduced by LSA-SAF (BRDF model Roujeanet al., 1992, k0parameter), model fitted over 5 days)
  18. 18. NetCDF format, integer, NDVI*10000, NDVI≥0, -1 = ocean</li></ul>8<br />
  19. 19. MSG – SEVIRI NDVI monthly synthesis january 2010 AMMASAT database <br />9<br />
  20. 20. MSG – SEVIRI NDVI daily data<br />Turkish State Met. Service pre-operational data (2010) <br /><ul><li>covered area: whole MSG disk
  21. 21. MSG native projection  3712 samples x 3712 lines
  22. 22. 176 days (February-August 2010)
  23. 23. NDVI calculatedfrom top of atmospherereflectances, with BRDF correction (dailymean, maximum and minimum NDVI, number of obervations)
  24. 24. HDF5 format, byte, NDVI*100, NDVI≥0</li></ul>10<br />
  25. 25. MSG-SEVIRI NDVI 10-daily synthesis<br />0<br />0.7<br />Maximum NDVI 20-30 March 2010<br />IGARSS 2011 24-29 July Vancouver, Canada<br />11<br />
  26. 26. MSG-SEVIRI NDVI 10-daily synthesis<br />21-31 May 2007<br />0<br />0.7<br />Maximum NDVI 20-30 March 2010<br />IGARSS 2011 24-29 July Vancouver, Canada<br />12<br />
  27. 27. MSG – SEVIRI NDVI daily data<br />NDVE :Eumetsat experimental data (2011) <br /><ul><li>covered area: whole MSG disk
  28. 28. MSG native projection  3712 samples x 3712 lines
  29. 29. daily data sinceFebruary 2011
  30. 30. NDVI calculatedfrom top of atmospherereflectances, with BRDF correction
  31. 31. HDF5 format, with 899 bytes header</li></ul>13<br />
  32. 32. MSG – SEVIRI NDVI daily data<br />Eumetsat experimental data (2011) <br />surface type = IGBP land cover classification<br />14<br />
  33. 33. From NDVI to Green Vegetation Fraction<br />GVF is the fraction of green vegetation covering a unit area of horizontal soil, varying from 0 (bare soil) to 1 (full cover)<br />GVF is independent of leaf and soil optical properties although it is defined with reference to green elements<br />It is generally close to FAPAR (varying from 0 to 0.95) with the advantage of being defined independently of illumination conditions, making it an intrinsic canopy attribute<br />for these reasons, GVF is a very good candidate for substitution of classical vegetation indices like NDVI<br />IGARSS 2011 24-29 July, Vancouver, Canada<br />15<br />
  34. 34. Availability of Green Vegetation Fraction data<br />SPOT-VEGETATION : GVF is named fCover and available since October 2009 from Geoland 2 BIOPAR products database (archived data to be available end of 2011) ; Geoland2 is carried out in the context of GMES, a initiative of the European Commission, which aims to build up a European capacity for Global Monitoring of Environment and Security; other sites for obtaining or disseminating data : GEOSUCCESS, VGT4Africa, EUMETCAST, DevCoCast <br />MSG-SEVIRI: daily GVF (named FVC Fraction of Vegetation Cover) is an operational product since March 2007 available from LSA SAF archive http://landsaf.meteo.pt/<br />IGARSS 2011 24-29 July, Vancouver, Canada<br />16<br />
  35. 35. Deriving Green Vegetation Fraction (Fcover) from SPOT-VEGETATION data<br />scaled NDVI<br />BioPar Product User Manual (2010)<br />IGARSS 2011 24-29 July, Vancouver, Canada<br />17<br />
  36. 36. Deriving Green Vegetation Fraction (Fcover) from SPOT-VEGETATION data<br />NDVIsoil = min (NDVImin, 0.14)<br />NDVImax = 0.85<br />BioPar Product User Manual (2009)<br />IGARSS 2011 24-29 July, Vancouver, Canada<br />18<br />
  37. 37. Green Vegetation Fraction (FCover) from SPOT-VEGETATION data<br />Fcover : 30-days composite, updated every 10 days using a sliding window <br />ADDITIONAL DATA:<br />FCover-ERR (estimated uncertainty) <br />SMB (Status Map or Quality Flag)<br />NMOD (number of clear observations)<br />LMK (Land cover map = GLC 2000 Global Land Cover Map) <br />BioPar Product FCover<br />IGARSS 2011 24-29 July, Vancouver, Canada<br />19<br />
  38. 38. Green Vegetation Fraction (FCover) from SPOT-VEGETATION data<br />10° x 10° tiles<br />GVF data available since oct. 2009; archived data available end of 2011<br />BioPar Product FCover<br />IGARSS 2011 24-29 July, Vancouver, Canada<br />20<br />
  39. 39. Green Vegetation Fraction (FCover) from SPOT-VEGETATION : West Africa, July 1-10, 2010<br />DN 0-250 = FVC*250<br />DN=255 : Invalid<br />Example of SPOT-VEGETATION 10-daily GVF<br />BioPar Product FCover<br />IGARSS 2011 24-29 July, Vancouver, Canada<br />21<br />
  40. 40. Deriving Green Vegetation Fraction (FVC) from MSG-SEVIRI data<br />EUMETSAT<br /><ul><li>The operational daily product FVC is based on the three short-wave channels (VIS 0.6µm, NIR 0.8µm, SWIR 1.6µm) using as input the k0 parameter of a parametric BRDF model (Roujean et al., 1992)
  41. 41. The algorithm relies on an optimised Spectral Mixture Analysis (SMA) technique. In a first step, an exhaustive training set for the soil and vegetation components is defined. Second, a Gaussian Mixture Model is fit to the training data. Third, a Bayesian model selection is used to compute the relative likelihood of membership in each soil/vegetation single-model. FVC is then estimated using a linear-weighted combination single-model estimate</li></ul>IGARSS 2011 24-29 July, Vancouver, Canada<br />22<br />
  42. 42. Daily Green Vegetation Fraction (FVC) from MSG-SEVIRI data<br />EUMETSAT <br />4 sub-images<br />HDF5 format<br />IGARSS 2011 24-29 July, Vancouver, Canada<br />23<br />
  43. 43. Results : comparison of NDVI products<br />Example : 1-10 July 2010, West Africa area<br /><ul><li>10-day SPOT-VEGETATION S10 NDVI MVC, resampled at 0.025° resolution
  44. 44. Maximum of 10 daily NDVI values, MSG-SEVIRI experimental product, resampled at 0.025° resolution (daily mean of n available data during each day)</li></ul>IGARSS 2011 24-29 July, Vancouver, Canada<br />24<br />
  45. 45. Results : SPOT-VEGETATION NDVI S10<br />Example : 10-day NDVI (1-10 July 2010), West Africa area<br />DN<br />Cloud contaminated pixels<br />IGARSS 2011 24-29 July, Vancouver, Canada<br />25<br />
  46. 46. Results : SPOT-VEGETATION NDVI<br />Example : 10-day NDVI (1-10 July 2010), West Africa area cloudy pixels (from status map) in white<br />DN<br />IGARSS 2011 24-29 July, Vancouver, Canada<br />26<br />
  47. 47. Results : MSG NDVI<br />Example : 10-day NDVI (1-10 July 2010), West Africa area maximum of 10 daily mean values<br />NDVI x <br /> NDVI x 100<br />IGARSS 2011 24-29 July, Vancouver, Canada<br />27<br />
  48. 48. Comparison of SPOT-VEG and MSG NDVI<br />Example : 10-day NDVI (1-10 July 2010), West Africa area<br /> Histograms of NDVI values (cloud-free pixels only)<br />SPOT-VEG<br />MSG-SEVIRI<br />IGARSS 2011 24-29 July, Vancouver, Canada<br />28<br />
  49. 49. Comparison of SPOT-VEG and MSG NDVI<br />Example : 10-day NDVI (1-10 July 2010), West Africa area<br />cloud-free pixels only<br />MSG<br />SPOT-VEG<br />IGARSS 2011 24-29 July, Vancouver, Canada<br />29<br />
  50. 50. Results : comparison of FVC products<br />Example : 1-10 July 2010, West Africa area<br /><ul><li>10-daily SPOT-VEGETATION FVC(Geoland 2 BioPar FVC), resampled at 0.025° resolution
  51. 51. Mean of 10 daily MSG-SEVIRI operational product FVC (LSA-SAF) , resampled at 0.025° resolution
  52. 52. Mean of 10 daily MSG-SEVIRI scaled NDVI, using threshold values NDVImin = 0.098 and NDVI max = 0.71 ( values proposed by NOAA-NESDIS, Bob YU pers. comm.)</li></ul>IGARSS 2011 24-29 July, Vancouver, Canada<br />30<br />
  53. 53. Results : SPOT-VEG GVF (scaled NDVI)<br />Example : 10-day FCOVER (1-10 July 2010), West Africa area<br />grey= no vegetation cover (GVF = 0) ; white = invalid data<br />BioPar Product FCover<br /> GVF (%)<br />BioPar Product FCover<br />IGARSS 2011 24-29 July, Vancouver, Canada<br />31<br />
  54. 54. Results : MSG-SEVIRI GVF (LSA SAF FVC)<br />mean of daily FCOVER (1-10 July 2010), West Africa area<br />Grey= no vegetation cover (GVF=0)<br />GVF (%)<br />derived from FVC product<br />IGARSS 2011 24-29 July, Vancouver, Canada<br />32<br />
  55. 55. Comparison of SPOT-VEG and MSG GVF<br />Example : 10-day GVF 1-10 July 2010), West Africa area<br />Cloud-free pixels with GVF>0 only<br />GVFmsg = 0.85 * GVFspot-veg + 10.49<br />r2 = 0.86 <br />IGARSS 2011 24-29 July, Vancouver, Canada<br />33<br />
  56. 56. Comparison of SPOT-VEG and MSG GVF<br />Example : all Africa, years 2008,2009<br />IGARSS 2011 24-29 July, Vancouver, Canada<br />34<br />
  57. 57. Results: MSG-SEVIRI GVF(scaled NDVI)<br />mean of daily GVF (1-10 July 2010), West Africa area<br />Grey= no vegetation cover<br />GVF (%)<br />GVF (%)<br />NDVImin = 0.098; NDVImax = 0.71<br />(NOAA-NESDIS, 2011)<br />IGARSS 2011 24-29 July, Vancouver, Canada<br />35<br />
  58. 58. Comparison of SPOT-VEG and MSG FVC<br />Example : 10-day GVF 1-10 July 2010), West Africa area<br />Cloud-free pixels with GVF>0 only<br />MSG<br />GVFmsg = 0.71 * GVFspot-veg + 17.88<br />r2 = 0.67<br />SPOT-VEG<br />IGARSS 2011 24-29 July, Vancouver, Canada<br />36<br />
  59. 59. Comparison SPOT-VEG vs MSG GVF<br />Example : desert pixels (GVF = 0)<br />yellow : GVF = 0 for both data sources<br />orange : only GVF SPOT-VEG=0<br />SPOT-VEG and MSG (FVC from LSA-SAF)<br />SPOT-VEG and MSG (GVF from scaled NDVI)<br />IGARSS 2011 24-29 July, Vancouver, Canada<br />37<br />
  60. 60. Conclusions 1<br /><ul><li>It is suggested to make use of Green Vegetation Fraction as a substitute to NDVI
  61. 61. Both SPOT-VEGETATION (10-daily) and MSG-SEVIRI (daily) GVF data can be obtained on a near real-time basis: status of products = operational
  62. 62. MSG-SEVIRI has lower spatial resolution than SPOT-VEG, but provides a higher number of available observations in regions with high cloud occurrence, and can be used for high temporal resolution monitoring (1 to 5 days)</li></ul>IGARSS 2011 24-29 July, Vancouver, Canada<br />38<br />
  63. 63. Conclusions 2<br /><ul><li>Different procedures are used to extract FVC from spectral data: all methods suppose that atmospheric and BRDF corrections are efficient
  64. 64. Discrepancies between GVF results from MSG and SPOT-VEG are observed, mainly overestimation of GVF in arid areas when using MSG data
  65. 65. Further research is needed to validate FVC estimations and to ensure intercomparability of results between MSG, SPOT-VEG, MODIS, METOP,… using preferably the same preprocessing/ processing methods to derive GVF</li></ul>IGARSS 2011 24-29 July, Vancouver, Canada<br />39<br />
  66. 66. Thank you for your attention<br />lacaze.bernard@gmail.com<br /> Télédétection<br />peer-reviewed electronic open-access journal<br />http://www.teledetection.net<br />IGARSS 2011 24-29 July, Vancouver, Canada<br />40<br />

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