MODIS Reflectance Anisotropy and Albedo (Collection V005)

1. MODIS Reflectance Anisotropy and Albedo (Collection V005) Crystal Schaaf, Alan Strahler, Jicheng Liu Department of Geography and Environment, Center for Remote Sensing, Boston University

2. MODIS: System Characteristics EOS-Terra Platform • Sun-synchronous, near-polar, 705.3 km, 98.21° inclination • 10:30 AM local solar equatorial crossing time (descending node • Launched December 18, 1999 EOS-Aqua Platform • Sun-synchronous, near-polar, 705.3km, 98.21° inclination • 1:30 PM local solar equatorial crossing time (ascending node) • Launched May 4, 2002

3. MODIS Surface Reflectance (MOD09) • The MODIS surface reflectance product is an estimate of the surface spectral reflectance for each band as it would have been measured at ground level if there were no atmospheric scattering and absorption. • Bands (in nm): • 1620-670 • 2 841-876 • 3459-479 • 545-565 • 1230-1250 Daily Browse • 6 1628-1652 Mostly Cloudy! • 7 2105-2155 • Home page: http://modis-sr.ltdri.org/html/surfref.htm 3

4. MODIS Anisotropy and Albedo • Inputs • Cloud-free, atmospherically-corrected, spectral surface reflectances from Aqua and Terra (MOD09/MYD09 BRFs) to sample the surface anisotropy over a 16 day period • Output • High quality full inversions provide well-sampled, best-fit anisotropy models of global land surfaces • Ross Thick Li Sparse Reciprocal semi-empirical model captures volumetric and geometric-optical scattering • Lower quality back-up algorithm performs magnitude inversions by coupling available reflectances with an a priori BRDF database

5. MODIS Anisotropy and Albedo

6. Semi-Empirical BRDF Model Rλ(θi, Φi; θr, Φr) = fiso + fvolkvol + fgeokgeo (Roujean et al., 1992) Volumetric Geometric Isotropic kvol,kgeoare kernels of view and illumination geometry fiso, fvol, fgeo are spectrally dependent weights

7. Kernel Models • Kernel model derivation • To derive a kernel model, we simplify and manipulate a complete physical model until it reaches the form • where k is a function only of view and illumination geometry (and fixed physical parameters) • c1 and c2 are constants containing variable physical parameters

8. MODIS Anisotropy and Albedo Products • BRDF Model parameters • RossThickLiSparseR model parameters • Use parameters directly in simple polynomial to estimate albedo or reflectance quantities • BRDF shape factors capture some measure of structure • Nadir BRDF-Adjusted Reflectance (NBAR) • View angle corrected surface reflectances • Operational MODIS land cover classification and phenology • Albedo quantities • Bihemispherical reflectance under isotropic illumination (BHRiso) • White-sky albedo (wholly diffuse) • Directional-hemispherical reflectance (DHR) at local solar noon • Black-sky albedo (direct) • Intrinsic albedos can be combined as a function of diffuse skylight (optical depth) to obtain instantaneous actual albedos

9. MODIS Anisotropy and Albedo Product • Product Output • Spectral (Collections 004 and 005) • 7 shortwave bands and three broad bands • Spatial • Sinusoidal 10deg2 tiles • 500m (005) • 1km (004, 005) • Climate Modeling Grid (CMG) • 0.05deg in global lat/lon (004, 005) • 30arcsec in global lat/lon (005) • Temporal • Every 16 days (004) • Every 8 days based on the last 16 days (005)

10. Multi-angle Indications of Vegetation Structure MODIS BRDF Shape Factors MISR RPV Classification M. Hill, Univ. North Dakota

11. NBAR NIR (0.10-0.45)Red (0.0-0.1)Green (0.0-0.15) Differences between MODIS surface reflectances from adjoining swaths and MODIS NBAR (Great Lakes/NY, 6 Sep 2000).

12. NBAR January 1-16, 2001 (2001001) April 7-22, 2001 (2001097) July 12-27, 2001 (2001193) October 16-31, 2001 (2001289)

13. Temporal Signal

14. MODIS Land Cover Product —IGBP MODIS data Nov 00–Oct 01 ~2300 sites globally Friedl, M. A., D. K. McIver, J. C. F. Hodges, X. Zhang, D. Muchoney, A. H. Strahler, C. E. Woodcock, S. Gopal, A. Schnieder, A. Cooper, A. Baccini, F. Gao, and C. Schaaf, Global land cover from MODIS: Algorithms and early results, Remote Sens. Environ., 83, 287-302, 2002.

15. Initial Efforts to Distinguish Crop Types Credit W. Boykin-Morris

16. MODIS Vegetation Phenology:(Zhang et al. 2003, RSE; Zhang et al. 2004 GCB; Zhang et al. 2004, GRL; Zhang et al., 2006, JGR) • Quantifies Intra-annual Variation (phenology) • Greenup, maturity, senescence, dormancy Use logistic functions fit to time trajectories of NBAR-EVIand use extreme points of the change rate of curvature to calculate phenology transition dates

17. Global Results -2001 (e.g., Northern Hemisphere Green Wave) 2001-2004 V004 MCD12Q2 available Credit: X. Zhang, M. Friedl, Bin Tan

18. MODIS Phenology Harvard Forest

19. 2001193 V005 500m White-Sky Albedo 500m 1km

20. Albedo of Sahara 1 km albedo – RGB composite Tsvetsinskaya et al., Relating MODIS derived surface albedo to soils andlandforms over Northern Africa and the Arabian Peninsula, Geophys. Res. Let., 29, 10.1029/2001GL014096, 2002.

21. CMG Broadband White-Sky Albedo (0.3-5.0mm)January 2001 No Data

22. CMG Broadband White-Sky Albedo (0.3-5.0mm)June 2001 No Data

23. Collection V005 Emphasis on Validation/Intercomparison • BSRN/Surfrad calibrated albedometers • http://www.gewex.org/bsrn.html • http://bsrn.ethz.ch/ • CERES/ARM Validation Experiment (CAVE) • http://www-cave.larc.nasa.gov/cave/cave2.0/SfcObs.html • EOS core sites (200x 200km) • http://landval.gsfc.nasa.gov/ • ORNL subsets (7x7 km to 200X200 km) • http://www.modis.ornl.gov/modis/index.cfm • Field Campaigns: SAFARI, ARM CLASIC • CLASIC - Cloud and LAnd Surface Interaction Campaign • Southern Great Plains, 10-30 June 2007 • Additional towers (radiation and flux), MAS, CAR • http://www.ars.usda.gov/Research/docs.htm?docid=15299

24. Oak Ridge National Lab Subsets http://www.modis.ornl.gov/modis/index.cfm

25. Boulder, CO

26. MODIS Anisotropy and Albedo Validation ARM SGP EF-15 2003 ARM CLASIC – Cloud and LAnd Surface Interaction Campaign 10-30 June 2007

27. MODIS Anisotropy and Albedo Validation 2003 Liu et al., GRL in review

28. Workshops October 2002 Boston April 2005 Vienna Product Intercomparison/Validation Roujean et al., (POLDER/SEVIRI/MODIS) Pinty et al., (MISR/MODIS/Meteosat) Rutan et al., (MODIS/CERES) Spring 2008 (Gabriela Schaepman-Strub has offered to host – venue TBD) Website (supported by NASA) http://lpvs.gsfc.nasa.gov CEOS/WGCV/LPV (Land Product Validation) Surface Radiation Subgroup

29. MODIS/CERES Intercomparison • Continental • Deserts Dave Rutan et al., 2007 ARM Meeting

30. MODIS Albedo for Modeling Applications • Produce CMG products and gap-filled (snow-free) products for model evaluations and parameterizations • NCAR CLM (Dickinson, Zeng, Oleson, Lawrence) • ECMWF (Morcrette) • ETH ECHAM (Roesch) • NCEP Noah (Mitchell) • GMAO LSM (Koster, Bounoua/Moody/King) • GISS (Y.-C. Zhang) • Establish long term data sets by linking MODIS with historical meterological satellites (AVHRR) • LTDR effort (Eric Vermote) • http://ltdr.nascom.nasa.gov/ltdr/ltdr.html

31. CMG Broadband Black-sky Albedo (0.3-5.0mm) Use multiple MODIS sensors to increase the directional sampling of the surface and thus increase high quality anisotropy and albedo retrievals Te rra Terra + Aqua Green: high quality Red: poorer quality

32. Spatially Complete White-Sky Albedo (LSN) January 1-16, 2002 Annual data sets and 5 year mean 2000-2004 Snow-free 0.8 0.6 Surface Albedo (0.86 µm) 0.4 0.2 0.0 Snow-covered http://modis-atmos.gsfc.nasa.gov/ALBEDO/index.html Moody, E. G., M. D. King, S. Platnick, C. B. Schaaf, and F. Gao, Spatially complete global spectral surface albedos: Value-added datasets derived from Terra MODIS land products, IEEE Transactions on Geoscience and Remote Sensing, Vol. 43, 144-158, 2005.

33. Gap-Filled Anisotropy Products True color WSA based on gap-filled BRDF Model Parameters September 2001-2005 http://www-modis.bu.edu/brdf_albedo/gapfill5years.html Q. Zhang et al., in preparation

34. MODIS Land Products: Data and Imagery • Collection 4 (V004) reprocessed MODIS Land Products (March 2000 to 2006). • Collection 5 (V005) reprocessing started (2000-mid 2002 complete – 2007 on). • LAADS (Collection V005 only) • http://ladsweb.nascom.nasa.gov:8300/index.html • EDC DAAC EDG (entire data set is available) and Data Pool (limited extent) • http://edcimswww.cr.usgs.gov/pub/imswelcome/ • http://lpdaac.usgs.gov/datapool/datapool.asp • ORNL DAAC MODIS subsets over vegetation field sites • http://www.modis.ornl.gov/modis/index.cfm • Gap-filled (V004) Terra Albedo (snow-free) • http://modis-atmos.gsfc.nasa.gov/ALBEDO/index.html • Gap-filled (V004) Terra Aqua BRDF model parameters • http://www-modis.bu.edu/brdf_albedo/gapfill5years.html • Global Browse Imagery • http://landweb.nascom.nasa.gov/cgi-bin/browse/browse.cgi

35. MODIS Land Products: Descriptions • MODIS BRDF/Albedo Product • Product description and userguide • http://www-modis.bu.edu/brdf/ • http://www-modis.bu.edu/brdf/userguide/index.html • MODLAND • http://modis-land.gsfc.nasa.gov/ • MODLAND QA • Single most useful site with links to QA Known Issues, Product Definitions (Users Guides and Specs), Global Browse, etc. • http://landweb.nascom.nasa.gov/cgi-bin/QA_WWW/newPage.cgi • MODLAND Validation • http://landval.gsfc.nasa.gov/

36. Albedo/BRDF References Salomon, J., C. B. Schaaf, A. H. Strahler, F. Gao, Y. Jin, Validation of the MODIS Bidirectional Reflectance Distribution Function and Albedo Retrievals Using Combined Observations from the Aqua and Terra Platforms, IEEE Trans. Geosci. Remote Sens. Vol. 44, 2006. Gao, F., C. Schaaf, A. Strahler, A. Roesch, W. Lucht, and R. Dickinson, The MODIS BRDF/Albedo Climate Modeling Grid Products and the Variability of Albedo for Major Global Vegetation Types, J. Geophys. Res., 110, D01104, doi:10.1029/2004JD005190. 2005. Moody, E. G., M. D. King, S., Platnick, C. B. Schaaf, and F. Gao, 2005: Spatially complete global spectral surface albedos: Value-added datasets derived from Terra MODIS land products. IEEE Trans. Geosci. Remote Sens., 43, 144-158. Stroeve, J., J. Box, F. Gao, S. Liang, A. Nolin, C. Schaaf, Accuracy Assessment of the MODIS 16-day Albedo Product for Snow: Comparisons with Greenland in situ Measurements., Remote Sens. Environ., 94, 46-60, doi:10.1016/j.rse.2004.09.001, 2005. Roesch, A., C. Schaaf and F. Gao, Use of Moderate-Resolution Imaging Spectroradiometer bidirectional reflectance distribution function products to enhance simulated surface albedos, J. Geophys. Res., 109, D12, doi: 10.1029/2004JD004552, 2004. Tian, Y., R. E. Dickinson, L. Zhou, R. B. Myneni, M. Friedl, C. B. Schaaf, M. Carroll, and F. Gao, Land boundary conditions from MODIS data and consequences for the albedo of a climate model, Geophys. Res. Let., 31, doi:10.1029/2003GL019104, 2004. Wang, Z., X. Zeng, M. Barlage, R. E. Dickinson, F. Gao, and C. Schaaf, Using MODIS BRDF and Albedo Data to Evaluate Global Model Land Surface Albedo, J. Hydrometeor., 5, 3-14, 2004. Zhou, L.et al., Comparison of seasonal and spatial variations of albedos from Moderate-Resolution Imaging Spectroradiometer (MODIS) and Common Land Model. J. Geophys. Res., 108, D15, 4488, doi:10.1029/2002JD003326, 2003. Gao et al., Detecting vegetation structure using a kernel-based BRDF model. Remote Sens. Environ., 86(2), 198-205, 2003. Oleson et al., Assessment of global climate model land surface albedo using MODIS data, Geophys. Res. Letters, 30(8), 1443, doi:10.1029/2002GL016749, 2003. Jin et al., Consistency of MODIS surface BRDF/Albedo retrievals: 1. Algorithm performance, J. Geophys. Res., 108(D5), 4158, doi:10.1029/2002JD002803, 2003. Jin et al., Consistency of MODIS surface BRDF/Albedo retrievals: 2.Validation, J.Geophys. Res., 108, 4159, doi:10.1029/2002JD002804, 2003. Schaaf et al., First Operational BRDF, Albedo and Nadir Reflectance Products from MODIS, Remote Sens. Environ., 83, 135-148, 2002. Liang et al., Validating MODIS Land Surface Reflectance and Albedo Products: Methods and Preliminary Results, Remote Sens. Environ., 83, 149-162, 2002. Jin et al., Improving MODIS Surface BRDF/Albedo Retrieval with MISR Multi-angle Observations, IEEE Trans. Geosci. Remote Sens., 40, 1593-1604, 2002. Jin et al., How does snow impact the albedo of vegetated land surfaces as analyzed with MODIS data?, Geophys. Res. Let., 29, 10.1029/2001GL014132, 2002. Tsvetsinskaya et al., Relating MODIS derived surface albedo to soils andlandforms over Northern Africa and the Arabian Peninsula, Geophys. Res. Let., 29, 10.1029/2001GL014096, 2002. MODIS BRDF/Albedo User Guide (http://www-modis.bu.edu/brdf/userguide/index.html)