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MODIS BRDF/ALBEDO PRODUCTSCrystal B. SCHAAF, Alan H. STRAHLER, Feng GAO, Wolfgang LUCHT, Yufang JIN,Xiaowen LI, Xiaoyang ZHANG, Elena TSVETSINSKAYA, Jan-Peter MULLER,Michael BARNSLEY, Philip LEWIS, Gareth ROBERTS, Christopher DOLL,Shunlin LIANG, David ROY, and Jeffrey PRIVETTECenter for Remote Sensing, Boston University, 725 Commonwealth Avenue, Boston, MA 02215, USATel. 617-358-0503, Fax 617-353-3200, für Klimafolgenforschung, Postfach 601203, D-14412 Potsdam, GermanyResearch Center for Remote Sensing, Beijing Normal University, Beijing, ChinaDepart. of Geomatic Engineering, University College London, Gower St., London, WCIE 6BT, UKDepartment of Geography, University College London, Gower St., London, WCIE 6BT, UKDepartment of Geography, University of Wales Swansea, Singleton Park, Swansea, SA2 8PP, UKDepartment of Geography, University of Maryland, College Park, MD 20742, USANASA/Goddard Space Flight Center, Code 923, Greenbelt, MD 20771, USA

MODIS BRDF/ALBEDO PRODUCTThe MODIS BRDF/Albedo Product uses multidate, multispectral, cloudcleared, atmospherically-corrected MODIS surface reflectances and a BRDFmodel to provide global measures of albedo, nadir surface reflectance andsurface anisotropy every 16 days at a 1km gridded spatial resolution.1. BRDF model parameters describe the anisotropy of the surface.Albedo and surface reflectance measures can be computed at any desiredview and illumination geometry.2. Bihemispherical albedo (white-sky) and directional hemispherical albedo(black-sky) at local solar noon are computed.Actual albedos can be estimated by interpolating the diffuse and direct beamalbedos as a function of diffuse skylight.3. Nadir BRDF-adjusted Reflectances (NBAR) at mean overpass.Surface reflectances corrected to a common nadir viewing geometry.

MODIS BRDF/ALBEDO PRODUCTThe primary BRDF retrieval algorithm is bolstered by a robustback-up algorithm.1. The full model inversion is used when sufficient high qualityMODIS observations are available to sample the BRDF.2. The lower quality magnitude inversion couples a priori knowledgeof the surface anisotropy with any MODIS observations that areavailable.3. Extensive Quality Assurance Flags are supplied with the productindicating both the quality of the product and the processing methodused.

MOD43B MODIS BRDF/ALBEDO PRODUCTProducts at 1kmMOD43B1: MODIS/Terra BRDF/Albedo Model-1 16-Day L3 Global 1km ISIN GridMOD43B3: MODIS/Terra Albedo 16-Day L3 Global 1km ISIN GridMOD43B4: MODIS/Terra Nadir BRDF-Adjusted Reflectance 16-Day L3 Global 1kmISIN Grid (NBAR)Products at 5kmMOD43B1C: MODIS/Terra BRDF/Albedo Model-1 16-Day L3 Global 5km ISIN GridMOD43B3C: MODIS/Terra Albedo 16-Day L3 Global 5km ISIN GridMOD43B4C: MODIS/Terra Nadir BRDF-Adjusted Reflectance 16-Day L3 Global 5kmISIN GridProducts at degreeMOD43C1: MODIS/Terra Albedo 16-Day L3 Global 0.25Deg CMGMOD43C2: MODIS/Terra BRDF/Albedo Parameters 16-Day L3 Global 0.25Deg CMGGao et al., Global Coarse Resolution Albedo from MODIS BRDF/Albedo Product for Climate Models (CMG),submitted Geophys. Res. Let., 2002.

CMG Broadband White-Sky Albedo (0.3-5.0µm)6 - 21 March, 2001No Data0.00.20.4

CMG Broadband White-Sky Albedo (0.3-5.0µm)9 - 24 May, 2001No Data0.00.20.4

CMG Broadband White-Sky Albedo (0.3-5.0µm)14 - 29 September, 2001No Data0.00.20.4

MOD43B MODIS BRDF/ALBEDO PRODUCTAQUA code (actually AQUA TERRA code) is delivered and baselined:Gridded surface reflectances from both the TERRA MODIS sensorand the AQUA MODIS sensor are used to retrieve the 16-day BRDFparameters and compute albedos at local solar noon.NBARs at both the TERRA overpass time and the AQUA overpasstime are computed.The TERRA only version and the TERRA AQUA version will run inparallel during the shakeout period.MODIS MISR code has also been successfully proto-typed on severalregional case studies.

STATUS of the MOD43B MODISBRDF/ALBEDO PRODUCTThe MOD43B 1km products:Operational production began in April 2000.Beta Products were released in July 2000.Provisional Products were released in November 2000.The MOD43C CMG degree Products are just enteringproduction (July 2001 onward).Currently awaiting evaluation of the reprocessed data for finalcharacterization of the product variability and for final comparisons withfield data before assigning product quality assessments and releasing thedata as Validated Products.

North American Nadir BRDF-Adjusted Reflectance (NBAR)31 October - 15 November, 2000No DataNIR (0.1-0.4) Red (0.0-0.16) Green (0.0-0.18)

North American Nadir BRDF-Adjusted Reflectance (NBAR)31 October - 15 November, 2000ReprocessedNo DataNIR (0.1-0.4) Red (0.0-0.16) Green (0.0-0.18)

MOD43B MODIS BRDF/ALBEDO PRODUCTEVALUATIONThe Team Evaluation is focused on:MOD43B Quality Assurance Flags.Variability of products by cover type.Temporal stability and consistency of products.Predictive capability of BRDF parameters.

NBAR from Land Cover Training Sites in the Southern USSchaaf et al., First Operational BRDF, Albedo and Nadir Reflectance Product from MODIS, inpress, Remote Sensing Environ., 2002

Snow versus Non-snow Albedos 40-50 N Nov00-Jan01Jin et al., How does Snow Impact the Albedo of Vegetated Land Surfaces as Analyzed with MODISData?, in press, Geophys. Res. Let., 2002

Using BRDF Parameters to Predict Future Surface ReflectancesObserved 1km Surface Reflectances20 November, 2000 (Day 325)Predicted 1km Surface Reflectancesfor 20 November, 2000, using BRDFParameters from 31 Oct - 15 Nov, 2000NIR (0.1-0.35) Red (0-0.12) Green (0-0.12)

0.0Full Inversions (Red)Observed0.120.0r 0.823Magnitude Inversions (Red)0.0Observed0.12r 0.7500.120.100.10Full Inversions (NIR)Observed0.350.10Predictedr 0.794r 0.8930.35Magnitude Inversions (NIR)0.10Observed0.350.35

MOD43B MODIS BRDF/ALBEDO PRODUCTVALIDATIONBARC Field Campaigns -- S. Liang (UMD)SAVE/SAFARI Field Campaigns -- J. Privette (GSFC)Barton Bendish Field Campaigns -- M. Barnsley (UWales, Swansea)China Field Campaigns -- X. Li (BU & Beijing Normal U.)SURFRAD Comparison -- Y. Jin (BU)

BARC Validation EffortsAlbedometer measurementsfrom a 10m tower and sunphotometer measurements areroutinely collected at the USDAAgricultural Research ServiceBeltsville Agricultural ResearchCenter (BARC) in Beltsville,Maryland, USA.A number of ground campaigns(ASD, LAI, leaf optics) havebeen completed.

BARC Validation EffortsETM imagery is used toscale Ground and Towermeasurements up to MODISspatial resolutions.Initial validation results fromNovember and December2000 show that these productsare quite accurate with lessthan a 5% error.Liang et al., Validating MODIS Land SurfaceReflectance and Albedo Products: Methodsand Preliminary Results, in press, RemoteSensing Environ., 2002.

South African Validation of EOS (SAVE)Tower data are beingcollected at the Mongu,Zambia woodland siteand the Skukuza, SouthAfrica savanna site.Ground measurementswere collected duringthe SAFARI IFCs.Comparisons withMODIS SurfaceReflectance and AlbedoProducts are currentlyunderway.

South African Validation of EOS (SAVE)

South African Validation of EOS (SAVE)Diurnal and Seasonal VariabilityRelative ErrorNIR Albedo from the Mongu TowerMean AlbedoQuality ControlTime Series:March 2000 topresent

Barton Bendish Field Validation EffortsLAI and albedo data werecollected at the agriculturalsite at Barton Bendish, EastAnglia, UK during the 2000and 2001 growing seasons.ETM data are used to scaleup to coarser spatialresolutions.

Barton Bendish FieldValidation EffortsBRDF Model ParametersComposite -- derived fromSPOT-VGT data of the UK.Reprocessed MODIS datafrom summer 2001 has justbecome available forvalidation effort.

Barton Bendish Field Validation EffortsAdditional hyperspectralimagery of Barton Bendishand other EOS core validationsites is being obtained fromthe Compact High ResolutionImaging Spectrometer(CHRIS) launched on theProject for On BoardAutonomy (PROBA) in Oct2001.

Field Campaign for Quantitative Remote Sensingin Beijing (2001)Institute of Remote SensingApplication (ChineseAcademy of Sciences) andBeijing Normal University.Agricultural field sites inShunyi, Yucheng, andLuncheng, China.Extensive groundmeasurements, someairborne data and varioussatellite imagery have beencollected since October,2000.Shunyi SiteBeijingTianjingShiJiazhuangLuan Cheng SiteYucheng SiteJi NanZhenZhou

Field ValidationEfforts in China

Surface Radiation Budget Network(SURFRAD)Six instrumented sites continuously measuring solarradiation (including PAR, direct and diffuse).Data packaged and distributed as half hour values bythe CERES/ARM Validation Experiment (CAVE).

MOD43B MODIS BRDF/Albedo Product SummaryInitial evaluations indicate that the MOD43B algorithms have performedwell throughout 2000 and 2001. Data (particularly the reprocessed data)appear temporally stable and consistent.Initial validations and comparisons are very encouraging with errors ofless than 10%.Team is awaiting completion of the reprocessed data to have a relativelyconsistent annual cycle before finalizing validation efforts and postingerror and variability estimates.We expect to upgrade reprocessed data to “Validated” status during thefirst half of 2002.

MOD43B MODIS BRDF/ALBEDO PRODUCTProvisional and Reprocessed Products (starting with the 16 day periodbeginning on Day 305 -- 31 October 2000) are available from EDC at Guide is available at rowse images (based on 5km resolution products) can be viewed at CMG Products on a degree resolution Geographical Grid will beavailable from EDC in the new year.

MOD43B3C: MODIS/Terra Albedo 16-Day L3 Global 5km ISIN Grid MOD43B4C: MODIS/Terra Nadir BRDF-Adjusted Reflectance 16-Day L3 Global 5km ISIN Grid Products at _ degree MOD43C1: MODIS/Terra Albedo 16-Day L3 Global 0.25Deg CMG MOD43C2: MODIS/Terra BRDF/Albedo Parameters 16-Day L3 Global 0.25Deg CMG

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