1. Stennis Space Center Time Series Product Tool Don Prados Computer Sciences Corp. John C. Stennis Space Center USDA Forest Service, Asheville, NC September 6-7, 2007

2. Time Series Product Tool Stennis Space Center 2National Aeronautics and Space Administration TSPT (Time Series Product Tool) Temporally processes various MODIS (Moderate Resolution Imaging Spectroradiometer) products on a per-pixel basis –MOD02 daily swath radiance and planetary reflectance –MOD09 daily gridded surface reflectance –MOD43 8-day and 16-day gridded BRDF (Bidirectional Reflectance Distribution Function)-adjusted reflectance –MOD13 16-day gridded NDVI (Normalized Difference Vegetation Index) and EVI (Enhanced Vegetation Index) Calculates NDVI or NDMI (Normalized Difference Moisture Index) from radiance or reflectance Uses cloud and other metadata to remove bad or low-quality pixels Fuses images from the Aqua and Terra satellites based on comparative pixel quality

3. Time Series Product Tool Stennis Space Center 3National Aeronautics and Space Administration TSPT (continued) Uses an outlier detection algorithm to remove suspect pixels Applies temporal interpolation and smoothing to further reduce noise Displays NDVI and NDMI time series plots for user-selected pixels at various stages of processing Recreates images from temporally processed pixels at various stages of processing Generates an ENVI ® header file for each image containing the map projection and other metadata –Allows images to be displayed in ENVI or ERDAS IMAGINE ® –Tracks processing parameters and settings Stacks images into 3D ENVI BSQ (Band Sequential) files

4. Time Series Product Tool Stennis Space Center 4National Aeronautics and Space Administration TSPT Input The TSPT can process output from the MRT (MODIS Reprojection Tool) –Developed software front end for MRT –Reprojects MODIS or simulated VIIRS (Visible/Infrared Imager/Radiometer Suite) HDF (Hierarchical Data Format) files to UTM, LCC, or LAEA The TSPT also can directly reproject MODIS HDF swath or gridded data into UTM or other map projections and can process the output The TSPT can convert MODIS HDF sinusoid gridded data to ENVI BSQ sinusoid and can process the sinusoid data Supports: –Radiance, planetary reflectance, surface reflectance, and BRDF- adjusted reflectance –MOD13 NDVI and EVI –MODIS and simulated VIIRS

5. Time Series Product Tool Stennis Space Center 5National Aeronautics and Space Administration TSPT State Diagram Reflectance or Radiance Fused Filtered Filter NDVI, EVI, or NDMI Calc NDVI or NDMI Fuse Clear Ideal Fused Filtered Filter Fused Ideal Fuse Remove Outliers Filtered Fused Remove Clouds Remove Outliers

6. Time Series Product Tool Stennis Space Center 6National Aeronautics and Space Administration TSPT Modules TSPT_Reproject: reprojects HDF gridded (sinusoid) or swath (no map projection) data to various map projections TSPT_GridToBSQ: converts HDF sinusoid to BSQ sinusoid TSPT_CalcNDVI: calculates NDVI and NDMI TSPT_Ideal: removes cloudy and bad pixel values TSPT_Outlier: removes time series outliers TSPT_Fuse: combines data from the Aqua and Terra satellites TSPT_Time: interpolates and filters time series TSPT_Plot: plots time series for selected pixels TSPT_Stack: stacks images into 3D BSQ files TSPT_DisplayBSQFiles: displays BSQ images

7. Time Series Product Tool Stennis Space Center 7National Aeronautics and Space Administration MOD02 Daily NDVI Cloud Removal MOD02 Terra NDVI (left) and Aqua NDVI (right) before and after cloud removal. Original NDVI in blue, clear NDVI in black. Clouds typically result in a drop in NDVI.

8. Time Series Product Tool Stennis Space Center 8National Aeronautics and Space Administration MOD02 Fusing of Clear Aqua NDVI and Clear Terra NDVI MOD02 Terra NDVI, clouds removed MOD02 Aqua NDVI, clouds removed Terra NDVI and Aqua NDVI fused using cloud metadata and sensor zenith angle Cloudy: 26.2% Mixed: 19.5% Cloudy: 37.2% Mixed: 9.0% Cloudy: 10.0% Mixed: 4.3%

9. Time Series Product Tool Stennis Space Center 9National Aeronautics and Space Administration MOD02 Outlier Removal Fused MOD02 Aqua and Terra NDVI before (blue) and after (black) outlier removal

10. Time Series Product Tool Stennis Space Center 10National Aeronautics and Space Administration MOD02 Temporal Interpolation and Filtering Temporal interpolation applied to replace MOD02 NDVI values eliminated in previous steps, followed by Savitzky-Golay filtering to further reduce noise

11. Time Series Product Tool Stennis Space Center 11National Aeronautics and Space Administration MOD43A Outlier Removal MOD43A 8-day BRDF-adjusted NDVI before (blue) and after (black) outlier removal

12. Time Series Product Tool Stennis Space Center 12National Aeronautics and Space Administration MOD43A Temporal Interpolation and Filtering Temporal interpolation applied to replace MOD43A values eliminated in previous steps, followed by Savitzky-Golay filtering to further reduce noise

13. Time Series Product Tool Stennis Space Center 13National Aeronautics and Space Administration MOD13 Cloud Removal MOD13 16-day Terra NDVI before (blue) and after (black) cloud removal

14. Time Series Product Tool Stennis Space Center 14National Aeronautics and Space Administration MOD13 Outlier Removal MOD13 16-day NDVI before (blue) and after (black) outlier removal

15. Time Series Product Tool Stennis Space Center 15National Aeronautics and Space Administration MOD13 Temporal Interpolation and Filtering Temporal interpolation applied to replace MOD13 NDVI values eliminated in previous steps, followed by Savitzky-Golay filtering to further reduce noise

16. Time Series Product Tool Stennis Space Center 16National Aeronautics and Space Administration Next Steps Investigate alternative methods for fusing Aqua and Terra data, such as choosing the pixel with the highest value Investigate alternative outlier removal techniques to reduce chance of removing good pixels Investigate/Compare temporal filtering methods Provide guidelines for selecting parameters for outlier removal and filtering techniques Support GeoTIFF (Geo-referenced Tagged Image File Format) format for TSPT input and output

17. Participation in this work by Science Systems and Applications, Inc., and by Computer Sciences Corporation was supported by NASA at the John C. Stennis Space Center, Mississippi, under Task Order NNS04AB54T.

18. Stennis Space Center Backup Slides

19. Time Series Product Tool Stennis Space Center 19National Aeronautics and Space Administration TSPT_Reproject Alternative to MRT and MRTSwath Reprojects MODIS or VIIRS HDF to UTM, LCC, or LAEA BSQ Creates corresponding ENVI HDR (header) file containing reprojection information BSQ/HDR files can be read by ENVI and by IMAGINE Copies metadata from HDF files to header file, modifying metadata where appropriate Adds new metadata to header file

20. Time Series Product Tool Stennis Space Center 20National Aeronautics and Space Administration TSPT_GridToBSQ Converts MODIS sinusoid HDF to sinusoid BSQ Creates corresponding ENVI header file containing sinusoid reprojection information BSQ/HDR files can be read by ENVI and by IMAGINE Copies metadata from HDF files to header file, modifying metadata where appropriate Adds new metadata to header file

21. Time Series Product Tool Stennis Space Center 21National Aeronautics and Space Administration TSPT_CalcNDVI Calculates NDVI from reflectance or radiance Optionally adjusts NDVI when reflectances are below a selected threshold: –Reduces sensitivity of NDVI to small changes in reflectance when reflectances are very small –Reduces upward spikes in NDVI due to noise –Prevents NDVI values from reaching or exceeding 1 or -1 For MOD02 datasets, creates an 8-bit Cloud Mask from the 48-bit MOD35 Cloud Mask Mosaics NDVI, Cloud Mask, and Sensor Zenith Angle into daily products if day contains more than one dataset

22. Time Series Product Tool Stennis Space Center 22National Aeronautics and Space Administration TSPT_Ideal Eliminates cloudy pixels using different metadata for different products –MOD35 Cloud Mask for MOD02 planetary reflectances –MOD09 quality metadata for MOD09 surface reflectances –MOD13 quality metadata for MOD13 NDVI and EVI –MOD43B4 quality metadata for MOD43B4 nadir reflectances –MOD43A2 quality metadata for MOD43A4 nadir reflectances Eliminates pixels flagged as bad and/or set to fill value using different metadata for different products

23. Time Series Product Tool Stennis Space Center 23National Aeronautics and Space Administration TSPT_Outlier Eliminates outliers –Eliminates downward spikes (large negative slope followed by large positive slope) –Eliminates upward spikes (optional) –User-selectable threshold is based on the angle change calculated from the change in slope –Default of 10 passes, reducing threshold on each pass Eliminates pixels acquired at high sensor zenith angles using selected maximum sensor zenith angle

24. Time Series Product Tool Stennis Space Center 24National Aeronautics and Space Administration TSPT_Fuse Fuses data acquired on the same day from the Aqua and Terra satellites –For each pixel, chooses Aqua or Terra NDVI based on cloud information, sensor zenith angle, and other metadata If Aqua is chosen, uses Aqua metadata and sensor zenith angle for that pixel If Terra is chosen, uses Terra metadata and sensor zenith angle for that pixel –Can be called after TSPT_Ideal, TSPT_Outlier, or TSPT_Time modules using the current state of TSPT to determine inputs and outputs

25. Time Series Product Tool Stennis Space Center 25National Aeronautics and Space Administration TSPT_Time Applies temporal interpolation to replace cloudy, bad, or suspect values (optional) Applies one or more of the following filters to the time series: –Weighted Savitzky-Golay algorithm weights based on pixel quality and temporal distances parameters: polynomial order, temporal frame size, full width half maximum for temporal-distance Gaussian function –weighted-average algorithm using the same weights as above –conventional Savitzky-Golay algorithm –median filter Applies extrapolation to replace cloudy, bad, or suspect pixels at beginning and end of time series (optional)

26. Time Series Product Tool Stennis Space Center 26National Aeronautics and Space Administration TSPT_Plot Plots time series given pixel locations and a date range Pixel locations provided as lists of latitudes and longitudes or in a shapefile Can be called after TSPT_NDVI, TSPT_Ideal, TSPT_Outlier, TSPT_Fuse, or TSPT_Time modules using current state of TSPT to determine what to plot Optionally, plots pixel quality along with NDVI

27. Time Series Product Tool Stennis Space Center 27National Aeronautics and Space Administration TSPT_Stack Replaces null values with user-selected value Writes output to user-selected output directory Optional: –Creates a binary cloud mask and writes it to the output directory –Stacks daily images into a single multiband BSQ file one date per band creates ENVI header for multiband BSQ file –Stacks binary cloud masks into a single multiband BSQ file allows easy calculation of spatial, temporal, or spatio-temporal cloud statistics

28. Time Series Product Tool Stennis Space Center 28National Aeronautics and Space Administration TSPT_DisplayBSQFiles Displays BSQ images in MATLAB ® figures using supplied date range Can be called after TSPT_NDVI, TSPT_Ideal, TSPT_Outlier, TSPT_Fuse, or TSPT_Time modules using current state of TSPT to determine which files to display User-selectable color map Optional: –Shows states, roads, other shapefiles –Saves images as JPEG or TIFF with worldfile –Converts null values to user-selected alternative –Converts snow and water values to user-selected alternative

29. Time Series Product Tool Stennis Space Center 29National Aeronautics and Space Administration ART Simulation and Reprojection Several features from the ART (Application Research Toolbox) are used to prepare data for input into the TSPT The ART is used to –reproject gridded MODIS HDF (Hierarchical Data Format) datasets to various map projections using the MRT (MODIS Reprojection Tool) –reproject swath MODIS HDF datasets to various map projections using the MRTSwath (MODIS Swath Reprojection Tool) –simulate VIIRS (Visible/Infrared Imager/Radiometer Suite) reflectance products from MODIS reflectance products before or after reprojection

30. Time Series Product Tool Stennis Space Center 30National Aeronautics and Space Administration MRT_Command Front end to the MRT and to the MRTSwath Reprojects MODIS or VIIRS HDF to binary UTM, LCC, or LAEA Creates corresponding ENVI HDR file containing reprojection information BSQ/HDR files can be read both by ENVI and by IMAGINE Copies metadata from HDF files to HDR file, modifying metadata where appropriate Adds new metadata to HDR file Output ready for input into TSPT

31. Time Series Product Tool Stennis Space Center 31National Aeronautics and Space Administration Application Research Toolbox The Application Research Toolbox is an integrated set of algorithms and models developed in MATLAB ® that allows users to generate and validate VIIRS and other National Polar-Orbiting Environmental Satellite System Preparatory Project (NPP) systems as well as “Landsat Data Continuity Mission-like” systems The ART provides a simulation solution by using data acquired by existing sensors with higher spatial and spectral resolution to create multispectral images with predefined characteristics Predefined characteristics include spatial resolution, spectral bands, signal-to-noise ratio, data quantization, and band-to-band registration

32. Time Series Product Tool Stennis Space Center 32National Aeronautics and Space Administration ART Simulation/ Reprojection State Diagram MODIS Swath HDF Sim VIIRS Swath Sim VIIRS Grid MODIS BSQ MODIS Grid HDF VIIRS BSQ VIIRS Swath HDF Reproject TSPT MODIS Sinusoid BSQ TSPT HDF to BSQ TSPT MODIS BSQ Reproject TSPT Sim VIIRS Grid

33. Time Series Product Tool Stennis Space Center 33National Aeronautics and Space Administration ART Modules used in Conjunction with the TSPT ART_SimVIIRS_Swath –simulates VIIRS imagery from MOD02 planetary reflectance and from MOD03 sensor zenith angle products, leaving the data in the swath format (no map projection) ART_SimVIIRS_Grid –simulates VIIRS imagery from MODIS gridded data, such as the output of MRT_Command (below) MRT_Command –is used as an automated front end to the MRT and to the MRTSwath –supports the following map projections: UTM (Universal Transverse Mercator) LCC (Lambert Conformal Conic) LAEA (Lambert Azimuthal Equal Area) –Input is HDF; output is BSQ format, ready for input into the TSPT or into ART_SimVIIRS_Grid

34. Time Series Product Tool Stennis Space Center 34National Aeronautics and Space Administration ART_SimVIIRS_Swath MODIS and VIIRS PSFs (Point Spread Functions) are used to simulate VIIRS from MODIS MOD02 swath data MOD02 reflectance/radiance values in HDF files are replaced by VIIRS values where the VIIRS PSF is larger than the MODIS PSF; otherwise values are not changed The location of the swath pixels is not changed The PSFs vary with sensor zenith angle, becoming progressively larger moving away from nadir MODIS MOD03 sensor zenith angles are replaced by VIIRS sensor zenith angles, accounting for different satellite altitudes Data remains in HDF files

35. Time Series Product Tool Stennis Space Center 35National Aeronautics and Space Administration ART_SimVIIRS_Grid Simulates VIIRS UTM BSQ from MODIS UTM BSQ Updates the ENVI HDR (header) file created by MRT_Command BSQ/HDR files can be read by both ENVI and IMAGINE Output is ready for input into the TSPT >