1. Introduction to MISR Data Analysis and Tools Linda Hunt Science Systems & Applications Inc., NASA LaRC Brian E. Rheingans Jet Propulsion Laboratory, California Institute of Technology Accessing and using MISR products in climate and environmental research IGARSS, Cape Town July 2009

2. Background Terra follows a pattern of orbital paths which repeats after 233 unique orbits A path begins at a particular longitude as the satellite crosses the ascending node MISR data are geolocated using the Space Oblique Mercator (SOM) projection to minimize shape distortion and scale errors along the MISR swath near the satellite ground track SOM defines a separate projection for each path

3. Terra Orbits, August 27, 2004 er 175191159143 127 2072236223854708611195

5. MISR Orbital Paths/Blocks

6. MISR Blocks

7. MISR Data File Organization MISR files are written in the HDF-EOS format based on HDF4 (Hierarchical Data Format http:// hdfgroup.org) HDF-EOS extends HDF by adding geolocation information MISR uses the HDF-EOS grid structure which geolocates based on map projection parameters and specification of the corner coordinates Extensive information is written into the file as metadata File attributes Grid attributes

8. MISR HDF-EOS “Stacked Block” File MISR Stacked Block Grid (180 Blocks) -Data stored as a three-dimensional array: sample by line by block -SOM coordinates of top-block corners are Grid metadata. -Projection and orbital parameters are Grid Metadata -Horizontal (sample) offset of each block from the one above is part of Stacked-block grid extension metadata. Block dimension Sample dim / SOM Y Line dim / SOM X Level 1B2 And Level 2 Products Standard Product Files are “Stacked-Block”

9. MISR “Conventional” Format File 2 2-dimensional array HDF-EOS grid format SOM map projection Same spatial resolution, grid names, metadata Identical data values, no resampling, except data at 35.2 at 70.4 km resolution Available via MISR Order Tool

10. Where does this pixel belong with the MISR HDF-EOS “Stacked Block” Scheme? Inside the HDF-EOS “stacked block grid” = (block, line, sample) Convert (block, line, sample) SOM (x,y) –Requires several metadata values and some arithmetic. Convert SOM (x,y) Lat/Lon –Requires use of GCTP map projection coordinate conversion library in HDF-EOS distribution. Units: Integral block, fractional line/sample; meters x/y; decimal degrees Lat/Lon. This process is described in the MISR Data Product Specification, Appendix A and also routines are provided in the MISR Toolkit. Or simply look up the Lat/Lon of the corresponding block, line, sample in the Ancillary Geographic Product (AGP) datasets (1.1km).

11. MISR Data Products Specifications http://eosweb.larc.nasa.gov/PRODOCS/misr/table_misr.html

12. MISRView For the “Stacked Block” Products Maps path/orbit to time and date Assembles MISR blocks Reports Lat/Lon using the AGP Displays true color MISR imagery Can reproject MISR imagery Requires IDL or IDL VM Perspective tool Band slider tool Scroll tool Vector overlay tool Reprojection tool Color / Contrast tools

13. MISRView – Main Menu

14. MISRView – L1B2 imagery

15. MISRView – MISR Vision (R-Ba, G-An, B-Bf)

16. MISR INteractive eXplorer (MINX) It includes high-level options to create: Map views of MISR orbit locations Scrollable, single-camera, RGB images of MISR level 1B2 (L1B2) radiance data Animations of the nine MISR camera images that provide a 3D perspective of the scenes that MISR has acquired Some of the specialized options in MINX enable the user to: Display plots of top-of-atmosphere BRF vs. camera-angle for pixels you click on Save images and animations to disk in various formats Apply a geometric registration correction to camera images Difference the images of two MISR orbits that share a path (identical ground track) Construct pseudo-color images by assigning different combinations of MISR cameras to the RGB display channels Interactively digitize smoke, volcanic or dust plumes and automatically retrieve heights and winds, albedo, aerosol properties and fire power and brightness temperatures associated with those plumes A interactive application that functions both as a general-purpose tool to visualize MISR data and as a specialized tool to analyze properties of smoke, volcanic and dust plumes http://www.openchannelfoundation.org/projects/MINX/

17. MISR INteractive eXplorer (MINX) MISRVision Camera Ratios Program Options Animation Window Orbit Plot

18. MISR INteractive eXplorer (MINX) Digitized Plume Points Aerosol Histogram Albedo Profile Wind Height Histogram Wind & Height Profiles Plume Height Contour

19. MISR INteractive eXplorer (MINX)

28. MISR Level 3 Overview Web Page Can view jpegs of all available Level 3 data. Can view by product and by month or season. Can view animation through a year’s worth of data. Can directly download Level 3 HDF files. http://eosweb.larc.nasa.gov/PRODOCS/misr/level3/overview.html

29. MISR Level 3 Data File Format Level 3 data files In standard HDF-EOS grid format using a geographic (lat/lon) projection Also produced in netCDF format To simply view data images, use Level 3 web page Level 3 HDF-EOS data files can be downloaded directly from the overview web page.

30. Introduction to the MISR Toolkit API The MISR Toolkit API provides simplified MISR data access and geolocation functionality Reads MISR L1B2, L2 in Stacked Block and Conventional format Extracts MISR “stacked block HDF-EOS grid” to a geolocated SOM projected plane with blocks assembled into a 2-D array and fields unpacked and unscaled Enables selection of a subset or region defined either by path/block or lat/lon Available as a callable set of routines for C, IDL, and Python programming languages

31. MISR Toolkit API Concept (cont.) In addition to L1B2, and L2 MISR data access the MISR toolkit has the ability to: Perform coordinate conversions: lat/lon SOM x/y block/line/sample Query a MISR product file to retrieve such information as block range, file version, file type, grid list, field list, dimension list, and other metadata Construct MISR filenames and search a directory tree for the file Convert between path, orbit and time range Determine which paths/orbits cross a particular geographic location or region within a given time range

32. MISR Toolkit Platform and Language Availability Platforms and Languages Available (version 1.2) C library on Linux, Mac OS X and Windows XP IDL on all platforms via dynamically loadable library Python bindings for Linux and Mac OS X Command line utilities on Linux and Mac OS X (Useful for scripting or function usage examples)

33. Mtk Example (IDL API)

34. http://eosweb.larc.nasa.gov/PRODOCS/misr/tools/misr_tools.html Other Tools to access MISR data

35. Additional Links HDF4 information, library routines, HDFView tool http://hdfgroup.org HDF-EOS information, library routines, HDF-EOS Plug-in for HDFView, and other HDF-EOS tools http://hdfeos.net/ Open Channel Foundation for misr_view, MINX, MISR Toolkit https://www.openchannelsoftware.com/ Search for “MISR” in the Quick Applications Search field ITT Visual Information Solutions (IDL and IDL Virtual Machine) http://ittvis.com Atmospheric Science Data Center MISR main page http://eosweb.larc.nasa.gov/PRODOCS/misr/table_misr.html ASDC User Services larc@eos.nasa.gov