Tools for Working With HDF Data (Especially MODIS) PoDAG XVIII – April 2001 Terry Haran Siri Jodha Singh Khalsa

The Need Read and extract data out of HDF files MODIS tiles and the ISIN projection Use geolocation info in HDF-EOS files Subsetting, Stitching, and Subsampling Visualization

Overview of Tools (from presentation to the USWG 11/00) NCSA Utilities HDF dumper can display contents of and extract data from any HDF-EOS file For example, to extract the snow cover array from a MOD10A1 granule simply type: hdp dumpsds -n Day_Tile_Snow_Cover -b MOD10A1xyz.HDF > snow.out

Solutions Developed at NSIDC The Polar HDF-EOS Data Imaging and Subsetting (PHDIS) Tool The MODIS Swath-to-Grid Toolbox (MS2GT) The MODIS Reprojection Tool originated with EDC, enhanced by NSIDC

PHDIS Tool Began as support to the Polar Pathfinder Project samples of AVHRR, SSM/I and TOVS converted to HDF-EOS Specifically for data in EASE Grid newest version also reads swath data Visualize and extract data from the same area across multiple data sets

PHDIS zoom window SSM/I 85V TB over Hudson Bay. Legend includes: - color bar - thumbnail locator - lat/lon, value under cursor

One granule of MODIS Level 1b Band 2 radiance data, displayed with PHDIS. 24 May 2000 All 15 reflective visible bands selectable from pull-down list.

MS2GT Reads MODIS level 2 (swath) data Level 1b radiances Level 2 snow and ice products Outputs binary data arrays selection of projections can stitch together multiple swaths In beta testing draft user documentation available poster at Spring AGU EOS Tools session

Orbit map on MODIS browse page can be used to select swath segments of interest.

1 June 2000, 1445Z1 June 2000, 1450Z MODIS BAND 1MODIS BAND 1

Two MODIS swaths stitched together and gridded to EASE grid.

Due to the “bowtie” effect, images made directly from swath data have a “double vision” appearance away from nadir. The same region after gridding.

MODIS band 1 in a relatively featureless region of the Greenland plateau, showing striping due to detector-to-detector miscalibration. ALL YOUR BASE ARE BELONG TO US!!!

Band 2 – 250m Sea Ice – 1 km land ice open ocean cloud

MODIS Ice Surface Temperature (Level 2, not gridded) for the same swath shown in the previous images. land cloud

MODIS Reprojection Tool Regrids MODIS ISIN tiled data NSIDC enhancement – hdf2hdr stitches NxM array of tiles together resultant “super-tile” then used as input

The Integerized Sinusoidal Grid The four tiles used in the following example.

horizontal-9, vertical-4 Four tiles individually reprojected into EASE Grid horizontal-10, vertical-4 horizontal-9, vertical-5horizontal-10, vertical-5

A “Super-tile” Reprojected The 4 tiles on the previous figure first combined then reprojected into EASE Grid

Commercial Solutions MS Windows only Noesys (from RSI) good support for HDF-EOS files lat/lon readout of grid cell subsetting can also create HDF files Windows Image Manager (WimSoft) reads and writes HDF HDF Explorer (Space Research Software) reads and write HDF free version available (HDF Inspector)

Commercial Solutions Multi-Platform IDL includes HDF browser and HDF-EOS library MATLAB includes HDF-EOS library ENVI (has free version) PCI-GeoGateway (has free version) PV-Wave (HDF read/write)

Public and Community Solutions Free, Multi-Platform NCSA Tools utilities Java HDF Viewer Scientific Data Browser (used by DIAL) Webwinds ISIS-cv (Cube Visualization) ISIS is free but cv plug-in requires IDL HDFLook/Msphinx Unix/Linux only

DAAC and IT HDF Pages Goddard DAAC HDF page includes user-contributed software library MODIS Data Tools at GSFC lists many tools, commercial, public and DAAC-developed MODIS-Atmospheres Tools at GSFC includes subsetting and visualization tools LaRC DAAC HDF page

URL’s of Interest NCSA’s list of tools that support HDF 37 freeware, 18 commercial NASA/ESDIS’ list of HDF-EOS tools shorter list (source must provide info) NSIDC’s HDF-EOS page contains links to presentations on HDF and tools for working with it

The Future – MS2GT Enhancements to MS2GT Enable IDL to automatically geolocate output De-stripe Level 1b radiances Minimize memory usage Do inverse navigation Integrate with PHDIS? Use GCTP in place of mapx? GeoTIFF output for GIS tools

The Future - PHDIS Release of PHDIS to public Unveiling at Spring AGU EOS Tools session Requires users to have IDL Invest in licenses for distribution? Additional features/fixes Perform in-house? Convert heritage data to HDF-EOS?

The Future - NewDISS Earth-Science Markup Language Developing a standard description for all aspects of the data, including its format Allows applications to become independent of format Data accessed over the web in a way that makes the format transparent

Question: Should NSIDC be in the tools business? to some degree it has been all along Pros: enhances user support Cons: development and maintenance costs

Backup Charts

mod02.pl. gl1_ _1445 listfile.txt Gl1250.gpd chanfile.txt ancifile.txt 3 3 N200correct.mpp map projection parameters columns rows 160 grid cells per map unit map origin column,row Azimuthal Equal-Area lat0 lon0 0.0 rotation scale (km/pixel) center lat lon lat min max lon min max grid label lat lon cil bdy riv 1 reflectance 2 reflectance 31 temperature 32 temperature seze scaled soze scaled output: Apr 19 14:24 gl1_ _1445_refa_ch01_01860_01740.img Apr 19 14:24 gl1_ _1445_refa_ch02_01860_01740.img Apr 19 14:25 gl1_ _1445_scaa_seze_01860_01740.img Apr 19 14:25 gl1_ _1445_scaa_soze_01860_01740.img Apr 19 14:24 gl1_ _1445_tema_ch31_01860_01740.img Apr 19 14:25 gl1_ _1445_tema_ch32_01860_01740.img MOD021KM.A hdf MOD021KM.A hdf