2002 Annual

Monday, 14 January 2002: 4:30 PM
GES DAAC improved methods and tools for accessing MODIS data
Dimitar Ouzounov, NASA/GSFC, Greenbelt, MD; and S. Ahmad, P. Eaton, J. Koziana, G. Leptoukh, A. Savtchenko, G. Serafino, A. K. Sharma, M. Skider, J. Qu, and B. Zhou
Poster PDF (20.1 kB)
The unique position of the NASA Goddard Earth Sciences Distributed Active Archive Center (GES DAAC) as an intermediary between users and MODIS data led us to explore and develop tools that could help users access and manipulate data. Some tools are DAAC unique extensions like search and order web pages or channel subsetting programs. Other data access and simple visualization tools were developed as MODIS Data Support Team (MDST) work aids. A list of the suggested tools is available at http://daac.gsfc.nasa.gov/CAMPAIGN_DOCS/MODIS/software.html.

The key features of some of the tools available from GES DAAC are described below:

Terra WHOM: The Terra Web based Hierarchical Ordering Mechanism (WHOM) is a customized version of the larger DAAC web-based data gateway. Terra WHOM offers enhanced graphic interfaces to identify temporal and spatial data coverage while searching and ordering MODIS data archived at the GES DAAC. Visual inspection of the spatial data distribution for the selected region, a calendar page showing dates with available data, single point and click navigational protocols, and recursive web page generation using templates make this tool unique and attempt to address the needs of the user community.

Subsetting Tools: Calibrated radiance (Level 1B) channel subsetting is being developed as a DAAC unique extension to the EOS Core System (ECS). The front end, a graphic user interface, will be an added feature of the Terra WHOM system. The back end will be driven by the new Simple Scalable Script-Based Science Processor (S4P) that will interact with ECS for data retrieval, archiving and distribution of the subsetted data. All three resolutions of MODIS Level 1B data will be available for channel subsetting.

Visualization Tools: The GES DAAC MDST has developed two very simple IDL-based tools dedicated to mapping MODIS swath products. The first, geoview, has a simple, graphic interface, while the second, simap, is a command line utility. While the two tools are almost identical, simap has the added feature of stitching multiple granules into a single map.

Browse MODIS L1B: The purpose of browse images is to allow science data users to evaluate the Level 1B data before ordering. Browse images are produced from the 1 km Calibrated Radiances product using channels 1, 4, 3 as true color during the day, and channel 32 as false color during the night. The C code program is implemented as a part of the EOS Data Gateway (EDG) and is also freely available to the user community.

HDFLook_MODIS : This latest tool is under development as a joint collaboration between the GES DAAC MDST and the University of Lille, France to update the popular HDFLook for future MODIS needs. The program includes multi-level MODIS data functionality and is designed to process all MODIS products. Its main features include: re-mapping, geo-projection conversion, interactive and batch mode capabilities, subsetting features, mosaic or stitch, multi-granule processing, and GIS conversion.

This presentation will describe methods and tools implemented or planned for the Goddard DAAC that are intended to optimize access to MODIS data for the Earth Science community.

Supplementary URL: