GES DAAC tools for accessing and visualizing MODIS data

The NASA Goddard Earth Sciences Distributed Active Archive Center (GES DAAC) has the unique position of an intermediary between users and MODIS data. To help users accessing and manipulating MODIS data, various tools were developed the MODIS Data Support Team (MDST). Some of these tools are described below: WHOM. The Web based Hierarchical Ordering Mechanism (WHOM) for Terra data is a customized version of the larger DAAC web-based data gateway. WHOM offers enhanced graphic interfaces to identify temporal and spatial data coverage while searching and ordering MODIS data archived at the GES DAAC. An alternative "No Frills" page provide a quick access (by passing navigation) directly to WHOM pages for products users want to order. Browse images allow science data users to evaluate the data before ordering. MODIS Level 113 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. Subsampled at 5-km resolution products are generated at the GES DAAC so users can download smaller files. Subsetting Tools. Calibrated radiance (Level 1B) channel subsetting is being developed as an extension to the EOS Core System (ECS). The front end, a graphic user interface, is part of WHOM. The new Simple Scalable Script-Based Science Processor (S4P) that interacts with ECS drives the back end for data retrieval, archiving and distribution of the subsetted data. Visualization Tools. The MDST has developed two very simple IDL-based tools to map MODIS swath products. The first, geoview, has a simple, graphic interface, while the second, simap, is a command line utility. Modis_atmos was designed to work with atmospheric products. HDFLook for MODIS is a result of joint collaboration between the GES DAAC and the University of Lille, France. An RDF-EOS version of a popular MSPHINX program was developed to work with all MODIS and many other HDF-EOS data. Its main features include: geo-mapping, geo-projection conversion, interactive and batch mode processing, subsetting and subsampling, stitching of several granules, multi-granule processing, and conversion into GIS-compatible formats.