Remote Sensing Information Gateway (RSIG)

The Remote Sensing Information Gateway (RSIG) is a tool for selecting, subsetting, downloading, assembling, and visualizing environmental data. After the data has been assembled, it can be stored on the user’s workstation, if desired. RSIG is developed by the US Environmental Protection Agency (EPA).

The RSIG application is operated by selecting from among fifteen or so variables available from the following data sources:

• NASA's Moderate Resolution Imaging Spectroradiometer (MODIS) satellite data
• AIRNow data via the AIRNow Gateway
• Air Quality System (AQS) data via the Air Quality Data Mart
• EPA's Community Multi-scale Air Quality (CMAQ) model output
• National Environmental Satellite, Data, and Information Service (NESDIS) biomass burning data
• UVNet
• Ozone and PM2.5 Statistical Fused Air and Deposition Surfaces (SFADS) datasets originating from the US EPA Landscape Characterization Branch

More details on RSIG's data sources can be found at http://www.epa.gov/rsig.

The user runs RSIG to specify the time/spatial coordinates and the data products of interest. RSIG uses OGC-WCS-compliant servers/subsetter programs at remote sites, such as NASA Goddard or Sonoma Tech, to parse, aggregate, and subset data files on the data owner's server. RSIG then transfers to the user's workstation only the specified subset of data (variables, lon-lat box, time-range). Transmission volume over the Internet to the user is thereby greatly reduced (by three orders-of-magnitude) compared to the common approach of using FTP to transfer numerous large files.

The RSIG Java client can then visualize the data on a latitude-longitude map, automatically locating the data in the correct geographic position.

RSIG can also save the subset of data to a local disk in the following formats:

• Binary External Data Representation (XDR) format (simple, efficient)
• NetCDF-COARDS format
• NetCDF-IOAPI format (regridding the data to a CMAQ grid)
• HDF (unsubsetted satellite files)
• ASCII tab-delimited spreadsheet
• MCMC (used for input into HB model)
• PNG images
• MPG movies
• KMZ movies (for display in Google Earth and similar applications)
• GeoTIFF RGB format and 32-bit float format

Access and Status

The RSIG application is in use and evolving with new features and additional data sources. Users outside the EPA can access the application at http://www.epa.gov/rsig.

RSIG Update, May 1, 2009

On May 1, 2009, EMVL released a new version of RSIG. Among the new features and developments:

• The entire 2002 CMAQ model output can be visualized and downloaded, including computed Aerosol Optical Depth (AOD) values
• Images can now be saved in GeoTIFF RGB format and 32-bit float format. Both formats contain embedded georeferencing data, but the 32-bit float format has a rasterized/approximated data value at each pixel rather than a color.
• RSIG now serves ozone and PM2.5 Statistical Fused Air and Deposition Surfaces (SFADS) datasets originating from the US EPA Landscape Characterization Branch.
• RSIG can now optionally calculate and output Moderate Resolution Imaging Spectroradiometer (MODIS) polygon corners, enabling more accurate measurements by atmospheric researchers.
• RSIG is now compatible with Internet Explorer 7.

Java and Browser Requirements

RSIG has a Web browser-based Java applet for interactive visualization.

RSIG requires Internet Explorer 7 or earlier, or Firefox 3 or earlier.

Note: Run RSIG in its own browser window rather than in a browser tab. We have received reports of Java only partially redrawing the RSIG screen when switching between tabs. Running RSIG in its own browser window should alleviate this problem.

RSIG carries the following Java requirements:

• Java Runtime Environment (JRE)
• Configure Java memory to be larger than the default
• a .java.policy file saved to your Home directory. The .java.policy file is a simple text file that ensures you can save data from the RSIG applet to your computer.

The RSIG web site contains full information on setting up Java for Linux, UNIX, Mac OS, and Windows systems, and includes the required .java.policy file.

Access to RSIG Data

In addition to the Web browser-based Java applet, RSIG has an OGC-WCS/WMS-compliant web server application to enable streaming access to RSIG's data and images. This can effectively automate access to any data that RSIG can access and deliver the data to your application in various formats. For external users (outside the EPA network) use: http://www.epa.gov/rsig/. Refer to the site's section on "web Access to RSIG Data" for usage examples.

Sponsorship and Contacts

The RSIG application has been sponsored and managed by the EPA Office of Research Development's (ORD) National Exposure Research Lab (NERL). The Principal Investigator is Dr. Jim Szykman. The application is being developed by the EPA's Environmental Modeling and Visualization Laboratory (EMVL).

• Dr. Jim Szykman, james.j.szykman@nasa.gov, EPA ORD (757) 864-2709
• Heidi Paulsen, paulsen.heidi@epa.gov, EPA NCC (919) 541-1834
• For technical support contact the EMVL contract developers:
  • Todd Plessel, plessel.todd@epa.gov, (919) 541-5500
  • Matt Freeman, freeman.matt@epa.gov, (919) 541-4293

See RSIG Data Summit Profile