North-Central Gulf of Mexico Imagery

Open-File Report 98-484

U.S. GEOLOGICAL SURVEY OPEN FILE REPORT 98-484

Satellite Imagery of the North-Central Gulf of Mexico
June, 1993 - May, 1997

Project and Data Overview

This CD contains imagery collected by the Advanced Very High Resolution Radiometer (AVHRR) on the NOAA polar-orbiting weather satellites. The AVHRR provides almost daily coverage of a site at a resolution of approximately 1 km. The data types included are sea surface temperature (SST), water reflectance (REF), and a false-color infrared overview (FCI).

Data Types for the Imagery

The regional view data sets include sea surface temperature (SST), water reflectance (REF), and a false-color image (FCI) of the near-red and red channels. These are included in both GIF and geoTIFF formats. The GIF format is used for thumbnail views of the geoTIFF images. The geoTIFF files can be read by a variety of programs. Also, the digital values in the geoTIFF images may be converted into physical units, making these images suitable for digital analysis.

Regional Imagery

The regional view displayed here is presented in GIF format files having a size of 512 pixels by 256 lines. The nominal pixel size in the images is approximately 1 km x 1 km. Three data types are available: false-color infrared, sea surface temperature, and reflectance.

The false-color infrared imagery provides a photographic view of the area, allowing the user to identify cloud patterns, land features, and other patterns such as glint off the water. These images correspond approximately to color-infrared film. The near-infrared band (channel 2) is shown in red and the red band (channel 1) in green and blue. Bright red areas on land represent a dense, vegetated canopy. White areas indicate cleared, bare fields or urban areas. In the water, river plumes may appear as turquoise, and glint tends to have a whitish appearance.

All other images have a color table included. Purple corresponds to low values (low temperature or reflectance), red and pink to the highest values. Identified clouds are masked in gray, land is masked in black, the coastline is in white, political boundaries are in yellow, and rivers are in turquoise.

Tick-marks around the edge of the image are found every 6 minutes (0.1 degrees). SST is in degrees Celsius, and reflectance is in units of 0 to 1 (corresponding to 1 to 100%).

Other Imagery Files

The data sets are also available in the original PCISDK 5.0 format (developed by PCI Remote Sensing, Toronto Canada, http://pcigeomatics.com). The files are located on both CDs: the first CD contains years 1993-1994, and can be found in the "pix" directory. The remainder of the files are located on the second CD. The file names are identical to the geoTIFF files, except for the .pix extension.

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