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BCO-DMO dataset:  AVHRR WNA 2008

Data Object AVHRR WNA 2008


Name         Role
James J Bisagni         Principal Investigator
Robert C. Groman         BCO-DMO Data Manager

Dataset brief description

Western North Atlantic Sea Surface Temperature (SST) images from 2008.

Dataset description

MCSST western North Atlantic full resolution domain for 2008. We chose this 2048 X 2048 pixel domain, as it covers almost the entire western North Atlantic region, from south of Florida to north of Newfoundland, Canada, thus incorporating the western Labrador Sea, and the entire eastern seaboard of the US and Canada, including the Florida Current and Gulf Stream regions.

Data Provider:
Dr. J. J. Bisagni
University of Massachusetts Dartmouth
School for Marine Science and Technology
200 Mill Rd., Suite 325
Fairhaven, MA 02719 USA
jbisagni at umassd.edu

As a courtesy, please notify Jim Bisagni via email about your intent to use these data, so that he may keep a record.

Acquisition description


57.566 latitude top, 24.499 latitude bottom, -82.448 longitude left, -38.798 longitude right

Center latitude: 41.000, center longitude: -60.580

2048 x 2048 pixels

Processing description

Special data fields are defined to enable the satellite images to be plotted in the MapServer interface including the following: x_pixel_unit (pixel size in the X direction in map units per pixel),  y_pixel_unit (pixel size in the Y direction, which is usually negative map units per pixel), x_correction (rotation about the X axis in degrees), y_correction (rotation about the Y axis in degrees),  x_coordinate (X coordinate of the center of the upper left pixel in longitude degrees), and  y_coordinate (Y coordinate of the center of the upper left pixel in latitude degrees). These values are made accessible to the MapServer by including them as part of the data object. These six data fields correspond to the six lines in the so-called world file.

From Wikipedia (http://en.wikipedia.org/wiki/World_file), "a world file is a plain text computer data file used by geographic information systems (GIS) to georeference raster map images. The file specification was introduced by Esri.

Small-scale rectangular raster image maps can have an associated world file for GIS map software that describes the location, scale and rotation of the map. These world files are six-line files with decimal numbers on each line.

World files do not specify a coordinate system; this information is generally stored somewhere else in the raster file itself or in another companion file, e.g. Esri's .prj file. The generic meaning of world file parameters are:

This description is however misleading in that the D and B rotation parameters are not really rotations (in degrees or gradients) and in that as soon as D or B are not zero, the A and E parameters do not correspond to the pixel size anymore."

The data object is served with two columns representing the satellite image. The clickable link in the "time" column links to the satellite image that includes a color bar and a clickable link to the actual digital values of the image. This image undergoes a transformation during the serving to include, among other things, the color bar. The overlay image is another representation of the satellite image but this one is used by the MapServer in order to create the overlay image of the satellite image on the display map. This image also undergoes a transformation (by a different procedure) to enable it to be transparent among other changes.


Field Names List


Name of the NOAA satellite providing the images


Description of the NOAA satellite providing the AVHRR images


Name of the investigator providing the processed images.


Pixel size in the X direction

map units per pixel

Pixel size in the Y direction. This value is usually negative.

map units per pixel

Rotation about the X axis


Rotation about the Y axis


X coordinate of the center of the upper left pixel

longitude degrees

Y coordinate of the center of the upper left pixel

latitude degrees



Four digit year


Status of the image such as reviewed (by investigator)


UTC year day, starting with 001 as January 1

three digits

UTC day of the month

two digits

UTC time of the image as hours, minutes and fraction of minutes


UTC date and time formatted using the ISO standard


Link to the satellite image to be used as the overlay image on the MapServer

gif image

Color bar used for the AVHRR image representation of sea surface temperature. This scale is sometimes known as Pete's palette.


Deployment List

NOAA Satellites AVHRR_WNA_2004-2017

Instruments List

  1. Advanced Very High Resolution Radiometer:

    Short name: AVHRR
    PI supplied instrument name: AVHRR satellite
    Dataset-specific description:
    Generic description:

    "The AVHRR instrument consists of an array of small sensors that record (as digital numbers) the amount of visible and infrared radiation reflected and (or) emitted from the Earth's surface" (more information).

getinfor version: May 4, 2016/V1.34

This document is created from the content of the BCO-DMO metadata database.    2017-12-17  20:28:38