MGN RDRS Global Reflectivity Data Record (GREDR)

GREDR – Global Reflectivity Data Record

PDS Data Set ID: MGN-V-RDRS-5-GDR-REFLECTIVITY-V1.0 (DOI: 10.17189/1522517) (for first mapping cycle products, go here)

PDS4 Bundle:urn:nasa:pds:magellan_gxdrDOI: 10.17189/kv67-gt18

For more information about RDRS GREDR products, see the GREDR Data Set Description.

The Radar System (RDRS) Global Reflectivity Data Record (GREDR) consist of images of power reflection coefficients in four projections: mercator equatorial (MERC), sinusoidal equal area equatorial (SINUS), north polar (NORTH), and south polar (SOUTH).

The power reflection coefficients are derived by fitting altimeter echoes from the fan-beam altimetry antenna as a function of time to Hagfors’ radar backscatter model templates. The values are then corrected for the presence of multiple echo peaks and further corrected for diffuse scattering using backscatter data obtained by the side-looking mode of the Magellan radar. The reflectivities are then filtered to remove low-frequency instrument calibration errors, and re-sampled into sinusoidal, Mercator, and north and south polar stereographic projections at a resolution of about 5 x 5 kilometers per pixel.

In ODE, GREDR products have the following product IDs:

gredr_yyyy

where:

yyyyy = map projection (merc, sinus, north, or south)

Within the data directory under the bundle root directory, there are four subdirectories divided by map projection. They are: "mercator" for the Mercator projection products, "sinusoidal" for the sinusoidal map projection products, "north" for the north polar stereographic products, and "south" for south polar stereographic products.

Each map product consists of three files. There are the image file (*.img), the ENVI header file (*.hdr) for use in reading the data into the commercial ENVI software package, and the PDS4 label (*.xml) that describes both the image file and ENVI header.