The RGPS has its roots in the first Geophysical Processor System (GPS), also developed by Ron Kwok at the Jet Propulsion Laboratory, which operated at the Alaska SAR Facility (ASF) from 1991 through 1994. The GPS used ERS-1 SAR images for input, and created four types of output products: sea ice motion, sea ice type images, sea ice type grids, and wave spectra.
The ice tracking algorithm in the original GPS worked quite well. Using cross-correlation and edge detection, the regularly-spaced grid points defined in one image were followed to their new locations in a second image of the same area acquired three days later. This resulted in "Eulerian" vector fields of ice motion: for each pair of images, the ice motion was computed on a grid fixed in space.
Because of the small size of each image (100 x 100 km) and the finite range of the reception mask at ASF (3000 km radius), the spatial coverage of ice motion was patchy and limited to the western arctic. The temporal coverage was also patchy. While each ice motion product was generally accurate for its time and place, it was difficult to piece together the collection of products to see the bigger picture.
RGPS is meant to overcome these difficulties. First, the spatial coverage is the entire Arctic Ocean basin. This is made possible by the wide swath (500 km) of RADARSAT, the collection of data from both ASF and Tromso (Norway), and the on-board tape recorder. Second, the arctic snapshot will be acquired at regular (weekly) intervals.
Because of the complete spatial coverage and regular temporal coverage, RGPS will be able to do "Lagrangian" ice tracking, following the same parcels of ice for extended periods of time. This forms the basis for the RGPS products such as the age and thickness distributions of ice. See Publications for more details.
Investigators interested in RGPS development and/or products are encouraged to contact members of the RGPS working group.