A comparison of GOES-12 and GOES-13 visible channel images (Java animation) centered over northeastern Minnesota on 25 December 2006 shows the improvement in navigation accuracy with the new GOES-13 satellite. Note how the surface features (such as frozen/snow-covered interior lakes, and the Lake Superior shoreline) appear to have significantly less image-to-image movement on GOES-13 versus GOES-12 — this is a result of changes to the GOES-13 spacecraft bus, which now has an improved Image Navigation and Registration (INR) system that uses star trackers to provide precision image navigation and registration information. This improved navigation will allow for better accuracy of satellite products such as satellite derived winds (or “atmospheric motion vectors”).
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Another item of interest which is apparent in these images is the fact that Duluth, Minnesota (KDLH) recorded it’s first Christmas Day with no snow on the ground since snowfall records began there in 1875. A MODIS true color image of Wisconsin confirms the lack of snow cover over the immediate Duluth vicinity and adjacent portions of northwestern Wisconsin — while some snow cover did exist to the north, west, and south of Duluth, even those areas generally had only 1-4 inches on the ground.
