The AMSU's instantaneous FOV, 1.1 and 3.3 degrees for AMSU-A and AMSU-B respectively, remains constant with scan angle. This results in a ground resolution that steadily decreases with distance from nadir viewing. FOVs become approximately three times larger at the 48.3 degree maximum scan angle for AMSU-A and -B. The plot shows the resolution for AMSU-B decreasing from 15 km at nadir to 45 km at the edge of the swath.

Click the SSM/I Footprint button above.
Since the SSM/I scans at a constant 53.4 degrees from nadir across its 102-degree arc, ground resolution for individual channels remains the same throughout each scan. Notice from the diagram above, that even though resolutions for the four SSM/I channels are different, the SSM/I instrument scans such that the centroids for the FOVs of each channel remain collocated throughout the scan.

The next page describes how AMSU and SSM/I scan strategies (FOV resolution and viewing angle) can affect microwave product development and interpretation.