The Intrinsic Field-Of-View (IFOV) is defined as the FWHM of the
pixel response curve obtained when moving a point source in swath
and/or flight direction.
The IFOV of a sub-satellite OMI CCD-pixel is about 3 km in the swath direction and about 10 km in the flight direction.
In the swath (across track) direction, 4 or 8 pixels are binned to a
ground pixel of 12 or 24 km. Futhermore, OMI measurements are co-added
during 2 seconds. With a ground speed of the Aura spacecraft of about
7 km/s, this results in ground pixel size of 13 km in the flight
(along track) direction.
- Note that a measurement contains some information of the outside the 13 km in the flight direction, due to the IFOV of 10 km.
- Note The ground pixel size of the UV-1 sub-channel [270-310 nm] is twice as large in the swath direction compared to the UV-2 sub-channel and the visual channel. This is due to the optical design of the UV channel in order to reduce straylight in this wavelength range.
The pixel-size in the swath-direction increases from 13 × 24 km² (exact nadir position) to 13 × 128 km² at the most outer swath-angle (57 °). This effect is shown in the figure below.