A.1 Successfully characterize the instrument’s field of view
(FOV)
The ISS LIS instrument has a 78.5° x 78.5° rectangular FOV imaged on a
128 x 128 pixel charge coupled device (CCD). At 400-km altitude this
provides “storm-scale” pixel resolution (nadir) of ~4
km (and 50% larger at off-nadir boundaries), which is similar to TRMM
LIS after its orbit boost in 2001. Obscuration of the FOV by ISS solar
panels and radiator that periodically pass through the FOV was
quantified. Worst-case mean and peak obscuration is 4% and 12.5%,
respectively. Since ISS is a moving platform, small obstructions in the
FOV will only lower view-time of a point on the ground (e.g., storm)
momentarily, so there is no impact to science provided the view times
are appropriately adjusted. Current version 1 ISS LIS data likely have a
slight, artificially reduced (~1-2%) detection
efficiency (DE) due to overestimates of viewing times. FOV analysis
remains an ongoing process, and improved viewing time estimates are
expected in version 2 ISS LIS data.