i Detection of Smoke and Dust Aerosols Using Multi-sensor Satellite ...

where p(i) is the position given in pixel number, R(v,p(i)) is the response at the
position p(i) for a given band and valley v, k is the total pixels of one valley used for
calculation. The spatial shift, Pab between band a and band b is the average of all the
centroid location differences, ΔPab, within defined time range, expressed in Eq. 7.2.
P
ab
N M
NM
P
ab
105
(7.2)
where M is the total number of the valleys in one qualified L1B measurement (one
event or one pass) and N is the total events in defined time range such as one day, one
month, or one year. The value of M varies from event to event due to the fixed threshold.
Instead of using the number of pixels or the fraction of a pixel, the distance given in
meters is adopted for expressing spatial shift, which is equivalent to the spatial shift
multiple with spatial resolution.
7.1.3.4 Results
The average spatial deviations, from launch till the end of year 2007, for both
reflective solar bands and thermal emissive bands relative to band 1 are calculated with
qualified L1B measurements, and listed in the Table 7.1. However, not all bands can be
used to retrieve spatial shift with this approach such as some ocean color bands, water
vapor bands, cloud bands, and ozone bands. Most ocean color bands need the high scene
contrast, or signal-to-noise ratio, so that they are normally in the saturation status. Some
TEBs primarily focused on the properties of atmosphere, clouds, water vapor, and ozone
may not have enough response to the ground targets. Consequently, only the BBR shift of