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

FPAs and cold FPAs (because of different temperature, VIS and NIR FPAsare called
warm FPAs and SMIR and LWIR FPAs are named cold FPAs) (Xie et al., 2006). An
example on Jan 4, 2003 at the UTC time 11:50 with 500 m spatial resolution
measurements shows that the mis-registration exists between the warm and cold FPAs in
both track and scan directions. Theoretically, the measurements of different spectral
bands over the same target should match perfectly if there is no mis-registration. In the
example (Fig. 7.1), a dark target located at the center of the selected area produces a
lower signal than that of its neighboring pixels. In the along-track direction bands 1 and 4
on the warm FPAs scan the dark target at pixel number 11 while band 7 on the cold SMIR
FPA crosses the same target at pixel number 10, about one pixel earlier (Fig. 7.1(a)).
Likewise, in the scan direction, bands 1 and 4 scan the dark pixel at pixel number 10
while band 7 about one pixel later, at pixel number 11 (Fig. 7.1(b)). It indicates that the
relative mis-registration is approximately one pixel, or 500 m, between cold and warm
FPAs.
Reflectance
0.4
0.35
0.3
0.25
0.2
0.15
0.1
0.05
Band1 Band4 Band7
2 4 6 8 10 12 14 16 18 20
Pixel number
Location
96