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

mis-registration for Terra MODIS is generally less than tenth of a pixel. But for Aqua
MODIS, it is relatively large especially between the bands located on the warm FPAs and
the cold FPAs. Because of the mis-registration, measurements over slightly mismatched
areas from different spectral bands may produce undesired effects when used together,
and consequently lead to less accurate data products (Xie et al., 2008). In this chapter, the
impacts of the BBR shift on the L1B measurements and dust detection are assessed.
7.1 MODIS Sensor Spatial Calibration and Characterization
Before its launch, system level spatial characterization was performed with a ground
calibration device called integration alignment calibrator by the instrument vendor
(Barnes et al., 1998). Although MODIS Band-to-Band Registration (BBR) was carefully
characterized pre-launch, mis-registration between the spectral bands and FPAs still exist
or occur during its on-orbit operation. On-orbit, the MODIS has a unique device, the
SRCA, operated bi-monthly or tri-monthly for monitoring and tracking the BBR change
of all 35 bands relative to band 1. The quality of measurements is quite good. On the
other hand, the ground target approach serves as an alternative means for observing the
on-orbit BBR change with specific ground scenes located in Libyan Desert (Xie et al.,
2006). The ground target approach provides frequent measurements for more than half of
MODIS bands.
7.1.1 Mis-registration
Consistent with the pre-launch spatial characterization, relatively large spatial
mis-registrations are observed for Aqua MODIS between its spectral bands on the warm
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