Normalization method and application for MODIS TEB assessments using
Earth scene measurements
Selected Earth targets are commonly used for satellite sensor
calibration assessments (e.g. sensor stability and inter-comparisons).
Moreover, typical scenes used for the calibration assessment of the
thermal emissive bands (TEBs) include Dome Concordia (Dome-C), ocean,
desert, and deep convective clouds (DCC). Reference data used for these
calibration assessments can come from another band, another instrument,
or ground measurements. The Dome-C site, covered with
uniformly-distributed permanent snow, is normally used for the
assessment of the TEBs at cold temperatures. Furthermore, ocean and
desert measurements prove useful for scenes with higher temperatures.
The DCC, one of the most consistent and coldest targets, can be used for
the TEBs calibration and product stability assessments. MODIS band 31
(~ 11 mm) can be used as a reference for these scenes.
However, measurements over these scenes have seasonal variations, and
the DCC brightness temperatures (BTs) have asymmetrical distributions.
These features can introduce additional uncertainty to the stability
assessments. A normalization method is applied by using an empirical
model to derive reference-dependent BTs. Using the developed empirical
model, measurements can be normalized to a reference BT in order to
enhance the calibration assessment’s accuracy. This method is evaluated
using all four scene types (i.e. ocean, desert, snow (Dome-C), and DCC)
and applied to all the Terra and Aqua MODIS TEBs. Stability assessments
over the instruments’ entire data records are presented and discussed.
The technique can be applied in future efforts to support MODIS TEBs