Intercalibration of DMSP/OLS by Parallel Regressions

The Defense Meteorological Satellite Program-Operational Linescan System night lights offer a unique data set, covering more than two decades. However, for a number of reasons, an intercalibration procedure has to take place in order to reduce year-to-year inconsistencies before a meaningful time series can be established. Several intercalibration procedures have been proposed in the literature. However, they are rarely compared to each other. One difficulty in the comparison has been the lack of reference data in most, if not all, of the countries. Nevertheless, some metrics have been proposed, primarily based on quantifying year-to-year variation and comparing with auxiliary data sets. The objective of this letter is to introduce a new and more efficient intercalibration approach and compare it with commonly used procedures. The results show that the proposed method significantly improves intercalibration with respect to both reducing year-to-year fluctuations as well as improving correlation with auxiliary data sets.