A Saturated Light Correction Method for DMSP/OLS Nighttime Satellite Imagery

摘要

Several studies have clarified that electric power consumption can be estimated from the Defense Meteorological Satellite Program/Operational Linescan System (DMSP/OLS) stable light imagery. As digital numbers (DNs) of stable light images are often saturated in the center of city areas, we developed a saturated light correction method for the DMSP/OLS stable light image using the nighttime radiance calibration image of the DMSP/OLS. The comparison between the nonsaturated part of the stable light image for 1999 and the radiance calibration image for 1996–1997 in major areas of Japan showed a strong linear correlation $(R^{2} = 92.73)$ between the DNs of both images. Saturated DNs of the stable light image could therefore be corrected based on the correlation equation between the two images. To evaluate the new saturated light correction method, a regression analysis is performed between statistic data of electric power consumption from lighting and the cumulative DNs of the stable light image before and after correcting for the saturation effects by the new method, in comparison to the conventional method, which is, the cubic regression equation method. The results show a stronger improvement in the determination coefficient with the new saturated light correction method $(R^{2} =break 0.91, P = 1.7 cdot 10^{-6} < 0.05)$ than with the conventional method $(R^{2} = 0.81, P = 2.6 cdot 10^{-6} < 0.05)$ from the initial correlation with the uncorrected data $(R^{2} = 0.70, P = 4.5 cdotbreak 10^{-6} < 0.05)$. The new method proves therefore to be very efficient for saturated light correction.