Validation of ADEOS-II/GLI ocean-color atmospheric correction based on ship-board hand-held spectroradiometer measurements

摘要

The paper compares GLI-derived estimates obtained under "version 2" GLI standard atmospheric correction algorithm with in situ measured data collected by SIMBADA handheld above-water radiometer, intending the evaluating the performance of the algorithm which includes empirical absorptive aerosol correction as well as sun glint correction. Over 395 match-up data, average estimation error (difference between GLI-derived and SIMBADA-measured data) in normalized water-leaving radiance (nLW) is 0.3 μW/cm2/nm/sr in 412 and in 443 nm bands, showing improvement from version 1 GLI atmospheric correction by 10-30 %, whereas estimation bias is reduced significantly. The GLI-derived aerosol optical thickness (AOT) in 865 nm band show 0.1 RMS error against SIMBADA measurement on average, whereas Angstrom exponent estimate shows significant bias, suggesting potential calibration offset among GLI near-infrared bands. Despite relatively large scattering in nLW match-up analysis, comparison between GLI chlorophyll a concentration estimates and SIMBADA-derived estimation show highly correlated and consistent relation. This will suggest that fluctuations in nLW estimate are systematic over GLI visible channels although the nature of the variability requires further investigation.