Korean J. Remote Sens. 2023; 39(6): 1591-1604

Published online: December 31, 2023

https://doi.org/10.7780/kjrs.2023.39.6.2.7

© Korean Society of Remote Sensing

수증기 연직 분포에 의한 GOCI-II 해색 산출물 오차 분석

이경상 1)·배수정2)·이은경2)·안재현 1)*

1) 한국해양과학기술원 해양위성센터 선임연구원(Senior Researcher, Korea Ocean Satellite Center, Korea Institute of Ocean Science and Technology, Busan, Republic of Korea) 2) 한국해양과학기술원 해양위성센터 기술원(Research Specialist, Korea Ocean Satellite Center, Korea Institute of Ocean Science and Technology, Busan, Republic of Korea)

Analysis of Uncertainty in Ocean Color Products by Water Vapor Vertical Profile

이경상 1)·배수정2)·이은경2)·안재현 1)*

Abstract

In ocean color remote sensing, atmospheric correction is a vital process for ensuring the accuracy and reliability of ocean color products. Furthermore, in recent years, the remote sensing community has intensified its requirements for understanding errors in satellite data. Accordingly, research is currently addressing errors in remote sensing reflectance (Rrs) resulting from inaccuracies in meteorological variables (total ozone, pressure, wind field, and total precipitable water) used as auxiliary data for atmospheric correction. However, there has been no investigation into the error in Rrs caused by the variability of the water vapor profile, despite it being a recognized error source. In this study, we used the Second Simulation of a Satellite Signal Vector version 2.1 simulation to compute errors in water vapor transmittance arising from variations in the water vapor profile within the GOCI-II observation area. Subsequently, we conducted an analysis of the associated errors in ocean color products. The observed water vapor profile not only exhibited a complex shape but also showed significant variations near the surface, leading to differences of up to 0.007 compared to the US standard 62 water vapor profile used in the GOCI-II atmospheric correction. The resulting variation in water vapor transmittance led to a difference in aerosol reflectance estimation, consequently introducing errors in Rrs across all GOCI-II bands. However, the error of Rrs in the 412–555 nm due to the difference in the water vapor profile band was found to be below 2%, which is lower than the required accuracy. Also, similar errors were shown in other ocean color products such as chlorophyll-a concentration, colored dissolved organic matter, and total suspended matter concentration. The results of this study indicate that the variability in water vapor profiles has minimal impact on the accuracy of atmospheric correction and ocean color products. Therefore, improving the accuracy of the input data related to the water vapor column concentration is even more critical for enhancing the accuracy of ocean color products in terms of water vapor absorption correction.

Keywords Geostationary Ocean Color Imager-II, Ocean color, Water vapor absorption correction, Error analysis, Atmospheric correction

Korean J. Remote Sens. 2023; 39(6): 1591-1604

Published online December 31, 2023 https://doi.org/10.7780/kjrs.2023.39.6.2.7

Copyright © Korean Society of Remote Sensing.

수증기 연직 분포에 의한 GOCI-II 해색 산출물 오차 분석

이경상 1)·배수정2)·이은경2)·안재현 1)*

1) 한국해양과학기술원 해양위성센터 선임연구원(Senior Researcher, Korea Ocean Satellite Center, Korea Institute of Ocean Science and Technology, Busan, Republic of Korea) 2) 한국해양과학기술원 해양위성센터 기술원(Research Specialist, Korea Ocean Satellite Center, Korea Institute of Ocean Science and Technology, Busan, Republic of Korea)

Analysis of Uncertainty in Ocean Color Products by Water Vapor Vertical Profile

이경상 1)·배수정2)·이은경2)·안재현 1)*

Abstract

In ocean color remote sensing, atmospheric correction is a vital process for ensuring the accuracy and reliability of ocean color products. Furthermore, in recent years, the remote sensing community has intensified its requirements for understanding errors in satellite data. Accordingly, research is currently addressing errors in remote sensing reflectance (Rrs) resulting from inaccuracies in meteorological variables (total ozone, pressure, wind field, and total precipitable water) used as auxiliary data for atmospheric correction. However, there has been no investigation into the error in Rrs caused by the variability of the water vapor profile, despite it being a recognized error source. In this study, we used the Second Simulation of a Satellite Signal Vector version 2.1 simulation to compute errors in water vapor transmittance arising from variations in the water vapor profile within the GOCI-II observation area. Subsequently, we conducted an analysis of the associated errors in ocean color products. The observed water vapor profile not only exhibited a complex shape but also showed significant variations near the surface, leading to differences of up to 0.007 compared to the US standard 62 water vapor profile used in the GOCI-II atmospheric correction. The resulting variation in water vapor transmittance led to a difference in aerosol reflectance estimation, consequently introducing errors in Rrs across all GOCI-II bands. However, the error of Rrs in the 412–555 nm due to the difference in the water vapor profile band was found to be below 2%, which is lower than the required accuracy. Also, similar errors were shown in other ocean color products such as chlorophyll-a concentration, colored dissolved organic matter, and total suspended matter concentration. The results of this study indicate that the variability in water vapor profiles has minimal impact on the accuracy of atmospheric correction and ocean color products. Therefore, improving the accuracy of the input data related to the water vapor column concentration is even more critical for enhancing the accuracy of ocean color products in terms of water vapor absorption correction.

Keywords: Geostationary Ocean Color Imager-II, Ocean color, Water vapor absorption correction, Error analysis, Atmospheric correction

KSRS
December 2024 Vol. 40, No.6, pp. 1005-989

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