A study on the Estimation of GOCI daily PAR and Comparison with In-situ measurement

Abstract

Photosynthesis available radiation (PAR) is one of the major factors of primary production in the ocean. In this study, oceanic daily PAR around Korean peninsula was estimated from GOCI imagery using the PAR model based on Plane-parallel theory. And comparison with in-situ measurement data was carried out. To estimate daily PAR, radiance and solar/sensor geometry data were observed from GOCI images, first. Then atmospheric factors, such as cloud and aerosols, were calculated at the PAR model. Finally, daily PAR was integrated from GOCI instantaneous PAR. In-situ measurement data has been collected from Ieodo and Socheong-cho Ocean Research centers with ECO-PAR sensor which made by ©WET Labs. Estimates of GOCI daily PAR was ranged from 0 to 60 Ein/m2 /day around Korean peninsula, and seasonal variation of irradiance was well appeared. Comparison between GOCI and in-situ measurement was carried out using clear-sky condition data first. They showed high R2 value, 0.99. Also, daily PAR observed during all days, including cloud days, showed high accuracy with 0.96 of R2 value. However, there were some errors over 10 % of difference due to very cloudy weather or technical error of sensor. These errors can be decreased by correction of in-situ measurement data with modeled daily PAR values or sensor calibration. In further study, estimation of GOCI hourly PAR and possibility study of hourly primary production estimation will be carried out.