Estimating GOCI daily PAR and validation

Abstract

Photosynthesis available radiation (PAR) that makes primary producers to compose carbon compounds is the energy source of carbon circulation at the ocean. In these days, global scale PAR is efficiently observed from satellite remotesensing with low cost and high resolution. Here, Geostationary Ocean Color Imager (GOCI) which is geostationary orbit sensor is used to estimate daily PAR at smaller scale area for decreasing influence of diurnal variation such as cloud. GOCI daily PAR is estimated using PAR model based on Plane-parallel theory and compared with in-situ data observed during year of 2015 at two stations that has turbid and clear ocean area, respectively. Each band image of GOCI L1B data and solar altitude data are input data for PAR model to estimate daily PAR. Correlation coefficient between GOCI daily PAR and in-situ daily PAR is 0.98 and root-mean-square error (RMSE) is 4.50 Ein/m2 /day. To correct underestimated GOCI daily PAR, correction equation is developed from linear regression between GOCI daily PAR and in-situ daily PAR observed during clear sky condition days. RMSE of GOCI daily PAR which corrected with correction equation is decreased to 3.08 Ein/m2 /day and seasonal bias between GOCI and in-situ daily PAR is decreased, too. Validation is carried out with in-situ daily PAR observed during year of 2016. Correlation coefficient is 0.98 and RMSE is 2.69 Ein/m2 /day. Estimating GOCI daily PAR is expected to make accurate daily PAR by reducing meteorological element and regional error.