Application of MODIS on monitoring dissolved inorganic nitrogen and dissolved inorganic phosphorus in Haizhou Gulf

Abstract

Red tides have been increasingly observed in the gulf of Haizhou and considered a serious environmental problem from the beginning of the new century. Eutrophication of water is an important reason of red tide occurrence. This paper used the observation data of the concentration of dissolved inorganic nitrogen (DIN) and dissolved inorganic phosphorus (DIP) in Haizhou Gulf from 2004 to 2006 and selected synchronous MODIS Terra 1B data with 500m spatial resolution in this period of time. We established factors with single band and multi-bands, and then calculated the correlation of each factor with DIN concentration, DIP concentration, and their logarithm respectively. The factors with stronger correlation were used to establish regression models of DIN and DIP's concentration. After comparing these models, we chose the linear model of DIN concentration established by factor ) 4, 3 ( 11 F and inverse model of the logarithm of DIP concentration established by factor ) 5, 6 ( 7 F as their final regression model. The relative accuracy of DIN concentration model achieved about 70%; the retrieving results of DIN concentration were consistent well with real conditions. The relative accuracy of the logarithm of DIP concentration achieved about 90%. The results prove the feasibility of monitoring DIN concentration and the exponential order of DIP concentration in offshore of Jiangsu Province.