The calculation of the distribution of the Sun glitter radiance on the ocean surface by observing from a geostationary orbit

Abstract

This paper presents a method for calculating the distribution of Sun glitter radiances from the ocean surface and a definition of the contour of the Sun disc image on the smooth ocean surface. Remotely sensed data were recorded from geostationary orbit and the spherical form of the Earth and shadowing effect on the rough ocean surface were taken into account. The reflected Sun radiance was calculated using the stochastically distributed facets method. The results of the calculations showed that the size of the Sun glint-affected region of ocean and also the value of the Sun glitter radiance in this region depend on both the geometry of observation and the degree of ocean surface roughness (i.e. over ocean wind speed upsilon). The size of this region increased with wind speed upsilon and decreased with psi, the angle between the Sun beam and direction to the sensor from the centre of the Earth. In addition, the maximum value of surface reflectance factor, r(lambda), increased with angle psi and decreased with upsilon. The surface reflectance factor isolines for the different angles psi and wind speeds were also represented.