Azerbaijan National Academy of Science

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A method for determining of the geographical coordinates of sunlight on the ocean's surface by observing from a geostationary satellite on two parameters: time tand satellite longitude,φsat, was developed.

Geostationary orbit - is a circular orbit in the plane of Earth's equator at a distance of 35,786 km from the Earth's surface. Satellite placed at geostationary orbit has an angular velocity which is equal to the speed of rotation of the Earth, and so it is "hanging" over the fixed sub-satellite point. From the geostationary satellite the same region (about one third) of the globe is observed. Due to this property geostationary satellites are especially suitable for communications, meteorology and military applications.
By geographic coordinates of sunglint,  we mean latitude and longitude of the central point of a disc-shaped image of Sun on the ocean surface. Finding these coordinates is produced in three stages.
In the first stage, by the solving of Keplerequation the location of the Earth at the  orbit for a given point in time t was found.
In the second stage, for the same point in time tis: 1) the angle that defines the position of a satellite at geostationary orbit, and 2) the angle that determines the relative  position of the Sun and  satellite relative to the Earth were found;
In the 3rd stage, from  the law of reflection the nonlinear equation is obtainedand then by solving this equation and using  the formulas of spherical geometry the longitude and latitude of Sun glint were found.
On basis of this method, a packet of programs for determination of the geographical coordinates of the Sun glint were developedand it is used to revealthe Sun glint in the geostationary satellite images.

The input parameters of the program are:
1) Time t (GMT), taking the picture;
 2) satellite longitude, φsat.
The output parameters of the program are:
1) Geographical coordinates (longitude and latitude) of the central points of the Sun glint;
2) Daily, seasonal and annual paths (traces) of Sun glint;
3) Contour of the simultaneouslyilluminated and observed region of the Earth;
4) Contour of Sun glint (disk) on a smooth (without roughness) ocean surface;
5) Isolines of thesunlight brightness on the ocean surface.