Sat elev for reflection from nadir-pointing surface

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• Previous message: Leo Barhorst: "Obs 980308"

The calculation is actually simple to describe without the need for a diagram
[I hope].

psi = solar depression angle  (e.g. If Sun 12 deg below the horizon, psi=+12)
theta = angle observer-Earth centre-satellite

                            (R+h)^2 + R^2 -d^2
        where cos(theta) =  ------------------
                                 2.R.(R+h)

                 h=satellite height
                 R=Earth radius
                 d=range of satellite

Then the satellite elevation for reflection from a nadir-pointing surface is

             elev = psi - 2.theta

and in the same azimuth as the Sun unless the phase angle (defined as new=180,
full=0 deg) is less than 90 deg, in which case the azimuth is opposite
the Sun.

Cheers, Rob McNaught
(rmn@aaocbn.aao.gov.au)

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