Calculates the distance as measured over the earth's surface (the down range) for a given beam elevation and slant range.
beam_distance(range, elev, k = 4/3, lat = 35, re = 6378, rp = 6357)
range | numeric. Slant range in m, the length of the skywave path between target and the radar antenna. |
---|---|
elev | numeric. Beam elevation in degrees. |
k | Standard refraction coefficient. |
lat | Geodetic latitude of the radar in degrees. |
re | Earth equatorial radius in km. |
rp | Earth polar radius in km. |
numeric. Beam distance (down range) in m.
depends on beam_height to calculate beam height.
# down range of the 5 degree elevation beam at a slant range of 100 km: beam_distance(100000, 5)#> [1] 99495.13