TOPEX/Poseidon
orbits at an altitude of
1336 km above
the Earth.
The orbit is
inclined 66o from the equator.
There are 2.83o
(about 315.5 km at the equator) between
any two adjacent passes.
Every 1 hour
and 52 minutes, TOPEX/Poseidon (T/P) completes one orbitof
the Earth.
In the meantime,
the Earth has rotated underneath it, so its next orbit is slightly to the
west.
After 127
orbits, T/P repeats the first orbit path.
We call each
1/2 orbit (from south to north or from north to south) a pass.
Ascending
passes go from southwest to northeast and have odd pass numbers.
Descending
passes go from northwest to southeast and have even pass numbers.
Each time T/P
repeats a particular pass, we call that a cycle.
It takes 9.91564
(about 10) days to complete 1 full
cycle (all 254 passes).
But,
after just 1 day, T/P covers the whole earth, in sparse resolution.
After
3 days, T/P provides another complete and less sparse mapping, then
full
coverage after 10 days.
T/P
never covers every point on the Earth!!
T/P is an active sensor,
sending microwave pulses to points directly underneath it, not a passive
sensor, acquiring an image of a swath beneath the satellite.
Problems or questions? cholland at oceansci dot net
