Satellite Climatology - Orbits Geostationary orbits Sun synchroneous orbits Precessing orbit Discussion

Inclination inclination   satellite orbit perigee plane of satellite orbit equatorial plane

Basics Satellites in circular orbits attractive force F g = m g (R/r)² centrifugal force F c = m r  ² m: mass of the satellite R: radius of the earth (R = 6370 km) r: distance to the center of the earth g: acceleration of gravity (g = 9.81 m/s²)  : angular velocity (  = 2  f, f: rotation frequency) Stable orbit F g = F c

Satellite period and orbits x10 6 m radius satellite period [h] velocity [ x1000 km/h] synchronous distance 35,786 km

Different Orbital Distances

1. geostationary orbit

Geostationary Orbit

Geostationary Orbiting Satellites Satellite observes same area at all times. Continuous sampling km from Earth’s surface!

2. Low sun synchroneous orbit

Polar Orbiting Satellites Satellite observes globe in “swaths” km from Earth’s surface

Polar Orbit

Polar Orbiting Satellites

(Near) Polar Orbiting Satellites

Daily Coverage

3. Precessing orbit

Orbits shown in inertial space and size relative to Earth is correct Other orbits

Discussion: what's the effect of orbit on: Science: Viewing zenith angles? Revisit time? Diurnal cycle? Coverage? Tropics/polar regions? Sun glint? Technical: Data transmission? Data reception? Solar panel? Instruments optics? Space weather? Debris? Orbital drift?

Worldwide Operational Weather Satellite Observing

Polar Regions The satellite doesn't pass directly over the pole due to the slight inclination of the orbital plane. The transparent overlay identifies the 3000 km wide swath that is viewed by the AVHRR imaging instrument on the satellite. The yellow curves delineate the limits of the 60 degree viewing arcs from the six "standard" geostationary satellites included in these discussions.

Satellite Constellation A group of electronic satellites working in concert is known as a satellite constellation.electronicsatellites Such a constellation can be considered to be a number of satellites with coordinated ground coverage, operating together under shared control, synchronised so that they overlap well in coverage and complement rather than interfere with other satellites' coverage.coverageinterfere

Satellite Formation