Introduction to GPS Remote Sensing

• Global Positional System (GPS) satellites were originally developed for military purposes 

• 24 GPS satellites are evenly distributed around the earth

• The satellites transmit coded signals at two carrier frequencies:

  1. L1 - 1.57542 GHz

  2. L2 - 1.22760 GHz

• GPS receivers are commonly used to measure signals from three or more satellites to determine one's three-dimensional position by triangulation

• A pleasantly unexpected consequence of the GPS technology, however, is the ability to measure vertical profiles of: 

1. water vapor
2. temperature
3. pressure
4. refractive index

• Why is this important (especially for water vapor)?

  • current measurements of water vapor on ALL atmospheric scales, are inadequate:
    • data assimilation into mesoscale - climatic models
      • improve QPF and severe weather forecasts
    • hydrology
    • upper-atmosphere studies (electron densities)

• So, how can this be accomplished????