GPS on Metop (GRAS)
Metop is Europe's first polar-orbiting satellite dedicated to operational meteorology. It represents the European contribution to a new cooperative venture with the United States providing data that will be used to monitor our climate and improve weather forecasting. The satellite Metop-A was launched in October 2006.
A new generation of European instruments that offer improved remote sensing capabilities to both meteorologists and climatologists will be carried with a set of 'heritage' instruments provided by the United States. The new European instruments will augment the accuracy of:
- Temperature and humidity measurements
- Wind speed and wind direction measurements, especially over the ocean
- Profiles of ozone in the atmosphere
MetOp is a series of three satellites to be launched sequentially over 14 years, starting in 2006, and forms the space segment of EUMETSAT's Polar System (EPS).
GPS radio occultation with GRAS
The Global navigation satellite systems radio occultation GNSS Receiver for Atmospheric Sounding (GRAS) is a GPS (Global Positioning Satellite) receiver that operates as an atmospheric-sounding instrument. The GRAS provides more than 600 atmospheric profiles measured by GPS radio occultation. GRAS provides globally distributed vertical temperature and humidity profiles. In addition GRAS will provide navigation solutions of the MetOp satellite position along its orbit. The profiles will be assimilated into Numerical Weather Prediction (NWP) models.
The Gras instrument was developed by the instrument prime Saab Ericsson Space in Sweden, supported by Austrian Aurospace (A), Sener (E) and GMV (E) under contract to ESA/Eumetsat. GRAS will also fly on Metop 2 and 3.
GFZ submitted a research proposal within the RAO framework. The project title is "Evaluation, Calibration and Validation of GRAS measurements from MetOp" and was positive evaluated.
GFZ also contributes to the GPS groundnetwork for GRAS.
Zus F., Beyerle G., Heise S., Schmidt T., Wickert J., Marquardt C.: Validation of refractivity profiles derived from GRAS raw-sampling data, Atmos. Meas. Tech., 4, 1541-1550, 2011.