Assessment of Impact of the Assimilation of GPS Radio Occultation Observations

Josep M. Aparicio, Godelieve Deblonde

Abstract:	We present an evaluation, from the perspective of forecast performance, of the cost and benefits of the assimilation of GPS radio occultation observations. We have considered refractivity profiles and bending angle profiles. The second is considered a more primitive expression of the observation, thus preferable for assimilation, but computationally more expensive. We have analyzed, during one month, the performance of the forecast system that is in use operationally at the Canadian Meteorological Center (CMC), when data collected by satellites CHAMP and SAC-C is added to the ensemble of observational data assimilated. The parallel system thus prepared was in every other respect identical to the actual CMC operational system. The products obtained with the standard ensemble of observational data will be used here as control. The CPU overload when assimilating refractivity profiles is below 5%. On the other hand, positive impacts are found in most statistics. Although some improvements in accuracy can be expected from a better treatment of local gradients, which favors the assimilation of data in the form of bending angles, we can conclude that even the improvement here described for refractivity profiles justifies by itself the use of this kind of data.
Published in:	Proceedings of the 17th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2004) September 21 - 24, 2004 Long Beach Convention Center Long Beach, CA
Pages:	2337 - 2342
Cite this article:	Aparicio, Josep M., Deblonde, Godelieve, "Assessment of Impact of the Assimilation of GPS Radio Occultation Observations," Proceedings of the 17th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2004), Long Beach, CA, September 2004, pp. 2337-2342.
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