Refinement of an alternative method to the Abel inversion for the retrieval of atmospheric profiles from GNSS radio occultation data
Benedetto, C. ; Vespe, F. ; Pacione, R.
Jan - 2004

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type: Conference Proceedings

Abstract
An alternative method to the Abel inversion for the retrieval of atmospheric profiles from GNSS Radio Occultation measurements (CHAMP and GRACE space mission) was recently widely explained by the authors. Such method, named BPV, is able to retrieve the refractivity profiles performing a linearization of its integral relationship with the bending angles. The linearization is applied adopting as guess refractivity profile the dry Hopfield model. The parameters of the dry Hopfield model - namely pressure and temperature on the ground -- are evaluated by fitting the bending angles from the outer troposphere up to the stratopause. The differential increment of the refractivity is estimated applying in a iterative way the linearized integral relationship,. Such differential increment is supposed to be the contribution to refractivity of the wet component of the atmosphere as it is in Smith and Weintraub relationship. So the activities we plan to develop concern the refinement of the dry Hopfield by using balloon data (RAOB) just to make more reliable the retrieval of the profiles with the BPV method. Furthermore we plan to simulate Radio Occultation measurements by using RAOB data on which to apply the BPV method in order to have an its definitive validation. An approach for the integration of Radio occultation and ground GPS zenith total delays will be proposed. Finally results of a test concerning the sensitiveness of the atmospheric profiles to the orbital uncertainties of LEO satellites will be explained. With the proposed approach the retrieval of water vapor profiles, by using GNSS spaceborne and ground measurements, could be performed without using external information. Such improvement, together with the challenging task of providing LEO-POD in near real time, could make the GNSS RO a fully standalone and self consistent system for meteorology applications.

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