Analysis of GOES-R as a Constraint in GNSS Tropospheric Tomography

Abstract

GNSS tomography is an all-weather condition remote sensing technique in the field of meteorology that is gaining considerable attention in recent years. The water vapor distribution and related parameters like wet refractivity in the troposphere can be reconstructed with reasonable Spatio-temporal resolution in this method. To achieve this goal, the troposphere is divided into a number of 3D elements (voxels). Then, the system of the observation equations is defined by a relation between the wet refractivity field and the distance traveled by GNSS rays through voxels. However, propagated signals do not pass through some of the model elements. Thereby, the reconstructed wet refractivity field suffers in terms of solution uniqueness. Consequently, additional data sources and horizontal and/or vertical constraints should be applied to avoid the singularity of the estimated field. In this presentation, the combination of wet refractivity maps computed from Geostationary Operational Environmental Satellite (GOES) sounder and refractivity fields obtained by GNSS tomography is demonstrated to achieve a unique solution. The GOES-R sounder products are provided hourly with a 10 km spatial resolution. Therefore, GOES-R wet refractivity maps are used to constrain the system of equations and consequently, the tomographic solution leads to an improved reconstructed wet refractivity field. To analyze the efficiency of the proposed data, a 3D tomographic model is defined over a regional area covered by the Continuously Operating Reference Station (CORS) Network in the United States. Moreover, radiosonde measurements in the area of interest are used to achieve the feasibility and correctness of the estimated 3D wet refractivity images.