Use of Global Positioning Satellites (GPS) Occultation Data in Numerical Weather Prediction

Florida State University, Tallahassee FL

Investigators

Abstract

Extensive efforts have been made to properly incorporate remotely sensed atmospheric data from open oceans where conventional data are sparse into the numerical prediction models. Along this line, the PI seeks to advance the assimilation of the Global Positioning Satellites (GPS) occultation data by improving old approaches as well as exploring a new method. The degree of refraction of the radio signals transmitted by the GPS depends on the properties of the atmosphere through which the signals travel, and thus can be used to gain the knowledge of the atmospheric thermodynamic state. This research project is divided into four areas: 1) Improve the computational efficiency of the raytracing approach (a forward modeling calculation to match the bending angle profile with the observed profile) used by the PI in her previous study and improve its performance in the lower troposphere; 2) Develop an efficient refractivity assimilation method by estimating the averaged atmospheric refractivity information along the ray path to obtain the integrated effect of refractivity index; 3) Assess and quantify errors in the GPS-derived refractivity data; 4) Evaluate and examine existing physical parameterization schemes using the information retrieved by the GPS data. The potential impact of this study on weather predictions is significant considering the role that GPS data likely will play in the future.