Assimilation of GPS Radio Occultation Data for Numerical Weather Prediction

Abstract

With the availability of approximately 4,000 radio occultation sound ings per day within three hours of observation, COSMIC has the potential to contribute significantly to global and regional weather analysis and pre diction. However, the basic radio occultation measurements (phase delays) are very different from traditional meteorological measurements (i.e., tem perature, water vapor), and to effectively assimilate them into weather pre diction models is a challenging task. Over the past five years, considerable progress has been made in the development of an effective strategy for the assimilation of GPS radio occultation data. In this paper, we (1) review the measurement and data reduction procedures, (2) discuss the error charac teristics of the GPS radio occultation data, (3) discuss the various strategies for data assimilation, (4) review results from recent data assimilation re search, and (5) provide suggestions for future research.