Profiling the Atmosphere with an Airborne Gps Receiver System

− Since the GPS/MET mission was launched in 1995, an extensive dataset of spaceborne GPS radio occultation (RO) soundings have been derived and compared to in-situ measurements and numerical model analyses. The launch of the Constellation Observing System for Meteorology Ionosphere and Climate (COSMIC) introduces several thousand more profiles daily, which has attracted much wider attention in the atmospheric and space weather communities. However, due to the limited number of available satellites with GPS receivers and their fixed orbits, space-borne RO cannot provide dense sounding measurements in a specific region within a given time range on demand. With a GPS receiver onboard an airplane, the airborne GPS RO technique offers such an opportunity while retaining a high vertical resolution sounding capability. In July 2007, the GNSS Instrument System for Multistatic and Occultation Sensing (GISMOS), developed by Purdue University, was tested on the NCAR HIAPER (Highperformance Instrumented Airborne Platform for Environmental Research) aircraft. Some preliminary observations were made. More measurements will be expected in the near future. A geometric optics retrieval system has been developed and a sensitivity analysis of the airborne occultation demonstrates that an overall accuracy of 1% for the retrieved refractivity could be achieved from the surface up to the altitude of the airplane at around 10 km, where the airplane velocity errors up to 5mm/sec restrict the accuracy. * Corresponding author address: Feiqin Xie, Purdue University, Department of Earth & Atmospheric Sciences, West Lafayette, IN 47905; e-mail: [email protected] The sensitivity analysis and preliminary results from the first test flight will be presented. Such high-resolution targeted airborne RO measurements in the troposphere provide a new resource for regional weather and climate