Profiles of radio refractive index and humidity derived from radar wind profilers and the Global Positioning System

It has often been pointed out that the Bragg backscatter of radar waves fro m elevated turbulent layers is very highly correlated with the height gradi ent of radio refractive index (RI) through these layers. However, many user s need the profiles of RI, or the associated humidity, rather than profiles of their gradients. Simple integration of the gradients is usually not fea sible because of ground or sea clutter and because biological scatterers su ch as insects and birds often severely contaminate the lower range gates. W e show that if the total height-integrated RI is independently available (s ay, from the Global Positioning System (GPS)), and if the surface value of RI is known, the profiles of RI are retrievable with good accuracy. For tho se profiler systems equipped with a radio acoustic sounding system to measu re temperature, the humidity is also retrievable. The method is demonstrate d with data collected in southern California, where 7 hours of profiler dat a were recorded at 449 MHZ along with CPS data. Three radiosonde balloons w ere launched during the period, and the profiles of PI from the balloon and the profiler are compared. The advantages of the system are its invulnerab ility to nonprecipitating clouds (at frequencies of 449 MHZ or lower) and t hat it uses only facilities that will soon be deployed globally. Simulation s are used to assess errors from various factors such as loss of sign of th e gradient of the potential RI (important especially during some frontal ev ents) and the presence of biological contaminants in some geographical area s (such as coastal zones and some agricultural areas at night).