The Constellation Observing System for Meteorology, Ionosphere, and Climate(COSMIC) is capable of accurately measuring water vapor in remote regions of the atmosphere (Anthes et al. 2008). Six microsatellites in COSMIC measure the vertical profile of refractivity (N) of Global Positioning System (GPS) radio signals through the atmosphere. A vertical profile of moisture from COSMIC can be resolved to 100 m of depth, with negligible interference from clouds and precipitation.

Findings from the refractivity relationships are applied to 1) the observed profiles of GPS refractivity near hurricanes; 2) comparisons to METEOSAT and CALIPSO; and 3) the summertime climatology of GPS refractivity for a wide area of the central and eastern Atlantic Ocean, including the main development region off the coast of Africa.

Probability relationships of dry (RH<50%) and moist (RH>75%) as a function of N, T, and p have been developed for operational use. Examples of this technique will be shown in the poster. Such a technique may be very useful when aircraft reconnaissance is not available to observe dry air intrusion or moist environments in the vicinity of convection or cloud cover. The potential uses of a refractivity nomogram will also be shown.