The tiny ionospheric photometer: An instrument for measuring ionospheric gradients for the COSMIC constellation

We describe the specifications for an ultraviolet radiometer for measuring the F-region electron density gradients from the Constellation Observing Sy stem for Meteorology, Ionosphere, and Climate(COSMIC). We also present a te chnique for determining the two-dimensional structure of the ionosphere usi ng the measured ionospheric gradients inferred from observation of the radi ative recombination emission at 1356 Angstrom in conjunction with occultati ons of Global Positioning System satellites observed from the COSMIC satell ites. Our scheme uses a nadir viewing UV photometer to characterize the F-r egion gradients while obtaining altitude information about the F-region fro m the GPS occultation measurements. We present the results of simulations t hat demonstrate the applicability and accuracy of the technique and observa tional concept.