Comparisons of Electron Density Profiles Derived From TIMED/GUVI Data With Ionosonde Measurements.

The Global Ultraviolet Imager (GUVI) aboard the Thermosphere, Ionosphere, Mesosphere Energetics and Dynamics (TIMED) spacecraft has been systematically observing the nighttime F region of the ionosphere for nearly four years. Using ultraviolet remote sensing techniques, the GUVI data can be used to infer electron density profiles at mid and low latitudes. In this work we compare ionospheric measurements made at several digisonde stations with parameters inferred from airglow measurements made by the TIMED/GUVI instrument. We have found for electron densities in the approximate range of 3.0 to 11x105 cm-3 that the GUVI measurements are consistent with the ionosonde observations. A side benefit of this comparison will be a study of the consistency of the calibration of various ionosondes from a global perspective and the ability to identify potential biases in individual digisonde station records. It should be noted that this study (and others like it) which seek to quantify the uncertainties in different types of ionospheric measurements will be important to current efforts at ionospheric data assimilation models, such as the Global Assimilation of Ionospheric Measurements (GAIM) model.