The PI plans to use TOPEX/POSEIDON data to analyze the spatial structure and temporal evolution of the ionosphere. In particular, he is interested in TEC manifestations of the response of the middle and low latitude ionosphere to geomagnetic storms and in TEC wave signatures. This data analysis procedure will also prepare TEC data for utilization in other objectives of the space weather program. The data provide an excellent database for model validation purposes, especially important over large ocean areas where ionosonde, GPS TEC, or other ground-based data are not available. TEC measurements from the TOPEX/POSEIDON mission are an ideal data set for the validation of the new understanding of ionospheric storm effect distributions.