| Summary: | This report was prepared by Shengjie Ge, a graduate research associate in the Geodetic Science and surveying program of the Department of Geological Science at the Ohio State University, under the supervision of Professor C. K. Shum. This study was partially supported by grants from NASA Interdisciplinary Science Program NAG5-9518, and National Science National Space Weather Program ATM- 0418844. This report was also submitted to the Graduate School of the Ohio State University as a dissertation in partial fulfillment of the requirements for the Ph.D. degree. Dedicated satellite gravity missions are anticipated to significantly improve the current knowledge of the Earth’s mean gravity field and its time variable part–climate sensitive gravity signals. They could be measured by the Gravity Recovery and Climate Experiment (GRACE) twin-satellite with sub-centimeter accuracy in terms of column of water movement near the Earth’s surface with a spatial resolution of several hundred kilometers or larger, and a temporal resolution of one month or weeks. To properly recover the time variable gravity signals from space, the gravity measurements require the atmospheric pressure contribution to be accurately modeled and removed. The sparse coverage of measurements makes the weather products less accurate in the southern hemisphere, especially over the Southern Ocean and Antarctica. The asynoptic observation from GPS radio occultation could achieve dense spatial coverage even in remote regions. In this research, we investigate the potential use of GPS occultation to improve the pressure modeling over Antarctica. Atmospheric pressure profiles are retrieved and validated against ECMWF, NCEP and radiosonde observations. Our results show that occultation can provide compatible observations especially in the upper atmosphere. Large standard deviations and biases are found near the ground and in the Antarctic region. GPS occultation in the polar regions is less affected by multipath problem and can penetrate down near the ...
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