A First-Order Prediction Model of Total-Electron-Content Group Path Delay for a Midlatitude Ionosphere

摘要

An ionospheric total-electron-content prediction model has been developed at AFCRL for use in correcting range errors encountered by operational UHF radar systems and the proposed L-band 621B multisatellite position-fixing system. These system range errors are due to the excess time delay encountered as the radio wave passes through the earth's ionosphere, and are proportional to the total number of electrons through which the wave must pass on its way from transmitter to target. In response to a request by SAMSO, a model was developed by AFCRL in which the range error due to the ionosphere can be expressed in terms of the critical frequency of the ionosphere, f sub o F sub 2, a parameter that is currently predicted on a worldwide basis for military users by the Air Weather Service. Using total-electron-content data taken at the AFCRL Sagamore Hill Radio Observatory, an analytic model was constructed. It was tested against other data available from member countries in the Joint Satellite Studies Group, an informal affiliation of scientific groups from several countries who are studying ionospheric parameters using satellite beacon signals. Tests of the model using actual f sub o F sub 2 data show a smaller rms error than the use of monthly median values of the original total electron content data would have given. (Author)