Two methods to solve the ionospheric electron concentration horizontal gradient at Chongqing

The electron concentration horizontal gradient vector of the ionosphere and its south-north and east-west components over Chongqing station are analyzed and calculated, using the first approximation, time correlation and space correlation and another approach introduced. And then, the validity of the two methods is analyzed and compared. Foundation item: Supported by the National Natural Science Foundation of China (69571020) and the Research Fund for the Doctoral Program of Higher Education (RFDP1999048602) Biography: Chong Yan-wen(1972-), male, Ph. D. candidate, research direction: ionospheric modeling and inversion.