Results of the modeling of the topside electron density profile using the Chapman and Epstein functions Original Research Article

An attempt has been made to model the topside electron density profile by using the data obtained by the incoherent scatter radar in Malvern (−2.34°E, 52.1°N), UK and the topside sounder data over the European PRIME region (0–35°E, 30–70°N). Both the Chapman distribution function and the Epstein function are used to do the modeling. It is found that both functions cannot fit well the topside profiles if the thickness parameters are assumed to be constant along all the heights above the F2-peak. Our study showed that by assuming the thickness parameter changes linearly with height (HS= H0+a (h−hmax) for Chapman function and B2 = B0+k (h−hmax) for Epstein function), the result of the fitting could be improved very much. We found that with the two-parameter fitting, the topside profiles can be fitted to a height of about 400km above the F2-peak quite satisfactorily, while with the one-parameter fitting by fixing the slope parameter in the linear relationship, the results obtained are still good enough when the fitting is made to a height of about 300km above the F2-peak. The results showed that the thickness parameter near F2-peak varies very complicatedly. The correlation relationships of B0 with hmF2, NmF2, Ap and F107 are also studied.