Correction of B2_bot formula for NeQuick at Hainan station

Using the ionospheric data measured with DPS-4 digisonde at Hainan station,we study the diurnal and seasonal variations of ΔB2,the seasonal median values of B2_best and parameter R(ratio of B2_best to B2_{NeQuick 2}) in the ionosphere.The results show that there are some differences between B2_best and B2_{NeQuick 2} in all seasons and B2_{NeQuick 2} is generally less than the values of B2_bot at Hainan station. Meanwhile there is the same diurnal variation for R in different years during moderate solar activity and the annual variation of R is very small.Then,we make a revision for formula of NeQuick and results of revised formula show that the B2_bot of NeQuick is better consistent with the observations.