A comparison of thermospheric [O] derived at EISCAT with [O] predicted by MSIS

In recent years aeronomic considerations of the value of the O + −O collision cross‐section ( Q O + − O ) in the ionospheric F‐region have resulted in many values of a multiplicative adjustment factor ( F ) to the standard value of Q O + − O which had been in use from the mid sixties to the late eighties. Q O + − O and oxygen concentration ([O]) appear as a product in aeronomic calculations, so F can also be considered a multiplicative factor for the oxygen. [O] derived at EISCAT for data from 1984 to 1997 is compared to oxygen predicted by MSIS and values of F are calculated as a function of solar cycle and year. There is a solar cycle variation, with F varying from .65 at solar minimum to 1.18 at solar maximum. For solar fluxes between 100 and 160 solar flux units F at EISCAT is in good agreement with a value of F calculated for MSIS. No long term trend in the relationship between EISCAT [O] and MSIS [O] was found.