Determination of vertical plasma drift and meridional wind using the Sheffield University Plasmasphere Ionosphere Model and ionospheric data at equatorial and low latitudes in Brazil: Summer solar minimum and maximum conditions

The F region critical frequency f(0)F(2) and peak height h(m)F(2), measured simultaneously at the equatorial location Fortaleza (4 degrees S, 38 degre es W, magnetic latitude = 3.5 degrees S) and at the low-latitude location C achoeira Paulista (22 degrees S, 45 degrees W, magnetic latitude = 15 degre es S), are compared with their values calculated by the Sheffield Universit y Plasmasphere-Ionosphere Model(SUPIM) to determine the vertical (ExB) drif t velocity at the equator and the magnetic meridional wind velocity over th e two locations. The calculated and observed values of f(0)F(2) are then ma tched at both Fortaleza and Cachoeira Paulista to obtain the magnetic merid ional winds over their respective conjugate locations. To account for the o bserved f(0)F(2) diurnal variation pattern over Cachoeira Paulista, it was found necessary to include a small source of ionization, attributable to en ergetic particle precipitation in the South Atlantic anomaly region. The ve rtical drift velocity and magnetic meridional wind velocity derived for sum mer months during both solar minimum and solar maximum are compared with th eir values given by other published models. While the diurnal variation of the modeled vertical drift velocity shows general agreement with the values based on Jicamarca radar measurements (the exception being during the suns et-midnight period at solar maximum and between 2000-2300 LT at solar minim um), the magnetic meridional wind shows significant differences with respec t to the Horizontal Wind Model 1990 (HWM90) [Hedin et al., 1991] during bot h solar minimum and solar maximum at Fortaleza and at locations conjugate t o Fortaleza and Cachoeira Paulista.