Magnetospheric disturbances are known to modify<br>the equatorial thermospheric dynamics and<br>chemistry. The disturbance winds and electric fields<br>in turn could modify equatorial spread F /plasma<br>bubble irregularity development conditions in ways<br>to enhance or inhibit its occurrences. Digital<br>ionosonde/digisonde and optical data from Brazilian<br>equatorial/low latitudes are analyzed during some<br>recent magnetospheric disturbances to examine the<br>control of disturbance electric fields and winds<br>(especially the disturbance meridional winds) on the<br>generation and/or inhibition of the spread F. The<br>SUPIM (Sheffield University Plasmasphere-<br>Ionosphere Model) has been used (based on a new<br>methodology, Souza et al., 2000 JGR in press) to<br>model the maridional wind and equatorial zonal<br>electric field for quiet conditions to be used as<br>reference for determining the disturbance<br>components of these parameters and to identify their<br>possible effects on the spread F developments.<br>Preliminary analysis of some storm event that<br>occurred in 1998 already show disturbance associated<br>post sunset spread F development and associated<br>perturbations (in zonal and meridional) winds as<br>observed over Cachorira Paulista, Fortalez and Sao<br>Luiz. The paper will present results based on analysis<br>for a few quiet days and storm conditions.


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