An estimate of quiet time plasmaspheric electric fields from whistler observations at low latitude

Particular emphasis is laid on the application of whistlers recorded at low latitude ground station, Nainital during magnetically quiet times to estimate the eastward/westward electric field in the plasmasphere. The east-west components of electric field during quiet magnetic (average K-p = 1) are obtained for the first time from low latitude station on the basis of the available whistler data on March 7, 1971 (Sigma K-p = 8) in the 01:22 to 03:21 IST sector and 22:10 to 23:20 IST sector, April 18, 1971 (Sigma K-p = 19(-)) in the 22:15 to 23:44 IST sector and April 19, 1971 (Sigma K-p = 15) in the 01:26 to 03:31 IST sector. During above quiet times in the whistler activity period, a decrease in dispersion with time is observed. The method of measuring electric field from the observed cross-L motion of whistler ducts within the plasmasphere, indicated by changes in nose frequency of whistlers has been outlined The nose frequency of the non-nose whistlers under consideration have been deduced by means of an accurate curve fitting method as developed by Tarcsai (1975). Our measurements demonstrate an average estimated electric field of similar to 0.06 m Vm(-1) in the premidnight local time sector sind an average westward electric field of similar to 0.05 m Vm(-1) in the post-midnight local time sector. These values are in good agreement with similar results reported by earlier workers. Near midnight there is a sharp transition from eastward field to westward electric field. The electric fields during quiet days at low latitudes are thought to be generated by the dynamo mechanism.