Seasonal and geomagnetic control of equatorial scintillations in two longitudinal sectors

Simultaneous observations at UHF (257 MHz) from three stations in the equatorial region (Huancayo, Peru, Natal, Brazil and Accra, Ghana) were made between Jan. 1977 and Jan. 1978. The period of least scintillation activity for the three stations was May, June and July. Local season played no role since Accra, Ghana was north of the geographic equator and the other two were south. During May, June and July and during the post-midnight period, increased magnetic activity in general brought on increased scintillation activity under moderate solar flux conditions. In a second comparison between UHF observations from Guam and from Huancayo, Peru for the period March, 1978 to June, 1979, minimum scintillation activity was found for Guam in the months Nov., Dec. and Jan. In this period, increased magnetic activity produced increased scintillation activity. For Huancayo, minimum activity was again seen in the period May, June and July. In general (except for May, June and July in the 0–70°W sectors and in Nov., Dec. and Jan. in the 135–180°E sector), pre-midnight scintillation is inhibited by magnetic activity. Post-midnight, increased magnetic activity increases scintillation activity under moderate solar flux conditions. © 1980, All rights reserved.