Global pattern of plasma bubbles irregularities at midnight using ion drift spectrometer measurements

One of the anomalies which continue to receive much attention is the large-scale plasma depletions, the ionospheric plasma bubbles. Equatorial plasma bubble irregularity if not well monitored, can impair radio and Global Positioning System (GPS) navigations asides other systems. Consequently, the midnight seasonal and longitudinal variability of plasma bubbles occurrence rate had been presented. Data used spans January 1978-December 1979 (F10.7 = 143), and is obtained using the Atmospheric Explorer satellite ion drift meter. 18 longitudinal locations were examined and were divided into five sectors (African, Indian, Pacific, American and Atlantic) across the globe. The percentage occurrence rates (%R) of the bubbles revealed 10, 39, 34, and 16% for March and September equinoxes, June solstice, and December solstices respectively, with the highest activity in the African-Atlantic sector for all seasons. Seasons with the highest %R are characterized with corresponding higher correlation coefficients (R) of total number of trips (TT) to trips with bubbles (TB) relation. June solstice and September equinox recorded higher TT/TB correlation relation values of R = 0.8270 and 0.7543 respectively. The occurrence activity rate of DB , the percentage ratio of number of bubbles (B) relative to the number of trips with bubbles (TB) is lower during the solstices when compared with equinoxes for all longitudinal sectors. We suggested that the correlation value for the TT/TB relation is an indicator of the occurrence rate magnitude both seasonally and longitudinally. Past results especially in the Pacific sector were also confirmed. Keywords: ionosphere; solstice; equatorial plasma bubbles; GPS navigation; equator; electrodynamics.