A study on latitudinal variations of daytime and nighttime amplitude scintillations observed by GSATs over Indian sector

The fluctuation in the phase or amplitude of the radio signals as it transit the ionosphere is called scintillation. Nighttime scintillations are associated with F-region irregularities, while E-region irregularities produce daytime scintillations. In this work, characteristics of Earth’s ionospheric amplitude scintillations on L1-Band of geostationary Indian satellites GSAT-8 (PRN 127) and GSAT-10 (PRN 128) over equatorial/low-latitude Indian stations under day and night sectors were comp ared. The scintillation data were recorded using GNSS receiver placed at Trivandrum, Bangalore, Hyderabad, Delhi, and Hanle during 2014. Both daytime and nighttime scintillation events over near equatorial trough station Trivandrum and off crest station Delhi show maximum probability of occurrence during equinox and during winter for near crest station, Hyderabad. For equatorial trough station Trivandrum, the daytime amplitude scintillations for both satellites were highest during afternoon/evening sectors 14:00-17:59 IST, whereas for near equatorial crest station Bangalore and off crest station Delhi, this would be during morning sector 06:00-09:59 IST. During nighttime, the amp litude scintillations observed by both the satellites were generally highest during post sunset (18:00-21:59 IST) hours for near trough station Trivandrum, near crest station Bangalore, and low-latitude station Hanle. The probability for strong amplitude scintillation events were highest over near crest station Hyderabad and off crest station Delhi. The present study indicates that there exists a poor correlation between magnetic activity and S4 index.