L-band nighttime scintillations at the northern edge of the EIA along 95°E during the ascending half of the solar cycle 24. Issue 7 (1st April 2018)

• Record Type: Journal Article
• Authors: Dutta, Barsha; Kalita, Bitap Raj; Bhuyan, Pradip Kumar
• Is Part Of: Advances in space research. Volume 61:Issue 7(2018)
• Page Start: 1744
• Page End: 1760
• Publication Date: 2018-04-01
• Subjects: Scintillation -- L band -- TEC -- Rate of TEC (ROT) -- Rate of TEC index (ROTI); Space sciences -- Periodicals; Astronautics -- Periodicals; Geophysics -- Periodicals; 500.505
• DOI: 10.1016/j.asr.2017.07.027
• Languages: English
• ISSNs: 0273-1177

Abstract

Highlights: L-band night time scintillations at Dibrugarh along 95°E from 2010 to 2014 is presented. Scintillation and Es in June solstice peaks at dusk. Scintillations in the equinoxes are ascribed to equatorial irregularities. The location of Dibrugarh is affected by both equatorial and mid latitude irregularities. Abstract: The characteristics of nighttime ionospheric scintillations measured at the L-band frequency of 1.575 GHz over Dibrugarh (27.5°N, 95°E, MLAT ∼ 17°N, 43° dip) during the ascending half of the solar cycle 24 from 2010 to 2014 have been investigated and the results are presented in this paper. The measurement location is within or outside the zone of influence of the equatorial ionization anomaly depending on solar and geomagnetic activity. Maximum scintillation is observed in the equinoxes irrespective of solar activity with clear asymmetry between March and September. The occurrence frequency in the solstices shifts from minimum in the June solstice in low solar activity to a minimum in the December solstice in high solar activity years. A significant positive correlation of occurrence of scintillations in the June solstice with solar activity has been observed. However, earlier reports from the Indian zone (∼75°E) indicate negative or no correlation of scintillation in June solstice with solar activity. Scintillations activity/occurrence in solstices indicates a clear positive correlation with Es recorded simultaneously by a collocated Ionosonde. In equinoxes, maximum scintillations occur in the pre-midnight hours while in solstices the occurrence frequency peaks just after sunset. The incidence of strong scintillations (S4 ≥ 0.4) increases with increase in solar activity. Strong (S4 ≥ 0.4) ionospheric scintillations accompanied by TEC depletions in the pre-midnight period is attributed to equatorial irregularities whereas the dusk period scintillations are related to the sporadic-E activity. Present results thus indicate that the current location at the northern edge of the EIA behaves as low as well as mid-latitude location.