Equatorial plasma bubble association with lower atmospheric gravity waves – Further evidences

Abstract

Space based radio wave communication and navigation has become need of the society. Atmospheric (thermospheric-ionospheric) processes, such as Equatorial Plasma Bubbles (EPBs), affect the radio waves propagating through this region, causing heavy perturbations on signals received at ground. This paper investigates the causative mechanism of EPB through the ground based remotely sensed imaging observations of O (1S) 557.7 nm and O (1D) 630.0 nm emissions emanating from the upper mesosphere ( 100 km altitudes) and thermosphere-ionosphere ( 250 km altitudes) over a low-latitude station, Kolhapur (16.8 N, 74.2 E, and dip lat. 10.6 N). Our investigation revealed that the gravity waves evident in OI557.7 nm images exhibit a close association with the observed EPB structures. These mesospheric gravity waves were found to travel from the South to North with horizontal wavelengths 35 and 56 km on 13–14 April and 26–27 April 2015, respectively. The thermosphere-ionosphere measurements exhibited occurrence of the North–South aligned EPB moving to the east with an inter depletion distance (IDD) equal to 44 km and 64 km. These results provide evidences on association of the gravity waves with the EPB.