Unusual depletion of OI 630.0 nm dayglow and simultaneous mesopause heating during the penetration of interplanetary electric field over dip equator

Abstract

AbstractEvidence for simultaneous changes in the thermosphere and mesopause associated with penetration electric fields using the OI 630.0 nm and OH (8, 3) dayglow measurements are presented. An unusual decrease in the thermospheric OI 630.0 nm dayglow and an intense heating (~30 K) at OH emission altitudes over a magnetic dip equatorial station, Trivandrum, India, were observed on 9 April 2006, coincident with the penetration of a noontime westward interplanetary electric field. The Sounding of the Atmosphere using Broadband Emission Radiometry observations on board TIMED satellite also revealed heating at the mesopause heights during this period. In addition, ionosonde and magnetometer observations indicated the presence of strong penetration electric fields. We propose that strong heating at the mesopause resulted in the intrusion of additional neutrals, like N2, into the emission altitudes and quenched the O(1D) atoms therein. The reduced Cowling conductivity at the E region inferred using magnetometer observations further corroborates this proposed mechanism.