Sudden mesospheric warming over equatorial region

Abstract

Using M-100 meteorological rocketsonde data collected over Thumba Equatorial Rocket Launching Station (8°32′N, 76°52′E), Trivandrum, India for the period January to May 1972, a sudden mesospheric warming followed by an almost equal cooling has been detected over this region on 1st March 1972. The Thumba equatorial mesospheric temperature showed an increase of about 50 to 60 °C in an altitude region between 60 and 70 km from 23 February to 1 March 1972 which was followed by a cooling of about 50 to 70 °C from 1 to 15 March in that altitude region. Sudden warmings in the stratosphere at high latitudes during winter time are well known. However, sudden mesospheric warnings over equatorial regions have not been observed too frequently and are thus relatively less studied compared to high latitude warnings. The sudden warming observed in the equatorial mesosphere on 1st March 1972 is quite rare and unique event which followed minor midwinter stratospheric warmings at high latitudes in the Northern Hemisphere, although the equatorial stratosphere remained practically undisturbed in its thermal structure during this period.