High-Level Warmings Over a Tropical Station

Abstract

Examination of the available rocketsonde data for the tropical station, Thumba, India, has shown that warmings, less pronounced than in the case of middle and high-latitude stations but of noticeable magnitude, and coolings of similar magnitude occurred in the mesopheric and upper stratospheric levels during the period, December 1970?March 1971. This was the only winter period when observations were made at the station during all of the 4 mo. No prominent change in wind has been observed in association with the warnings, however. The maximum warming observed over a period of 1 week in the upper stratosphere was 26°C at 45 km. The upper mesosphere had been subjected to a continuous process of warming for over 3 weeks in December?January 1971 during which period the temperature rose by 48°C at 70 km. There is no definitive indication that these warmings were of the propagating type. However, they appear to have moved in the vertical at a rate of 3?5 km/day. The temperature behavior of the lower stratosphere (50 mb) and the upper troposphere (300 mb) in the winter of 1970?71 was different than that which was observed in the preceding 2 winters.