A comparison of optically measured daytime OH temperatures over the tropics during solar maximum and minimum periods

Abstract

This paper deals with the variability of optically measured daytime OH temperatures during two different solar activity epochs, over Trivandrum (8.5°N, 76.5°E), a tropical station in India. The data used for the present study were spanning over the period of February-March, during the solar maximum year of 2001 and a solar minimum year of 2005. The mean daytime temperature (180±5 K) over the above period during 2001 was found to be lesser than the mean temperature (195±9 K) during 2005 by ˜15 K. Apart from a noticeable shift in mean level temperature; the variabilities in temperature of both the years were strikingly similar. Moreover, the wave periodicities present during this period were also quite similar. The possible reasons for these observations were investigated in context of the various forcings, which control the energetics of the equatorial mesopause region. These observations presented in this study are unique and reveal some newer aspects of the energetics of the tropical mesopause.