Lidar measurements of mesospheric temperature inversion at a low latitude

Abstract

Abstract. The Rayleigh lidar data collected on 119 nights from March 1998 to February 2000 were used to study the statistical characteristics of the low latitude mesospheric temperature inversion observed over Gadanki (13.5 • N, 79.2 • E), India. The occurrence frequency of the inversion showed semiannual variation with maxima in the equinoxes and minima in the summer and winter, which was quite different from that reported for the mid-latitudes. The peak of the inversion layer was found to be confined to the height range of 73 to 79 km with the maximum occurrence centered around 76 km, with a weak seasonal dependence that fits well to an annual cycle with a maximum in June and a minimum in December. The magnitude of the temperature deviation associated with the inversion was found to be as high as 32 K, with the most probable value occurring at about 20 K. Its seasonal dependence seems to follow an annual cycle with a maximum in April and a minimum in October. The observed characteristics of the inversion layer are compared with that of the mid-latitudes and discussed in light of the current understanding of the source mechanisms.

Rayleigh lidar observations of enhanced stratopause temperature over Gadanki (13.5° N, 79.2° E) during major stratospheric warming in 2006

“…The system provides backscattered signals, which are integrated over 5000 transmitted pulses corresponding to a temporal averaging of 250 s. The temperature information is retrieved from the received photon counts using the method adopted by Hauchecorne and Chanin (1980). There have been quite a number of results reported from this site (Bhavani Kumar et al, 2000;Parameswaran et al, 2000;Siva Kumar et al, 2001, to state a few). Though the highest altitude is taken as 90 km and from which temperature is derived using downward integration, the standard error in the estimation of temperature information above 75 km is larger and hence the data for the heights 30 and 75 km are only presented.…”

Observations on Stratospheric-Mesospheric-Thermospheric temperatures using Indian MST radar and co-located LIDAR during Leonid Meteor Shower (LMS)

“…In fact, it is felt that the deviations in the present case could be due to inversion of temperature in that region, and the existing models do not usually account for them. Such inversions are found to occur more frequently in the equinox months and less during summer as well as winter months over Gadanki (Sivakumar et al, 2001). Above 100 km, while the CIRA profile shows a monotonic increase, the meteor profile shows extended altitude of the constant temperature in the lower thermosphere.…”

Influence of gravity waves and tides on mesospheric temperature inversion layers: simultaneous Rayleigh lidar and MF radar observations

“…They have been studied by several authors in the past few decades and most of the important findings are recently reviewed by Meriwether and Gardner (2000) and Meriwether and Gerrard (2004). They are found to occur more frequently in winter months at mid-latitudes (Leblanc and Hauchecorne, 1997) and in equinox months in low-latitudes (Siva Kumar et al, 2001). The mid-latitude observations show that they are longitudinally extended phenomena and are not local.…”