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Ann. Geophys., 19, 1039-1044, 2001
www.ann-geophys.net/19/1039/2001/
© European Geosciences Union 2001
Lidar measurements of mesospheric temperature inversion at a low latitude
V. Siva Kumar1, Y. Bhavani Kumar1, K. Raghunath1, P. B. Rao1, M. Krishnaiah2, K. Mizutani3, T. Aoki3, M. Yasui3, and T. Itabe3
1National MST Radar Facility, P. B. No: 123, Tirupati - 517 502, A. P. India
2Department of Physics, S. V. University, Tirupati - 517 502, A. P. India
3Communication Research Laboratory, 4–2–1, Nukai Kitamachi, Koganei, Tokyo 184–8795, Japan
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.
Key words. Atmospheric composition
and structure (pressure, density and temperature). Meterology and atmospheric
dynamics (climatology)
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