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Ann. Geophys., 24, 2471-2480, 2006
www.ann-geophys.net/24/2471/2006/
© European Geosciences Union 2006
Seasonal variation of gravity waves in the Equatorial Middle Atmosphere: results from ISRO's Middle Atmospheric Dynamics (MIDAS) program
G. Ramkumar1, T. M. Antonita1, Y. Bhavani Kumar2, H. Venkata Kumar2, and D. Narayana Rao2
1Space Physics Laboratory, VSSC, Trivandrum, India
2National Atmospheric Research Laboratory, Gadanki, India
Abstract. Altitude profiles of temperature in the stratospheric and mesopheric region
from lidar observations at NARL, Gadanki, India, during December 2002–April
2005, as part of ISRO's Middle Atmospheric Dynamics – "MIDAS
(2002–2005)" program are used to study the characteristics of gravity waves
and their seasonal variation. Month-to-month variation of the gravity wave
activity observed during the period of December 2002–April 2005 show
maximum wave activity, with primary peaks in May 2003, August 2004 and March
2005 and secondary peaks in February 2003 and November 2004. This month-to-month
variation in gravity wave activity is linked to the variation in the
strength of the sources, viz. convection and wind shear, down below at the
tropospheric region, estimated from MST radar measurements at the same
location. Horizontal wind shear is found to be mostly correlated with wave
activity than convection, and sometimes both sources are found to
contribute towards the wave activity.
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