Abstract:
Quasi-monochromatic gravity-wave-induced oscillations,
monitored using the mesospheric OH airglow
emission over Kolhapur (16.8◦ N, 74.2◦ E), India, during January
to April 2010 and January to December 2011, have
been characterized using the Krassovsky method. The nocturnal
variability reveals prominent wave signatures with periods
ranging from 5.2 to 10.8 h as the dominant nocturnal
wave with embedded short-period waves having wave periods
of 1.5–4.4 h. The results show that the magnitude of the
Krassovsky parameter, viz. |η|, ranged from 2.1 to 10.2 h for
principal or long nocturnal waves (5.2–10.8 h observed periods),
and from 1.5 to 5.4 h for the short waves (1.5–4.4 h
observed periods) during the years of 2010 and 2011, respectively.
The phase (i.e., 8) values of the Krassovsky parameters
exhibited larger variability and varied from −8.1 to
−167◦
. The deduced mean vertical wavelengths are found to
be approximately −60.2 ± 20 and −42.8 ± 35 km for longand
short-period waves for the year 2010. Similarly, for 2011
the mean vertical wavelengths are found to be approximately
−77.6 ± 30 and −59.2 ± 30 km for long and short wave periods,
respectively, indicating that the observations over Kolhapur
were dominated by upward-propagating waves. We
use a full-wave model to simulate the response of OH emission
to the wave motion and compare the results with observed
values. In the present report, we
discuss the observed wave characteristics and cause of the noted diferences.
