<p><strong>Abstract.</strong> Quasi-monochromatic gravity-wave-induced oscillations, monitored using the mesospheric OH airglow emission over Kolhapur (16.8°<span class="thinspace"></span>N, 74.2°<span class="thinspace"></span>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<span class="thinspace"></span>h as the dominant

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... urnal wave with embedded short-period waves having wave periods of 1.5–4.4<span class="thinspace"></span>h. The results show that the magnitude of the Krassovsky parameter, viz. |<i>η</i>|, ranged from 2.1 to 10.2<span class="thinspace"></span>h for principal or long nocturnal waves (5.2–10.8<span class="thinspace"></span>h observed periods), and from 1.5 to 5.4<span class="thinspace"></span>h for the short waves (1.5–4.4<span class="thinspace"></span>h observed periods) during the years of 2010 and 2011, respectively. The phase (i.e., Φ) 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<span class="thinspace"></span>±<span class="thinspace"></span>20 and −42.8<span class="thinspace"></span>±<span class="thinspace"></span>35<span class="thinspace"></span>km for long- and short-period waves for the year 2010. Similarly, for 2011 the mean vertical wavelengths are found to be approximately −77.6<span class="thinspace"></span>±<span class="thinspace"></span>30 and −59.2<span class="thinspace"></span>±<span class="thinspace"></span>30<span class="thinspace"></span>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.</p>