Informatics Publishing Limited

A. Taori ¹

Affiliations
1 National Atmospheric Research Laboratory, Pakala Mandal, Gadanki 517 112, IN

Abstract

Simultaneous mesospheric OH and O₂ temperature estimates are used in the present study to characterize the wave perturbations over Gadanki (13.5°N, 79.2°E), a low-latitude station in India. The 65° zenith angle scanning measurements show large variations from one direction to another. The zonal and vertical wavelengths of the observed wave perturbation are found to vary from 740 to 4500 km and 26 to 38 km. The temperature gradient between OH and O₂ layers has been calculated, which shows significant short-period variability. The temperature gradient measurements show large changes from one direction to another. The occurrence of such large temperature gradients within 400 km suggests thermal state of the upper mesosphere to be highly dynamic, which can severely impact the upward propagation of shortperiod gravity waves.

Keywords

Airglow Measurements, Mesosphere, Temperature, Thermal Gradient, Wave Perturbations.

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R. N. Ghodpage ¹, A. Taori ², P. T. Patil ¹, Devendraa Siingh ³, S. Gurubaran ⁴, A. K. Sharma ⁵

Affiliations
1 Medium Frequency Radar, Indian Institute of Geomagnetism, Shivaji University Campus, Kolhapur 416 004, IN
2 Atmospheric Research Laboratory, Gadanki 517 112, IN
3 Indian Institute of Tropical Meteorology, Pune 411 008, IN
4 Indian Institute of Geomagnetism, Navi Mumbai 410 218, IN
5 Department of Physics, Shivaji University, Kolhapur 416 004, IN

Abstract

The photometric measurements of mesospheric OH and O(¹S) emission, carried out from Kolhapur (16.8°N, 74.2°E), Maharashtra during January-April 2005 are used to study the wave characteristics. The nocturnal variability reveals the dominant long-period wave signatures with significant amplitudes of embedded short-period waves. We carry out a sensitivity study on the vertical wavelength (VW) derived with the help of Krassovsky parameters (η = |η|e^iΦ) of the OH data, which reveals VW to vary from 38.9 to 110.2 km. This was compared with the VW estimates using the phase difference of the simultaneously observed waves in both OH and O(¹S) emission intensities. Results reveal that in the absence of attitudinally resolved measurements, the VW estimated using Krassovsky method can be used.

Keywords

Airglow, Atmospheric Gravity Waves, Lower Thermosphere, Mesosphere, Vertical Wavelength.

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