Airglow Measurements of Gravity Wave Propagation and Damping over Kolhapur (16.5°N, 74.2°E)

R N Ghodpage,A K Sharma,S Gurubaran,D Nade,A Taori,P T Patil,S Nikte

doi:10.1155/2014/514937

Abstract

Simultaneous mesospheric OH and O (1S) night airglow intensity measurements from Kolhapur (16.8°N, 74.2°E) reveal unambiguous gravity wave signatures with periods varying from 01 hr to 9 hr with upward propagation. The amplitudes growth of these waves is found to vary from 0.4 to 2.2 while propagating from the OH layer (~87 km) to the O (1S) layer (~97 km). We find that vertical wavelength of the observed waves increases with the wave period. The damping factors calculated for the observed waves show large variations and that most of these waves were damped while traveling from the OH emission layer to the O (1S) emission layer. The damping factors for the waves show a positive correlation at vertical wavelengths shorter than 40 km, while a negative correlation at higher vertical wavelengths. We note that the damping factors have stronger positive correlation with meridional wind shears compared to the zonal wind shears.

Highlights

Upward propagation of gravity waves and tides is an important aspect in studying dynamical coupling between different regions in earth’s atmosphere (e.g., [1])
The intensity variability in a given night results from the superposition of various wave components prevailing on that night, which encompasses long-period planetary waves, tidal waves, and highly varying short period gravity wave
Our night airglow measurements from the low latitude Indian station, Kolhapur, (16.8∘N, 74.2∘E) during February and March 2010 lead to the following conclusions

Summary

Introduction

Upward propagation of gravity waves and tides is an important aspect in studying dynamical coupling between different regions in earth’s atmosphere (e.g., [1]). Though the negative density gradient and conservation of energy suggest that the amplitudes of these waves grow exponentially with altitudes, dissipation processes (such as saturation and interaction of these waves with background wind and other waves) limit the amplitude growth of these waves (e.g., [2]) Information on these gravity waves and tides in upper mesosphere is considered important because of their potential association with ionospheric phenomena [3,4,5,6,7,8,9]. Upward propagating gravity waves with vertical wavelengths larger than the airglow layer thickness (typical full width at half maxima, 10 km) can be observed at multiple airglow emissions almost simultaneously Such data can be used to estimate the amplitude growth and the propagation characteristics of gravity waves [13,14,15]. We report new data on damping factors of various dominant waves and their possible association with mesospheric winds

Instrumentation and Data Description

Results and Discussion

Conclusions