Gravity Wave and Seismic Signatures in the Airglow

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The night airglow comes from a layer in the upper atmosphere at a height of 80 - 100 km.  In this layer, chemical reactions involving the recombination of oxygen atoms lead to the emission of light that can be detected by instruments on the ground. Various dynamical processes in the atmosphere can lead to fluctuations in the brightness of the night airglow emissions.  We measure these fluctuations with ground-based instruments and use them to infer the nature of the processes that cause them.   Two processes of these dynamical processes will be studied in the present work.  Firstly, we will study the effects of gravity waves.  These waves are a major mechanism for transporting energy and momentum between atmospheric regions.  Understanding their nature and frequency of occurrance is important in the development of atmospheric models including numerical weather prediction models.  Secondly, we will examine the possibility that infrasonic waves generated by seismic activity can be detected in the airglow patterns we observe.  Of great interest is the possibility that airglow variations can be seen before the occurrance of the earthquake.  Such behaviour has been reported in the past but has not been convincingly verified. The nature of the variations that we study can vary greatly according to local factors such winds blowing over surface features such as mountain ranges as well as active weather patterns such as thunderstorms. As a result, we locate our instruments at widely separated locations around the world to observe in a variety of locales. Currently we have instruments both in Antarctica and within the Arctic circle in Norway.  In 2006, we will install a third instrument at a mountain site in India in a region of frequent seismic activity.