Dynamical origins of upper atmospheric variability

点击翻译按钮获取中文摘要

The upper atmosphere near 100 km is a complex region influenced by the atmosphere above and below. From above, solar ultraviolet radiation is absorbed, splitting molecules into atoms, and removing electrons to form ions. The resulting chemistry produces airglow, visible light that may be sensed using optical instrumentation on the ground below, or from space above. Atomic oxygen is a long-lived driver for airglow, and so may be used as a tracer for atmospheric motions, providing a way to study the dynamics at these altitudes, in part using a Canadian space instrument (WINDII) of the applicant's design flown on a NASA satellite from 1991 to 2003. A Spectral Airglow Temperature Imager (SATI) developed in his laboratory and located on the ground at Resolute Bay (74 N) in northern Canada has measured upper atmospheric airglow and temperature since 2001. Large winter to winter variations are found to be controlled by solar variation, as well as by the east-west wind at the equator, a remarkable dynamical influence. Large correlated variations in airglow and temperature during the winter are found to originate with planetary waves, weather waves, coming up from below. It was also discovered that the temperatures in the upper mesosphere at 87 km correlate with those at 22 km, in the lower stratosphere. These discoveries will be exploited in moving towards understanding this variability. It is proposed to extend the Resolute Bay dataset from its beginning in 2001 to cover one solar cycle of eleven years and at the same time to explore the coupling between the upper mesosphere and lower stratosphere through atmospheric models. The satellite data acquired from 1991 to 2003 will be further analyzed and data from other satellites will be employed as well. In addition, the applicant is involved in the design and fabrication of an airglow camera to be flown on a Kazakh spacecraft, to determine if earthquake precursors produce perturbations in the airglow. With the understanding of airglow variability that has been established, it will be possible to detect earthquakes in advance, a very unusual and important form of atmospheric variability if it is found to exist.