Fabry-Perot Studies of Equatorial Thermospheric Dynamics and Composition, Part II

Clemson University, Clemson SC

Investigators

Abstract

The investigators will make measurements of thermospheric winds and temperatures with an improved imaging Fabry-Perot Interferometer at Arequipa, Peru. Aeronomic research in recent years has determined the equatorial thermosphere-ionosphere system to be a highly-structured environment in which the ion-neutral coupling plays a crucial role in the physical processes that occur. Knowledge of the thermospheric neutral wind and temperature fields is essential to the improved understanding of how these processes function. The Arequipa Fabry-Perot interferometer (FPI) has been operating for two decades. Recently, this instrument was upgraded to get a five-fold increase in wind and temperature precision as compared with previous observations. Included in this research effort are twilight spectral profile measurements of the 732 nm oxygen ion emission rate to determine the thermospheric atomic oxygen density at low-latitudes. A new operating mode will allow the determination of the divergence and vorticity of the neutral wind field. The divergence measurement would provide an estimate of the mean vertical wind with a precision believed to be ten times better than that provided by direct measurements. These measurements are important for achieving an improved understanding of the Midnight Temperature Maximum (MTM), which is a significant feature of the nighttime equatorial thermosphere created by the convergence and downwelling of air near midnight at low latitudes. Two additional science objectives would be to achieve thermospheric gravity wave observations within a common volume between Arequipa and Huancayo with a bistatic FPI observatory. These results would allow for the examination of the frequency of thermospheric gravity waves by searching for simultaneous fluctuations in zonal and meridional wind components as well as thermospheric temperature. The science objectives of the Arequipa and Huancayo FPI instruments are significantly enhanced by the coordinated and synergistic activity of both instruments working together and with the Jicamarca Radio Observatory. Clemson Physics undergraduate and graduate students as well as Peruvian students would be exposed to technical problems of a practical nature that will broaden their experience and introduce them to the practice of research at the cutting edge of optical technology. Valuable experience in the operations of unattended FPIs at remote sites would be gained that would assist future expansion of the global FPI observatory network, a highly desirable goal for space weather forecasting applications.