CEDAR Postdoc: Determination of Charged Dust Characteristics in the Earth's Mesosphere Utilizing Radio Wave Modification

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This project is to perform heating experiments on polar mesosphere summer echoes (PMSEs) as a means to characterize the charged dust layer involved in this phenomenon. As the name states, PMSEs are anomalous radar echoes observed in the summer polar mesosphere; the echoes are associated with charged dust or aerosol particles and are of considerable current interest because of a possible connection with global change. The exact generation mechanism for the echoes is a current topic of debate, and information on the charged dust particle density and radius as well as on the charging mechanism is needed. These characteristics have been difficult to explore thus far but recent efforts to actively modify PMSE with radio waves to obtain diagnostic information appears promising: important charged dust characteristic information, like dust density and dust radius can be obtained once a firm theoretical interpretation of the temporal behavior of the irregularities during heating is understood. This project's goal is to develop this capability by performing two tasks: (1) develop and utilize new computational and analytical models of PMSE modification by radio wave heating; and (2) participate in the European Incoherent Scatter (EISCAT) modification experiments scheduled for the summers of 2007 and 2008. The project may request follow-on heating experiments at the High Frequency Active Auroral Research Program (HAARP) or the High Power Auroral Stimulation (HIPAS) if the EISCAT results are compromised due to high operating frequencies. The models to be developed will incorporate diffusion effects, more accurate charging models, and plasma temperature evolution, features not found in earlier models, and will be used to simulate the temporal behavior of PMSEs during heating episodes with varying dust parameters. The observational data will be compared with the model results to refine the model and to develop new diagnostic capabilities. The goal is to provide a firm theoretical foundation for interpreting the temporal electron density behavior during the heating cycle and ultimately developing diagnostic predictions for experimental measurements. The broader impacts include the support of a new postdoctoral scholar in the Coupling, Energetics and Dynamics of Atmospheric Regions (CEDAR) program while the experiment will ultimately provide new diagnostic instruments for future PMSE modification and PMSE observation. The research results are likely to be beneficial for investigations of polar mesospheric and noctilucent clouds.