This project will use ground-based optical remote sensing to obtain two-dimensional spatially resolved maps of horizontal neutral winds in Earth's night-time auroral E-region. The maps will be derived from Doppler shifts of the atomic oxygen auroral emission line at 557.7 nm. While several other ground and spaced-based techniques exist for measuring E-region winds, they are all difficult, and they do not duplicate the coverage and resolution that is anticipated in this project. The wind maps will cover a geographic region approximately 700 km in diameter, centered on Poker Flat, Alaska. This fully includes the E-region field of view of the National Science Foundation's new AMISR radar. Vertical coverage will span approximately 110 km to 140 km. With the mapping region resolved into 60 to 100 sub-fields, integration times for a single map will vary between one and five minutes, depending on signal levels, for typical uncertainties of a few meters per second. Doppler temperature maps will also be obtained with the same spatial and temporal resolution, with typical uncertainties of less than 10K. A number of scientific studies will be conducted. All depend on combining E-region wind maps with data from other instruments monitoring the same field of view, including the Poker Flat AMISR radar. Topics to be studied include the role of ion-neutral momentum coupling in E-region neutral dynamics at small (< 100 km) spatial scales, the role of horizontal transport in the evolution of storm-induced thermospheric composition perturbations, horizontal velocity perturbations due to gravity waves, the role of neutral winds in determining the partitioning of magnetospheric energy deposition between heating and bulk motion of the neutral atmosphere, and the relationship between horizontal divergence and vertical wind in the E- and F-regions. The project includes work to significantly upgrade the instrument's self-calibration capability with a 5-color helium neon laser, a new frequency stabilized laser, and an automated calibration source viewing system. In addition to CEDAR-specific science topics, a number of broader impacts are anticipated. A graduate student will be supported to participate in this research, whose work will be integral to all aspects of the project. With a major emphasis on optical calibration, this project has obvious relevance to the University of Alaska's 400-level undergraduate optics class - which is required for all physics majors. Aspects of both the optical design and the resulting calibration data will be incorporated into the students' laboratory and homework projects. The E-region wind mapping would add to the infrastructure of atmospheric science at a general level by demonstrating a new capability that other experimenters could exploit according to their research needs. More specifically, there is a high degree of synergy with two major existing NSF funded projects at Poker Flat: The AMISR radar and a tristatic array of three narrow-field Fabry-Perot spectrometers.
