CEDAR: South American Observations of Thermospheric Neutral Winds and Temperatures during Daytime

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The investigators will operate a dayglow-capable, remote Internet access, triple-etalon Fabry-Perot interferometer at the Cerro Tololo Interamerican Observatory (CTIO) near La Serena, Chile (-17O magnetic latitude), to supply critical ground-based observational support for the Communication/Navigation Outage Forecasting System (C/NOFS satellite). These observations support C/NOFS by measuring neutral wind fields, known to be central to the over-arching C/NOFS goal of scintillation forecasting and modeling. Currently, empirical models are used to provide non-local neutral winds, but the need to replace model winds with actual winds is vital to the prediction of the Equatorial Spread-F (ESF) phenomenon. The primary observational objective is to provide the all-sky (at least eight vector) thermospheric wind field across the sunset terminator, with 15-minute resolution in the dayglow, and better than five-minute resolution in the nightglow. Correlating ESF events with these wind fields will demonstrate whether meridional winds affect the growth of ESF. Current state of the art limits this correlation to winds taken 1 hour after sunset, but the instrument proposed here will allow a correlation of ESF with winds prior to sunset. A secondary objective is to measure zonal winds during passage of the brightness wave driven by the midnight temperature maximum pressure bulge in conjunction with another dayglow Fabry-Perot located at the magnetic equator. The two instruments will also observe the location and migration of the southern Appleton Anomaly during the day. Similarly patrol mode operation of the robotic, remotely operable systems will be used to detect and categorize the nature of soliton disturbances propagating from the pole toward the equator. These disturbances are known as traveling atmospheric disturbances, or TADs, and heretofore have only been seen using incoherent scatter radars. This study will help in forecasting communication disturbances from ionospheric irregularities at low latitudes. The project also features international cooperation between United States scientists and Chilean scientists and support staff at CTIO. Establishment of the Fabry-Perot at CTIO is an important extension of the infrastructure available to the Aeronomy community, which will now have access to a spectacular clear-sky site at 2400 meters in the Andes Mountains. In addition, this facility will be only one of two extant sites capable of daytime Doppler airglow measurement.