This is a 3-year instrumentation project to refurbish and upgrade an existing Fabry-Perot interferometer (FPI) at the Arecibo Observatory into a modern capable facility. Resulting from the effort will be a dual line imaging FPI with new hardware and software that will have greater sensitivity, will be automated and remotely operable, and will be able to simultaneously measure E-region and F-region neutral winds. The upgrade will allow thermospheric neutral winds and temperatures to be measured routinely and continuously with high accuracy at the Arecibo Observatory. Ground-based FPIs constitute a crucial source of wind information and the activity would secure and improve the capability of the Arecibo instrument, which is located at a key location with respect to electrodynamic processes. Specifically, the upgrade will allow for a continuation of an ongoing thermospheric climatology that has been collected at Arecibo for more than 30 years. The automated data collection will increase the amount of storm time data, needed to understand how the thermospheric wind field is modified during periods of high magnetic activity.
Community infrastructure building and service is at the heart of the activity. Processed data will be made readily and freely available via the existing aeronomy community Madrigal database and will facilitate a wide range of upper atmosphere dynamics and thermodynamics science investigations. Such studies fit within the larger context of Global Climate Change research. The facility and data will also be used in support of various educational activities.
SSI has been operating four Fabry-Perot Interferometers (FPI) as well as an All-Sky Imager at the facility since 2005. Our most recent additions are an upgrade to the 630.0nm â€˜redlineâ€™ and 557.7nm â€˜greenlineâ€™ interferometers. These two FPIâ€™s form part of SSIâ€™s neutral wind monitoring system which includes an additional two FPIâ€™s at Millstone Hill and our automated analysis engine (Airglow Server) at SSI. The remaining two interferometers at Arecibo probe other atmospheric layers and are capable of monitoring hydrogen and helium to altitudes well into the exosphere. SSIâ€™s research program at AO has two components; the first consisting of two FPIâ€™s configured as "Doppler Imagers" remotely measuring winds and temperatures of the neutral background atmosphere at ionospheric altitudes of ~250Km and ~95Km. The second component is two low resolution FPIâ€™s measuring the dynamics and temperature of the atmosphere above the F-region peak, in some cases out to the plasmasphere. These FPI systems provide valuable data to forecasters and ionospheric scientists and represent a significant leap in the state of the art in interferometers deployed for thermospheric aeronomy. Notably, SSIâ€™s interferometers fulfill important community roadmap goals, in particular a NASA 2009 Heliophysics roadmap goal to "understand the coupling between planetary ionospheres and their upper atmospheres mediated by strong ion-neutral interactions". SSIâ€™s research program also responds to the 2013-2022 NRC Space Science Decadal survey in Solar and Space Physics, Space Weather [Baker, et al., 2013] which recognizes neutral winds, neutral temperatures, composition of the major species and all scales of wave activity as important continuous measurements needed for space weather research and forecasting. Additionally the NRC recommends further ground-based observation and technology development as well as the development of a "Heterogeneous Ionospheric Facility" of which neutral wind measurement would be an important component. The primary data product from the Doppler imagers addresses a current major flaw in existing nowcasting systems, the lack of data available for ingestion into the assimilation algorithms. Figure 1 demonstrates the importance of neutral wind measurements with respect to the research thrusts and important scientific topics covered in the CEDAR Phase 4 report. While DOD and NASA use satellite assets to collect ionospheric data [Crowley and Meier, 2008], our understanding of the ionosphere remains fairly limited [Crowley et al., 2006]. The global ionosphere is so variable it has been difficult to collect sufficient data to characterize its behavior. The Defense Meteorological Satellite Program (DMSP) experience proved that two or three large satellites provide insufficient data to characterize the global ionosphere. SSIâ€™s extant Doppler imagers and their progeny are inexpensive enough to allow for deployment of a sufficient number of instruments to collect the volumes of data needed to advance the collective understanding of the global ionosphere. Arecibo Observatory has been an invaluable test bed for the development of these novel interferometers. SSIâ€™s redline and greenline Doppler imagers at both Arecibo and Millstone Hill are each collecting about 300 nights of data/year. Each nightâ€™s data consists of meridional and zonal wind vectors (interpolated) every 3 minutes. Temperatures in each look direction, intensities and vertical velocities are also calculated automatically and sent to the Madrigal database and SSIâ€™s website www.neutralwinds.com. The addition of imaging detectors and automated observing has increased the amount of data collected by 10-fold and has increased the precision of the measurements by a factor of 10.