The project focuses on electrodynamic phenomena in the nighttime ionosphere over Arecibo Observatory. Of particular interest are newly discovered quasi-periodic E/F-region Medium-Scale Traveling Ionospheric Disturbances which have been identified over both Arecibo and Millstone Hill Observatory. The chain of incoherent scatter radars, including superDARN, will be used to investigate the disturbances, their source(s), and the underlying wave propagation mode(s). This aspect will include extensive modeling and simulation studies of nighttime F region electrodynamics; of particular interest are the possible influences or contributions of horizontal gradients in total electron content. The project will include the maintenance, upgrading, and remote operation of an instrument suite at Arecibo; the instruments are an all-sky camera, a magnetometer/variometer, and four microbarographs. These instruments will be used in conjunction with the Incoherent Scatter Radar and GPS Total Electron Content data to explore the local/mesoscale nighttime F-region instability processes that give rise to the space weather phenomenon known as mid-latitude spread-F. Of particular interest is the question of "local" versus mesoscale initiation of spread-F as well as the origin of F-region "plumes" seen in the camera. These two phenomena, Spread-F and the plumes, are manifestations of plasma instabilities. Closely coupled simulations of generalized Perkins instabilities under initial conditions similar to those observed will be performed to better understand the seeding mechanisms that initiate instabilities, how the instability structures evolve, and the role of horizontal gradients in the production of kilometer-scale instability structures and associated space weather effects. All the instrumentation funded under this project will be available to the community; the camera, magnetometer, and microbarograph data are immediately and freely available via web-access (http://allsky.ee.psu.edu). An educational outreach component explaining airglow imaging science, atmospheric tides, space-weather, and other related topics will be added to this website. The project involves REU (Research Experiences for Undergraduates) students during the summer as well as two graduate students.
Under this grant we investigated a variety of complex space weather topics. These topics include the form and role of the meteoroid mass flux to the Earth’s upper atmosphere and the origins of the ubiquitous (apparently global), quasi-periodic (~1 hr. period) thermospheric waves that were first detected at Arecibo Observatory. These two space weather phenomena were studied using radar and optical techniques as well as numerical modeling. The incoherent scatter radars used in this work are located at Arecibo Observatory (Puerto Rico), Jicamarca Radio Observatory (Peru), Haystack Observatory (MA), the Poker Flat Incoherent Scatter Radar facility (Alaska), and the Resolute Bay (Nunavut, Canada) incoherent scatter radar facility. Major results include the discovery of radar meteors at altitudes well above the usual meteor zone in 80-120 km altitude region of the atmosphere. Other research has included the modeling of the radio science of radar meteors and the development of novel signal processing techniques required for radar holography. This grant has supported student research leading to the award of four PhD degrees and one MS degree. Additionally the grant has supported the activities of two post-doctoral fellows and four Research Experiences for Undergraduates (REU) students along with numerous publications and talks given at professional meetings.
