The Space Physics & Aeronomy research group studies the Earth’s geospace environment, which extends from the surface of the sun to Earth’s stratosphere. Major topics investigated by the group are associated with the response of the magnetosphere and ionosphere to solar disturbances that reach the Earth after propagating through interplanetary space. Researchers in the group carry out their studies using theory and simulation, sounding rockets, analysis of satellite-based observations, and ground-based observations of magnetic fluctuations, low-frequency sound waves, light from auroral emissions, and radio signals reflected from atmospheric irregularities. The group is affiliated with the UAF Physics and Electrical Engineering departments, Poker Flat Research Range, the Poker Flat Incoherent Scatter Radar, SuperDARN, and Chaparral Physics.
The group's main research areas are:
- Auroral studies
- Ionospheric physics
- Magnetospheric physics
- Space weather
Specific research projects include the following:
SuperDARN is an international HF radar network designed to measure global-scale magnetospheric convection by observing plasma motion in the Earth’s upper atmosphere. Plasma convection is controlled by a series of interactions between the solar wind, the Earth’s magnetosphere, and the high-latitude (Arctic and Antarctic) ionosphere. By measuring the global-scale plasma motions and studying their temporal evolution, we obtain a better understanding of the processes that couple the solar wind’s energy and momentum to the upper atmosphere, and thereby obtain a better understanding of space weather processes at polar latitudes. SuperDARN is the only approach that will enable us to make direct measurements of these motions on a global scale for the foreseeable future.
Magnetic turbulence exists in many regions of space plasmas throughout the heliosphere and beyond, including the solar corona, solar wind, and the magnetosphere and ionosphere of the Earth. It potentially can play a major role in many fundamental problems of space physics, including heating of the solar corona, acceleration of the solar wind and charge particles, and magnetic reconnection. We study both the basic properties of magnetic turbulence and its effects on these fundamental problems through large-scale simulations and theoretical analysis. An output from one of our simulations is shown above.
The thermospherics dynamics group is interested in how the aurora perturbs temperatures and winds in the very upper layers of Earth's atmosphere — specifically at altitudes above 100 km or so. We have learned that the aurora and its associated electrodynamic processes can project dominant sources of heat and momentum into the neutral atmosphere at these heights in the auroral zone. The figure (right) shows how the neutral wind field at 250 km altitude (white arrows) reversed from blowing eastward at latitudes equatorward of the aurora to blow westward in latitudes near where the aurora (green) was occurring. Colored "streamers" indicate the trajectories of selected air parcels during the preceding hours of time. Red-and-yellow arrows show the direction of ion motion, as measured by the Poker Flat Incoherent Scatter Radar.
The overall objective of this work is to characterize the major disturbances that auroral processes drive in the upper atmosphere's "weather," with a particular emphasis on how this weather behaves at synoptic scales and smaller.
Ionospheric Plasma Irregularities:
Studies of plasma structures naturally occurring in the auroral ionosphere have traditionally attracted a lot of interest in such areas as communications, navigation, auroral and plasma physics. Modulations in the free electron concentration are caused by various plasma instability processes driven by the large-scale plasma density gradients, electric fields and neutral atmospheric winds. These modulations or waves are routinely detected by over-the-horizon radars such as SuperDARN, which provides an excellent opportunity for studying ionospheric plasma waves. Radars detect backscatter from magnetic-field-aligned irregularities or waves that also act as tracers of the large-scale plasma flows in the ionosphere and magnetosphere. Studies of auroral irregularities involve data analysis from a variety of sources, both ground- and satellite-based. Satellite communication and positioning systems such as GPS are adversely affected by scintillation — random fluctuations in radio signal amplitude and phase caused by the ionospheric irregularities. A detailed knowledge of the irregularity production mechanisms is required in order to predict scintillation occurrence.
When the Comprehensive Nuclear-Test-Ban Treaty opened for signature in 1996, infrasound (acoustic waves with frequency < 20 Hz) was selected as a means of detecting clandestine atmospheric nuclear tests. Auroral infrasound research pioneered at the Geophysical Institute in the 1960s and conducted through the 1980s was given a second life as groups around the world began to resurrect a then-dormant field. Nowadays infrasound research is again a vibrant field with efforts spanning a number of disciplines. Infrasound researchers within the UAF Space Physics Group are organized as the Wilson Alaska Technical Center. They focus on treaty-specific and defense-related applications as well as on acoustic signal processing, volcanic eruptions and auroral infrasound. Apart from basic and applied research, the group manages a number of infrasound arrays in support of the treaty, from the UAF campus to the south Pacific to Antarctica.
One of the group’s stations is located near McMurdo Station on the Antarctic's Ross Ice Shelf. In the photograph above the annual service crew from UAF/GI is preparing one of the sensors for another Antarctic season. Each year 1 to 2 meters of accumulated snow covers the sensors and must be removed. In the background, Mount Erebus (a source of constant infrasonic energy) looms and the remote power station “BOB” stands at the left. The array runs for 11 months without direct human intervention.
Chaparral Physics, a division within the Geophysical Institute, makes commercially available infrasound sensors and is also staffed by members of the group.
The Space Physics Group's main observatory at Poker Flat Research Range hosts a wide variety of instruments, including optical equipment at the Davis Science Center, LIDARs at the LIDAR Research Laboratory, an imaging riometer, and the Poker Flat face of the Advanced Modular Incoherent Scatter Radar. PFRR also supports rocket launches and operates remote observatories in Fort Yukon and Barter Island. Many instruments, including the Super Dual Auroral Radar Network, magnetometers, interferometers, cameras, spectrometers and photometers are deployed at remote observatories across Alaska to provide a complete picture of continental-scale phenomena.
For more information on research projects, data access, facilities, the aurora forecast, and the people involved in the group see the links under Explore above. Please also visit the UAF Physics Department's Website.