Space Physics & Aeronomy
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 main areas of research carried out in the group are:
- Auroral Studies
- Ionospheric Physics
- Magnetospheric Physics
- Space Weather
The following describe research focus areas within the group:
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, the magnetosphere and ionosphere of the Earth. It potentially can play a major role in many fundamental problems of space physics, including the heating of the solar corona, the acceleration of the solar wind and charge particles, and magnetic reconnection. In our research, we study both the basic properties of magnetic turbulence and its effects on these fundamental problems by 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 provide the dominant sources of heat and momentum into the neutral atmosphere at these heights in the auroral zone. The accompanying figure 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 4 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, neutral atmospheric winds. These modulations or waves are routinely detected by the 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 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 14 years ago, 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 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 University of Alaska Fairbanks Space Physics Group are organized as the Wilson Infrasound Observatories. Together they focus on acoustic signal processing, volcanic eruptions and auroral infrasound, as well as Treaty-specific and defense-related applications. 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. Chaparral Physics makes commercially available infrasound sensors and is also staffed by members of the group.
One of the group’s stations is located nearby McMurdo Station, on the Ross Ice Shelf. In the photograph the annual service crew from UAF/GI is preparing one of the sensors for another Antarctic season. Each year the sensors must be brought back to the surface from under 1-2 m of snow accumulation. In the background, Mt. Erebus looms (a source of constant infrasonic energy) and the remote power station “BOB” stands at the left. The site runs for 11 months without direct human intervention.
The group's main observatory at Poker Flat Research Range hosts a wide variety of instruments at the Davis Science Center, the LIDAR Research Laboratory, an imaging riometer, and the Advanced Modular Incoherent Scatter Radar Poker Face. PFRR also supports rocket launches and operates remote observatories in Ft Yukon and Barter Island. A large instrument suite and remote observatories that include the Super Dual Auroral Radar Network, magnetometers, and cameras, spectrometers, and photometers is deployed across the State of Alaska to provide a complete picture of continental scale phenomena.
For more information on research projects, data access, facilities, the people involved in the group, and the aurora forcast see the links on the left side.
Please also visit the UAF Physics Department's Website