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 group's main research areas are:

  • Auroral studies
  • Ionospheric physics
  • Magnetospheric physics
  • Space weather
  • Infrasound

Specific research projects include the following:

SuperDARN:
SuperDarn radar at McMurdo Station Antarctica photo by Bill BristowSuperDARN 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.

 

Numerical Simulation:
Numerical Simulation Chung-Sang NgMagnetic 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.

 

Ground-based Optics:
Ground Based Optics - figure courtesy Mark CondeThe 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.

 

Infrasound:
Preparing Sensor on Ross Ice Shelf near McMurdo StationWhen 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.

Data

  • Geospace Environment Data (GEDDS)
  • Magnetometers
  • Thermospheric Wind Imagers
  • Toolik Lake All Sky Imager
  • Eagle All Sky Imager

Space Physics & Aeronomy links

Emeritus Pages

Space Physics and Aeronomy emeritus faculty continue to produce and publish research today - some additional information about our emeritus faculty can be found on their personal web pages, listed below:

Joe Kan

Joe Kan

The book entitled below is under preparation by Joseph Kan for publication by John Wiley & Sons, Inc.

Geomagnetic Storms and Auroral Substorms: 

Driven by Tail Current Loops Powered by the Solar Wind

 

A summary by Joseph Kan

 

This book introduces a unified model of the geomagnetic storm and auroral substorm, focusing on recent developments of unresolved issues in these subjects, as summarized below:

Chapter 1 Introduces the background knowledge of the Solar Wind, which is the energy source for the geomagnetic storm and auroral substorm

Chapter 2 describes the transport of solar wind kinetic energy into the closed magnetosphere by the viscous interactions, as well as into the open magnetosphere by the tail current loops developed jointly by the Dayside-Tail Reconnection System. The tail current loops connect the solar wind dynamo directly to the plasma sheet motor.

This chapter is based on the paper presented at the Chapman Conference on Magnetospheric Dynamics, published in EOS by J. R. Kan and J. L. Burch, “Exploring New Knowledge on Magnetospheric Interactions”, 97, 10, 15 May (2016).

Chapter 3 describes the breakdown of entropy conservation in the collision-free plasma sheet due to dissipations in the M-I coupling system caused byparticle precipitations to the ionosphere. The breakdown of the entropy conservation facilitates the penetration of the global earthward convection into the inner magnetosphere to buildup the ring current during the storm main phase.

This chapter is based primarily on Wolf et al. (2009), Entropy and plasma sheet transport, J. Geophys. Res., 114, A00D05, doi:10.1029/2009JA0-14044, and on Newell et al. (2009), Dissipations in the M-I coupling, J. Geophys. Res.,114, A09207, doi:10.1029/2009JA014326.

Chapter 4 describes the THEMIS observations of a pseudo-breakup and a full-scale substorm obtained on March 1, 2008. The Alfvén wavefront of the CECL propagates along field lines toward the near-Earth plasma sheet. Brightening of the substorm onset arc leads the substorm dipolarization onset by ~80 sec when the Alfvén wavefront incident on the near-Earth plasma sheet to disrupt the cross-tail current and trigger the substorm dipolarization onset. The expanding auroral bulge is the signature of the substorm expansion phase obtained by Akosfu (1964).

This chapter is based primarily on the THEMIS observations obtained by Kan et al. (2011). Brightening of onset arc precedes the substorm dipolarization onset by ~80 sec: THEMIS observations of two events on 1 March, 2008, Ann Geophys., 29, 1-15, doi: 10.5194/angeo.

Chapter 5 describes the latest comprehensive estimates on the energetics of geomagnetic storms and auroral substorms. The energy dissipated in the M-I coupling system is shown to be less than 1% of the total available solar wind kinetic energy. The energy input to the magnetosphere governed by the day-tail reconnection system plus < ~20% contributions from viscous interactions between the solar wind and the low-latitude-boundary-layer.

This chapter is based primarily on Østgaard and Tanskanen (2003), Energetics of isolated and stormtime substorms, in Disturbances in Geospace: The Storm-Substom Relationship, AGU Geophysical Monograph 142 (2003).

 

On the Origin of Inspired Creativity

Human beings are created in God's image, as spiritual being, capable of interacting  with God. Human creativity can be inspired by the power of the Holy Spirit, which will be called inspired creativity.

Inspired creativity need not be logical, often unpredictable and seems always mysterious. My favorite example of inspired creavitity is Newton’s (1642-1727) theory of gravity. It governs the motions of heavenly bodies in the universe. But the origin of Newton’s gravity is still a mystery today.

I thank God for watching over me, leading my life day-by-day, and guiding my research in Space Physics step-by-step:

• For bringing my wife Rosalind and I together since we met in our college days almost 60 years ago.

• For blessing our family with three children of good characters.

• I am humbled to have experienced the power of “inspiration” in  my retirement years since 2003.

The lessons I learned in life are to be humble, patient and honest at all times.

Remember, one can lie his way to the White House, but no one can lie his way into Heaven.

 

 

Joseph R. Kan

July, 2017

Fairbanks, Alaska, USA

 

 

Retirement Lecture



Selected Publications

Selected Publications

 

 

Kan, J. R., Ion-wave instabilities and anomalous resistivity, Phys. Rev. Lett., 25, 348, 1970.

Kan, J. R., Equilibrium configurations of Vlasov plasmas carrying a current component along external magnetic field, J. Plasma Phys., 7, 445, 1972.

Kan, J. R., and H. M. Lai, A highly force-free relativistic electron beam equilibrium, Phys. Fluids, 15, 2041, 1972.

Kan, J. R., On the structure of the tail current sheet, J. Geophys. Res., 78, 3773, 1973.

Kan, J. R., Nonlinear tearing structures in equilibrium current sheet, Planet. Space Sci., 27, 351, 1979.

Kan, J. R., and L. C. Lee, Energy coupling function and solar wind-magnetosphere dynamo, Geophys. Res. Lett., 6, 577, 1979.

Kan, J. R., and L. C. Lee, On the mechanism producing the backscattered and trapped electrons along auroral field lines, Planet. Space Sci., 28, 1073, 1980.

Lee, L. C., and J. R. Kan, Nonlinear ion-acoustic waves and solitons in a magnetized plasma, Phys. Fluids, 24, 430, 1981.

Vasyliunas, V. M., J. R. Kan, G. L. Siscoe, and S.-I. Akasofu, Scaling relations governing magnetospheric energy transfer, Planet. Space Sci., 30, 359, 1982.

Kan, J. R., Towards a unified theory of discrete auroras, Space Sci. Rev., 31,71, 1982.

Kan, J. R., and D. W. Swift, Structure of the quasi-parallel bow shock: results of numerical simulations, J. Geophys. Res.,88, 6919, 1983.

Kan, J. R., and Y. Kamide, Electrodynamics of the westward traveling surge, J. Geophys. Res., 90,7615, 1985.

Cao, F., and J. R. Kan, Finite-Larmor-radius effect on field-aligned currents in hydromagnetic waves, J. Geophys. Res.,92, 339, 1987.

Zhu, L., and J. R. Kan, Time evolution of the westward traveling surge on an ionospheric time scale, Planet Space Sci.,35, 145, 1987.

Kan, J. R., A theory of patchy and intermittent reconnections for magnetospheric flux transfer events, J. Geophys. Res., 93, 5613, 1988.

Mandt, M. E., and J. R. Kan, Ion equation of state in quasi-parallel collisionless shocks: A simulation result, Geophys. Res. Lett., 15, 1157, 1988.

Cao, F., and J. R. Kan, Reflection of Alfvén waves at an open magnetopause, J. Geophys. Res., 95, 4257,   1990.

Kan, J. R., and W. Baumjohann, Isotropized magnetic-moment equation of state for the central plasma sheet, Geophys. Res. Lett., 17, 271, 1990.

Lyu, L. H., and J. R. Kan, Ion leakage, ion reflection, ion heating and shock-front reformation in a simulated supercritical quasi-parallel collisionless shock, Geophys. Res. Lett., 17, 1041, 1990.

Kan, J. R., Tail-like reconfiguration of the plasma sheet during the substorm growth phase, Geophys. Res. Lett., 17, 2309, 1990.

Miura, Akira, and J. R. Kan, Line-tying effects on the Kelvin-Helmholtz instability, Geophys. Res. Lett., 19, 1611, 1992.

Lyu, L. H., and J. R. Kan, Ion dynamics in high-Mach-number quasi-parallel shocks, J. Geophys. Res., 98, 18,985, 1993.

Kan, J. R. and W. Sun, Substorm expansion phase caused by an intense localized convection imposed on the ionosphere, J. Geophys. Res, 101, 27,271, 1996.

Kan, J. R. (2007), On the formation of near-Earth X-line at substorm expansion onset, J. Geophys. Res., 112, A01207, doi:10.1029/2006JA012011.

Kan, J. R., X. Xing, R. A. Wolf (2007), Intensity of geomagnetic storms depends on the X-line location in the plasma sheet, J. Geophys. Res., 112, A04216, doi:10,1029/2006JA011945.

Kan, J. R., H. Li, C. Wang, B. B. Tang, and Y. Q. Hu (2010), Saturation of polar cap potential: Nonlinearity in quasi-steady SW-M-I coupling, J. Geophys. Res., 115, A08226, 9 PP., doi:10.1029/2009JA014389.

Kan, J. R., H. Li, C. Wang, H. U. Frey, M. Kubyshkina, A. Runov, C. J. Xiao, L. H. Lyu, and W. Sun (2011), Brightening of onset arc precedes the dipolarization onset: THE MIS observations of two  events on 1 March, 2008, Ann Geophys., 29, 1-15, doi: 10.5194/angeo.

Kan, J. R. and A. M. Du (2013), Storm-substorm both driven by solar wind-magnetopause dynamo powered up or down by dayside or tail reconnection, in preparation

Inspired Creativity

 

Inspired Creativity Motivates Individuals to Achieve

Great Personal Goals

 

Joe Kan

Professor and Dean Emeritus

Geophysical Institute, University of Alaska Fairbanks

 

Extended Abstract:

There are two levels of creativity: Inspired creativity and worldly creativity. In research as well as in any serious work we do in life, creativity depends on our intent and motivation. People tap worldly creativity when they are motivated to publish as many papers as possible following existing ideas. People channel inspired creativity when they write few papers introducing new idea breakthroughs.

Inspired creactivity can be attained by interaction with nature, humanity, faith, and one's inner self under unconditional freedom. Inspired creativity often occurs unexpectedly and unpredictably, need not be logical, sometimes controversial, but outcomes are invariably beyond expectation.

Humans are spiritual beings differt from other creatures on Earth. Faith is the deep personal belief gained through experience; faith does not need not be linked to any religion. Believing in oneself is the first step toward developing faith, gaining confidence to dream big and to achieve great personal goals. To reach full human creative potential, one needs a balanced development of human intelligence including: Intellectual intelligence (IQ), emotional intelligence (EQ) and spiritual intelligence (SQ). Education develops IQ. Teamwork improves EQ. Faith strengthens SQ.

In my research career at UAF, I spent 31 years pursuing research of worldly creativity under the constraits of the university system. After I retired from UAF in 2003, the freedom of retirement life revived my long-lost dreams. I am convinced that freedom is essential to inspired creativity.

Inspired creativity has guided my post-retirement research. After 10 years of unconditional research freedom, I finally reached a goal in 2013 of developing a new model of geomagnetic storm and auroral substorm that both are griven by the solar wind-magnetopause dynamo. This new model represents a paradigm change to be tested and pondered by space scientists for many years to come. I never would have achieved the breakthrough had I not the serenity and the faith to trust the inspired creativity with all my heart.

A story of storm-substorm for general public

 

 

A story of geomagnetic storm and auroral substorm

for the public

 

 

J. R. Kan 

Geophysical Institute, University of Alaska Fairbanks

  

Extended Abstract:

Geomagnetic storm is characterized by the magnetic disturbance generated by currents in the inner magnetosphere. This current is called the storm-time ring current. Magnetic fields generated by the ring current measured by ground-based magnetometers at mid-latitudes is the storm Dst index. Storm-time ring current is driven by the global earthward convection in the plasma sheet powered by solar wind-magnetopause (SW-MP) dynamo during prolong southward IMF (interplanetary magnetic field), lasting for ~10 hours or longer. The time scale for the storm main phase is ~5 hours. The recovery phase of storm can last for several days.

On the other hand, auroral substorm is characterized by brightening of onset arc in the ionosphere and dipolarization onset in the near-Earth plasma sheet. The auroral electrojet intensified into Cowling electrojet by the induced southward E-field due to blockage of northward Hall current from closure in the plasma sheet. The Cowling electrojet current for an intense substorm is estimated to be ~ 1 MA (Mega Amp), distributed over ~5˚ latitudinal width between ~60˚ to ~70˚ latitudes in the mid-night sector. The dipolarization onset region is centered between ~9 to 11 RE in the near-Earth plasma sheet. THEMIS observations show that the brightening of the onset arc precedes the dipolarization onset by ~80 sec, which is estimated to be the Alfvén travel time from the ionosphere to the dipolarization onset region.

Both geomagnetic storm and auroral substorm are driven by the global earthward convection of ~20 to ~40 km/s powered by solar wind-magnetopause (SW-MP) dynamo. The dynamo output powers up or down by dayside or tail reconnection. The global earthward convection powered by the SW-MP dynamo during prolonged period of southward IMF leads to the storm-time ring current. At the same time, the global earthward convection intensifies the auroral electrojet to the Cowling electrojet. Divergence and convergence on the dusk and dawn sides of the Cowling electrojet produce upward and downward field-aligned currents. Closure of field-aligned currents in the Alfvén wavefront completes the Cowling electrojet current loop (CECL). Alfvén wavefront, leading the propagation of the CECL, incident on the near-Earth plasma sheet triggers the dipolariza-tion onset to mark the onset of substorm expansion phase. Identifying the SW-MP dynamo as the driver for both storm and substorm, and the tail reconnection as reducing the open field lines and thereby reducing the dynamo power out is the climax of the story.

 

Magnetometer

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About the Array & Aurora

Learn more about Earth's magnetic field, magnetometers, and studying the aurora that light up the sky.

About the Array & Aurora

Magnetometer Array

Earth's climate and space environment are significantly determined by the impact of plasma, particle, and radiative outputs from the Sun. With remote sensors at locations across Alaska, the Geophysical Institute Magnetometer Array (GIMA) senses the interactions between this "solar wind" and Earth's magnetosphere. They also sense the currents associated with auroras to determine their strength and location – and help scientists at the Geophysical Institute's Poker Flat Research Range predict which auroras are worth launching scientific sounding rockets into. At several magnetometer locations, all-sky cameras also provide optical data.

Magnetosphere

In this NASA image, Earth is surrounded by green lines that represent the magnetosphere. The bulb shape on the left is the bow shock from the solar wind, which is streaming left to right.

The Earth's magnetosphere is a fluctuating magnetic envelope surrounding the planet. Its uneven and stretched shape is created by the interaction of the solar wind, a stream of charged particles emitted by the Sun, with Earth's own magnetic field. As part of a complex system that includes the ionosphere and upper atmosphere, the magnetosphere helps protect Earth from the solar storms that create aurora, also known as northern lights.

Space Weather and Earth's Aurora

In the image below, the glowing bundle of lines on the right represents billions of tons of plasma released from the Sun during a solar storm, traveling as fast as 8 million km an hour, headed for Earth. The video reveals what happens next.

For more information on Earth's magnetosphere, space weather, and auroras, explore the NASA website.

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Citing Magnetometer Data

Cite data in publications such as journal papers, articles, presentations, posters, and websites. Please send copies of, or links to, published works citing data, imagery, or tools accessed through RCS to uaf-rcs@alaska.edu with "New Publication" on subject line.

Format Example
Magnetometer data, Geophysical Institute, UAF [year of data acquisition]. Retrieved from Research Computing Systems [day month year of data access]. Magnetometer data, Geophysical Institute, UAF 2016. Retrieved from Research Computing Systems 5 October 2016.

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