Progress was made on the following two projects within the semiannual period: (1) simulations of the magnetic storm of April 1988 using the Magnetospheric Specification Model; and (2) improvement of a user-oriented electric-field model

Reiff, Patricia H.

English

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NASA-CR-192138
SEMIANNUAL PROGRESS REPORT -- NASA GRANT NAGW-!655
"Magnetospheric and Auroral Processes"
Time covered in report: 3/1/90-8/31/90
Scientific Results and Plans for Next Year
1. Magnetospheric Convection Modeling
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Progress was made on the following two projects within the semiannual period:
A. Simulations of the magnetic storm of April 1988 using the Magnetospheric Specification
Model;
B. Improvement of a user-oriented electric-field model.
However, neither of these projects had reached fruition by the end of the August 1990. For
the sake of efficiency, therefore, we will describe these efforts in the next semi-annual report.
2. Empirical Studies of Polar Cap Convection
In the past year we have continued our studies of the dependence of the convection pattern on
the IMF. We were asked to review magnetospheric convection for the Hakone substorm meeting,
and work is in progress pulling together all the relevant material for that talk, and the publication to
follow from it. We are including in that talk a review of our latest results - that the functional form
of the dependence of the potential on the IMF does not strongly depend on solar cycle (therefore on
polar cap conductivity). Our student helper also found that that functional form also is independent
of the phase of the substorm as well.
Concerning the convection pattern itself, our paper outlining multiple-cell convection drivers
[Reiff and Burch, 1985] has sparked a good deal of research in possible observable distinctions
between, for example, a "four-cell" convection pattern and a "distorted two-cell" pattern, in which
the sunward flow is just a perturbation on an otherwise normal two-cell convection pattern.
Working with R. A. Heelis of the University of Texas at Dallas, we have obtained a sequence of
orbits in which a strong sunward flow in the central polar cap is observed, both in the Northern
and Southern hemisphere. By using the integrated electric potential, one can show the necessary
flow pattern using either a four-cell model or a distorted two-cell model. There are several possible
configurations for the distortion of the two-cell, but in each case there is at least one area in which
the distorted two-cell model would require a flow component along the spacecraft track which is
opposite to that observed. Thus, although we do not argue that distorted two-cell patterns do nol
occur, we present evidence that at least at times a four-cell pattern is most consistent with the flo_
data. This work is being written up [Reiff and Heelis, 1990; Heelis and Reiff, 1990].
3. Auroral Processes
Our extensive analysis of four magnetic conjunctions of DE- 1 at high altitudes and DE-2 at lo_
altitudes [Reiff et al., 1986; 1988; 1989] has continued apace, with graduate student Gang L
examining the mutual self-consistency of the electric currents derived in at least three ways: i:
integrating the particle distribution; by calculating the curl of the magnetic field; by calculating t!
0
u_
I
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Semiannual Report (3/90-8/90) - NAGW-1655 - Page 2
divergence of the horizontal ionospheric Pedersen current [Smiddy et al., 1980)]; and by
calculating the predicted current from the high altitude density and temperature plus the total
potential drop. In each case the agreement is very encouraging, but some areas of interest remain.
At some times the parallel potential drop is of the sense to accelerate electrons downward, but the
presence of a cold upward-flowing component of the electrons results in a net current which is
actually downward. In general, the Knight formula [Knight, 1973; Lyons, 1980, 1981] appears to
be verified, and an empirical coefficient of about 0.5-2 x 10-9 appears to be the best-fit ratio
between the parallel current (AJm 2) and the parallel potential drop (V). A paper on this subject has
been submitted to the Journal of Geophysical Research [Lu et al., 1990]; in addition, the full
electrodynamic study of these aurorae is the basis for her Ph.D. thesis, which was completed this
half-year.
We have also investigated the effects on spacecraft and on the ground of a major auroral storm
which occurred on March 13-14, 1989. Auroras were observed as far south as Brownsville,
Texas, and power outages as far south as Los Alamos, New Mexico were experienced. Over six
million people depending on the city of Quebec for their electric power were in the dark for 9 hours
when a transient current induced in a tranmission line tripped the breakers and then overloaded the
system. The DE-1 spacecraft observed the largest auroral oval it ever recorded. A study of these
effects was published in EOS [Allen et al., 1989]; and a summary was be published in Sky and
Telescope [Reiff and Allen, 1990].
4. Methods of Statistical Analyses
In response to a request from M. A. Shea, we presented a talk at the 1989 IAGA discussing
techniques of data analysis and their pitfalls. That paper, an update of our earlier grant-supported
work [Reiff, 1983], includes a new discussion of the bootstrap and jacknife techniques, as well as
publishes our latest formula for the dependence of the polar cap potential drop on the IMF. The
paper [Reiff, 1990] was published this half-year.
New Publications Supported by NAGW-1655
Bergmann, R., H+-O + two stream interaction on auroral field lines, Physics of Space Plasma
(1989), SPI Conference Proceedings and Reprint Series, Number 9, T. Chang, G. B. Crew,
and J. R. Jasperse, eds., in press, Scientific Publishers, Cambridge, MA, 1990).
Fejer, B. G., R. W. Spiro, R. A. Wolf and J. C. Foster, Latitudinal variation of perturbation
electric fields during magnetically disturbed periods: 1986 SUNDIAL observations and model
results, Ann. Geophys., 8, 441-454, 1990.
Reiff, P. H. and J. A. Allen, "Devastating Solar Activity in 1989", News Note, Sky and
Telescope, 79, (1990), pp. 584-585.
Reiff, P. H., "The use and misuse of statistics in space physics," Journal of Geomagnetism and
Geoelectricity, 42, (1990), pp. 1145-1174.
Semiannual Report (3/90-8/90) - NAGW-1655 - Page 3
Other Completed Works
Erickson, G. M., R. W. Spiro, and R. A. Wolf, The physics of the Harang discontinuity, J.
Geophys. Res, (submitted), 1990.
Wolf, R. A., R. W. Spiro, and F. J. Rich, Extension of the Rice Convection Model into the high-
latitude ionosphere, J. Arm. Terrest. Phys., (submitted),1990.
Lu, G., P. H. Reiff, J. L. Burch, J. D. Winningham and J. A. Slavin, On the auroral current-
voltage relationship, J. Geophys. Res., (submitted), 1990.
Marshall, J. A., J. L Burch, J. R. Kan, P. H. Reiff, and J. A. Slavin, "Sources of field-aligned
currents in the auroral plasma", Geophys. Res. Lett., (submitted), 1990.
Heelis, R. A. and P. H. Reiff, The ionospheric convection pattern response to changes in IMF
direction, Geophys. Res. Lett. (in preparation), 1990.
Reiff, P. H., and D. Alexander, Independence of the polar cap potential drop on solar cycle,
Geophys. Res. Len. (in preparation), 1990..
Reiff, P. H., and R. A. Heelis, Four cells or two? Are four convection cells really necessary?,
Geophys. Res. Lett. (in preparation), 1990.
Presentations
Reiff, P. H., "The FY 92 NASA Budget", invited testimony to Space Subcommittee, House
Committee on Space, Science, and Technology, March I2 (1990).
Wolf, R. A., "Magnetospheric Structure," two lectures at Rubey Colloquium, UCLA, Los
Angeles, CA, March 1990.
Reiff, P. H., "What is a Space Scientist?", "Science Week" talk, Pine Forest Elementary School,
April 10 (1990).
Reiff, P. H., "Auroral Electric Fields", Space Physics Departmental Colloquium, Rice University,
April 18, (1990).
Wolf, R. A., "Convection Codes, Current State and Prospects," Workshop on the Modeling and
the Physics of the Global Magnetosphere, Goddard Space Flight Center; Greenbelt, Maryland;
May (1990).
Wolf, R. A., "The Magnetospheric Specification Model," Los Alamos National Laboratory; Los
Alamos, New Mexico; June (1990).
Wolf, R. A. and R. W. Spiro, "Coupling of the Magnetosphere and Ionosphere at Auroral and
Subauroral Latitudes," COSPAR Meeting; The Hague; July (1990).
Wolf, R. A., "Plasma Sheet Confusion," Gordon Conference on Modeling in Solar Terrestrial
Physics; Plymouth, New Hampshire; July (1990).
Semiannual Report (3/90-8/90) - NAGW-1655 - Page 4
Theses Awarded, Graduate Students Supported
Bonnie A. Hausman, M. S. Thesis "Particle Fluxes at Geosynchronous Orbit and in the Plasma
Sheet During Substorms: Implications for Adiabatic Convection."
Gang Lu, Ph.D. "Auroral Electrodynamics from Simultaneous Measurements at High and Low
Altitudes", Department of Space Physics and Astronomy (1990).
References
(* Indicates our previous grant-supported work)
*Allen, J. A., H. Sauer, L. A. Frank, and P. H. Reiff, Effects of the March 1989 solar activity,
Eos, Trans. AGU, November 14, 1989.
*Burch, J. L., P. H. Reiff, R. A. Heelis, J. D. Winningham, W. B. Hanson, C. Gurgiola, J. D.
Menietti, R. A. Hoffman and J. N. Barfield, Plasma injection and transport in the mid-altitude
polar cusp, Geophys. Res. Lett., 9, 921-924, 1982.
Heppner, J. P. and N. C. Maynard, Empirical high-latitude electric field models, J. Geophys.
Res., 92, 4467-4489, 1987.
Knight, S., Parallel electric fields, Planet. Space Sci., 21,741-750, 1973.
Lyons, L. R., Generatior of large-scale regions of auroral currents, electric potentials, and
precipitation by the divergence of the convection electric field, J. Geophys. Res., 85, 17, 1980.
Lyons, L. R., The field-aligned current versus electric potential relation and auroral
electrodynamics, in Physics of Auroral Arc Formation, edited by S.-I. Akasofu and J. R. Kan,
p. 252, Geophys. Monogr. 25, AGU, Washington, D.C., 1981.
*Reiff, P. H., The use and misuse of statistical analyses, in Solar-Terrestrial Physics, ed. R. L.
Carovillano and J. M. Forbes, D. Reidel, Hingham, MA, 493-522, 1983.
*Reiff, P. H., and J. L. Burch, "By-Dependent Plasma Flow and Birkeland Currents in the
Dayside Magnetosphere: 2. A Global Model for Southward and Northward IMF," J. Geophys.
Res., 90, 1595-1609, 1985.
*Reiff, P. H., T. W. Hill, and J. L. Burch, Solar wind plasma injection at the dayside
magnetospheric cusp, J. Geophys. Res., 82, 479-491, 1977.
Smiddy, M., W. J. Burke, M. C. Kelley, N. A. Saflekos, M. S. Gussenhoven, D. A. Hardy and
F. J. Rich, Effects of high-latitude conductivity on observed convection electric fields and
Birkeland currents, J. Geophys. Res., 85, 6811-6813, 1980.
*Spiro, R. W., R. A. Wolf, and B. G. Fejer, Penetration of high-latitude-electric-field effects to
low latitudes during SUNDIAL 1984, Ann. Geophys., 6, 39-50, 1988.


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