Millstone Hill Convection Models

The Millstone Hill convection models are computed from observed radial
(line-of-sight) velocities. First, the observed velocities are sorted
into bins with (typically) 1/2 hour apex local time extent and 2°
apex latitude extent. Since each of these cells has been viewed by the
radar over a wide range of aspect angles over the course of many
experiments, the true mean drift velocity can be obtained in a
statistical sense. The data are further separated by index parameters
such as Kp, or measured solar wind parameters, such as B_{z}.
This results in several statistical models corresponding to different
geophysical conditions.
An electrostatic potential is then fit to the average vector
velocities. The fit is extended over the polar cap by solving Laplace's
equation in that region. The potential is represented by a periodic
bi-cubic spline function in apex latitude and apex local time. The
coefficients for all available models, and a Fortran program to recover
the potential and electric field from the coefficients (TABMOD) are available
for download.

A PDF document containing
potential plots
for each of the 37 available models
is available.
Details of the individual models are given in the references.

## References

**Models based on k**_{p} and inferred IMF

Holt, J. M., J.
V. Evans, W. L. Oliver and R. H. Wand, Millstone Hill observations of
ionospheric convection, *Physics of Space Plasmas*, pp. 53-72,
edited by J. Belcher, H. Bridge, T. Chang, B. Coppi and J. R. Jasperse,
Scientific Publishers, Inc., Cambridge, Mass., 1984

Holt, J. M., R. H. Wand, J. V. Evans and W. L. Oliver, Empirical models
for the plasma convection at high latitudes from Millstone Hill
observations, *J. Geophys. Res., 92* 203-212, 1987.

**Models based on the Power Precipitation Index**

Foster, J. C., J. M. Holt, R. G. Musgrove and D. S. Evans, Ionospheric
convection associated with discrete levels of particle precipitation,
*Geophys, Res. Lett., 13*, 656-659, 1986.

Foster, J. C., J. M. Holt, R. G. Musgrove and D. S. Evans, Solar Wind
dependencies of high-latitude convection and precipitation, *Solar
Wind-Magnetosphere Coupling*, edited by Y. Kamide and J. A. Slavin,
pp. 447-494, Terra Scientific Publishing Company, Tokyo, 1986

Revised 22 November, 1999 by John Holt -
jmh@chaos.haystack.edu