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 Bz. 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.

Access the Models


Models based on kp 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 -