High‐latitude ionospheric convection models derived from Defense Meteorological Satellite Program ion drift observations and parameterized by the interplanetary magnetic field strength and direction

Abstract

[1] A series of new high-latitude ionospheric convection models have been constructed using Defense Meteorological Satellite Program (DMSP) thermal ion drift measurements. The models are obtained by sorting cross polar cap electrostatic potentials into magnetic latitude/magnetic local time bins. A regression analysis of the potentials in each bin is then implemented for establishing the relationships to the interplanetary magnetic field (IMF) for three seasons: summer, winter, and equinox. A linear modeling formula for the ionospheric electrodynamics (LIMIE) yields a convection response to the average solar wind (i.e., the ''quasi-viscous'' interaction) and to changes in the IMF B y , B z 0, and B z > 0 components. The modeled convection is a superposition of the first two parameters with either the IMF B z 0 or the B z > 0 component. A global model is created by fitting the regression analysis results to a spherical harmonic function. The resulting DMSP-based ionospheric convection model (DICM) is fully parameterized by the IMF strength and direction. With this model, ionospheric convection patterns can be generated for any IMF configuration during quiet to moderate geomagnetic conditions. We compare the DICM model with other available high-latitude convection patterns organized by the IMF. The new elements in DICM are its quasi-viscous and separate IMF-dependent terms for both the northern and southern polar regions, which are not explicitly found in other ionospheric convection studies. The DICM's seasonal dependence and interhemispheric symmetry/asymmetry features show that the summer cross-polar potentials are 10-15% smaller than the winter potentials. The latter is in agreement with the seasonal dependence of field-aligned currents and with the voltage-current relationship required for the proper magnetosphereionosphere coupling.

What is the best method to calculate the solar wind propagation delay?

“…Ogino et al,of magnetospheric convection (e.g. Papitashvili and Rich, 2002;Weimer, 2005;Ruohoniemi and Greenwald, 2005, and references therein) sort the results according to concurrent IMF direction. Weimer et al (2003) applied a running minimum variance analysis technique to determine the orientation of the IMF for each data point in a continuous time series of magnetic field data.…”

Dynamical critical scaling of electric field fluctuations in the greater cusp and magnetotail implied by HF radar observations of F-region Doppler velocity

“…The intermittency of avalanches means the probability of major, sometimes life-threatening energy release is far greater than predicted by simple Gaussian statistics. For example, nivologists aim to incorporate the powerlaw behaviour of self-organised systems into routine predictions of avalanche risk for the European Alps (Palmer, 2003). This is an example of the way in which complexity science might contribute to the preservation of human life.…”

IMF effect on sporadic-E layers at two northern polar cap sites: Part I – Statistical study

“…The global plasma convection pattern is such that the dusk cell is larger in spatial extent than the dawn cell and its maximum potential is also greater (Ruohoniemi and Greenwald, 1996;Papitashvili and Rich, 2002). When B y is negative in the Northern Hemisphere, the zero potential line is aligned at about 00 MLT, and when B y is positive, the convection pattern and the zero line are rotated to an earlier time by a few hours.…”

“…As a consequence, the Es occurrence is expected to be connected to the IMF direction and strength. Several empirical models of the IMF effect on the convection pattern have been constructed, for example, by Heppner and Maynard (1987), Papitashvili et al (1994), Ruohoniemi and Greenwald (1996), Weimer (1995), and Papitashvili and Rich (2002). Bristow and Watkins (1994) studied theoretically the effect of different convection patterns on the geographic distribution of Es by applying the Heppner and Maynard (1987) convection model.…”