scostep 2010 (stp12) - Leibniz-Institut für Atmosphärenphysik an der ...

STP12 Abstracts
Berlin, 12 - 16 July 2010
SCOSTEP Symposium 2010
Transmission the influence of solar wind to middle atmosphere and troposphere via
high-latitudinal ionospheric potential pattern
Tonev Peter , Velinov Peter
Institute for Solar-Terrestrial Influences, Bulgarian Academy of Sciences
Space weather influences the earth's atmosphere in different ways. One way of mapping of
such influences down to the middle atmosphere and below is due to the field-aligned currents
which are generated in the magnetosphere by the solar wind and are determined by the IMF.
These currents determine the electric potential pattern in the ionosphere in both polar caps,
where a potential difference of magnitude 40-160 kV (80-100 kV in average) is formed
between the dawn and dusk sides. Because of that, while the ionospheric potential at
geomagnetic (gm) latitudes below about 600 remains uniform (~250 kV with respect to the
ground), at higher gm latitudes it is modified by up to ±80 kV. Because of the large horizontal
scale of the trans-polar potential difference (~3000 km), the fair-weather currents which flow
from the ionosphere to the ground in the global atmospheric electrical circuit at polar and high
latitudes are modified, and this modification spreads downward to the surface. We evaluate
theoretically the relative variations of the currents flowing in the global electrical circuit, as a
function of altitude, gm coordinates, and gm local time, depending on IMF carried by the
solar wind. For this goal we create a 3D numerical steady-state model based on the continuity
equation for the electric current density. The dawn-to-dusk difference, as well as the pattern
of the ionospheric potential distribution, which are related to specific IMF parameters, are
evaluated by the Weimer model. A relatively simple global model of the atmospheric
conductivity is used. We examine by our model the role of different factors in the formation
of the electric currents and related electric fields which are superimposed to the global
atmospheric electrical circuit at different gm locations and altitudes and under different
conditions - these factors concern the solar wind and the atmospheric conductivity and their
variations. Our study can be important in estimation of the ways of transmission of space
weather influence to the Earth's atmosphere.