Relations Between Traveling Convection Vortex (TCV) Signatures in Near-Cusp Ground Data, at Geosynchronous Orbit, and in Low Latitude Ground Data

Abstract:

Traveling Convection Vortices (TCVs) occur as solitary localized ~2- 5 mHz transients near the

ionospheric footpoint of the dayside magnetopause. Ion foreshock instabilities are now understood to

drive all or nearly all TCVs; they generate localized changes in dynamic pressure at the dayside

magnetospheric boundary, resulting in transient magnetic field variations that generate field-aligned

currents that propagate to the high latitude ionosphere and also compressional waves that produce

signatures at geosynchronous orbit and lower latitudes on the ground. In this work we extend earlier

multistation event studies by means of a statistical study comparing isolated TCV events observed

between 2010 and 2014 by the MACCS array (Magnetometer Array for Cusp and Cleft Studies) in Arctic

Canada, GOES-13, and several low-latitude INTERMAGNET magnetic observatories, all in the same

longitude sector. We found essentially no correlation between the amplitude of TCV events and the

amplitude of magnetic field compressions (ΔB) at GOES-13 and low-latitude ground stations. Comparing

TCV amplitudes to time derivatives (dB/dt) at geosynchronous orbit and low latitudes, as suggested by

published approximate theoretical analyses, resulted in modest correlations. Consistent with earlier

studies, the low latitude response was strongest at stations under or very near the equatorial electrojet. 

We also analyzed a set of sudden impulse (SI) events with bipolar high-latitude signatures; the

geostationary and low latitude compressions associated with them were relatively higher than those for

TCVs.