SURFACE-WAVES ON THE LOW-LATITUDE BOUNDARY-LAYER INNER EDGE AND TRAVELING CONVECTION VORTICES

Surface waves on the inner boundary of the low-latitude boundary layer (LLBL) are considered as a possible cause for dayside high-latitude t ravelling convection vortices (TCVs). A dispersion equation for the su rface waves with regard to their attenuation in the ionosphere is dedu ced. The current system of the surface wave is consistent with a pair of upward and downward field-aligned currents. The wave velocity depen ds upon the wavelength; taking the latter to be equal to 1000 km in th e ionosphere, which is typical for the TCVs, we obtain the velocity of these waves to be to about 50-100 km/s in the magnetosphere, which co rresponds to several kilometers per second in the ionosphere. The surf ace waves on the LLBL inner boundary may be generated by a sharp defle ction of this boundary from the equilibrium position. A cause of this may be sudden impulses of the solar wind dynamic pressure or bursty re connection at the dayside magnetopause. Surface waves may play an impo rtant role in the relaxation of the magnetosphere. The velocity of the surface waves on the LLBL inner edge is close to or slightly less tha n the magnetosheath plasma velocity near the magnetopause; the movemen t of the magnetosheath plasma along the magnetopause with a speed more than that of the surface waves may favor the formation of impulsive T CVs. It follows from the considered mechanism that the disturbance max imum is to be observed on the LLBL inner edge, and the TCV velocity ha s to increase with the wavelength that might be verified from experime ntal data.