Magnetic Shear Damped Polar Convective Fluid Instabilities

The influence of the magnetic field shear is studied on the \(E\times B\) (and/or Gravitational) and the Current Convective Instabilities (CCI) occuring in the High latitude F-layer ionosphere. It is shown that magnetic shear reduces the growth rate of these instabilties. The magnetic shear induced stabilization is more effective at the larger scale sizes (\(\geq\) tens of kilometers) while at the scintillation causing intermediate scale sizes (\(\sim\) a few kms), the growth rate is largely unaffected. The eigen mode structure is localised about a rational surface due to finite magnetic shear and has broken reflectional symmetry due to centroid shift of the mode by equilibrium parallel flow or current.