CHARTS OF JOINT KELVIN-HELMHOLTZ AND RAYLEIGH-TAYLOR INSTABILITIES ATTHE DAYSIDE MAGNETOPAUSE FOR STRONGLY NORTHWARD INTERPLANETARY MAGNETIC-FIELD

We present maximum growth rate charts of the Kelvin-Helmholtz (KH) and Rayleigh-Taylor (RT) instabilities at the dayside magnetopause (MP), considering two orientations of the interplanetary magnetic field (IMF ) (due north and 30 degrees west of north). We input parameters in the plasma depletion layer calculated from an MHD code. We study both a s harp MP transition and an MP with an attached boundary layer (''thin'' and ''thick'' approximations, respectively). Our analysis applies to wavelengths (lambda) from similar to 2 x 10(3) km to less than or equa l to 9 R-E. Thin model results are as follows: For a stationary MP and due north IMF, the off-noon, low-latitude MP is very low shear (less than or equal to 10 degrees) and is substantially KH active. With an I MF inclined to north, extremely low shear, KH-active regions are confi ned to two strips, one in each hemisphere, where short lambda perturba tions are generated, which propagate as surface ripples on the high-la titude, duskside MP. For a sunward accelerating magnetopause and IMF n orth, a large part of the MP is unstable. With an inclined IMF, the KH +RT unstable strips are broader and growth rates are higher. Thick mod el results are as follows: For IMF due north and a stationary MP, the middle-to high-latitude MP is stable. At middle to low latitudes, the inner edge of the boundary layer (IEBL) is active, except fora 2-hour local time band on either side of noon. For the inclined IMF, the MP i s stable for long lambda, with activity for short lambda confined to t wo strips, as before, with slightly reduced growth rates. For the IEBL , a clear dawn-dusk asymmetry in KH activity is evident. When the MP a ccelerates sunward and the IMF points north, we have to consider also the lambda of the perturbation. For short lambda, growth rates are enh anced with respect to stationarity at both the NIP and the IEBL. While there are extensive regions of negligible growth at the MP, the entir e IEBL is RT + KH unstable. We give an example of a long lambda pertur bation where both interfaces are coupled and oscillate together. Final ly, for an inclined IMF, we have at the MP unstable strips which are w ider and have higher growth rates. The IEBL, by contrast, is completel y destabilized, with larger growth rates than under stationary conditi ons.