CHORUS SOURCE LOCATIONS FROM VLF POYNTING FLUX MEASUREMENTS WITH THE POLAR SPACECRAFT

Previous studies have used indirect evidence to argue that whistler-mo de chorus emissions are generated near the magnetic equator. In this p aper a spatial survey of wave normals and Poynting vectors computed fr om three-component electric and magnetic field measurements is used to show that chorus is generated very close to the magnetic equator. One surprising result is that there are almost no chorus emissions propag ating toward the magnetic equator, such as might be expected from high -latitude magnetospheric reflections. The absence of a reflected compo nent indicates that the chorus is reabsorbed, probably by Landau dampi ng, before returning to the magnetic equatorial plane.