Lightning whistler waves in the high-latitude magnetosphere

Whistler waves caused by lightning are known to penetrate the ionosphere wi th significant wave amplitudes. Recent rocket experiments have shown that l ightning from sources as far as 1000 km from the ionospheric rocket subtrac k are easily seen. The spectral energy density of lightning in the ionosphe re often has significant power at frequencies near and below 1 kHz. Such lo w-frequency whistler waves can propagate all the way to the magnetopause bo undary layer if they begin in the cusp or polar cap. Lightning is common ov er high-latitude continental land masses in the summer months which places this wave Source function well within range of the cusp and polar cap. Ray tracing studies using a global three-dimensional two-fluid code are conduct ed to investigate the propagation of these whistler waves into the high lat itude magnetosphere. The estimated, mapped lightning whistler wave amplitud e is compared to wave intensity measurements from ISEE and AMPTE and suppor ts the argument that falling tone whistler waves, seen by Geotail near the dayside magnetopause, may have been from intense lightning. It is found tha t the mapped whistler wave amplitude from lightning is comparable to the in situ wave amplitudes measured in the outer dayside magnetosphere and low l atitude boundary layer.