Intense bursts of electron cyclotron harmonic waves near the dayside magnetopause observed by GEOTAIL

We report GEOTAIL/PWI observations of intense bursts of electron cyclotron harmonic (ECH) waves detected at the dayside equatorial magnetopause region on October 17, 1992. Along a magnetopause skimming orbit of the GEOTAIL spacecraft, the intense ECH emissions were observed intermittently and sporadically in time, superimposed on weak diffuse ECH waves. On account of the spectral shape of the dynamic spectra, we name this burst of ECH waves ''Totem Pole'' emission (TP emission). The duration time of the TP emission is less than a few minutes and its maximum electric field intensity is approximately -100 dB V/m/root Hz. Although not always observed, the TP emission has harmonic components even above the local plasma frequency. This type of emission is often observed along the magnetopause crossing orbits. It is also found that the TP emission often has two discrete spectral components in the first harmonic band between f(ce) and 2f(ce), where f(ce) denotes the electron cyclotron frequency.