Jovian hectometric beam observed by PWS and WAVES experiments on board Galileo and Wind spacecraft

We report on the jovian hectometric radio emission (HOM) observed simultane ously by PWS and WAVES experiments on board Galileo and Wind spacecraft, re spectively. The positions of both spacecraft allow us to analyse the occurr ence of the HOM emission in the frequency range from 300 kHz to 3 MHz. The jovian hectometric occurrence enables the study of the emission beams, in p articular the geometric conditions where Galileo spacecraft is orbiting in the jovian magnetosphere and Wind satellite is close to the Earth magnetosp here. We select HOM features (arcs) observed by both spacecraft when Jupite r, Galileo and Wind spacecraft are aligned. In such a geometric configuration it is possible to compare the characteris tics of the hectometric beams taking into consideration the corresponding H OM beam patterns. We show the presence of a selective effect at four specif ic longitudes where only small parts of this beam are observed by the Wind/ WAVES experiment which may appear surprising because the global beam intens ity level is nearly the same as that measured by the Galileo/PWS experiment . Those longitude values are found to be comparable to the minima and maxim a of the attenuation band reported in previous studies (Gurnett et al., Geo phys. Res, Lett. 25 (1988) 1841-1844). It appears that the Io satellite and its torus may have an important influence on the generation of radio emiss ions in HOM and also DAM domains which could explain the large frequency ra nge of some HOM/DAM arcs which extend from 300 kHz and reach up to 40 MHz. (C) 2001 Elsevier Science Ltd. All rights reserved.