Solar wind effects on Jupiter non-Io DAM emissions during Ulysses distant encounter (2003–2004)

Abstract

Aims. We analyze solar wind data from the Ulysses spacecraft during the distant Jupiter encounter from 2003 November to 2004 March as well as Nançay decametric (DAM) radio observations non-controlled by Io. Methods. The Ulysses solar wind data are balistically propagated towards Jupiter and are correlated with Nançay non-Io DAM emissions. Results. It is found that the average solar wind dynamic pressure around the time of DAM emissions is 1.7 times higher than its average value during the Ulysses encounter. The occurrence of fast forward (FS) and reverse (RS) interplanetary shocks and heliospheric current sheet crossings (HCS) is correlated with the occurrence of non-Io DAM emissions. We note an enhanced probability of occurrence of non-Io DAM emissions after the expected arrival of FS, RS and HCS at Jupiter. However, about half emissions (54%) did not seem to be associated with these interplanetary structures. We also note that the average duration and power of non-Io DAM emissions are enhanced during periods associated with those interplanetary structures. Conclusions. From the results obtained in this work it seems that non-Io DAM emissions occur during intervals of enhanced solar wind dynamic pressure. Yet, there is no direct correlation between the non-Io DAM emissions duration or power versus the solar wind pressure values and the interplanetary shock Mach number.

Interplanetary Shock Parameters Near Jupiter's Orbit

“…During the period of the analysis, 148 shocks have been identified: 46 RS (31%) and 102 FS (69%). In another study of shocks at the ecliptic plane, also at 5 AU, focused on the post maximum solar cycle phase (2003–2004), Echer, Zarka, et al () have found for a limited interval that ~72% of shocks were FS and ~28% were RS, which is also similar to the results obtained in this paper. For comparison, at 1 AU, the proportion of FS and RS was 88% to 10% in solar maximum and 66% to 33% in solar minimum (Echer et al, ).…”

“…From Figure , it is seen that histograms for M ms have a skewed to the right distribution, with few shocks at extreme values. It also can be noted that M ms is slightly higher for ICME‐FS (2.5) and CIR‐FS (2.7) than for CIR‐RS (2.4), similarly to what was noted in Echer, Zarka, et al () who have found for a limited interval that FS had average M ms = 2.6, and RS had M ms = 2.4. In fact, the M ms distribution from Figure shows that most shocks have values around M ms = 1.5–3.0 (71% of ICME‐FS, 62% of CIR‐FS, and 67% of CIR‐RS).…”

The impact of an ICME on the Jovian X‐ray aurora

“…Prangé et al [] and Lamy et al [] have used these enhancements in radio emission to trace the progress of ICME‐induced shocks through the solar system. Further, Echer et al [] and Hess et al [, ] found that non‐Io decametric radio emission bursts are correlated with periods of increased solar wind dynamic pressure.…”

Solar Wind and Internally Driven Dynamics: Influences on Magnetodiscs and Auroral Responses

“…It has long been known that Jupiter's radio emissions associated with auroral processes are controlled by conditions in the interplanetary medium incident on Jupiter's magnetosphere (Terasawa et al 1978;Barrow et al 1986;Zarka and Genova 1983;Genova et al 1987;Bose and Bhattacharya 2003;Echer et al 2010;Hess et al 2012). The first evidence that Jupiter's auroras themselves are modulated by conditions in the interplanetary medium was reported by Baron et al (1996), who analysed NASA IRTF observations of the planet's H + 3 emissions in conjunction with Ulysses solar wind data over a ∼100 day interval near the Jupiter encounter in 1992.…”