Effect of solar UV/EUV heating on the intensity and spatial distribution of Jupiter's synchrotron radiation

Kita, Hidetoshi; Misawa, Hiroaki; Tsuchiya, F.; Tao, Chihiro; Morioka, A.

doi:10.1002/jgra.50568

Cited by 16 publications

(23 citation statements)

References 31 publications

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“…Changes in the spatial distribution of the electron belt are supposedly driven by either internal or external parameters (e.g., Bolton et al 1989;Brecht et al 2001;de Pater and Brecht 2001;Horne et al 2008;Santos-Costa et al 2008, 2011Kita et al 2013, and references therein). Determining the exact cause(s) of changes in the radio maps in Fig.…”

Section: Data Analysis Results From Rotation-averaged Imagesmentioning

confidence: 99%

“…Investigating the source of fluctuations in early January 2001 will provide new opportunities to re-examine the scenarios of temporal changes in Jupiter's synchrotron radiation (e.g., Bolton et al 1989;Santos-Costa et al 2008;Kita et al 2013, and references therein). The results of our data analysis will help constrain models of Jupiter's electron belt.…”

Section: Introductionmentioning

confidence: 99%

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Multifrequency analysis of the Jovian electron-belt radiation during theCassiniflyby of Jupiter

Santos-Costa

Pater

Sault

et al. 2014

A&A

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Aims. We examine Very Large Array (VLA) observations of Jupiter to present evidence of fluctuations in the emission produced by the electron belt in January 2001. Investigating the source of fluctuations will provide new opportunities to discuss the scenarios of temporal changes in Jupiter's synchrotron radiation (i.e., the electron belt) in future data analysis and modeling work. Methods. To discuss the electron belt dynamics during the Cassini flyby of Jupiter, we compare the radio measurements from 2−3 January 2001 with VLA observations obtained on 20−21 December 1988, when viewing geometry and array configuration are comparable. All data are scaled to a standard Earth-Jupiter distance of 4.04 AU for comparison purposes. Brightness distribution maps with identical spatial resolutions and cartography of the equatorial radiation are constructed and examined at the wavelengths of ∼21 cm and ∼90 cm. Results. Rotation-averaged maps show that the emission from the equatorial zones of maximum intensity is weaker by ∼5−40%, but the brightness distribution is spatially more extended on 2−3 January 2001, resulting in a total emission at both wavelengths stronger by ∼35%. Between observation periods, the brightness distributions are observed to evolve differently during the planet rotation. Tomographic reconstructions of the equatorial radiation support our conclusion that the electron-belt population was differently distributed around the planet in December 1988 and January 2001. Conclusions. Our analysis of VLA data sets suggests that the spatial distribution of the electron belt on 2−3 January 2001 is different from that usually observed. Our knowledge of solar activity at the time of the Cassini flyby of Jupiter suggests that the emission from the electron radiation belt was responding to external influences, most likely to solar wind structures rather than to solar radio flux, on a timescale of days to a couple of weeks. Combined results from a multisource data analysis -including spacecraft and radio observations -are needed to confirm this relationship.

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Section: Data Analysis Results From Rotation-averaged Imagesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Multifrequency analysis of the Jovian electron-belt radiation during theCassiniflyby of Jupiter

Santos-Costa

Pater

Sault

et al. 2014

A&A

View full text Add to dashboard Cite

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“…Tsuchiya et al (2011) demonstrated that short-term variations in the Jupiter Synchrotron output correlated positively with the Mg II solar UV/EUV index with a time lag of 3-5 days. Kita et al (2013) also showed that the average ratio of the dawn/dusk asymmetry was likely related to the Brice and McDonough mechanism, but that the daily variations in the asymmetry did not correspond to the solar UV/EUV output. Changes in the UV output of the Sun are also thought to influence the electron radiation belts at Saturn (Krupp et al 2014).…”

Section: Control Of the Radiation Beltsmentioning

confidence: 97%

“…The origin of the ionospheric wind variations lies in solar heating of the planet's atmosphere which means that variations in solar UV/EUV output should affect the rate of radial diffusion. Indeed, variations with solar output have been found at Jupiter (Kita et al 2013) and at Saturn (Krupp et al 2014).…”

Section: Characteristics Of the Different Bodies On Which The Solar Wmentioning

confidence: 99%

“…Recent studies have examined the possibility that the strength of Jupiter's radiation belts, as measured through its synchrotron radiation output, is affected by the solar UV/EUV output (Tsuchiya et al 2011;Kita et al 2013). The commonly accepted mechanism for driving radial diffusion at Jupiter and Saturn is electric field variations in the ionosphere driven by the neutral wind dynamo effect, which in turn are a result of solar heating of Jupiter's atmosphere by UV/EUV (Brice and McDonough mechanism 1973).…”

Section: Control Of the Radiation Beltsmentioning

confidence: 99%

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What characterizes planetary space weather?

Lilensten

Coates

Déhant

et al. 2014

Astron Astrophys Rev

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Space weather has become a mature discipline for the Earth space environment. With increasing efforts in space exploration, it is becoming more and more necessary to understand the space environments of bodies other than Earth. This is the background for an emerging aspect of the space weather discipline: planetary space weather. In this article, we explore what characterizes planetary space weather, using some examples throughout the solar system. We consider energy sources and timescales, the characteristics of solar system objects and interaction processes. We

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Response of the Jovian thermosphere to variations in solar EUV flux

et al. 2014

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Examining the response to solar extreme ultraviolet (EUV) radiation is an established diagnostic method used to understand the physics of planetary environments. In this study, we focus on the response of the Jovian thermosphere to variations in the solar EUV flux and discuss the consequences for the coupled thermosphere-ionosphere-magnetosphere system. We use a model that simulates both the thermospheric dynamics and the magnetospheric plasma velocity distribution under conditions of angular momentum transport between these regions. The simulations show that when the EUV flux increases by~100% and 200%, the thermospheric neutral wind velocity at~45°latitude increases by 16% and 22%, respectively. The short-term variation over a few Earth days causes an increased velocity at middle latitudes which are magnetically conjugate to the Jovian radiation belt. Increased heating due to solar EUV contributes to this velocity change. The other contribution arises~30 planetary rotations after the initial solar EUV flux increase. This second ("delayed") effect is due to propagation of momentum from high latitudes (the auroral region), where Joule heating is dominant, and is related to the behavior of the ionospheric conductance and magnetosphere-ionosphere coupling currents. The modeled velocity enhancement is smaller than that required to explain the observed enhancement of the synchrotron emission by radial diffusion of the trapped energetic electrons. In this context, we discuss the sensitivity of the underlying thermosphere-ionosphere response to short-wavelength solar radiation and the ensuing three-dimensional wind fields.

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Effect of solar UV/EUV heating on the intensity and spatial distribution of Jupiter's synchrotron radiation

Cited by 16 publications

References 31 publications

Multifrequency analysis of the Jovian electron-belt radiation during theCassiniflyby of Jupiter

Multifrequency analysis of the Jovian electron-belt radiation during theCassiniflyby of Jupiter

What characterizes planetary space weather?

Response of the Jovian thermosphere to variations in solar EUV flux

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