A hot flow anomaly at Mars

Collinson, G.; Halekas, J. S.; Grebowsky, J. M.; Connerney, J. E. P.; Mitchell, David; Espley, J. R.; DiBraccio, G. A.; Mazelle, C.; Sauvaud, J. A.; Fedorov, A.; Jakosky, B. M.

doi:10.1002/2015gl065079

Cited by 27 publications

(34 citation statements)

References 41 publications

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“…Thirdly, there are bounding | B | enhancements associated with the bounding compressive regions. These magnetic signatures are in most ways very similar to the classic Martian HFA reported recently by Collinson et al [], with one important distinction. Consistent with these events being SHFAs, no attendant IMF discontinuity was observed, and the ambient magnetic field remained in the same average orientation after the event as before it.…”

Section: A Spontaneous Hot Flow Anomaly At Marssupporting

confidence: 86%

“…Both exhibited similar magnetic and plasma properties to those observed at Earth, although the solar wind velocity perturbations observed by MAVEN at Mars were very much weaker than those reported at Earth by Zhang et al []. Since similarly weak flow perturbations were reported in a classical HFA at Mars [ Collinson et al , ], one important topic for future statistical studies of foreshock transients at Mars is whether this is typical, and if so would be a key difference between those observed at Earth's much larger foreshock.…”

Section: Discussionmentioning

confidence: 57%

“…Following Collinson et al [], for a first‐order approximation as to how far the location of the Martian ionopause ( R i ) might shift from its nominal radial distance ( R r ) as a response to the observed pressure pulse at Mars, we assume a simple static Newtonian pressure balance as below in equation .

(R_{i} - R_{r}) = - H \ln ((), \frac{P_{i}}{P_{r}})

If we assume that, as with Collinson et al [] Martian HFA, the change in pressure is dominated by the dynamic pressure of the solar wind, then this highly simplistic model suggests this SHFA increased the scale height of Martian topside ionosphere ( H ≈40 km [ Withers , ]) by ∼200 km. Work is currently underway to implement an ionosphere into our hybrid models which will enable a better insight into the effects of foreshock transients on the ionospheres of unmagnetized planets.…”

Section: Discussionmentioning

confidence: 99%

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Spontaneous hot flow anomalies at Mars and Venus

Collinson

Sibeck

Omidi³

et al. 2017

JGR Space Physics

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We report the first observations of Spontaneous Hot Flow Anomalies (SHFAs) at Venus and Mars, demonstrating their existence in the foreshocks of other planets beyond Earth. Using data from the ESA Venus Express and the NASA Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft, we present magnetic and plasma observations from events at both planets, exhibiting properties similar to “classical” Hot Flow Anomalies, with bounding shock‐like compressive regions and a hot and diffuse core. However, these explosive foreshock transients were observed without any attendant interplanetary magnetic field discontinuity, consistent with SHFAs observed at Earth and our hybrid simulations.

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Section: A Spontaneous Hot Flow Anomaly At Marssupporting

confidence: 86%

Section: Discussionmentioning

confidence: 57%

(R_{i} - R_{r}) = - H \ln ((), \frac{P_{i}}{P_{r}})

Section: Discussionmentioning

confidence: 99%

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Spontaneous hot flow anomalies at Mars and Venus

Collinson

Sibeck

Omidi³

et al. 2017

JGR Space Physics

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“…Similar structures can form when IMF rotations interact with the shock. Hot flow anomalies (HFAs) [ Schwartz et al ., ; Thomsen et al ., ], which form when a tangential discontinuity (TD) comes into contact with the bow shock in such a way that reflected ions are channeled toward the TD by the motional electric field [ Schwartz , ; Thomas et al ., ], occur upstream from Earth, Venus [ Collinson et al ., ], Mars [ Collinson et al ., ], and Saturn [ Masters et al ., ]. Related structures include foreshock bubbles (FBs) [ Omidi et al ., ; Turner et al ., ] and spontaneous hot flow anomalies (SHFAs) [ Omidi et al ., ; Zhang et al ., ].…”

Section: The Foreshock and Upstream Region Of Marsmentioning

confidence: 99%

Structure, dynamics, and seasonal variability of the Mars‐solar wind interaction: MAVEN Solar Wind Ion Analyzer in‐flight performance and science results

et al. 2017

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We report on the in‐flight performance of the Solar Wind Ion Analyzer (SWIA) and observations of the Mars‐solar wind interaction made during the Mars Atmosphere and Volatile EvolutioN (MAVEN) prime mission and a portion of its extended mission, covering 0.85 Martian years. We describe the data products returned by SWIA and discuss the proper handling of measurements made with different mechanical attenuator states and telemetry modes, and the effects of penetrating and scattered backgrounds, limited phase space coverage, and multi‐ion populations on SWIA observations. SWIA directly measures solar wind protons and alpha particles upstream from Mars. SWIA also provides proxy measurements of solar wind and neutral densities based on products of charge exchange between the solar wind and the hydrogen corona. Together, upstream and proxy observations provide a complete record of the solar wind experienced by Mars, enabling organization of the structure, dynamics, and ion escape from the magnetosphere. We observe an interaction that varies with season and solar wind conditions. Solar wind dynamic pressure, Mach number, and extreme ultraviolet flux all affect the bow shock location. We confirm the occurrence of order‐of‐magnitude seasonal variations of the hydrogen corona. We find that solar wind Alfvén waves, which provide an additional energy input to Mars, vary over the mission. At most times, only weak mass loading occurs upstream from the bow shock. However, during periods with near‐radial interplanetary magnetic fields, structures consistent with Short Large Amplitude Magnetic Structures and their wakes form upstream, dramatically reconfiguring the Martian bow shock and magnetosphere.

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“…HFAs have not only been observed at Earth but also at Mercury [Uritsky et al, 2014], Venus [Collinson et al, 2012], Mars [Øieroset et al, 2001;Collinson et al, 2015], and Saturn [Masters et al, 2009]. HFAs have not only been observed at Earth but also at Mercury [Uritsky et al, 2014], Venus [Collinson et al, 2012], Mars [Øieroset et al, 2001;Collinson et al, 2015], and Saturn [Masters et al, 2009].…”

Section: Introductionmentioning

confidence: 99%

Hot flow anomaly observed at Jupiter's bow shock

Valek

Thomsen

Allegrini

et al. 2017

Geophysical Research Letters

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A Hot Flow Anomaly (HFA) is created when an interplanetary current sheet interacts with a planetary bow shock. Previous studies have reported observing HFAs at Earth, Mercury, Venus, Mars, and Saturn. During Juno's approach to Jupiter, a number of its instruments operated in the solar wind. Prior to crossing into Jupiter's magnetosphere, Juno observed an HFA at Jupiter for the first time. This Jovian HFA shares most of the characteristics of HFAs seen at other planets. The notable exception is that the Jovian HFA is significantly larger than any HFA seen before. With an apparent size greater than 2 × 106 km the Jovian HFA is orders of magnitude larger than those seen at the other planets. By comparing the size of the HFAs at the other planets with the Jovian HFA, we conclude that HFAs size scales with the size of planetary bow shocks that the interplanetary current sheet interacts with.

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A hot flow anomaly at Mars

Cited by 27 publications

References 41 publications

Spontaneous hot flow anomalies at Mars and Venus

Spontaneous hot flow anomalies at Mars and Venus

Structure, dynamics, and seasonal variability of the Mars‐solar wind interaction: MAVEN Solar Wind Ion Analyzer in‐flight performance and science results

Hot flow anomaly observed at Jupiter's bow shock

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