Latitude dependence of solar wind velocity observed ≳1 AU

Mitchell, D. G.; Roelof, E. C.; Wolfe, J. H.

doi:10.1029/ja086ia01p00165

Cited by 25 publications

(12 citation statements)

References 20 publications

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“…Moreover, the one-to-one correlation of solar wind structures seen by different spacecraft is not straightforward. While sharp latitudinal stream boundaries have been observed having widths of 1.5 degrees at 0.8 AU (Schwenn, 1990) and up to 5 degrees at 5 AU (Mitchell, Roelof, and Wolfe, 1981), clear stream interface signatures were found at locations separated from the backmapping predictions on scales up to three times larger than the expected backmapping accuracy. In addition a careful inspection of the solar wind data shows that in some cases multiple stream interfaces or multiple crossings of the same SI seem to be present.…”

Section: Investigation Of Carrington Rotations 2059 and 2060mentioning

confidence: 89%

Multi-spacecraft Observations of CIR-Associated Ion Increases During the Ulysses 2007 Ecliptic Crossing

et al. 2009

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The period between 21 June and 8 October, 2007 (Carrington rotations 2058 to 2061, comprising the Ulysses ecliptic plane crossing, was characterized by low solar activity. Excluding the small solar energetic particle events observed during July, the ion increases observed in the inner heliosphere between 100 keV/n and 10 MeV/n were associated with Corotating Interaction Regions (CIRs). In this work, we investigate CIR-related ion increases using multipoint observations from Ulysses, ACE, and the twin STEREO spacecraft. The ballistic backmapping technique has been used to correlate in situ observations of these spacecraft and remote-sensing observations of coronal holes. Although the radial, longitudinal and latitudinal separation of the spacecraft (except Ulysses) are relatively small, we find discrepancies when a detailed comparison of narrow structures like stream interfaces and CIR-associated shocks is performed. Therefore we concentrate on the two CIR events from day 5 to day 10 of August 2007 and from day 25 to day 31 of August 2007, which lend themselves to a more undisturbed comparison. Using the multi-spacecraft measurements we could determine a radial gradient of 230 ± 30% AU −1 , which is consistent with previous results by van Hollebeke et al. (J. Geophys. Res. 83, 4723, 1978) of ∼ 350% AU −1 using Helios and Pioneer data.

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Section: Investigation Of Carrington Rotations 2059 and 2060mentioning

confidence: 89%

Multi-spacecraft Observations of CIR-Associated Ion Increases During the Ulysses 2007 Ecliptic Crossing

et al. 2009

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“…Schwenn (1990, p. 121) gives an example of a latitudinal gradient of (250 km=s)=1:5 • ). Boundaries of ≈ 5 • width were observed out to 5 AU (Mitchell et al, 1981). Ulysses (McComas et al, 1998) also measured a large latitudinal gradient of the speed at the boundary of the corotating stream that originated from a polar coronal hole.…”

Section: Corotating Streamsmentioning

confidence: 99%

Magnetic fields and plasmas in the inner heliosphere: Helios results

Burlaga

2001

Planetary and Space Science

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The magnetic ÿeld of Mercury and the structure and dynamics of Mercury's magnetosphere, which will be studied by the spacecraft orbiting Mercury, are strongly in uenced by the interaction of the solar wind with Mercury. In order to understand the internal magnetic ÿeld, it will be necessary to correct the observations of the external ÿeld for the distortions produced by the solar wind. Understanding of the solar wind interaction with Mercury is essential for understanding the structure and dynamics of the magnetosphere and phenomena such as magnetic storms. Helios 1 and 2 made a number of passes in the region traversed by the orbit of Mercury, and each pass provided a sample of the solar wind environment of Mercury. This paper reviews the plasma and magnetic ÿeld observations from Helios that provide a general basis for interpreting the observations of Mercury that will be made by orbiting spacecraft. The variables that govern the structure and dynamics of the magnetospheres of Mercury and Earth are approximately 5 -10 times larger at Mercury than at Earth. Thus, the solar wind interaction with Mercury will be much stronger than the interaction with Earth. Moreover, the solar wind at Mercury is probably more variable than that at Earth. There is a clear need for measurements of the solar wind during the approach of spacecraft to Mercury and while they are in orbit around Mercury.

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“…Simultaneous observations at multiple spacecraft by Rhodes and Smith [1975, 1976a, 1976b, Schwenn et al [1978], and Mitchell et al [1981] showed a systematic increase of solar wind speed with latitude for hellographic latitudes less than 8 ø. Interplanetary scintillation (IPS) measurements [Sime and Rickerr, 1978;Coles et al, 1980;Kakinuma and Kojima, 1986] Unfortunately neither IPS observations nor previously reported in situ observations of the solar wind are adequate to examine stream structure at high latitudes. IPS observations provide extensive latitudinal coverage, but are rarely able to resolve individual solar wind streams.…”

Section: Introductionmentioning

confidence: 99%

Pioneer and Voyager observations of the solar wind at large heliocentric distances and latitudes

Gazis

Mihalov

Barnes

et al. 1989

Geophysical Research Letters

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The Pioneer 10, 11 and Voyager 2 spacecraft are well suited for exploring spatial gradients in the distant solar wind. Between 1984 and 1986 Pioneer 11 and Voyager 2 were located at nearly the same heliocentric distance (≃20 AU) and longitude but were widely separated in latitude; Pioneer 11 was at a heliographic latitude of ≥15° while Voyager 2 was near the solar equator. Pioneer 10 was located near the solar equator but at a considerably greater heliocentric distance (≃40 AU). IMP observations at 1 AU provide an inner heliosphere baseline. Prior to mid‐1985, Pioneer 11 and Voyager 2 observed nearly identical solar wind structures. The characteristics and arrival times of these structures were similar at both spacecraft. After day 150 of 1985 this situation changed dramatically. The velocity structure at Voyager 2 became flatter. The velocities seen at Voyager 2 also fell with respect to Pioneer 11; the difference in velocities observed by the two spacecraft grew to 200 km s−1 by late 1986. In late 1985 Pioneer 10 observed a change in the solar wind similar to that observed at Voyager 2. These changes in the solar wind at low latitudes may be related to a change which occurred in the coronal hole structure in early 1985.

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Latitude dependence of solar wind velocity observed ≳1 AU

Cited by 25 publications

References 20 publications

Multi-spacecraft Observations of CIR-Associated Ion Increases During the Ulysses 2007 Ecliptic Crossing

Multi-spacecraft Observations of CIR-Associated Ion Increases During the Ulysses 2007 Ecliptic Crossing

Magnetic fields and plasmas in the inner heliosphere: Helios results

Pioneer and Voyager observations of the solar wind at large heliocentric distances and latitudes

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