scholarly journals Solar Cycle Variations in the Position of Vortex Structures in the Venus Wake

2021 ◽  
Author(s):  
H. Pérez-de-Tejada ◽  
R. Lundin
Keyword(s):  
Fluid Dynamics ◽  
Solar Wind ◽  
Solar Cycle ◽  
Solar System ◽  
Wind Direction ◽  
Vortex Structures ◽  
Stellar Systems ◽  
Entry And Exit ◽  
Downstream Distance ◽  
Plane Transverse

Measurements conducted with the Venus Express (VEX) spacecraft at its entry and exit through vortex structures in the Venus wake reveal that their position varies with the solar cycle. Both crossings are consistently measured closer to Venus during minimum solar cycle conditions and are gradually encountered at larger distances downstream from the planet along the solar cycle. At the same time their width along the VEX trajectory on the plane transverse to the solar wind direction is larger during minimum solar cycle conditions and show a gradual decrease along the solar cycle. As a result the vortex structures are envisioned as features that gradually become thinner as they extend along the Venus wake and agree with the geometry of a vortex flow in fluid dynamics whose thickness decreases with the downstream distance from an obstacle. Similar conditions should also be applicable to Mars and other bodies within the solar system and also possibly to exo-planets in external stellar systems.

scholarly journals Vortex Dynamics in the Wake of Planetary Ionospheres

2021 ◽  
Author(s):  
Hector Pérez-de-Tejada ◽  
Rickard Lundin
Keyword(s):  
Solar Wind ◽  
Solar Cycle ◽  
Kinetic Energy ◽  
Vortex Dynamics ◽  
Vortex Flow ◽  
Rotation Period ◽  
Vortex Structures ◽  
Momentum Transport ◽  
Wake Vortex ◽  
Downstream Distance

Measurements conducted with spacecraft around Venus and Mars have shown the presence of vortex structures in their plasma wake. Such features extend across distances of the order of a planetary radius and travel along their wake with a few minutes rotation period. At Venus, they are oriented in the counterclockwise sense when viewed from the wake. Vortex structures have also been reported from measurements conducted by the solar wind-Mars ionospheric boundary. Their position in the Venus wake varies during the solar cycle and becomes located closer to Venus with narrower width values during minimum solar cycle conditions. As a whole there is a tendency for the thickness of the vortex structures to become smaller with the downstream distance from Venus in a configuration similar to that of a corkscrew flow in fluid dynamics and that gradually becomes smaller with increasing distance downstream from an obstacle. It is argued that such process derives from the transport of momentum from vortex structures to motion directed along the Venus wake and that it is driven by the thermal expansion of the solar wind. The implications of that momentum transport are examined to stress an enhancement in the kinetic energy of particles that move along the wake after reducing the rotational kinetic energy of particles streaming in a vortex flow. As a result, the kinetic energy of plasma articles along the Venus wake becomes enhanced by the momentum of the vortex flow, which decreases its size in that direction. Particle fluxes with such properties should be measured with increasing distance downstream from Venus. Similar conditions should also be expected in vortex flows subject to pressure forces that drive them behind an obstacle.

scholarly journals A 15N-Poor Isotopic Composition for the Solar System As Shown by Genesis Solar Wind Samples

Science ◽  
2011 ◽  
Vol 332 (6037) ◽  
pp. 1533-1536 ◽  
Author(s):  
B. Marty ◽  
M. Chaussidon ◽  
R. C. Wiens ◽  
A. J. G. Jurewicz ◽  
D. S. Burnett
Keyword(s):  
Solar Wind ◽  
Solar System ◽  
Isotopic Composition

Ulysses solar wind plasma observations during the declining phase of solar cycle 22

1995 ◽  
Vol 16 (9) ◽  
pp. 85-94 ◽  
Author(s):  
J.L. Phillips ◽  
S.J. Bame ◽  
W.C. Feldman ◽  
J.T. Gosling ◽  
C.M. Hammond ◽  
...  
Keyword(s):  
Solar Wind ◽  
Solar Cycle ◽  
Solar Wind Plasma

Numerical Investigation of Thermal Flow Field of Air-Cooled Condensers for Yongshou Plant

2012 ◽  
Vol 248 ◽  
pp. 391-394
Author(s):  
Wen Zhou Yan ◽  
Wan Li Zhao ◽  
Qiu Yan Li
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Wind Speed ◽  
Power Plant ◽  
Flow Field ◽  
Wind Direction ◽  
Rotational Speed ◽  
Power Plants ◽  
Thermal Flow ◽  
Air Cooled Condensers

By using the computational fluid dynamics code, FLUENT, Numerically simulation is investigated for Youngshou power plant. Under the constant ambient temperature, the effects of different wind speed and wind direction on the thermal flow field are qualitatively considered. It was found that when considering about the existing and normally operating power plants, the thermal flow field is more sensitive to wind direction and wind speed. Based on the above results, three improved measures such as: increasing the wind-wall height and accelerating the rotational speed of the fans near the edge of the ACC platform and lengthen or widen the platform are developed to effectively improving the thermal flow field, and enhanced the heat dispersal of ACC.

scholarly journals Mars Under Primordial Solar Wind Conditions: Mars Express Observations of the Strongest CME Detected at Mars Under Solar Cycle #24 and its Impact on Atmospheric Ion Escape

2017 ◽  
Vol 44 (21) ◽  
Author(s):  
Robin Ramstad ◽  
Stas Barabash ◽  
Yoshifumi Futaana ◽  
Masatoshi Yamauchi ◽  
Hans Nilsson ◽  
...  
Keyword(s):  
Solar Wind ◽  
Solar Cycle ◽  
Mars Express ◽  
Ion Escape ◽  
Solar Cycle 24 ◽  
Cycle 24

scholarly journals Probability density functions for the variable solar wind near the solar cycle minimum

2015 ◽  
Vol 120 (8) ◽  
pp. 6152-6166 ◽  
Author(s):  
Z. Vörös ◽  
M. Leitner ◽  
Y. Narita ◽  
G. Consolini ◽  
P. Kovács ◽  
...  
Keyword(s):  
Solar Wind ◽  
Solar Cycle ◽  
Probability Density ◽  
Probability Density Functions ◽  
Density Functions ◽  
Cycle Minimum

scholarly journals Remotely distinguishing and mapping endogenic water on the Moon

2017 ◽  
Vol 375 (2094) ◽  
pp. 20150391 ◽  
Author(s):  
Rachel L. Klima ◽  
Noah E. Petro
Keyword(s):  
Solar Wind ◽  
Spatial Distribution ◽  
Solar System ◽  
The Moon ◽  
Testing Hypotheses ◽  
Origin And Evolution ◽  
Lunar Interior ◽  
Geological Features ◽  
Insight Into

Water and/or hydroxyl detected remotely on the lunar surface originates from several sources: (i) comets and other exogenous debris; (ii) solar-wind implantation; (iii) the lunar interior. While each of these sources is interesting in its own right, distinguishing among them is critical for testing hypotheses for the origin and evolution of the Moon and our Solar System. Existing spacecraft observations are not of high enough spectral resolution to uniquely characterize the bonding energies of the hydroxyl molecules that have been detected. Nevertheless, the spatial distribution and associations of H, OH − or H 2 O with specific lunar lithologies provide some insight into the origin of lunar hydrous materials. The global distribution of OH − /H 2 O as detected using infrared spectroscopic measurements from orbit is here examined, with particular focus on regional geological features that exhibit OH − /H 2 O absorption band strengths that differ from their immediate surroundings. This article is part of the themed issue ‘The origin, history and role of water in the evolution of the inner Solar System’.

scholarly journals Solar cycle changes of large-scale solar wind structure

2009 ◽  
Vol 5 (S264) ◽  
pp. 356-358 ◽  
Author(s):  
P. K. Manoharan
Keyword(s):  
Solar Wind ◽  
Solar Cycle ◽  
Large Scale ◽  
Interplanetary Space ◽  
The Sun ◽  
Wind Structure ◽  
Level Of Activity ◽  
Solar Wind Structure ◽  
Current Minimum ◽  
Inner Heliosphere

AbstractIn this paper, I present the results on large-scale evolution of density turbulence of solar wind in the inner heliosphere during 1985–2009. At a given distance from the Sun, the density turbulence is maximum around the maximum phase of the solar cycle and it reduces to ~70%, near the minimum phase. However, in the current minimum of solar activity, the level of turbulence has gradually decreased, starting from the year 2005, to the present level of ~30%. These results suggest that the source of solar wind changes globally, with the important implication that the supply of mass and energy from the Sun to the interplanetary space has significantly reduced in the present low level of activity.

scholarly journals Solar Wind Helium Abundance Heralds Solar Cycle Onset

2021 ◽  
Author(s):  
Benjamin L Alterman ◽  
Justin C Kasper ◽  
Robert J Leamon ◽  
Scott W McIntosh
Keyword(s):  
Solar Wind ◽  
Solar Cycle ◽  
Sunspot Number ◽  
Cycle Length ◽  
Phase Lag ◽  
Helium Abundance ◽  
Solar Cycles ◽  
Wind Speeds ◽  
Solar Wind Acceleration ◽  
Solar Cycle Length

Abstract We study the solar wind helium-to-hydrogen abundance's ( A He ) relationship to solar cycle onset. Using OMNI/Lo data, we show that A He increases prior to sunspot number (SSN) minima. We also identify a rapid depletion and recovery in A He that occurs directly prior to cycle onset. This A He Shutoff happens at approximately the same time across solar wind speeds ( v sw ) and the time between successive A He shutoffs is typically on the order of the corresponding solar cycle length. In contrast to A He 's v sw -dependent phase lag with respect to SSN (Alterman and Kasper, 2019), A He Shutoff's concurrence across v sw likely implies it is independent of solar wind acceleration and driven by a mechanism near or below the photosphere. Using Brightpoint (BP) measurements to provide context, we infer that this shutoff is likely related to the overlap of adjacent solar cycles and the equatorial flux cancelation of the older, extended solar cycle during solar minima.

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