Modeling Solar Energetic Particle Transport Near a Wavy Heliospheric Current Sheet
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Effect of Solar Variability on the Earth's Climate Patterns
Advances in Space Research 40 (2007) 1146–1151 www.elsevier.com/locate/asr Effect of solar variability on the Earth’s climate patterns Alexander Ruzmaikin Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA Received 30 October 2006; received in revised form 8 January 2007; accepted 8 January 2007 Abstract We discuss effects of solar variability on the Earth’s large-scale climate patterns. These patterns are naturally excited as deviations (anomalies) from the mean state of the Earth’s atmosphere-ocean system. We consider in detail an example of such a pattern, the North Annular Mode (NAM), a climate anomaly with two states corresponding to higher pressure at high latitudes with a band of lower pres- sure at lower latitudes and the other way round. We discuss a mechanism by which solar variability can influence this pattern and for- mulate an updated general conjecture of how external influences on Earth’s dynamics can affect climate patterns. Ó 2007 COSPAR. Published by Elsevier Ltd. All rights reserved. Keywords: Solar irradiance; Climate and inter-annual variability; Solar variability impact; Climate dynamics 1. Introduction in solar irradiance. The solar cycle variations in total solar irradiance are small, 0.1%. However the magnitude of The center of attention of this paper is the response of irradiance variations strongly depends on the wavelength the Earth to solar variability on Space Climate time scales. and increases for the shorter wavelengths. Thus solar UV, In the context of Space Climate, the Earth can respond to which amounts to only a few percentage of the total irradi- solar variability on the 27-day solar rotation time scale, the ance, contributes 15% to the change in total irradiance 11-year solar cycle, the century scale Grand Minima, and (Lean et al., 2005). -
1 Solar Wind at 33 AU: Setting Bounds on the Pluto Interaction For
Solar Wind at 33 AU: Setting Bounds on the Pluto Interaction for New Horizons F. Bagenal1, P.A. Delamere2, H. A. Elliott3, M.E. Hill4, C.M. Lisse4, D.J. McComas3,7, R.L McNutt, Jr.4, J.D. Richardson5, C.W. Smith6, D.F. Strobel8 1 University of Colorado, Boulder CO 2 University of Alaska, Fairbanks AK 3 Southwest Research Institute, San Antonio TX 4 ApplieD Physics Laboratory, The Johns Hopkins University, Laurel MD 5 Massachusetts Institute of Technology, CambriDge MA 6 University of New Hampshire, Durham NH 7 University of Texas at San Antonio, San Antonio TX 8 The Johns Hopkins University, Baltimore MD CorresponDing author information: Fran Bagenal Professor of Astrophysical and Planetary Sciences Laboratory for Atmospheric anD Space Physics UCB 600 University of Colorado 3665 Discovery Drive Boulder CO 80303 Tel. 303 492 2598 [email protected] Abstract NASA’s New Horizons spacecraft flies past Pluto on July 14, 2015, carrying two instruments that Detect chargeD particles. Pluto has a tenuous, extenDeD atmosphere that is escaping the planet’s weak gravity. The interaction of the solar wind with Pluto’s escaping atmosphere depends on solar wind conditions as well as the vertical structure of Pluto’s atmosphere. We have analyzeD Voyager 2 particles anD fielDs measurements between 25 anD 39 AU anD present their statistical variations. We have adjusted these predictions to allow for the Sun’s declining activity and solar wind output. We summarize the range of SW conDitions that can be expecteD at 33 AU anD survey the range of scales of interaction that New Horizons might experience. -
Determining the Rotation Period of the Sun
SOLAR PHYSICS AND TERRESTRIAL EFFECTS 2+ Activity 8 4= Activity 8 Determining the Rotation Period of the Sun Relevant Reading Chapter 2, section 3 Purpose Determine the rotation period of the Sun. Although numerous methods for accurate measurement are used in solar research, the method described here, using photographs taken over several days, will allow determination to within an Earth-day. Materials Photo set that shows at least one solar feature that can be followed over a several-day period. For real challenge, take the photos yourself, or make a simple projection sketch of sunspots over several days. 1 sheet of clear plastic used for overhead transparencies or viewgraphs, or something similar such as a clear plastic report folder a mm ruler, compass and protractor a fine-tipped marking pen suitable for plastic graph paper with 1-mm squares Procedures 1. Measure, to the nearest millimeter, the diameter of the Sun on the photo taken near the middle of the data period. 2. Use a compass and draw a circle with the same diameter on the transpar- ent sheet. 3. With the circle aligned over the photo on the date used for the diameter, trace the axis orientation marks onto the transparency. 4. Pick a solar feature that traverses the solar disk for as many days as pos- sible. Align the circle on the transparency over each successive photo and carefully mark the position of the chosen solar feature along with its date. 5. Carefully draw the best fitting straight line through the marked positions and measure its length across the circle as accurately as possible. -
Development of Tearing Instability in a Current Sheet Forming by Sheared Incompressible Flow
Development of tearing instability in a current sheet forming by sheared incompressible flow The MIT Faculty has made this article openly available. Please share how this access benefits you. Your story matters. Citation Tolman, Elizabeth A., Nuno F. Loureiro, and Dmitri A. Uzdensky. “Development of Tearing Instability in a Current Sheet Forming by Sheared Incompressible Flow.” Journal of Plasma Physics 84, no. 01 (February 2018). As Published http://dx.doi.org/10.1017/S002237781800017X Publisher Cambridge University Press Version Author's final manuscript Citable link http://hdl.handle.net/1721.1/117098 Terms of Use Creative Commons Attribution-Noncommercial-Share Alike Detailed Terms http://creativecommons.org/licenses/by-nc-sa/4.0/ Under consideration for publication in J. Plasma Phys. 1 Development of Tearing Instability in a Current Sheet Forming by Sheared Incompressible Flow Elizabeth A. Tolman1 , Nuno F. Loureiro1 and Dmitri A. Uzdensky2,3 † 1Plasma Science and Fusion Center, Massachus etts Institute of Technology, Cambridge, Massachusetts 02139, USA 2Center for Integrated Plasma Studies, University of Colorado, Boulder, Colorado 80309, USA 3Institute for Advanced Study, Princeton, NJ 08540, USA (Received xx; revised xx; accepted xx) Sweet-Parker current sheets in high Lundquist number plasmas are unstable to tearing, suggesting they will not form in physical systems. Understanding magnetic reconnection thus requires study of the stability of a current sheet as it forms. Formation can occur due to sheared, sub-Alfv´enic incompressible flows which narrow the sheet. Standard tearing theory (Furth et al. 1963; Coppi et al. 1976; Rutherford 1973) is not immediately appli- cable to such forming sheets for two reasons: first, because the flow introduces terms not present in the standard calculation; second, because the changing equilibrium introduces time dependence to terms which are constant in the standard calculation, complicating the formulation of an eigenvalue problem. -
Physics of Stellar Coronae
Physics of Stellar Coronae Manuel G¨udel Paul Scherrer Institut, W¨urenlingen and Villigen, CH-5232 Villigen PSI, Switzerland [email protected] 1 Introduction For the plasma physicist, the solar corona offers an outstanding example of a space plasma, and surely one that deserves a lifetime of study. Not only can we observe the solar corona on scales of a few hundred kilometers and monitor its changes in the course of seconds to minutes, we also have a wide range of detailed diagnostics at our disposal that provide immediate access to the prevalent physical processes. Yet, solar physics offers a rich field of unsolved plasma-physical problems. How is the coronal plasma continuously heated to > 106 K? How and where are high-energy particles episodically accelerated? What is the internal dy- namics of plasma in magnetic loops? What is the initial trigger of a coronal flare? How does the corona link to the solar wind, and how and where is the latter accelerated? How is plasma transported into the solar corona? Why, then, study stellar coronae that remain spatially unresolved in X- rays and are only marginally resolved at radio wavelengths, objects that require exposure times of several hours before approximate measurements of the ensemble of plasma structures can be obtained? There are many reasons. In the context of the solar-stellar connection, stellar X-ray astronomy has introduced a range of stellar rotation periods, gravities, masses, and ages into the debate on the magnetic dynamo. Coronal magnetic structures and heating mechanisms may vary together with varia- tions of these parameters. -
Solar Differential Rotation in the Period 1964–2016 Determined by the Kanzelhöhe Data Set
A&A 606, A72 (2017) Astronomy DOI: 10.1051/0004-6361/201731047 & c ESO 2017 Astrophysics Solar differential rotation in the period 1964–2016 determined by the Kanzelhöhe data set I. Poljanciˇ c´ Beljan1, R. Jurdana-Šepic´1, R. Brajša2, D. Sudar2, D. Ruždjak2, D. Hržina3, W. Pötzi4, A. Hanslmeier5, A. Veronig4; 5, I. Skokic´6, and H. Wöhl7 1 Physics Department, University of Rijeka, Radmile Matejciˇ c´ 2, 51000 Rijeka, Croatia e-mail: [email protected] 2 Hvar Observatory, Faculty of Geodesy, University of Zagreb, Kaciˇ ceva´ 26, 10000 Zagreb, Croatia 3 Zagreb Astronomical Observatory, Opatickaˇ 22, 10000 Zagreb, Croatia 4 Kanzelhöhe Observatory for Solar and Environmental Research, University of Graz, Kanzelhöhe 19, 9521 Treffen am Ossiacher See, Austria 5 Institute for Geophysics, Astrophysics and Meteorology, Institute of Physics, University of Graz, Universitätsplatz 5, 8010 Graz, Austria 6 Astronomical Institute of the Czech Academy of Sciences, Fricovaˇ 298, 25165 Ondrejov,ˇ Czech Republic 7 Kiepenheuer-Institut für Sonnenphysik, Schöneckstr. 6, 79104 Freiburg, Germany Received 26 April 2017 / Accepted 5 July 2017 ABSTRACT Context. Kanzelhöhe Observatory for Solar and Environmental Research (KSO) provides daily multispectral synoptic observations of the Sun using several telescopes. In this work we made use of sunspot drawings and full disk white light CCD images. Aims. The main aim of this work is to determine the solar differential rotation by tracing sunspot groups during the period 1964–2016, using the KSO sunspot drawings and white light images. We also compare the differential rotation parameters derived in this paper from the KSO with those collected fromf other data sets and present an investigation of the north – south rotational asymmetry. -
Effects of Interplanetary Disturbances on the Earth's Atmosphere And
Effects of Interplanetary Disturbances on the Earth’s Atmosphere and Climate COST Action ES1005 TOSCA - Towards a more complete assessment of the impact of solar variability on the Earth’s climate background • The Sun is the only significant external energy source in the vicinity of the Earth • The solar variability is due to the action of solar dynamo • The solar dynamo transforms two types of solar magnetic fields: poloidal and toroidal • All geoeffective manifestations of solar activity are related to these two faces of solar magnetism How the solar dynamo operates Dipolar, or poloidal magnetic field in sunspot min poloidal to toroidal field (Ω-effect ) The buoyant magnetic field tubes rise up, piercing the Differential rotation stretches surface at two spots the poloidal field (sunspots) with opposite magnetic polarities. Toroidal to poloidal field (α-effect) Babkock-Leighton mechanism Due to the Coriolis force during the flux tube emergence, the sunspot pairs are tilted to the E-W direction Late in the sunspot cycle: leading spots diffuse across the equator cancel with the opposite polarity leading spots in the other hemisphere. ⇒ excess trailing spots flux carried to the poles cancels the flux of the previous cycle accumulates to form the poloidal field of the next solar cycle with the opposite polarity Interplanetary disturbances affecting weather and climate • Energetic particles (EPP, SPE) • Coronal mass ejections (CMEs) • High speed streams (HSS) • Galactic cosmic rays (GCR) • Solar wind carrying EP, SP, CMEs, HSS, modulating -
Large Scale Properties of the Interplanetary Magnetic Field
https://ntrs.nasa.gov/search.jsp?R=19710010992 2020-03-23T17:29:22+00:00Z X-692-71-96 LARGE SCALE PROPERTIES OF THE INTERPLANETARY MAGNETIC FIELD KENNETH -. SCHATTEN '(A ~67t4>(THRU) 0 "(CODE) (NASA CR OR TMX OR AD NUMBER) (CATEGORY) MARCH 1971 GODDARD SPACE FLIGHT CENTER GREENBELT, MARYLAND PRESENTED AT THE CONFERENCE ON THE SOLAR WIND AT ASILOMAR, CALIFORNIA Reprduced by NATIONAL TECHNICAL INFORMATION SERVICE Springfierd, Vft 22151 x-692-71-96 IARGE-SCALE- PROPERTIES OF THE INTERPLANETARY MAGNETIC FIEL Kenneth H. Schatten Laboratory for Extraterrestrial Physics NASA-Goddar& Space Flight Center Greenbelt, Maryland 20771 March 1971 TABLE OF CONTENTS PAGE Abstract .......................................... I I. Introduction ................................................... 2 II. Large-Scale Spatial Structure .................................. 5 A) Quasi-Stationary Structure ................................. 5 B) Interplanetary Magnetic Field Mapping ...................... 6 C) Magnetic "Kinks" and Velocity Gradient Variations .......... 9 D) Dynamic Effects Upon Field Structure ....................... 11 E) Magnetic Field Diffusion ................................... 12 F) Radial Variation of the Interplanetary Magnetic Field ...... 14 III. Relationship to Solar Features ................................. 17 A)' Early Thoughts Concerning the Source of the Interplanetary Magnetic Field .............................. 17 B) Direct Extension of the Solar Fields-Solar Magnetic Nozzle Controversy .............................................. -
Chapter 2 Time-Distance Helioseismology
Chapter 2 Time-Distance Helioseismology 2.1 Solar Oscillations Solar oscillations were rst observed in 1960 by Leighton et al. 1960; 1962, who saw ubiquitous vertical motions of the solar photoshere with p erio ds of ab out 5 minutes and amplitudes of ab out 1000 m=s. Ten years later, it was suggested that these os- cillations might b e manifestations of acoustic waves trapp ed b elow the photosphere Ulrich, 1970; Leibacher and Stein, 1971. Deubner 1975 later con rmed this hy- p othesis by showing that the observed relationship b etween the spatial and temp oral frequencies see gure 2.1 of the oscillations was close to that predicted by theory. This con rmation marked the birth of helioseismology as a to ol for probing the solar interior. The identi cation of the solar oscillations with waves trapp ed in a resonantcavity leads naturally to an analysis in terms of normal mo des. In section 2.2 I will brie y describ e this formalism and mention some of the earliest helioseismic results. Since this work is concerned with the large-scale dynamics of the Sun, I will describ e in slightly more detail the metho ds used to measure the Sun's internal rotation using a normal mo de analysis. After p ointing out some of the limitations of this metho d, section 2.3 will describ e the foundations of time-distance helioseismology, the metho d used in this work, and its application to the measurementof ows. 14 CHAPTER 2. TIME-DISTANCE HELIOSEISMOLOGY 15 8 6 (mHz) 4 π /2 ω 2 0 0.0 0.5 1.0 1.5 2.0 -1 kh (Mm ) Figure 2.1: The greyscale denotes the p ower sp ectrum computed from 8 hours of Dynamics Dopplergrams from MDI. -
Coronal Heating and Nanoflares: Current Sheet Formation and Heating
A&A 560, A89 (2013) Astronomy DOI: 10.1051/0004-6361/201116652 & c ESO 2013 Astrophysics Coronal heating and nanoflares: current sheet formation and heating R. Bowness, A. W. Hood, and C. E. Parnell School of Mathematics and Statistics, University of St Andrews, North Haugh, St Andrews, Fife, KY16 9SS, UK e-mail: [email protected] Received 4 February 2011 / Accepted 14 November 2013 ABSTRACT Aims. Solar photospheric footpoint motions can produce strong, localised currents in the corona. A detailed understanding of the formation process and the resulting heating is important in modelling nanoflares, as a mechanism for heating the solar corona. Methods. A 3D MHD simulation is described in which an initially straight magnetic field is sheared in two directions. Grid resolutions up to 5123 were used and two boundary drivers were considered; one where the boundaries are continuously driven and one where the driving is switched off once a current layer is formed. Results. For both drivers a twisted current layer is formed. After a long time we see that, when the boundary driving has been switched off, the system relaxes towards a lower energy equilibrium. For the driver which continuously shears the magnetic field we see a repeating cycle of strong current structures forming, fragmenting and decreasing in magnitude and then building up again. Realistic coronal temperatures are obtained. Key words. magnetohydrodynamics (MHD) – magnetic reconnection – Sun: corona 1. Introduction It is well known that current layers can form at null points in both two dimensions (e.g. Green 1965; Syrovatskiˇı The Sun’s corona is much hotter than its visible surface: the pho- 1971; Bungey & Priest 1995; Craig & Litvinenko 2005; tosphere’s average temperature is 6000 K compared to over a Fuentes-Fernández et al. -
The Rotation of the Sun
THE ROTATION OF THE SUN The sun turns once every 27 days, but some parts turn faster than others. Such variations are clues to interrelated phenomena from the dense core outward to the solar wind that envelops the earth by Robert Howard hen Galileo turned his tele cause the gas that gives rise to them is sun's rotation. When sunspots are ob scope on the sun in 1610, he moving, and the amount of the shift is served with a small telescope, they ap Wdiscovered that there were proportional to the velOCity of the gas in pear simply as spots on the photosphere: dark spots on the solar disk. Observing the line of sight. Unfortunately for solar the bright surface of the sun that is seen the motion of the spots across the disk, observers each method has disadvan in ordinary white-light photographs. In he deduced that the sun rotated once in tages that limit its usefulness. larger telescopes they may appear as about 27 days. One of his contempo saucer-shaped depressions near the edge raries, Christoph Scheiner, undertook a iming a tracer as it crosses the disk of of the sun. Therefore it is hard to be systematic program of observing the the sun is a good technique for de sure that the same point in the sunspot is spots. From these observations Scheiner terminingT the solar rotation rate only if . being used for the purpose of measure found that the rotation period of the the tracer meets certain requirements. ment as the spot traverses the solar disk spots at higher solar latitudes was slight First, it must survive long enough un and is seen from a different angle each ly longer than that of the spots at lower changed in its appearance to be useful day. -
MHD Simulation of the Three-Dimensional Structure of the Heliospheric Current Sheet
A&A 376, 288–291 (2001) Astronomy DOI: 10.1051/0004-6361:20010881 & c ESO 2001 Astrophysics MHD simulation of the three-dimensional structure of the heliospheric current sheet P. L. Israelevich1,T.I.Gombosi2,A.I.Ershkovich1,K.C.Hansen2,C.P.T.Groth2, D. L. DeZeeuw2, andK.G.Powell3 1 Department of Geophysics and Planetary Sciences, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Ramat Aviv, 69978 Tel Aviv, Israel 2 Space Physics Research Laboratory, Department of Atmospheric, Oceanic and Space Sciences, University of Michigan, Ann Arbor, MI 48109, USA 3 Department of Aerospace Engineering, University of Michigan, Ann Arbor, MI 48109, USA Received 18 April 2001 / Accepted 15 June 2001 Abstract. The existence of the radial component of the electric current flowing toward the Sun is revealed in numerical simulation. The total strength of the radial current is ∼3 × 109 A. The only way to fulfil the electric current continuity is to close the radial electric current by means of field- aligned currents at the polar region of the Sun. Thus, the surface density of the closure current flowing along the solar surface can be estimated as ∼4 A/m, and the magnetic field produced by this current is B ∼ 5 × 10−6 T, i.e. several percent of the intrinsic magnetic field of the Sun. This seems to mean that any treatment of the solar magnetic field generation should take into account the heliospheric current circuit as well as the currents flowing inside the Sun. Key words. solar wind – Sun: magnetic fields 1.