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Solar Variability THETHE EVEREVER CHANGINGCHANGING SUNSUN SolarSolar influenceinfluence onon climateclimate C. de Jager SolarSolar activityactivity duringduring holoceneholocene [ref: Solanki et al.] PresentPresent maximummaximum isis highesthighest ofof pastpast 99 millenniamillennia (as(as farfar asas plasmaplasma ejectionejection fromfrom sunsun isis concerned;concerned; butbut notenote conflictingconflicting evidenceevidence AntarcticAntarctic vs.vs. GreenlandGreenland iceice cores)cores) [Solanki et al.; Muscheler et al.] NorthernNorthern HemisphereHemisphere TemperaturesTemperatures [source: Anders Moberg et al., 2005] •• Medieval maximum (AD 1000 – 1200) •• Broad minimum around 1600 (Little Ice Age) •• Strong 20th century increase BasicBasic datadata forfor thethe periodperiod 16191619 –– 19641964 Smoothed Group Sunspot Number (left; ref. Hoyt & Schatten) and smoothed Northern Hemisphere Temperature [ref: Moberg et al.] BasicBasic datadata forfor thethe periodperiod 16191619 -- 19641964 Smoothed Group Sunspot number (left) and Source function (= ejected plasma ~ open solar flux) [refs: Hoyt & Schatten for GSN; Usoskin & Solanki for S-function] OutlineOutline ofof talktalk •• TwoTwo mainmain aspectsaspects ofof solarsolar variability:variability: - Active regions around sunspots - Coronal plasma ejections of various kinds •• DoDo thesethese influenceinfluence tropospherictropospheric temperaturestemperatures andand whatwhat isis thethe mainmain driverdriver ofof sunsun--inducedinduced climateclimate change?change? •• TheThe solarsolar dynamodynamo •• ForecastingForecasting solarsolar activityactivity BASICBASIC SOLARSOLAR DATADATA ActivityActivity CentersCenters andand EjectionEjection ofof solarsolar plasmaplasma SunspotsSunspots andand activeactive regionsregions AA sunspotsunspot groupgroup [DOT observations] SurroundingSurrounding facularfacular fieldsfields higherhigher temperaturestemperatures areare locatedlocated onon toptop ofof photosphere;photosphere; emitemit variablevariable (UV)(UV) radiationradiation fluxflux CoronalCoronal massmass EjectionsEjections (Lasco on SOHO spacecraft) TheThe centercenter ofof activityactivity •• SunspotsSunspots andand thethe surroundingsurrounding activeactive regionsregions •• FacularFacular fieldsfields •• SolarSolar flaresflares andand theirtheir effectseffects •• CoronalCoronal MassMass EjectionsEjections •• ProminencesProminences ofof variousvarious kindskinds (will(will notnot beenbeen discusseddiscussed here)here) SunspotSunspot numbersnumbers •• RZ = Zürich sunspot number (dashed) •• RG = group sunspot number (solid; ref. Hoyt & Schatten) •• Use of RG advisable •• Maunder minimum from 1652 – 1704 •• During MM few spots but normal activity in plasma ejection TimeTime delaysdelays ofof variousvarious kinds:kinds: •• HighHigh latitudelatitude activityactivity followsfollows oror precedesprecedes (?)(?) sunspotsunspot activityactivity byby halfhalf aa SchwabeSchwabe cyclecycle •• GnevyshevGnevyshev Gap:Gap: spotspot activityactivity maximamaxima inin thethe twotwo hemisphereshemispheres areare notnot simultaneous;simultaneous; delaysdelays averageaverage aa yearyear •• EnergeticEnergetic EmissionsEmissions Delay:Delay: energeticenergetic emisissionemisission followfollow spotspot maximummaximum byby roughlyroughly 11 –– 22 yryr TheThe energeticenergetic emissionsemissions delaydelay •• EnergeticEnergetic emissionsemissions suchsuch asas XX oror γγ--rayray flaresflares (black)(black) delayeddelayed byby aboutabout oneone yearyear withwith respectrespect toto spotspot numbersnumbers ((lighterlighter shadedshaded;; ref. J. Allen)) EquatorEquator--wardward andand polepole--wardward driftdrift sunspotsunspot areaarea andand highhigh latitudelatitude magneticmagnetic fieldsfields [ref: Hathaway) VariationVariation intensityintensity GreenGreen CoronalCoronal lineline [Green line: 530.3 nm; FeXIV; ref. Makarov et al.] PlasmaPlasma ejectionejection LowLow-- andand highhigh--latitudelatitude ejectionsejections LatitudesLatitudes ofof ActiveActive RegionsRegions comparedcompared withwith thosethose ofof plasmaplasma ejectionejection [ref: Hundhausen] TwoTwo sourcessources forfor plasmaplasma ejection.ejection. ThreeThree questionsquestions •• From Centers of Activity; chiefly Coronal Mass Ejections (latitude below 40 ̊̊ ) •• At higher latitudes: from coronal holes, polar faculae, ephemeral active regions. •• The totality of all these ejections define the Source Function S (Solanki; Usoskin et al.) •• Q1: How is S known? •• Q2:Relation S – cosmogenic radionuclides deposit rate •• Q3: Relative contribution of low- and high-latitude sources to S function AnswersAnswers toto threethree questions:questions: •• 1.1. SourceSource functionfunction describesdescribes strengthstrength ofof openopen solarsolar fluxflux inin EarthEarth environmentenvironment →→ modulationmodulation ofof cosmiccosmic rayray fluxflux →→ changechange inin depositdeposit ofof cosmogeniccosmogenic radionuclidesradionuclides ((14C,C, 10 BeBe ……)) [refs: Solanki, Usoskin et al.; Beer et al.; Muscheler et al.] •• Hence,Hence, sourcesource functionfunction isis derivedderived (via(via physicalphysical theory)theory) fromfrom thethe raterate ofof depositdeposit ofof cosmogeniccosmogenic radionuclidesradionuclides 2.2. RelationRelation SS--functionfunction –– 10BeBe depositdeposit raterate [Ref. De Jager and Usoskin, submitted] 3.3. StronglyStrongly variablevariable plasmaplasma ejectionejection fromfrom lowlow-- resp.resp. highhigh--latitudelatitude areasareas •• OpenOpen solarsolar fluxflux duringduring MAXMAX oror MINMIN ((notenote:: arbitraryarbitrary units)units) •• LowLow latitudeslatitudes:: 2.752.75 0.550.55 •• HighHigh latitudeslatitudes:: 0.480.48 2.382.38 3.3. HighHigh-- andand lowlow--latitudelatitude plasmaplasma fluxesfluxes •• AverageAverage ratioratio betweenbetween SS--fluxesfluxes fromfrom lowlow latitudeslatitudes andand highhigh latitudeslatitudes == 1.21.2 (= average over 3 cycles; 1967.5 – 1998.5; refs. Wang, Kane, re. Wang & Sheeley, 2002; Cf. also Shrivastava, 2003: ~ 1.0) •• Note:Note: lowlow latitudelatitude ejectionsejections (CME(CME’’s)s) areare fromfrom ActivityActivity CentersCenters andand hencehence correlatecorrelate stronglystrongly withwith SunspotSunspot numbers.numbers. HighHigh latitudelatitude ejectionsejections areare not.not. HOWHOW DOESDOES THETHE SUNSUN INFLUENCEINFLUENCE CLIMATECLIMATE IrradianceIrradiance variationsvariations oror cosmiccosmic rayray modulationmodulation byby plasmaplasma clouds?clouds? 1.1. SolarSolar irradianceirradiance variationsvariations •• Less than 0.1% variation during cycle (upper frame) •• Correlated with average magnetic field (middle) •• and sunspot numbers (lower frame) •• Sunspot number R is proxy for irradiance variation •• Gnevyshev Gap (two maxima) OriginOrigin ofof irradianceirradiance variationsvariations •• Variations largest in ultraviolet spectrum, less in infrared; little or none in visible [ref Lean, 2000] •• Photospheric emissions (emitted in visual part of spectrum) do not vary •• Origin of variations: low- chromospheric levels of Active Regions •• Sources: scattered magnetic fields ( ~ 50 – 200 Gauss) in Active Region area SolarSolar UVUV emissionsemissions areare absorbedabsorbed inin terrestrialterrestrial stratospherestratosphere •• DoDo notnot reachreach tropospheretroposphere •• Hence,Hence, inin orderorder toto affectaffect tropospherictropospheric physicsphysics somesome kindkind ofof stratospherestratosphere –– tropospheretroposphere couplingcoupling isis neededneeded 2.2. TheThe otherother aspectaspect ofof solarsolar variability;variability; a.a. lowlow--latitudelatitude ejectionsejections •• FromFrom ActiveActive Regions:Regions: coronalcoronal massmass ejectionsejections •• CMECME--massmass isis 101012 toto 101013 kgkg •• SpeedSpeed atat EarthEarth distancedistance 200200 toto 25002500 km/seckm/sec •• MagneticMagnetic fieldsfields fromfrom CME’sCME’s carriedcarried alongalong intointo heliosphereheliosphere contributecontribute forfor ~~ 54%54% toto ‘Open‘Open solarsolar flux’flux’ (interplanetary(interplanetary magneticmagnetic fieldfield atat EarthEarth distance)distance) b.b. HighHigh latitudelatitude componentcomponent (~(~ 46%)46%) •• Solar wind, mainly high latitude coronal holes; varies during cycle; prominent during minimum •• Other ejection: from high latitude (ephemeral) active regions, polar faculae, structures associated with polar prominence zone •• All abrupt ejections (low- and high-latitude) cause: •• Co-rotating Interaction Regions = interplanetary shocks at collision of solar plasma ejections with earlier emitted slower wind OpenOpen solarsolar fluxflux (( ~~ SS--function)function) Left:Left: annualannual data;data; Right:Right: smoothedsmoothed [ Refs: Lockwood et al.; Solanki et al.] OpenOpen solarsolar fluxflux again.again. [Smoothed data from Solanki, Usoskin et al.] ModulationModulation ofof cosmiccosmic rayray fluxflux byby magneticmagnetic shieldingshielding inin heliosphereheliosphere CloudCloud coveragecoverage variationvariation parallel to cosmic ray flux [ref Svesnsmark&Friis-Christensen] CosmicCosmic rayray –– cloudsclouds scenarioscenario IncreasedIncreased solarsolar activityactivity yields:yields: •• StrongerStronger openopen solarsolar flux;flux; hencehence •• LargerLarger cosmiccosmic rayray deflection;deflection; causingcausing •• decreasedecrease ofof cosmiccosmic rayray flux;flux; causingcausing •• ReducedReduced cloudcloud formation;formation; hencehence •• IncreasedIncreased solarsolar irradianceirradiance
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