Climate and Weather of the Sun-Earth System (CAWSES): Highlights from a Priority Program PDF
Preview Climate and Weather of the Sun-Earth System (CAWSES): Highlights from a Priority Program
Climate and Weather of the Sun-Earth System (CAWSES) Springer Atmospheric Sciences Forfurthervolumes: www.springer.com/series/10176 Franz-Josef Lübken Editor Climate and Weather of the Sun-Earth System (CAWSES) Highlights from a Priority Program Editor Franz-JosefLübken LeibnizInstituteofAtmosphericPhysics RostockUniversity Kühlungsborn,Germany ISSN2194-5217 ISSN2194-5225(electronic) SpringerAtmosphericSciences ISBN978-94-007-4347-2 ISBN978-94-007-4348-9(eBook) DOI10.1007/978-94-007-4348-9 SpringerDordrechtHeidelbergNewYorkLondon LibraryofCongressControlNumber:2012945619 ©SpringerScience+BusinessMediaDordrecht2013 Thisworkissubjecttocopyright.AllrightsarereservedbythePublisher,whetherthewholeorpartof thematerialisconcerned,specificallytherightsoftranslation,reprinting,reuseofillustrations,recitation, broadcasting,reproductiononmicrofilmsorinanyotherphysicalway,andtransmissionorinformation storageandretrieval,electronicadaptation,computersoftware,orbysimilarordissimilarmethodology nowknownorhereafterdeveloped.Exemptedfromthislegalreservationarebriefexcerptsinconnection with reviews or scholarly analysis or material supplied specifically for the purpose of being entered and executed on a computer system, for exclusive use by the purchaser of the work. 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Printedonacid-freepaper SpringerispartofSpringerScience+BusinessMedia(www.springer.com) Foreword The Sun, combined with the Earth’s orbit, has always governed the activities of humanity on timescales from the changing seasons to glacial cycles. Changes in climate can be driven by alterations of the total solar irradiance (TSI) but recent evidencefromsatellitesshowsonlymodestchangesinTSIwhichhasonlyamin- imal impact on the current changes that are being observed in the climate system. However the solar insolation at ultra-violet and extreme ultra-violet wavelengths changesfrom∼7%tomorethan100%overasolarcycleandhencecanresultin majorchangesinthemiddleandupperatmospheres.Forexample,weakerwesterly winds at the Earth’s surface are observed in winters at sunspot minimum, and at sunspotmaximumthetemperatureofthethermosphereisabout400Kgreaterthan atsunspotminimumandthewindsareabouttwiceasstrong. EnergeticparticlesfromtheSuncanchangetheclimatesystemtoo.Observations ofsurfaceairtemperatures,derivedfromclimatere-analysisdata,showdifferences betweenperiodswhentherearesignificantspaceweathereventscomparedtothose periods when events are absent [Seppälä et al., 2009]. Differences can be as large as ∼4 K with areas of warming and cooling approximately the same suggesting a redistributionofenergy.However,themechanismbywhichthesechangesoccuris notknown. v vi Foreword AschangesintheEarth’satmosphereoccur,whetherduetochangesofsolarorigin or in response to enhanced green house gas concentrations, the propagation and dissipationofgravityandplanetarywaves,andtidesisaltered.Clouds,whetherthey occurinthetroposphere,stratosphereandmesospherehaveamarkedimpactonthe atmosphere. Thus, changes can occur on all spatial and temporal scales and both withinandbetweendifferentlevelsoftheatmospherecausedbysolarvariations. Addressing the Sun-Earth connections is both an essential and urgent issue. To understand both the natural variability of the climate system and those caused by humanityisessentialforthepredictionoffutureclimatescenariosthathavegreater confidence.Thereforeitistimelyfortheinternationalcommunitytohaveafocused scientificefforttoaddressthesecriticalissues. Researchoverpreviousdecadeshasprovidedsolidexplanationsofmanyofthe individual processes that are involved in the coupling of the Sun to the Earth en- vironmentbuttomakerealprogressatthesescientificfrontiersasystem-levelap- proachisnowrequired,andindeedpossibleforthefirsttime.Thenecessaryscience infrastructurehasdevelopedtoapointwhereitispossibletoaddressthesetopics. Theworldwideresearchcommunitynowhasaccesstointernationaldatasetsfrom every critical region in the space environment, a highly-distributed, ground-based networkofsensor,virtualobservatories,advancedcomputationalandvisualisation facilities,andsophisticatedSun-to-Earthcommunitymodels. But the availability of data and models is not enough; an operating framework is also required and this has been provided by the Scientific Committee on Solar- TerrestrialPhysics(SCOSTEP).ItwasestablishedasanInter-UnionCommissionof InternationalCouncilofScience(ICSU)in1966withtheaimtopromoteandorgan- iseinternationalinterdisciplinaryprogrammesoflimiteddurationinsolar-terrestrial physics.In2004SCOSTEPbegantheClimateandWeatheroftheSun-EarthSys- temprogram—CAWSES—withthespecificobjectivetoenhanceunderstandingof thespaceenvironmentanditsimpactonspaceweatherandtheclimate.CAWSES madeverysubstantialprogresssinceitsinceptionnotonlyinpushingbackthefron- tiersofknowledgebutalsoinbuildingsciencecapacityindevelopingcountries.It heldthefirstvirtualconferencewhichhad270participants.Afterfiveyears,itwas recognisedthattherewasmuchstilltobeachievedandhenceSCOSTEPendorsed CAWSES-IItorunfrom2009–2013.Therewasre-focusingoftheworkinggroups toreflecttheevolutionofsciencequestionsbutthefundamentalaimremainedthe same. CAWSESandCAWSES-IIonlyprovideascientificstrategyandframeworkthat givesfocusforthedevelopmentofrelevantscienceactivities.Forsuchinternational initiativestobesuccessfultheengagementofscientistsacrossmanydisciplinesin many countries is essential. It needs passionate scientific leadership, and champi- onswhocanpersuadefundingorganisationstosupporttheresearch.Fundingagen- cies also have to be willing to take initiatives, and sometimes risks. The Deutsche Forschungsgemeinschaft (DFG) German Research Foundation recognised the im- portanceofSun-EarthconnectionscienceandcreatedaGermanCAWSESPriority Programme. The Programme, very ably led by Prof. Dr. Franz-Josef Lübken, has exploredmanyaspectsofSun-climatelinksasisamplydemonstratedbythecom- prehensiveandilluminatingchaptersinthisbookstretchingfromfundamentalsolar Foreword vii physicsthroughto thesurface of theplanet.There is an excellentblendof theory, observationandmodelling.TheProgrammehasalsobeenverysuccessfulineduca- tionaltermsgivingmanyopportunitiesforearlycareerscientists.Wecommendboth theGermanCAWSES PriorityProgrammeandthebook—botharetrulyexcellent exemplarsfortheresearchcommunity. References Seppälä,A., Randall, C.E., Clilverd, M.A., Rozanov, E., & Rodger, C.J. (2009). Geomagnetic activityandpolarsurfacelevelairtemperaturevariability.JournalofGeophysicalResearch, 114,A10312.doi:10.1029/2008JA014029. ChairsofCAWSES AlanRodgerandSusanAvery Preface TheSunisthemostimportantexternaldriverofclimate.Althoughthetotalsolarir- radiance(TSI)fluctuatesbylessthan0.1%duringasolarcycle,thesolarimpacton the terrestrial atmosphere can be significant, in particular in the upper atmosphere wherethehighlyvariableenergeticpartofthesolarspectrumisabsorbed.TSIvaria- tionsoncentennialtimescalesareofsimilarmagnitude.Unfortunately,thescientific understandingofthevariationofsolarradiation(anditsspectralcomponents)and itsimpactontheatmosphereisratherlimited.Thisconcernsthedirectmodification ofcompositionbysolarradiation,butevenmoresovariouscouplingmechanisms. Forexample,photochemicallyactivegasesaregeneratedintheupperatmosphere, propagate to lower layers where they substantially alter the composition, e.g., the abundance of ozone. Planetary waves, gravity waves, and tides are excited in the atmosphereandpropagateoverlargedistances.Theytransporttracegases,energy, and momentum. Although these waves are most pronounced in the middle atmo- sphere,theymaymodifythebackgroundcirculationintheentireatmosphere,even inthetroposphere.Ascanbeseeninvariouschaptersinthisbook,majorprogress has been achieved in our understanding of solar radiation, its impact on the atmo- sphere,andcouplingmechanismswithintheatmosphere.Still,variousuncertainties exist.Forexample,theobservedsolarsignalinsomepartsofthemiddleatmosphere islargerthancanbeexplainedbymodels. Thepurposeofthisbookistosummarisethescientificresultsrelatedtoamajor research program of the international SCOSTEP organisation (Scientific Commit- teeonSolar-TerrestrialPhysics)calledCAWSES(ClimateAndWeatheroftheSun Earth System). The German Research Foundation (Deutsche Forschungsgemein- schaft, DFG) ran a priority program (‘Schwerpunktprogramm’, SPP) from 2005 to 2011 focusing on several important science topics from CAWSES. The aim of theCAWSESSPPisabetterunderstandingoftheinfluenceoftheSunontheter- restrial atmosphere and the physical/chemical processes involved in various cou- plingmechanismswithintheatmosphere.TheDFGspentapproximately10Million Euro for a total of 25–30 institutes. Most of the financial support from DFG was usedforpostdoctoralandPhDstudentpositions.In31chapters,thisbookpresents the scientific summaries from 28 projects supported under a total of 93 individual ix x Preface grants. Internationalcooperationwas strongly encouragedand supportedby funds for travel, etc. At each stage of the proposals, an international team of reviewers assistedtheDFGintheirselections.Severalhundredpaperswerepublishedinin- ternationalpeerreviewedjournalswithinthepriorityprogram. The book is structured in six parts, namely i) solar radiation, heliosphere, and galactic cosmic rays (Chaps. 2 to 6), ii) solar influence on trace gases (Chaps. 7 to 10), iii) thermosphere, energetic particles, and ionisation (Chaps. 11 to 17), iv)mesosphericiceclouds(Chaps.18–20),v)gravitywaves,planetarywaves,and tides (Chaps 21 to 28), and vi) large-scale coupling (Chaps. 29 to 32). The evolu- tionofsolarradiation,itseffectongalacticcosmicrays(GCR),andtheirpotential impactonclouddropletsinthetropospherearestudiedindetail.Somechapterscon- centrateonthedirecteffectofsolarradiationontracegases,mainlyonozoneand watervapourinthestratosphereandmesosphere.Precipitatingparticlesofsolaror geomagneticoriginmodifytheupperatmospheredirectly.Theyalsoproducepho- tochemically active species which can be transported downward and significantly affectthemesosphereandupperstratosphere.Thisaspectisstudiedinseveralchap- ters. Results on short and long-term variations of mesospheric ice clouds, as well asrelatedmicrophysicalaspectsarepresented.Planetarywaves,gravitywaves,and tides play a key role in distributing and modifying a signal being imposed some- where in the atmosphere by, for example, the solar cycle. Physical details of this process and implications of wave morphology for the entire atmosphere, from the thermosphere to the troposphere, are presented in several chapters. Finally,results onglobalaspectsofthesolarcycle,long-termvariations,andcomparisonwithan- thropogenicclimatechangearecovered. Thisbookaddressesresearchersandstudentswhoareinterestedinactualresults onsolarcycleandlongtermvariationsintheatmosphere.Thechaptersarewritten byleadscientistsfromnearlyallmajorGermanresearchinstitutionswheretheter- restrialatmosphereisinvestigated.Abriefintroductionisprovidedatthebeginning ofeachchaptertofamiliariseabroadercommunitywiththescientificbackground. Each chapter was subject to an international peer review process to ensure high quality. InthenameoftheGermanCAWSEScommunityIthanktheGermanResearch Foundation for funding the CAWSES priority program. We appreciated the con- structiveandstimulatingsupportfromthereviewers,someofwhomaccompanied our program for the entire six years. As speaker of this program I would like to express my appreciation for all the activities, excitement, and success being cre- ated in various groups. Perhaps most important, many students were involved and contributedtotheenthusiasmwhenworkingonawiderangeofscientifictopicsof solar-terrestrialphysics.IthankDr.NorbertEnglerandMonikaRosenthalfortheir excellentassistancewhencompilingthisbook. Kühlungsborn Franz-JosefLübken February2012
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