Table Of ContentISSI Scientific Report Series
Forfurthervolumes:
http://www.springer.com/series/10151
Lennart Bengtsson • Roger-Maurice Bonnet
David Grinspoon • Symeon Koumoutsaris
Sebastien Lebonnois • Dmitri Titov
Editors
Towards Understanding
the Climate of Venus
Applications of Terrestrial Models
to Our Sister Planet
Vol. No. 11
123
Editors
LennartBengtsson Roger-MauriceBonnet
InternationalSpaceScienceInstitute InternationalSpaceScienceInstitute
Bern,Switzerland Bern,Switzerland
DavidGrinspoon SymeonKoumoutsaris
DepartmentofSpaceScience PeninsularHouse
DenverMuseumofNatureandScience RiskManagementSolutionsLtd
Denver,CO,USA London
UnitedKingdom
SebastienLebonnois
LaboratoiredeMeterologie DmitriTitov
Dynamique ESA-ESTEC
Paris,France Noordwijk,TheNetherlands
ISBN978-1-4614-5063-4 ISBN978-1-4614-5064-1(eBook)
DOI10.1007/978-1-4614-5064-1
SpringerNewYorkHeidelbergDordrechtLondon
LibraryofCongressControlNumber:2012951841
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Coverillustration:
–Galaxy,NASA/JPL-Caltech/C.Lonsdale(Caltech/IPAC)andtheSWIRETeam
–WholeEarth,NASA
–HemisphericviewofVenus(Magellan),NASA/JPL-Caltech
–UltravioletimageofVenus’clouds(Pioneer),NASA
–Artist’simpressionofVenusExpressspacecraft,ESA-AOESMedialab
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Foreword
Back in 2003, ISSI organized one of its regular internal reflexion meetings and
invitedafewscientiststosharefortwodaystheirviewsonthefutureorientations
ofthescientificactivitiesoftheinstitute.Theirscientificexpertisecoveredabroad
range of disciplines and interests, from astronomy to solar physics, planetology,
and Earth sciences. One important recommendation of that meeting was to open
ISSIactivitiestoEarthsciences,inparticulartoatmosphericphysicsanddynamics,
and also to the solid Earth, to volcanology and desertification, insisting that they
be considered in the broader context of comparative planetology. A few years
later these recommendations were implemented. A contract was established with
the ESA Directorate of Earth Observations, and Lennart Bengtsson, the leading
force behind the preparation of this book, was recruited as ISSI Director for
Earth sciences. Lennart did not participate in the 2003 reflexion but he rapidly
assimilated its conclusions, in particular as to what concerned Earth sciences and
comparative planetology, as well as the unique opportunities offered by ISSI for
hostingscientificvisitorsfromallaroundtheworldandfrommanyareasofspace
science.HerapidlyproposedthatISSIdedicatesoneofitsfutureWorkingGroups
to the climate of Venus. The study of Venus climate would indeed offer a natural
responseto the 2003meetingrecommendations.Openingthe ISSI programto the
field of Earth sciences through comparative planetology was in continuity with
the traditional space science orientations characterizing previous ISSI activities.
Whenplanetologistsareaskedtojustifytheiractivitiesandthecostsoftheirspace
missions some very often respond that the study of planets should improve our
understandingoftheEarth.
Amazingly, the logics which led Lennart to establishing a Working Group on
theclimateofVenusisnearlytheopposite,asthetitleofthisbookexplicitlysays:
“Towards understanding the climate of Venus: Applications of terrestrial models
to our sister planet”! The work reported here aims at showing how the modelling
of the EarthatmospherethroughGeneralCirculationModelshelpsimprovingour
understandingofVenus.IntheSolarSystem,amongalltheotherplanets,theEarth
is exhibiting the largest complexity. It is all at the same time: a solid planet, a
magneticplanet, a liquid planet, an icy planet, and an atmosphericplanetand last
v
vi Foreword
butcertainlynotleastalivingplanet(ithostslife).Venusisindeedoftencalledour
sisterplanet.Itisratherourfalsetwin.ItwasformedatthesametimeastheEarth
4.6billion yearsagofromthe same proto-solarnebula.With a diameter95% and
amass80%thatoftheEarth,Venusisalittlesmallerhowever.Bothplanetshave
nearlythesamedensityandchemicalcomposition.Theybothhaveanatmosphere
and clouds. But they also have marked differences. Contrary to Venus, the Earth
evidencesplatetectonics,ithasamagneticfield,anditssurfaceiscoveredat70%
bywater.VenushadprobablythesameamountofwaterastheEarthbutlostitvery
earlyinitshistory.Today,itisanariddesertanditssurfacetemperatureis460ıCas
a consequenceof the enormousatmosphericpressureand the extremegreenhouse
effectproducedearlyinitslifebythehighconcentrationofCO ,re-enforcedbythe
2
presenceofcloudparticlesanddropletsofsulphuricacid.Besidestheunbreathable
atmosphere,atthistemperature,lifeisimpossible.TheRussianprobeswhichlanded
onVenusin1970and1982couldtransmitsignalsandpicturesofthesurfaceforno
morethan2hmaximum(Venera-13),afterwhichtheheatdestroyedtheequipment.
Furthermore,theabsenceofwaterthatplaysanessentiallubrificationroleinEarth’s
tectonic activity has probablyput to a standstill any such activity that might have
existedonVenus,nowasingle-plateplanet.Nevertheless,acomparativestudyofthe
poorlyknownatmosphereofVenusbasedonthemodelsthathavebeendeveloped
fortheextensivestudiesoftheEarthatmosphereisanapplicationthatmayhelpus
understandingtheirenormousdifferencesandforecastingtheirlong-termevolution.
Forexample,theEarthmightfollowthesame trendasVenuswhentheincreasing
luminosity of the Sun at a rate of 1% per 100 million years would have raised
its temperature to the point where as was the case for the young Venus, water
moleculeswouldstartbeingphoto-dissociated,anirreversibleprocessleadingtothe
endoflifeinaboutonebillionyears.Theproblemisnotthatsimplehowever,asthe
atmosphericcirculation,verydifferentonbothplanets,mustplayanimportantrole
intheprocess.Therefore,itisofimportancetounderstandatmosphericcirculation
inthedifferentphysicalconditionscharacterizingthetwoplanets.
The work described in this book is unique and well in line with the inter-
disciplinary approach that characterizes ISSI activities. While the Earth has been
observed by several hundreds of artificial satellites, in addition to an enormous
amountof insitu measurements,thenumberof satellites launchedto Venustotals
todayjust 40(mostly Russian) of whichonly 20were successful. The similarities
andthelargedifferencesbetweenthetwoplanetswouldsupportamorecontinuous
international effort in Venus exploration. This book offers an excellent basis on
whichtobuildtheconvincingargumentsforsustainingsuchlong-termexploration.
Let me address my compliments to all the contributors to this book among
whomI would like to explicitly mentionLennartBengtsson who deservesspecial
acknowledgements.Similarly,SimosKoumoutsarisshouldbeacknowledgedforhis
dedicationandhelpinorganizingthemeetingsandintheeditingofthebook.
Bern,Switzerland Roger-MauriceBonnet
Contents
1 Introduction................................................................. 1
LennartBengtsson
PartI WhatDoWeKnowAboutVenus?
2 HistoryofVenusObservations............................................ 7
Roger-MauriceBonnet,DavidGrinspoon,
andAngeloPioRossi
3 TheSurfaceandAtmosphereofVenus:Evolution
andPresentState ........................................................... 17
DavidGrinspoon
4 RadiativeEnergyBalanceintheVenusAtmosphere................... 23
DmitrijV.Titov,GiuseppePiccioni,PierreDrossart,
andWojciechJ.Markiewicz
5 AtmosphericCirculationandDynamics................................. 55
SanjayS.LimayeandMiriamRengel
PartII ModelingtheAtmosphericCirculationofVenus
6 TheDynamicsandCirculationofVenusAtmosphere.................. 73
PeterL.Read
7 ModelingEfforts............................................................ 111
StephenR.Lewis,JonathanDawson,SebastienLebonnois,
andMasaruYamamoto
vii
viii Contents
8 ModelsofVenusAtmosphere ............................................. 129
SebastienLebonnois,ChristopherLee,MasaruYamamoto,
JonathanDawson,StephenR.Lewis,JoaoMendonca,
PeterRead,HelenF.Parish,GeraldSchubert,LennartBengtsson,
DavidGrinspoon,SanjayS.Limaye,HaukeSchmidt,
Ha˚kanSvedhem,andDimitriV.Titov
9 ComparingEarthandVenus ............................................. 157
HaukeSchmidt
PartIII Outlook
10 FutureProspects............................................................ 171
Ha˚kanSvedhemandDavidGrinspoon
Chapter 1
Introduction
LennartBengtsson
Theultimatepurposeofthisbookistoincreaseourunderstandingoftheclimateof
planetVenus. We will endeavor to do so by bringingtogetherrecent observations
from Venus with the general knowledge of the Earth’s atmosphere that has been
collectedoveralongperiodoftimefrommodelinganddatastudies.
Superficially, there are many similarities between Earth and Venus when ob-
servedfroma greatdistance buta close inspectionrevealscriticaldifferencesthat
make life on Venus inconceivable. In fact our sister planet is highly inhospitable.
Itssurface temperatureisaround460ıCwhere leadand tin willstart to melt, and
ithasacloudcoverwherethedropletsarenotwaterbutsulphuricacid.Thecause
of the high surface temperature is not that Venus is receiving more sunlight than
the Earth. In fact it receivessignificantly less as can be seen in Table 1.1. Instead
thehighsurfacetemperatureofVenusresultsfromthedifferentcompositionofits
atmosphere,consistingof96%carbondioxide,aswellasitshugeatmosphericmass
that is 92 times larger than that of the Earth’s atmosphere.There are also marked
differencesduetothe slow rotationofVenus,whichmeansthattheCoriolisforce
thatiscrucialindeterminingthedynamicalstructureoftheEarth’satmosphereplays
asecondaryroleonVenus.
ThepresentunderstandingofVenusistheresultofalargenumberofsuccessful
space missions to the planet that started in 1962 with Mariner1. The latest in the
series,tobediscussedinmoredepthinthisbook,istheVenusExpressmissionof
theEuropeanSpaceAgency.VenusExpress,bynowhasbeencollectinginformation
sinceApril2006.
However,ourknowledgeofplanetaryatmospheresdoesnotcomefromempirical
studiesonlybutalsofromtheoreticalconsiderationsbymakinguseofourgeneral
knowledgeof fluid mechanics and thermodynamics.This has been the alternative
approach for the Earth’s atmosphere through the use of physically based general
L.Bengtsson((cid:2))
InternationalSpaceScienceInstitute,Bern,Switzerland
e-mail:[email protected]
L.Bengtssonetal.(eds.),TowardsUnderstandingtheClimateofVenus,ISSIScientific 1
ReportSeries11,DOI10.1007/978-1-4614-5064-1 1,
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