NASA Technical Reports Server (NTRS) 20170000649: Extratropical Weather Systems on Mars: Radiatively-Active Water Ice Effects

0.74 MB·English

by  NASA Technical Reports Server (NTRS)

EXTRATROPICALWEATHERSYSTEMSONMARS:RADIATIVELY-ACTIVE
WATER ICE CLOUD EFFECTS.
J.L.Hollingsworth,M.A.Kahre,R.M.Haberle,SpaceScienceandAstrobiologyDivision,PlanetarySystems
Branch,NASAAmesResearchCenter,MoffettFieldCA94035USA([email protected]),R.A.Urata,
BAERInstitute/NASAAmesResearchCenter,MoffettFieldCA94035USA,F.Montmessin,LaboratoireAtmosphe`res
Mileux,ObservationsSpatiales(LATMOS),78280GuyancourtFR.
Introduction:Extratropical,large-scaleweatherdis- meantemperaturecontrasts(i.e.,“baroclinicity”). Data
turbances,namelytransient,synoptic-period,baroclinic- collected during the Viking era and observations from
barotropiceddies–or–low-(high-)pressurecyclones boththeMarsGlobalSurveyor(MGS)andMarsRecon-
(anticyclones), are components fundamental to global naissanceOrbiter(MRO)indicatethatsuchstrongbaro-
circulation patterns for rapidly rotating, differentially clinicitysupportsvigorous,large-scaleeastwardtravel-
heated, shallow atmospheres such as Earth and Mars. ing weather systems [Banfieldetal., 2004; Barnesetal.,
Such“wave-like”disturbancesthatarise via(geophys- 1993]. A good example of traveling weather systems,
ical) fluid shear instability develop, mature and decay, frontalwaveactivityandsequestereddustactivityfrom
andtravelwest-to-eastinthemiddleandhighlatitudes MGS/MOCimageanalysesisprovidedinFigure1(cf.
withinterrestrial-likeplanetaryatmospheres. Thesedis- Wangetal. [2005]).
turbancesserveascriticalagentsinthetransportofheat Utilizing an upgraded and evolving version of the
and momentum between low and high latitudes of the NASA Ames Research Center (ARC) Mars globalcli-
planet. Moreover,theytransporttracespecieswithinthe mate model, investigated here are key dynamical and
atmosphere(e.g.,watervapor/ice,otheraerosols(dust), physicalaspectsofsimulatednorthernhemisphere(NH)
chemicalspecies,etc). large-scaleextratropicalweathersystems,withandwith-
outradiatively-activewatericeclouds.
Mars Climate Model: Over the past 5+ years,
several major improvements have been made to the
NASA ARC Mars global climate model (Mars GCM)
to enhance its capabilities and to standardized its in-
frastructure. Physicsimprovementsincludeanupdated
radiation code based on a generalized two-stream ap-
proximation for radiative transfer in vertically inho-
mogeneousmultiple-scatteringatmospheres[Toonetal.,
1989],togetherwithacorrelated-kmethodforcalculat-
inggaseousopacities[LacisandOinas, 1991]. Inappli-
cationshere,theradiationcoderespondstoaprescribed
dust distribution based on an opacity climatology de-
rivedfromMGSThermalEmissionSpectrometer(TES)
9-µmopacitymeasurementsduringMY24. Thevertical
distributionvarieswithseasonandlatitude.
A complex cloud microphysics package has been
includedbasedontheworkofMontmessinetal.[2002];
Montmessinetal.[2004]. Thismicrophysicsmoduleas-
sumesalog-normalparticlesizedistributionwhosefirst
twomomentsarecarriedastracers,andwhichincludes
the nucleation, growth and sedimentation of ice crys-
tals [Montmessinetal., 2004]. The cloud microphysics
package includes a time-splitting (sub-stepping) prog-
Figure 1: MGS/MOC hemispheric image analyses [Wang et nosticalgorithm,anditinteractswithatransporteddust
al., 2005] of large-scale synoptic extratropical weather sys- tracer whose surface source is adjusted to maintain an
temsduringNHautumnandlatewinterwithsequestereddust atmospheric column abundance as observed by TES.
activitywithincyclones/frontalwaves. Aerosolsofdustandwaterice,inadditiontowaterva-
por, can be separately or collectively either radiatively
inert (default case) or radiatively active (in combina-
Betweenearlyautumnthroughearlyspring,middle tion). Otherimprovementsintheclimatemodelinclude
andhighlatitudesonMarsexhibitstrongequator-to-pole implementing a new planetary boundary layer (PBL)
Mars’NorthernHemisphereTraveling,SynopticWeatherSystems&Water-IceClouds
model(i.e.,alevel-2MellorandYamadaapproach[Mel- nucleationcontactparameter,m).
lor and Yamada, 1982]; incorporation of a sub-surface Figure2showsmeanzonalcrosssectionofthezonal
landmodel;utilizationofahighlymodularizedfinitedif- wind (color) and temperature (white dashed contours)
ferencedynamicalcore(basedonanArakawa“C”-grid) during northern early spring (Ls = 30◦) from the two
[Suarez and Takacs, 1995] that incorporates improved simulations. IntheRACcase(toppanel),thereisstrong
tracer transport [Hourdin and Armengaud, 1995]. This baroclinicity within middle and high latitudes of both
latest version has been termed NASA ARC Mars GCM, northernandsouthernhemispheres,andstrongwesterly
version2.3 (gcm2.3). Please see Kahreetal. [2017]for jetsareindicatedwithmaximumspeedsover110ms−1.
furtherdetailsonthisparticularrelease. Innorthernmidlatitudes,themeanzonalisothermsshow
Results: We focushereontwomulti-annualwater littletiltwithinthefirstcouplescaleheights(i.e.,theyare
cycle simulations: (i) one where water-ice clouds are
radiativelyactive(“RAC”case);and,(ii)onewhereice
clouds are radiatively inert (“nonRAC” case). These Daily Ave Surface Pressure
two cases are subsets detailed in Kahreetal. [2017] to Arcadia
assess attributes of the simulated water cycle together
RAC
with comparisons with recent MGS and MRO obser- 10.0 Baseline
mbar) 9.0
Pressure ( 8.0
7.0
0 60 120 180 240 300 360
Ls (deg)
Figure3: DailyaveragedsurfacepressureintheArcadiare-
gionasafunctionofLsfortheRACcase(redcurve)andthe
baseline(nonRAC)case(blackcurve).
moreverticallyoriented)thaninthenonRACcase. This
characteristic holds also at other seasons. Differences
(i.e.,RAC–nonRAC)betweenthesetwocorresponding
fields(bottompanel)showthatradiatively-activewater
icecloudsprofoundlyaffecttheseasonalmeanclimate.
Thereis a bulkwarmingofthe atmospherein thesub-
tropicsaloft,acooling(warming)oftheatmospherein
lower (upper) regions at high latitudes, and, increases
inthemeanpole-to-equatortemperaturecontrasts(i.e.,
stronger mean “baroclinicity”) resulting in augmented
zonaljets. Suchthermalandmeancirculationchanges
have also been found in the studies by Haberle et al.
Figure 2: Time and zonally averaged temperature (K) and [2011],Madeleineetal. [2014]andNavarroetal. [2014].
zonal wind(ms−1)duringearlynorthernspring(Ls =30◦) Themeanoverturning(i.e.,“Hadley”)circulationisalso
fortheRACcase(a)andthecorresponding differencefields enhanced in the RAC case. These changes are signif-
(i.e., RAC–nonRAC) (b) from the water cycle simulations icant in the middle and high latitudes. Comparisons
conducted with the ARC Mars GCM. The contour interval withMGS/TESandMRO/MCSmeasurementsindicate
is 10 K and 2 K in panels (a) and (b), respectively, and in betteragreementbetweenthemodel’ssimulatedclimate
(b)negativevaluesaredashed. Colorshadingcorrespondsto comparedtoobservations.
zonalwind. The increased baroclinicity is robust and signifi-
cantly affects the intensity and seasonality of synoptic
weather systems. Figure 3 shows time series of the
vations, and further, several sensitivity experiments to daily-averaged surface pressure in the northern hemi-
the assumed cloud microphysicalparameters (e.g., the sphere(NH)Arcadiaregion,ageographicregionprevi-
Mars’NorthernHemisphereTraveling,SynopticWeatherSystems&Water-IceClouds
ouslyfoundto indicateenhancedsynoptic-periodtran- ing heat, momentum and other scalar quantities (e.g.,
sientwaveactivity(i.e.,a “stormzone”)[Hollingsworth atmospherictracers)withinmiddlelatitudes.
etal.,1996;Hollingsworthetal.,1997]. Itcanbeseenthat
thereis enhancedsynopticperiodvariability(i.e., day-
to-dayweather)inbothamplitudeandintra-seasonality 90 Stat Geopot Height Deviat (m), p = 3.0 mb : Run 14.110M, Ls = 190o
inthesimulationwithradiatively-activewatericeclouds 80 -50
(redcurve). Similarcharacteristicsarefoundintheother 70 350450 50
stormzoneregionsoftheNH.Inaddition,theSHextra- 60
tiartlyos,oppiacapsrptaieclsauorlsairntlodyibcienatitenhseeennwhsaeintsitcveeerdntoshymenmoopidstepilch-(ephreoerr.iiozTdohnvitsaarlri)earsbeuisll--t Latitude (deg)23450000 -50 21550500 -150 50 -1-52050
olution. High-resolution(×2)simulationsfortheRAC 10 -50
and baseline cases indicate very similar transient eddy 0
amplitudesandseasonality. 90-180 -120 Stat- 6T0emp Deviat (K), Lpo n=g i3tu.0d0e m (dbe g:) Run 14.110M, L6s 0= 190o 120 180
AsindicatedinFigure4,synopticperiodvariability 80
is significantly enhanced in the RAC case. Transient- 70
etprdaodrpeyidcpstooaltrehewevanerodrynhRmeAautCcflhcuaxesneesh(awin.eict.he,dianfianthcetthoNerHoRfAathnCrdeceSaHsstereocxnotgmrae--r Latitude (deg)34560000 2 -2 2 -2
2
at least). As such, the baroclinic/barotropic eastward 20
10 -2 2 -2
0
0.01 Trans vT Covar (K ms-1) : Run 14.110M, Ls = 0230o 6.6 8900-1809 3-120 -3Stat Mer-i6d0 Wind Deviat (m Lso-1n)g,i tpu0d =e (3d.e0g )mb : Run 14.1106M0, Ls = 190o 120 180
70 9
-2 5.6 60
0.10 4.6 Latitude (deg)4500 -9 3
3.6 30 -9 -3
6 2.6 1200 -3 -9 -33 39 -33 9 -9
0
1.00 1.6 -180 -120 -60 Longitu0de (deg) 60 120 180
-14-6 0.6 Figure 5: NH longitude-latitude cross sections during early
-10-2 1011482226 2 northern autumn (Ls = 190◦) at 3.0 mbar of stationary (a)
10.00 2 6 -0.4
geopotentialheight(m);(b)temperature(K);and,(c)merid-
-90 -70 -50 -30 L-a1t0itude (d1e0g) 30 50 70 90 ionalwind(ms−1)fromtheMarsGCMwithRAC.Theabove
Trans vT Covar (K ms-1) : Run 14.111M, L = 030o
s fieldsareshowninwhitecontours(negativedashed) andthe
0.01 6.6
-2 colorshadingisthesmoothedtopographyattheresolutionof
5.6
theGCM.
4.6
0.10
3.6 Considerationofthestationary,forcedRossbymodes
2.6 withintheRACcaseduringearlyNHautumn(Ls=190◦)
2 in termsofa longitude-latitudesectionatthe 3.0mbar
1.00
1.6 level are presented in Figure 5. Within the northern
hemisphere,thisfigurepresentsthestationarygeopoten-
-6 0.6
-2 2 101418 tialheight(toppanel);temperature(middlepanel);and
10.00 6 -0.4 meridionalwind(bottompanel). Inallthreemeanzonal
-90 -70 -50 -30 -10 10 30 50 70 90
Latitude (deg) departure fields, a clear zonal wavenumber s = 2 sta-
tionarypatternisevident. ThisisgenerallyarobustNH
Figure4:Transienteddypolewardheatflux(Kms−1)forthe pattern,andisfurtherdiscussedinHaberleetal. [2017]
RAC case (top panel) and the nonRAC case (bottom panel) forotherseasons,andcomparisonswithMRO/MARCI
duringearlynorthernspring(Ls=30◦). Thecontourinterval UV water-ice cloud observations. What is apparentin
inbothpanelsis2Kms−1.Positivevaluesaresolid,negative Figure 5 is a strong correlation of the forced Rossby-
valuesaredashed. wave pattern with the large-scale orography: namely,
highreliefcollocatedwithhighgeopotential;lowrelief
collocatedwithlowgeopotential—aclassicsignatureof
traveling waves are much more efficient in transport- forcedRossbywaveresponseswithinabaroclinicatmo-
Mars’NorthernHemisphereTraveling,SynopticWeatherSystems&Water-IceClouds
sphere[HoskinsandKaroly,1981]. InthenonRACcase
(not shown) the forced Rossby wave pattern presents 90 Trans Geopot Ht RMS Deviat (m), p = 3.0 mb : Run 14.110M, Ls = 190o
a more zonal wavenumber s = 1 stationary pattern in 80 18
middleandhighlatitudes,andoneofmuchweakeram- 70 18
60
plituTdheeirnetihsesthigrneeifificealndtsicnotnerspidlaeyredb.etween the forced Latitude (deg)4500 12 18 12
Rossbystationarymodesandthetravelingsynopticpe- 30
riodtransientwaves. In particular,the geographic“lo- 20 6 6
10
calization”ofmaximumband-passtransientvarianceis
0
h6igfohrlythtieedRtAoCthMefaorrsceGdCRMosssibmyumlaotdioens.dSuhroinwgneianrFlyigNurHe 90-180 -120 Trans T-e60mp RMS Deviat (LKo)n,g pitu 0=de 3 (.d0e gm)b : Run 14.110M60, Ls = 190o 120 180
80
autumn(Ls=190◦)intermsofalongitude-latitudesec- 70 4 4
tionatthe3.0mbararesimilarfieldspresentedinFigure 60 6
5sdileyenepttafgonereotlph);oetabenandnti,dam-lpheaersiisgdfihiolttn(eatrolepdwp(iina.end.e,(l2b)–;o1ttet0omdmpaeypr)aaRtnueMrle)S.(mtrTaihdne-- Latitude (deg)345000 2 4 42
20
amplitude and location of the transient RMS maxima
10
arevastlydifferentintheRACcaseversusthenonRAC 0
cteamsep(enraottusrheovwanri)a:ntcheerjuesitsnloocrtahleizaasttioonftohfepTehakartsriasnhsiigehn-t 8900-1806810 -120 Trans Me-6ri0d RMS Deviat1 (m2L osn-1g)i,tu p0d e= 8( d3e.g06) mb : Run 14.1106M0, Ls = 1940o 120 4 180
landsintheRACcasewhereasamorezonallyuniform 70 12 12
andweakerpatternoccursinthenonRACcase. Further, 60 10 12
tihneammeprliidtuiodneaalnwdingdeotgraranpsiheinctalfilyelldoscaalriezemduicnhthsteroRnAgeCr Latitude (deg)4500 8 68 4 1086
casecomparedtothenonRACcase(notshown). 30 4 2
20 2 4
Such transient synoptic period storm zone patterns 10 2 2
varybetweentheRACandthenonRACcasesinsubtle 0 2
-180 -120 -60 Longitu0de (deg) 60 120 180
yet nontrivial ways, and the maxima and geographic
localization of transient variability occur differently at Figure 6: NH longitude-latitude cross sections during early
thesameseasonswithintheannualcycle. northern autumn (Ls =190◦) at 3.0mbar of transient band-
Summary: ManyupgradestotheNASAAmesRe- passfilteredRMS(a)geopotentialheight(m);(b)temperature
searchCenter(ARC)Marsglobalclimatemodel(GCM) (K); and, (c) meridional wind(m s−1) fromthe Mars GCM
have occurredrecently and include a modern radiative withRAC.Theabovefieldsareshowninwhitecontoursand
transfer package and cloud microphysics package that thecolorshadingisthesmoothedtopographyattheresolution
permitradiativeeffectsandinteractionsofsuspendedat- oftheGCM.
mosphericaerosols(e.g.,watericeclouds,watervapor,
dust,andtheirmutualinteractions)toinfluencethenet
diabatic heating within the atmosphere. Atmospheric
aerosolsarecritically importantin determiningthe na- References:
tureof the meanthermalstructureandcirculation,and Banfield et al., 2004: Icarus, 170, 365; Barnes et
hencetheoverallclimateoftheplanet[Hobbs,1993]. al., 1993: J. Geophys. Res., 98, 3125; Haberle et al.,
OurMarsGCMsimulationsindicatethatradiatively 2011: MAMO4, Paris, France; Haberle et al., 2017: In
activeicecloudsprofoundlyaffecttheseasonalandan- prep; Hobbs, 1993: Aerosol-Cloud-Climate Interactions,
nual mean climate in a variety of ways. Such results Academic Press; Hollingsworth et al., 1996: Nature,
suggestthatthebulkthermalstructureandresultantcir- 380, 413; Hollingsworth et al., 1997: Adv. Space Res.,
culationpatternsarestronglymodifiednearthesurface 19, 1237; Hoskins and Karoly, 1981: J. Atmos. Sci.,
andaloft. Generallyspeaking,itisfoundthereiswarm- 38, 1179; Hourdin and Armengaud, 1995: Mon. Wea.
ing of the atmosphere in subtropical and high-latitude Rev., 127, 822; Kahre et al., 2017: MAMO6, Granda,
upper layers, cooling of the atmosphere in the lower Spain; Lacis and Oinas, 1991: J. Geophys. Res., 96,
high-latituderegions,and,increasesinthemeanpole-to- 9027; Madeleine et al., 2014: Geophys. Res. Lett., 41,
equatortemperaturecontrasts(i.e.,strongermean"baro- 4873; Mellor and Yamada, 1982: Rev. Geophys. Space
clinicity")andaugmentedzonaljets. Comparisonswith Phys.,20,851;Montmessinetal.,2002: J.Geophys.Res.,
MGS/TES and MRO/MCS measurements show better 106,E65037;Montmessinetal.,2004: J.Geophys.Res.,
agreementbetweenthemodel’ssimulatedclimatecom- 109,E10004;Navarroetal.,2014: J.Geophys.Res.,119,
paredto thatobserved. An increasedbaroclinicitysig- 1479; Suarez and Takacs, 1995: NASA Tech. Memo.
nificantlyaffectstheintensityandseasonalityofsynop- 104606;Toonetal., 1989: J.Geophys.Res., 94, 16287;
ticweathersystems. Wangetal.,2005: J.Geophys.Res.,110,E07005.