BullethofGlacierResearch4(1987)1S一之ヲ
◎DataCerlter女)rGはcierResearcわ,Japan鴇eSocietyofSr10WandIce
Jβ
Chavactevistics of precipitation and verticai structure of air temperature in the northevn
Patagonia
YasushiFujiyoshi..HiroshiKondo.Jirolnoue andTomomiYamada、
1InstituteofLowTemperattlreScience,HokkaidoUniversityりSapporoO60Japan
2 DisasterPreventiorlResearchInstitute,KyotoUniversity.,Uji611Japan
(ReceivedDecemberi乳1986;RevisedmanuscriptreceivedJanuary24,1987)
Abstract
MeteorologlCalobservatiorlSWereCarriedoljt鉦omOctober1985toFebruary1986alongSanRaねelG主acier,
locatedat4603rSand73053TW.Majorfindingsareasfollows:
1)FromthedatacollectedatthemeteorologicalstationslocatedonthewestsideofChilefrom43O12′Sto53㊥10F
S,itwasねund班atitrainsmore王妃aVilyirlWiIlterthanillStlmmerinlaもittldes重owertban46GS.‡mcorltraSt,it
rainsmoreheavilyinsummerthaninwinterattheterminusofSanRafaelGlacierandinlatitudeshigherthan46¢
S,althoughtheseasonalvariationisratherobscure.Monthlymeanamountofprecipitationathigherlatitudcsis
largerthanthatinlowerlatitudesthroughouttheyear.
2)From血edatacollectedt〉ytheMeteorologica10fficeatIノagOOmSanRaねelfromJtlne1981toDecember1985,
itwasfolユndthatbothtwelve−hourlyamourltOfprecipitation(P(12hr))andchanceofhavingprecipitat主ondecrease
Withincreasingsurfaceairpressure(Pr).PrecipitationrarelyoccurswhenPrislargerthanlO20mb.Themean
annualamountofprecipitationattheterminusofSanRafaelGlacierinrecentfouryeal−Sis3.7×103mm− The
maximumanntlal,mOr引払IyanddaiiyamotlntSOfprecipitatio王1are4.1×103,5.6×102andl.27×102mm,reSpeCtively.
3)From ourradiosondeobser・vation,itwasnotedthatstrongtemperatureinversionarldaconsiderably stable
layerbelowthelevelof3kmappearedattheterminusofSanRafaelGlacierduringtheperiodwhenananticyclone
Centeredi11tbe王}ac漬cOceanoff也ecoastoま1)eruspreadovertbeT10rtbernPatagoni乱 Undertbisconditi(恥air
temperaturebelowthelevelof3kmwashigherthanぴC.
4)The amount ofprecipitationincreasedwithincreasing altitude below thelevelof639m.The amount of
precipitationontheicefieldwasestimatedtobeaboutthreetimeslargerthanthatattheterminusofSanRafael
Giacier.
1.lntroduction
Meteoroiogicai observations were carried out
fromOctober19S5toFebruary1986neartheterminus
ofSanRafaelGiaeier(46O377S,73¢53rW,6.1ma.s−l.),
wbich wi11be reねrred to as BH hereafter.Major
鑑ientific objectivesⅥrere focu§ed on clar主毎ing the
Characteristicsofprecipitationandthevcrticalstruc−
ture of air temperaturein the region.These are
Significantfactorstoconsiderinanydiscussionofthe
growtbandsわrinkageoftheglacier,
Three automatically recorded rain−gaugeS Were
SetatpOintsof BH,Cl(422m)andC2(川40m),and
ねurtotalizerraiれ−ga11geSWereSeとatpoinもSGl(89m),
G2(209m),ClandG4(639m)(詑eMap2,わidedirl).
PointG2isiocatedbetweenpointsGlandCl.Upper
airsoundin酢WereCarriedoutbyradiosondeatBHin
払edayti王Ⅵe,MeteoroユogicalobservationsalongSan
RafaeiGlacierandatSolerGlacierwerestlmmarized
by‡noueetal.(1987)andFukamietal.(1987),reSpeC∼
tively,Pictl汀eSOfclolユdsoverBHweretakenbyan
8mmイ主imcameraeverylOseco!ldsatBHandbya35
mm-film calnera twice a day from an airplane of
LADECO(LineaAereaDelCobre).
21Seasonalvariation ofprecipitation
FigureslaarldlbshowthemontもIymeanar‡10urlt
Ofprecipitation(ダ(M))at pointslto6andl′to6′.
J(J
Bu11etir主OfGIacier Researc壬1
汀椚町村
毒 200卜
」 F M A M JJ A 5 0 N D
lsla Guユーロ2
ZOロト
Gユbo F且P訂3
Fig.2.Locations of each sta−
tion at whichstatistics of pre欄
Cipitationwereper毎rmed.
Tbeiocations of eacb point are showninI?ig.2.
Thereisam(〉untainchainbetⅥ7eenlinesト6andl′−61
AsshowninFig.1a,itrainsmoreheavilyin winter
thaninsouthernsummeratnorthernpointsfromlto
3.Incontrast,itrainsmoreheavi1yinsummerthan
inwinteratsouthernpointsfrom4to6,altho11ghthe
Co肋如quo之
C仙●Chicoゴ
しα8C8Cn.1∩●ノ
Cコbo Po量●暮j血5
」F M A MJJ A S O N O
PunはAr8nai6
Fig.1.Seasonalvariations ofthe monthly amount
Ofprecipitationatthemeteoroloきぎ1Calstationfroml
to6(a)andfroml’to6’(b).These values are av−
eraged
from1931to1960in Puerto Montt(1),Isla Guafo(2)
andCaboRaper(3),
from1933to1960三nSa王1Pedro擁,
打0王Ⅵi949to1962i‡lIslaGtlarelio(5),
打om1921to1960主nBabiaFelixく軋
丘om1960toi9朗inFuta】eufu(1’),
育om1961to1985inCoibaiqlユe(2りalldCbileCbico
(3’),
from1980to1984inLordCochrane(4’),
from1915to1950inCabo Posesi6n(57)and
from1988to1960inPuntaArenas(67).
SeaSOnalvariationofP(M)isratherobscurethanthat
atnorthernpoints.P(M)atsouthernpointsislarger
thanthatatnorthernpoints.AsshowninFig,1b,the
amount of precipitation at pointsl′to6′is much
Smallerthantbat at pointslわ6.ThismearlSthat
prec主pitaたionisconcentratedincoastaireg王OnSandin
tbe west side of tile mOuntain slope,Wbi(:b willbe
discusse(ま1ater,
EnomotoandNakajima(1985)statedthatprecipi−
tation does not show regular seasonal variation at
BH,basedonthescantdataobtainedbytheMeteoro−
logicalOffice at Lagoon San Rafaelfor one year
(1983).Moredetailedandprolongedworkshouldbe
done to e】ucidate the seasonalvariation of precipi−
tation at BH.The Chilean Air Force has been
makingmeteorologicalobservationsatBHsirlCeJune
1981.The maxiIⅥum anilual,mOnthly arld daiIy a−
motlntSOfprecipitationare4.1×103mm(1983),5.6×
102mm(January1982)andl.27×102mmく5Åpr吏i1983ラ,
respectively.MeanamolユntOfprecipitationinrecent
fouryearsis3.7×102mm.Figures3aand3bshowa
hythergraphatBHandtherelationbetween′㍍化and
thefrequencyofprecipitation,reSpeCtively.Wedeq
Fujiyoshietal.
j7
isseerlthattIlefreque王1CyOfダ(12hr)1argerthan20
Oc
12
mmishigherinPeriodlthanthatinPeriod2.That
is,heavy precipitation occurs more frequentlyin
Periodlthanin Period2.
U
摩8
る
0
0 200 400mmO
Amount o†pr8Cipitation
a
輌叩画P抽鋸兼椚
Fig.3.Hythergrapbくa)a王1dtbemearlnumberofraillydaysper
OnemOnth(b)atBH.
finethefrequency ofprecipitation asthemeannum−
ber of rainy days per one month when the daily
Fig.5.Variation of surface air pressure(乃′)and the daily
amountofprecipitation(P(D))withtimeobservedfromlOct.to
29Nov.1985atBH.
3・SLJrfaceairpressurcandtheamounto†precipi・
ainOu11tOfprecipitation(タ(D))islargertbanO.1m乱
tation
‡trai11SmOre‡leaViiyたomDecembertoM野(wewill
CallthisperiodasPeriodl,hereafter)thanfromJune
Fiきざure5shows an example ofthe variation of
to November(Period2)at BH,butthefrequency of
Surface air pressure(jケ)and the daily amount of
precipitationisnearlythesamethroughouttheyear.
precipitation(P(D))withtimeatBH.Itisseenthat
precipitationoccurredwhenthesurfaceairpressure
VaSbeiovabol止1020mb.Aswevillsbowinseく:tioI1
5,the value oflO20mbis a typicalone defining
anticyclones overlying the Pacific Ocean.This
meansthat precipitationrarelyoccurs when anticy・
ClonesarepresentoverthenorthernPatagonia,The
figurealsos11ggeSt感theexistenceofaquantitative
reiatiorlbetⅥreen t‡1eintensity of cyclone a11d the
amourlt Of precipitation.Naturally,the amount of
precipitationisnotdeterminedonlybythesurfaceair
10 20 30 40 50 60 70 80
Precipitalion(mm/12h)
pressure.However,therelationbetwecntheamount
Fig.4.Frequencydistributionofthctwelve−hourlyamountof
precipitatiorl(ヂ(12hr))iTIPeriodsIandI‡averagedねrrecerlと
fouryears.
OfprecipitationandthesurfaceairpressureispossiL
blyoneofindexesdlaraCとerizingtbeciimateof班e
piace.
Tablelshowsthemeantwelve−hourly(from9:00
to2l:00LST)amountofprecipitationandchanceof
havingprecipitation(〔争)foreachrangeofsurfaceair
Figure4showsthemeanfrequencydistributions
OfthetwelveYhourlyamountofprecipitation(P(12hr))
measured at9:000r21:00LSTinPeriodsland2.It
Tab王el・Meantwel関一わ0ば三y(たom9to21LST)a王ⅥOuntOfprecipitationi薫12br);mm)andchanceo=laV王将preCipitaモjon(母;%)
foreachrangeof$urfaceairpresstjrC(fケ;mb)at15LST.N:Totainumber ofdays.cT:Standarddeviation.
985≦ 9 0≦ 9 5≦ 10 ≦ 10 5≦ 10 ≦ 10 5≦ 102 ≦ 1025≦ 103 ≦ 1035≦ 1 .1 10 ” 10 97 94 83 74 46 25 23 0 小
13.7
19.4
14.5
14.8
9,3
6.3
2.9
l.0
1.0
00
10.7 12.9
12.2
8.7
8,9
5.7
2.9
2.3
0 0
5 書 13 30 78 134 176 190 130 書 22
∈ 8.0 6.0 9.3 7.5 8.2 6.9 6.1 3.1 1.0 0.1 10(J 91
93
Pγ(mb) 975
戸(12hr) = 「コ (ブ 0 ○ ー= 〔透 100 くじ nl jV ロ =】 ≧戸(12hr) 0 「コ ○ (ア て こ 印 P■ Ar
83
77
72
54
3
6 2 四 76 108 129 184 15 73 24
24
14
4
0
Bu11etinofGlacier Research
jβ
pressure(Pr)at15:00IJST.These data were
obtai11edbytheMete(汀0logicalOfficeatLagoonSan
Raねelなom1981to1985.Bot壬l昂12br〉and(拳
rangesofP(12hr).Thisfactsuggeststhatthediffer−
enceintlleamOllntO宮戸(12br)wasnotcausedbythe
durationtilneOfprecipitationbl珪by thea‡nOunt Of
decreasewithincreasingPrinthestatisticallysignifiTP(lhr),thatis,larger P(12hr)was composed of
cantrangc(1000mb≦丹<1025mb).薫12hr)is
largerinPeriodlthaninPeriod2,andthegradientis
largerf)(1hr).
Two peaks appearclearlyinthe distribution of
largerinPeriodl(−0.67mm/mb)thaninPeriod2L
P(12hr)=20∼40mm.Thismeansthat there were
O.35m汀i/mb)iritherallge.珍islargertbanabotlt
possibly two kinds ofcloud systems when Pく12hr)
50%andsmallerthan25%whenきケissma11ertban
waslargerthan20mm:OneWaSCOmpOSed ofrain
lO15mbandlargerthanlO20mb,reSpeCtively.Thisclouds which brought rather weak andlonglasting
means that precipitation rarely occurs when乃′is
precipitation,and the other was made up of rain
largerthanlO20mb.
cloudswhichbroughtratherstrongandshortlasting
prec壬pitation.
Figure7s壬10WSthetime一九eigbtcrosssectionofair
4.Cloud,PreCipitationandtheverticalstructureof temperattlreObservedatBH.Theheightoffr’eeZlng
air temperature at the terminus of San Rafae]
level(OOClevel)wa$below2km from the ground
Glacier during the observational period
From ourdata onrainfail,themaximumhouriy
arldthree−bollrlyamountsofprecipitationduring払e
surfacebefore16Novemberandabovethelevelof3
kmaftel−18November.Whentheheightoffreezing
levelwasabove3km,meltingofsurfaceiceorsnow
occurredin払ewholeareaoftheNortlュern‡)atagonia
Icefield.Therewasno rainfrom17NovembertoI
December1985notonlyatBHbutalsointhewholeof
the northern Patagonia(Fukamiet al.,1987).The
abscnceofrainforsuchalongperiodoftimeatBH
were the existence of temperature inversion and a
verystablelayerbelowtheleve13km.
As cold fronts associated with cyclones moved
l
U
wasanexcepとio†1allylユnuSualeve†lと,The短aturesof
verticalprofileofairtemperaturea鮎r17Noveml)er
O
〓
コ
q
て
一
U
q
U
fromthewest(seaside)and/orthenorthtotheeast
(mollntain side〉arld/or the sot血†mOSt Of the rain
clouds moved eastⅥ7ard and70r SOuthward.Tbe汀
types were Ns and C。at BH,judging from photoM
graphs.Lowlevelclouds were formed by forced
liftingbymountainswhenever’theraincloudsmoved
5
10  ̄
Hou「ly Pre⊂ipit且tion(mm/h)
Fig.6.Perce−−tageinwhicheach壬−Ourly
amount of precipitation contributes to
each range oftwelve−hotlrly amounts of
precipitation.
observatio11alperiod werell▲5a‡−d28mm,reSpeC−
tively.Figure6showsthepercentageofeachhouriy
eastward or southward_ There was no rain when
soutber重yandeasとerlywi王1dsble乳 Cutypeofclollds
usuallyappeared,andbothScandSttypesofclouds
SOmetimes appeared only over the mountain side.
WhenthesecloudswentdowntheslopeofthemounN
tain,they disappeared above Lagoon San Rafael
because oftbedovrlWardmo昌on ofair.
amountofprecipitation(P(lhr))tothecorresponding
amOunt Of precipitationpcr half a day(P(12hr))t
5.Atmospheric conditionin synoptic scale durjng
theobservationalperiod
percentageineacbrangeofダ(12br)†areO・5,l・5and
3.5TⅥm,reSpeCtively.1fダ(12br)isdividedbyデく1hr‥
intbePacificOcearl.HlandIi2arecailedass11btro−
ThevaluesofP(1hr:Max),Whichshowsthelargest
Max),thevalueisnearlythesame(∼10)forthethree
TwomainiligbpresslireareaS(‡ila王1dH2)exist
picalhigh and subpolar high,reSpeCtively.Typical
Fujiyoshiet al.
1.9
、・、、._ノ・ノ.′・一・一一 ̄ ̄ ̄ ̄ ′
・、..}ノ//
..−−、、、、/ノー
†′′ −・、 ′ ′へ・、、/ 一一
芸/(‡ご、・・二′く.ゲ′
■
一一一一
一㌦・●…一一●−
ー′
l
︵
∈
き
ト
エ
望
山
エ
こ
:、、t、・../.ノ′
、、−■_...■/J′ ● J l
′′
′・〝 ̄ ̄ ̄…′二\\\二
†Il 、、・・.一叫ノノノ/
′ll
/ l ′
5
l 、・._/’
、ノー一−
∴
5ノーー′ ̄、・・.、・、−一−−・
ヽ
10−・・・・・・一一−・・−・→、\・叫∼____
3
′
′
ヽノーー
′
壱
t
I
\
、−■■●−●一一一−
さ
、∼∵二一−′
」」⊥
_′ノ
9】】h
220ct. 28 290ct.
131(1516171819 20 2122 23 2‘25 26 27 28
Nov.1985
Fig.7.Time−heightcrosssectionofairtemperatureabove且Ii.observedon22,28and290ct.and
from13to28Nov‖Inversionlayersareshaded.
S「C t51SIPコ0【・t.拍85
正
好
好
扉
吋
a
b
Fig・8・Surfaceweathermapsat15LSTon230ct.1985(a)and
at9LSTon2ONov.1985(b).
examplesareshowniTIFigs・ぬand8b・InFig.8a,
a鵬icyc王one‡i2′wasseparated鉦omIi2.ThereⅥraS
norainat BH whenHlorH2spreadoverthenor−
thernPatagonia.Southernandeasternwindsblewat
BHwhenHlandH2spreadoverthenorthernPat堀0Ⅰ血,
a
b
Fig,9.Mapsofairtemperatureatthelevelof700mbat9LST
On230ct・1985(a)andat9LSTon20Nov.1985(b).
respectively.On fhe days before and afterl
November,H2 arld 王ilspread over the norther王1
Patagonia,reSpeCtively・Asshowninthemapsofair
temperatureat700mb(Figs.9aand9b),Warmerair
invadedfr・OmthenorthonlywhenHIspreadoverthe
BⅥ1ieとinofG王acier Researcb
2り
a
21LST14Nov.1985
9ばT230軋1985
900
800
700
600
5(ア
︵
U
O
∧
U
痛
5
0
6
0
▲…Il叩1. Q小冊.。 P….,。H。n.1†pun.‥..。こ;
b
9ほT之ON猟場る5
500 600Fig.11.Sameinぎig.8,eXこeptねr21LSTon14Nov.
1985−
l ̄
小==9.… 。州t… .U..t。H。n=†p。n=.一..nJi
9しST15Nov.1985
Fig.ユ0.Cr()SSSeCtionsofwindきndairtem卵ratt汀ea10ngthe
linefromAr主tOねgasも汲もOpⅥntaArenasat9LSTon230ct,ユ985
(a)andat9LSTo†】20Nov.1985(帆Locat主onsoftbemeteoro−
logicalsta扇onsandSanRafaelGlacierareshownbyopenand
full(:ircles,reSpeCtively.
nor挽ernPatagoniaaridcycionesmo閥dsouthward・
Fi那reSlOaandlObsわow払etypまcalrar噂e−heigbt
cross sectぬns ofⅥrind and air temperature on fi11e
daysatBH・Datawereobtainedfromtbeupperair
soumdings made at Antoねぎasta,Quintero,puertO
Montt and Punta Åre‡1aS.A surface coid front
existedbe摘eenAntofagasはandQt血terovben H2
spreadover払ePatagoniar喝ion(ぎig・8a)・‡nco!ュー
trast,aSurfacecoldfrontexistednearPuntaAreriaS
whenHIspreadovertbePatagoniaregion(Fig・8軋
As洩owninFig.10b,t‡杷reWaSatemperaturei‡lVer◆
sionbe里ow850mbandafreezi‡lglevel洩atexisted
above700mb重ntheairmassまy喜nginaloweriatiとude
thanthe鉦ont.Tberes111tsareconsistentwith ours
obtainedbylユpperairsoundingsmadeatB王i(SeeFig・
7).
PrecipぬtionoccurredatB壬iwberltbecoid鉦orlt
passedthrougbtbePatagonia・Atyp呈calexampieof
asurねcewe盆tbermapwasぬ0Ⅵ昭inぎig−11t The
Fig.12t Same董nFig.10,eXCeptfor9王ノST(Ⅲ」5Nov.ま985。
cyclonemoved抒omt壬IeWeSttOtbeeasta−1dgenera11y
insuccession.Figure12shoⅥrStbecrosssectionof
wind and air temperature.The coはfront exists
betweerlQuまnteroandPuertoM()ntt.
6.lncrement of the amount of precipitation with
altitude
Annualamountofpr∝ipitationaroundtheaccl圭一
mulaも主on area of San RafaelGiacier bas notl)een
FujiyosIli房1正
之∼
elucidatedsofar.Asstatedinsection2,theamount
Of precipitation on thelee side of the mountainsis
quitesmallcomparedwiththatonthewindwardside
Ofthemountains.Thisfactsuggeststhatalmostall
WaterVapOrisconsumedonthewindwardsideofthe
3
02
巾
◆J
mountains.
Totalamountofprecipitationduringtheobservar
tionalperiodwasmeasuredalongSanRafaelGlacier.
Totalamountofprecipitationateachpointduringour
obsenrational period was divided by that at BH in
OrdertoeiucidatetbecbaIlgeintbeamountofprecipi−
tatioTIWitbaltitude,InFig.13,theratiooftiletOtal
arnountofprecipitationiscomparedwiththegradient
∝1
8圧ぶ G2 口
Range(km)
C2
Gi
ぎ主g.13.C†1a‡唱eOft()talamolユntOfprecipitationwithalti餌de
and払erangeノheightcrosssectionofgiacierstlrfaceaiol唱盗e
linefrom B‡itoC2.
Ofslope.王nspiteofthesmalldifferencein altitude
betweenpointsBHandGl,ahighvalueoftheratio(1.
7)wasobtained.Theratioincreasedwithincreasing
altitude belowthelevelofG4.However,it did not
l
ポ
︶
u
O
;
コ
q
盲
U
O
U
increasebetween thelevelsG4andC2.Theratio of
O.5was obtained when the totalamount of precipi−
tationatBHiscomparedwiththatatBaseCampon
SolerGlacier,Whichislocatedontheeastsideofthe
Nor払ern PatagoniaIce㌫eld.From t‡leSeねcts,We
CanSafelyexpectthatthearmualamountofpreeipi−
tationaroundt壬Ieheartoftbeice員eldisnearly払ree
timeslargert壬IanthatatB牲i.e,,10,000mm.
Figure14showsthe distribution ofcontribution
2 4 6 8 10 12 14
ratioofP(1hr)tothetotalamountofprecipitationat
什oc回tat】0∩(mm/hI
differentaltitudes(BH,ClandC2).Itisseenthatthe
COntribution ratio oflarge P(lhr)increased with
Fig.14.Di$tributionofcontributionratioofP(1hr)tothetotal
increasirlgaltitude− Figure15indicatesthefrequency
distribution of the duration time(hour)of precipi−
tationwithP(1hr)≧0.5mm.Itwasalsofoulldthat
amountofprecipitationatthreedifferentaltitude$(BH,Cland
C2).
thedurationofprecipitationincreasedwithincreasing
aititⅥde.
7.Summary and discussion
Itrainedmoreheavilyinwintcrthaninsummer
atthestationslocatedinlatitudeslowerthan46OS.In
contrast,it rained moreheavilyln Summer thanin
winterathigherlatitudes,althoughtheseasonalvari・
ationisratherobscure.Themonthly mean amount
ofprecipitatio‡1attheformerstationsⅥ7aSlargerthan
tbat at thelatter stations tbrotユghotit the year.It
rained morebeavilyin Periodl(froInDece一双ber to
May)thaninPeriod2(froTnJurletONovember)atthe
terminus of San RafaelGlacier,but the number of
rainydaysdidnotshowseasonalvariation・Taljaard
(1967)madeadistributionmapofcyclonecentersin
5 10
15
二ニュ
さミ;・ご!∼−卜t (
10
D川柑Ibn ol騨8C申181bn t‖
ろ§
50
Fig.ほ Frequencydistributionofthedurationtime(hour)of
precipitationatBH,ClandC2.
22
Bulletin ofGlacier Research
the Southcrn Hemisphere.He showed that areas
annualamount ofprecipitation at the center of the
resultspresentedabovesuggestthatSan RafaelGla−
altitudeaboveG4(639m).AndtheratiobetweenBH
Withhighco11Centrationsofcyclonecen仁ersexistata
hig王1erlatittideins11mmertわan払atin winter.Our
icefieldis estimated to be aboutlO,000mm.Tbe
ratiohadate王−dencynottoincreasewitbi∝reaSlng
Cierissituatedinthenorthernlimitofheavypreclpト
andBaseCamponSolerGlacierwasO.5.Therefore,
tationcauscdbycyclonesinsouthernsumrrler.
itissuggestedthatthemeanannualamount ofpre.
Bothtwelve−hotlrlyamountofprecipitation(P(12
br))andchanceofhavil唱preCipitationdecreasedwitil
increasingsりrfaceairpressure(丹)atBH.Precipi−
tationrarelyoccurredwhen乃′WaSlargerthanlO20
mb.P(12hr)islargerin Periodlthanin Period2.
TherateofdecreaseinP(12hr)withPrwasstatisti−
Cally evaluated;it was=…0.67mm/mbi11Periodl
arld −0.35mm/mbin Period2_ These vaiues can
CipitationontheicefieldaboveC2(1040m)wouldnot
exceedlO,000mm.
Acknowledgments
Thepresent authorsareindebtedto thestaffof
汰eMeteorolo衰ca10拝iceatLagoonSanRafael,tbe
AirForceofCbile,andt‡leDirectionMeteorology(事f
possiblybeusedasoneoftheindexeswhichcharac−
terizetheclimaticconditionofaplace−
ChileatSantiagoforthemeteorologicaldatausedin
thiswork.Specialgratitudeisreservedforthestaff
Theremarkablefeaturesoftheverticalstructure
OfairtemperatureaboveBflaretheexistenceofboth
StrOngtemperatureinversionandaratherstablelayer
OftheNationalCorporationofForests(CONAF)for
theirsupportoftheworkatLagoonSanRafael.The
autbors also wisb to acknowledge tbe belp of Mr.
belowt‡1eievelof3km.SuchastrliCttlreappeared
only when an anticyclone centered in the Pacific
OceanoffthecoastofPeruspreadoverthcnorthern
A釘1Stin M,Brajovic V一,Operations Ma王1ager Of
LADECO,Whoarrangedtotheplanefromwhichthe
Patagonia.Inthiscase,theweatherwasfineatBH photographsweretaken.
andtheairtemperaturebelowthelevelof3kmwas
highertbanOOC.1Vhensuchaco†lditionⅥJaSSatisfied,
melting ofice would proceed rapidly,eVeriOIltile
References
paidtotheanticycloneto estimatethemassbalance
Oftheglacier.
It wasfoundthatbothintensity andduration of
Enomoto,N.andNakajima,C,(1985):Recentclimate−fluctua−
tionsin Patagonia.GlaciologicalStudiesin Patagonia
NorthernIcefield,1983−1984.Data CenterforGlacier ReN
栄arCb,JapaneseSocietyofSnowandIce,7−14.
Flユkami,H,,E斑Ober,F.,Quinteros,J.,Casassa,G.alldⅣaru父,
R−(i987):Meteoroiogicalmeasurerr肥nt$at SolerGlacier,
Patagonia,in1985.B1111etinofGlacierResearch,4,3ト36.
lnoue,]リKondo,H.,Fujiyoshi,Y.,Yamada,T.,Fukami,H.and
Nakajima C.(1987):Summer climate of the Northern
PatagoniaIcefield.Bu11etinofGlacierResearch,4,714.
Taりaard,J。J.(1967):Development,distriblエtiorlandmovemerlt
OfcyclolleSaIldanticyc】on缶iれ琉eSoutbern Hemispbere
during払eIGY.J.Appl.Meteor.6,973椚987、
icefieldoftheglacier.Therefore,attentionshouldbe
precipitationincrea獣道 withincreasing aiti仁udet
Therearefourgeneralmechanismsthatexplainthis
result:
a)Upslopeliftingwithrapidhydrometeorformation
andfall・Out;
b)seeder≠feedercloudmechanism;
C〉 deep or sba王王0VCOnVeCtion produced by collVer−
genceinthethermallycreatedmol王ntain−Valleycircu−
1ation;and
d)deep or shallow convection produced by oro,
graphiclifting.Judgingfromthephotographstaken
from a LADECO airplane,there seemed to be no
dif良renceintbelevelofcioudtopal)0Vetわemoun−
tainous region and that above Lagoon San Raねel.
Therefore,deepconvectionwouldnotbeproducedon
the mountain More than one of these four mecha,
nismsmaybeatworkatanygiventime.
T‡妃ratio of totalamo11nt Of precipitation bet一
瞥eerlpOintsBIiandC2was2.6.ÅsthemeanaIlnual
amount of precipitationis3.7×103mm at BH,the
Resumen
CaracterEsticasdetaprecipitaci6nyestructuraverti・
CaldelatemperaturadelaireenelnortedePatago・
nia
Se realiz60bservaciones meteoro16gicas desde
Octubrede1985aFebrerode1986cercade巨丘entedel
Glaciar San Raねel(460377S,73053′W).Los
Objetivosprincipalessonclarificarlascaracter王sticas
FujiyoshiβgαJ.
dela precipitati6n yla estructura vcrticaldela
temperaturadeiaireenlaregi6n.
taci6ndecrecenalaumentarlapresi6natmosf6ricaen
CuatrO pltlVi6metros totalizadores se midi61a canti−
daddeprecipitaci6nalolargodelGlaciarSanRafael.
mediamensualenelfrentedelGlaciarSanRafaelen
Por medio de tres pluviるmeとros alユtOm孟ticos y
Durante eld‡a en elfrente delglaciar se realiz6
sondeos dela alta atm6sfera con radiosondas− Los
hallazgosm畠simportantessonlosslgtlientes:
1)A par昌r deIain払maciるn recoiectada en es・
tacionesmeteoro16gicasubicadasenlacostaocciden・
talde Chile entrelos 43O12′S ylos 53010’S,Se
encontr6quealatitudesmenoresde46O Slaprecipi・
taci6n es mayor eninvierno que en verano_ Sin
之ヲ
Stlperficie(タ,′)(Tabial).Hayescasaprecipitaciぬa
presiones mayores delO20 mb.La precipitaci蝕
los 屯1timos cuatro a毘os es de 3,7・103 mm.La
precipitacionm畠Ⅹima anual,menSualy diaria esde
4,1・103,5,6・102yl,27・102mm,reSpeCtivamente.
3)ApartirderlueStraSObservacio!ュeSderadiosomda,
Se enCO‡lとr6 qlユe Cllando e王 anticiciるn deiOc¢ano
Pac壬fico se centraba frente alas costas de Per色,
extendiendosesobreelnortedcPatagonia,enelfrente
delGlaciar San Rafaelbajo elnivelde 3 km se
presentabaunacapabastanteestableconunafuerte
言nversi6n t套rmica.Bajo tales condicio11eS,1a
eIれbargo,en elfrente delGlaciar SarlRafaely a
latitudes mayores que46D S,Sueedelo contrario,a temperaturadelairebajoelnivelde3kmeras11perior
pesarquelavariaci6nestacionalespoco clara.En
latitudesaltaslaprecipitaci6nmediamensualatrav6s
a OOC.
2)A partir delainformaci6n recolectada porla
CentrOdelcampodehielolaprecipitaci6nesunastres
dela鍋oesmayorqueenlatitudesbajas(Fig.1)■
4)Tantolaintensidadcomolacantidaddeprecipi・
taci6naumentabanconlaaltur乱 Seestimaqueenel
VeCeSmayOrqlユeaquella observada erle王frentedei
Direcci蝕Meteorolるgica de Cbile en Laguna San
RafaeldesdeJunio1981a Diciembre1985,Se en− GlaciarSan Rafael,eSdecirdelordendelO.000mm
(Figs.13,14y15).
Cuentra quetantOla precipitaci6n en12horas(P(12
hr))comola probabilidad de ocurrencia de precipi・
ダウンロード

Characteristics of precipitation and vertical structure of air