BulletinofGlaciologicalResearch20（2003）49−55⑥JapaneseSocietyofSnowandIce

49

Field・Performancetestsofa portable10W・frequencylCe・Penetratingradar
and a ground・PenetratingradaratAthabasca GIacier，Canadian Rockies
KenichiMATSUOKA＊，TatsutoAOKl＊＊，TatsuyaYAMAMOTOand RenjiNARUSE

InstituteofLowTemperatureScience，HokkaidoUniversity，SapporoO60−0819Japan．
（ReceivedSeptember18，2002；RevisedmanuscriptreceivedNovember19，2002）

Abstract

Field tests of a novelportablelow−frequencyice−penetrating radar（IPR）and a commercial
ground−penetratingradar（GPR）wereperformedinSeptember2001atAthabascaGlacierinJasper
NationalPark，Alberta，Canada．WemeasuredaboutllOmoficethicknesswiththeIPRatapoint

inthemiddlereachesoftheglacierandacquiredexperiencesforfuturepracticalusages．TheGPR

detectedthebedrockreflectioncontinuouslybeneath＜15−m−thickiceattheglacierterminus andpseudoreceivedpowerfromtheenglacialandsubglacialreflectorswerecalculatedinthisrange．On

thelateralice−COredmoraine，WetraCedwiththeGPRalongtwolines，Wheredebristhicknesschanged

from zeroto55cm．Theinterfacebetweendebrisandicewasclearlyrecognizedwhendebrishad

Sandy−Siltmatrix，Whereasitwasnotidentifiedwhendebriswerecomposedofcobbles．Itisprobabiy

due tolarge scattering of radio wave from thelarge gravels．Preliminaryinterpretations on the
Velocityandattenuationwithiniceanddebriswerealsodiscussed．
1．lntroduction

Mountainglaciersplayimportantrolesonwater
andenergycyclesintheearthenvironments．Sincethe
responsetimeofmountainglacierstoclimatechange
isatleasttwoorderslessthanthatofpolaricesheets，monitoring ofglacier volumeis required from the（e．g．Bogorodskiy et al．，1985；Plewes and Hubbard，
2001）．However，Currentinstrumentsarenotsufficient

toinvestigate glacier and periglacialenvironments；
We need an advanced system whichislow−POWer

COnSumption，1ight，and user−friendly．Moreover，

knowledge of performance and limitation of radar
SurVeyareStil11imited．

pointofviewofglobalsea−1evelrise（IAHS／UNESCO，
Based on previousice−penetrating radars（here−
1998；Meier，1984）．Large amounts of melt cause toafter，IPR），WeStartedtodevelopaless−Weight，1ess−
form subglacial，englacial，and supraglacialwater power−COnSumption，mOre−uSer−friendlyIPR since
Channelsinsummer．Water−inducedcomplexfeatures 2000．TheIPRisapartofthenovelglacierprofiler

makeusdifficulttounderstandmechanismsofglacier

Variations．Nevertheless，realglacierfeaturesmustbe

known before modeling the glaciers to predict their
futurevariations．Besidesglaciers，SuChaperiglacial

landform as anice−COred moraine stores significant

SyStem，With which we can know the elevations ofglacierandbedrocksurfaces．Bedrockelevationsare
essentialtonumericalglaciermodels．
InadditiontotheaboveIPR，Wehavecarriedout
basic experimentssince2000winterto applyacom−

mercialground−penetratingradar（hereafter，GPR）for
Criticalfortheheatbalanceofunderlyingice．How− glaciologicalstudies．As a consequence，We Carried
ever，therearenowell−developedpracticalmethodsto OutfieldtestsoftheglacierprofilerandtheGPRat
knowthespatialvariationsofthethickness．
AthabascaGlacierinJasperNationalPark，Alberta，Radio・WaVe remOte SenSingis one of the most
CanadafromSeptemberlOto22，2001，tOknowtheirpowerfulmethods to achieve these requirements．
performance andlimitation，and to acquire experi−amount ofice．Debris thickness of the moraineis

Since there are significant contrasts of dielectric

propertiesamongice，Water，air，androck／sediments，

we can visualize subsurface structures with radars

encesoftheseoperations．Thisreportisanoverview
Ofthefieldactivities，andpresentspreliminaryresults
andtheirinterpretations．

＊Presentaffiliation：ResearchInstituteforHumanityand Nature，Kyoto602−0878Japan．
＝Presentaffiliation：DepartmentofGeography，Kanazawa University，Kanazawa920rl192Japan．

50

BulletinofGlaciologicalResearch

Fig．1．Athabasca Glacier．（a）Geographicalmap．Thickline represents the glacier boundary，and
hatchedareasindicatethreeicefalls．Counterlineintervalsare200feet（61m）．Adottedlineshowsthesnocoachtrailfromtheparkingareaonthelateralmorainetotheturnaroundinthemiddleof
theglacier．Shadedareasaretestsitesforice−penetratingradar（IPR）andforground−penetratingradar（GPR）．Astarshowsthesitewhereweobtainedicethickness．（b）GPRsurveylinesontherightmarginallateralmoraine．DJlandDBShowlocations（distances）alongthesetwolines．

2．Geographicalsetting

WaSteStedonthesnocoach（specialbusfortourists）

2．J．AJ血z∂αざC（Z Gんzcねγ

glacier（Fig．1a），Sincetheyweremaintaineddailyby
Brewster Company and hence kept smooth．In addi−

AthabascaGlacieris a northeastward tongue oftheColumbiaIcefield（Fig．1a）．Followingthreesteep

icefalls，the relatively gentleglacier spreadslkm

trailand the turnaroundin the middle reaches ofthetion to the current trail，the former trailnear theCurrent One WaS also used．Previous studies showed

Wideand3．5kmlongbetween2000ma．s．1．（thetermi−thaticethicknessesaroundtheturnaroundandpreviTnus）and2400ma．s．1．（thelowesticefall）．Icethickness
OuS／currentsnocoachtrailnearbythelateralmoraine
OVer theglacier was wellinvestigatedby Trombley
areabout300m andlOO m，reSpeCtively（Trombley，（1986）．Ice becomes thickerwith the distance upg・1986）．

lacier，and reaches the maximum thicknesslarger

The GPR was tested at the glacier terminus，
than320m．Ananalysisofaerialorterrestrialphoto− tracing along alongitudinalline from the glaciergraphs showed that the glacierlost2．344×108m30f

VOlume and downwasted significantly for the period

terminus（Fig．1a）．Inaddition，WeCarriedoutdetailed

investigationswherefoliationandmoulinsexisted，Of

1919−1979（Reynolds and Young，1997）．The glacier
Whichresultswillbepresentedelsewhere．
underwentarapidrecession；1．2kmduring1922／1980（RutterandLuckman，1987）．Inadditiontotherecent 2．2．2．0乃娩g gcβ− 明通夕肌用滋肌
glacierretreat，AthabascaGlacierhasretreatedlarge−
TheGPRwastestedalso ontheice−COredlateral
1ysincetheLittleIceAge（RutterandLuckman，1987）．
moraineadjoiningtheglacier（Fig．1b）．Themoraineis
CharacterizedwithsteepslopeontheglaciersideandAs a result，We Can See Well−developedlateralandterminalmoraines．

Older moraine sequences on the other side．The top

usefulinformation for the future practicalusage oftheIPR andGPR．

tionandwatercontent forupper andlowerparts ofthemiddlelayerweremeasuredatasitealongtheline

2．2．7セ5Jざグね5

matrix onthesideslope（DB＞8m）andthetoparea

WeperformedthefieldtestsfromSeptemberlO

areais flat with small（＜about O．3m）undulations．
to22，2002．Thisperiodwasinthelatemeltingseason， TwostudylinesweresetasshowninFig．1b；OneWaS
15mlongonthetoparea（1ineA），andtheotherwas
Or a tranSition between the melting season and theearly winter．We found many supraglacialand eng−
35mlongacrossthemoraine（1ineB）．Debris−Surface
1acialwaterchannels，andmoulins．Theseconditions conditions along the lines A and B are uniform andaretypicalformountainglaciersinthe ablationsea−
Change，reSpeCtively．Debrisstratigraphieswerestud・
SOn．Then，these field testsin this period provide
iedbypitworkatthreesites，andgrain−Sizedistribu−

2．2．J．0邦吉ゐgg血ござβγ

The novelglacier profiler systemwith theIPR

B（Fig．2）．Therearerelativelylargegravelsandsmall（DB＜8m），reSpeCtively．SincelineAislocatedonthe

top gentle area，We Can COnSider that debris matrix

5J

Matsuoka et al．

（a）DB：6m；d：42cm
0

︵
∈
エ
勺

1
2
3
4

CummuIatedrat10（％L（b）Db＝13m；d＝55cm
L

●

●●

一

ー ● ● ● ● ●Pebb】e

○

0

SSM

0

○・N
8．0％

＋

9raVel

l
d
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＿▲

∧ ∧ ∧ ∧でロ田（C）Dβ＝20m；d＝35cm

010
Sandy−Siltmatrix

20＋

Pebble

30
0

12．2％

0

40
50

Fig．2．Debrisstratigraphyat（a）DB＝6m，（b）DB＝13m，and（c）DB＝20malongthe
lineB．Thedepth（d）ateachsiteisgivenatthetopofeachpanel．Graybands
representtopsurfacesofthecoreice．Sites（a）and（b）areonthetopflatareaof
thelateralmoraine，Whereas the site（c）is on the steep slope．SSM represents
Sandy−Siltmatrix．Notethatwatercontentsandgrain−Sizedistributionrepresent
withweightpercentandphaiscale，reSpeCtively．

alongthelineAisuniformwiththesandy・Siltmatrix
highbrightnessdisplayandiswaterproofed．Thetotal
asobservedatDA＝DB＝6m．SinceitwasdifficulttoWeight of this systemislO kgincluding batteries．

pullthe GPR on the gravelsurface，We Carried the
GPR about5cm above the debris．
3．Testedinstruments
3．ヱ．Gぬcグβγ ♪叩斤Jgγ 即ざね∽ 紺g娩 ♪0γね∂Jg わ棚−
ノkqⅥぐ〃（：l，′（・（イぐ〃lイ用／JJJgJlJdJJ−

Our novelglacier profileris composed of the

Totalpowerconsumptionis24W（display：On）and19W（display：Off）．

TheIPRis composed of a transmitter（Tx），areceiver（Rx），andtwosets（transmitting and receiv・ing）of resistivity−loaded half−1ength dipole antennas（ANTs）．Weused5−MHzantennasforthisfieldtest，

but we can change the frequency．The ANTs are
COnneCtedtotheTxorRxdirectly．Notelectricalbut

Originally−designedIPR，aGlobalPositioningSystem Optical−fiber cables connect Tx and Rx to CT，tO
receiver（GPSR），abarometerandan odometer（Fig． prevent interference between such communication
3a）．Allcomponents are connected to the controllerlines（30minlength）andANTs（10minlength）．To（CT），Whichis basically composed of conventional
avoidcableshardenunderlowtemperatures，WeCar−partsofpersonalcomputers．However，theCThasa riedoutmechanicaltestsincoldroomsinadvanceand
ミCさ

JcerpeJlef相加9帽由r
Fig．3．Testedinstruments．（a）Blockdiagramoftheglacierprofilersystem．Thickand thinlinesshow optical−fiber and electricalcables，reSpeCtively．Length ofelectricalcablesislessthan2m．Antennas（ANTs）aredirectlyconnectedtothe
Tx and Rx．（b）Photo oftheglacier profiler system．Althoughthere are both
externalswitchandodometer，eaChofthemcanbeusedforthetriggeringata
time．（c）Photo oftheground−penetratingradar（GPR）．Package ontheglacierCOntainsantennas，RxandTx．TheCTtriggersTx and Rx accordingtogiven
ObservationparametersfromthePC．AIso，thePCdisplaysquick−lookdata．

52

BulletinofGlaciologicalResearchchose flexible rubber−COVered cables for ANTs andcommunicationlines．

TheIPRworksasthefollowingarchitecture．A
900VpulseisgeneratedwithintheTxaccordingtoa
trigger from the CT and sent to the transmitting

ANT．Time series ofthereceivedvoltage are digit−
izedandstackedintheRx．Afteraveragingthestack−ed waveforms，an aVeraged datumis sent finally to
the CT．The timing of data acquisitionis provided
automatically accordingto agiventime or distanceinterval，Or manua11y with an external button．

Althoughdurationto acquireonedatumdepends on
flexibleparameters（timewindowwidthandstacking

number），itrequiresusbetweenlOand30secondsfor
thetypicalcases．Inaddition，autO−tranSmissionmodeisequippedfor checkingtheinstrument．Pushing aninternalswitch，Txsendsthepulsecontinuously and
We Can Observe WaVeform with an oscilloscope con−nectedTx directlyorconnectedRx antenna（thatis
Checkingtransmittingvoltageandtotalperformance

3．2．G，℃〟乃d少β乃gわ℃fわ曙和（ねγWeusedRamacground−penetratingradar，WhichisamanufactureofMALÅGeoScience，Sweden（Fig．
3c）．It was appliedfor glacier studies（Moore et aL，
1999）．MALÅGeoScienceprovidesantennaunitsof

SeVeralfrequencies，andwechoose800MHzantenna
unit．RamacGPRrequiresalaptoppersonalcomputer（PC）．Weusedoneforheavy−Outdooruse（Panasonic，
Toughbook series），Which has high−brightness andtouch−paneldisplay，andis semi−Water prOOf．Such
flexibleparameters astimewindowwidth and sam・plingratearesetwithasoftwareonthePC．Including

this PC and batteries，tOtalweight and power con・
Sumptionare17kgand70W，reSpeCtively．

GPR observations can be carried out by one

person（Fig．3c）．He／shecarriesacontrolleronhis／herback，OperateS the PC，and pulls a package which
includesTx，Rx，andANTs．Nevertheless，Operations

Withtwopeoplearemuchmoreeffective．

OfTxandantennas，reSpeCtively）．

4．Resultsandinterpretations

and O．2hPa，Whichis equivalent to the2−m−height
Change，reSpeCtively．Therefore，COmbining withanotherbarometer at afixedsite（e．glCampSite）to

GPRforfiveandsixdays，reSpeCtively．Thetestshad

TheGPSRandthebarometerprovidehorizontal
positionsandheightdifferenceswithinerrorsof15m

We tested the glacier profiler system and the

twoparts．Thefirstoneistochecktheirappropriate
WOrkundersevereconditionsandto acquireexperi−
encesforthefutureusage．Thesecondoneistoknow
theirpotentialperformance．Thetargetoftheglacierknowtimeseries ofairpressuredueto the weather
Change，WeCan aChieve elevationchanges ofglacierandbedrocksurfaceswiththisglacierprofilersystem．

profilersystemisice−thicknessprofilesoveraglacier，

attached to eachIPR datum．Data are storedin aterminus and debris thickness of the ice−COred

Time，horizontalposition，and air pressure areremovalharddisk（flushcard）intheCT．

Continuousobservationswiththisglacierprofiler

and that of GPRisice thickness near theglaciermOralneS．

SyStemCanbecarriedoutbytwo（minimum）orthree 4」．（砂e和放）乃お5ね（recommended）people．AsshowninFig．3b，thefirst
Glacierprofiler workedwellingeneral，eVen at
person carries the CT on his／her back and pulls alowtemperaturesandonthewetsurface．Moreover，
Climbingrope（diameter3mm）．Communicationlines the high−brightness display enabled us to watchit
andANTs are tiedwiththerope to prevent signifi−
Clearlyevenundersunshine．However，datatransmis−
CanttenSionappliedtothesecables．Thesecondper− sion from Rx to CT was sometimes broken．Post
SOnpulls the Rx，and the third person pulls the Tx
laboratorytestsinacoldroom（−150C）showedthatit（optional；itcanbepulledbythesecondpersonwith
WaSduetotemperaturedependenceofacommunica−
theclimbingrope，iftheglaciersurfaceisgentle）．The
tionmoduleintheCT．Exceptthispoint，Otherinstru−
distancebetweenthesepeopleisaround13m，andthe
ments worked well，We confirmed that the output

transmittingandreceivingANTsareinthecollinear

VOltageoftheTxwasthesameasthedesignedone

Inadditiontotraversemeasurements，thissystem
Canbeusedformeasurementswithcommon−midpoint
method，WhichisusuallyusedtoknowwatercontentstingANTonweticewasabout500hm，Whichwasthe

relation．

（Macheretetal．，1993）．Thecommon−midpointmethod（900V）．Thisindicatesthatimpedanceofthetransmit−

designedvalueforTx−Outputimpedance．

TheGPRworkedwellevenatlowtemperatures．

requiresmultiplemeasurementsatapointwithdiffer−entantennaseparationsbetweenseveraltensmeters

AIso，the heavy−uSe PC enabled us to operateit
Without significant stress．However，batteries ofthe
GPR were not sufficient for full−day use．We could

1engthofthecablewithCT．

Ramac（7．2V）．

and one hundred meters．For this measurement，We Operateitonlyoneortwohours，eVenifwechargedit
Canreplace30−mOpticalfibercablewithlOO−mOne． fully．To overcome this point，high−density compact
If we use opticalfiber cable with differentlength，batteries for home−uSevideo cameras（SONY Han−
propagationtimeofatriggerbetweenRxandTxwill
dycom，forexample）willbeapplicable．Thevoltageof
Change．Tocalibratethistimelag，Wehavetoidentify the battery（Lithiumion）matches to that of the丘プ

Matsuoka et al．

4．2．fセが）乃乃α乃Cgね5怨イ．エノ．左り−−肋／＝／両ぐハ〟山り；り ん・一 助才一・人〃−∫＝仙小J…−〝‡g乃ね

SincecommunicationsbetweenRx andCTofthe

glacier profiler system were sometimes broken，We
usedauto−tranSmissionmodeoftheTxandconnected
the receiving ANT to the oscilloscope directly toobserve the received waveform．Antennas were set
paralleltoeach other and perpendicular toice flow

direction（asitusuallyusesforthecommon−midpoint

about5mJLSrl，aSthewatercontentincreasesl％．If
WeaSSumethewatercontentas3％，thedepthis95m．

Nevertheless，eStimatedicethicknessnearlymatched

theice−thicknessmapofTrombley（1986）．Asaresult，

although our novel glacier profiler system needs
improvementsespeciallyonthecommunicationcom−

ponents of Rx and CT，its design and basic perfor−

manceachievedourrequirements．

4．2．2．GγP〝乃d少g乃gわⅦめ昭 和（おγ カγ 才cg 肋fc々乃どぶS

method）．

〝7eα5〟γg〝7β乃ね

Figure4showstimeseriesofreceivedvoltageat

Apseudo・CrOSSSeCtion（socalledZ−SCOpe）ofthe

the fina11arge change of voltage．Dipole antennas
radiateradiowavenotonlyintotheicebutalsoother（d）issmallerthanabout2m，itisdifficulttoseparate
itfromtheairwave．Besidesthesubglacialreflection，radiationcomponentsofradiowaveinthedirectionof
lateralmountainsisslgnificantlysmallerthanthatof

due to water−induced open cavity or subglacialcre−

thesiteshowninFig．1a．Alargevoltagechangewasglacier terminus obtained withthe GPRis shownin
foundatthedelaytimeofl．28FES．Ifweused169m Fig．5．Thedelaytimewasconvertedtodepthwitha
propagationspeedof169mJLS」．SlopeoftheglacierJLS￣1forawavepropagationspeedwithinthepureice
Surface was constant at130，and the slope of theatlowtemperatures（Fujitaetalリ2000），itcorrespond−
reflection surface was about140．This agreement
edtolO5mindepth．Weconsideredthatthisvoltage
SuggeStedthatthesubglacialtopographywasalmost
Changewasreflectedfromsubglacialsurfacebeneathflat and the water content ofice（which affects totheobservationsitebasedonthefollowingtwofacts．
propagation speed）was almost constant．Figure 5
First，pOlarityisoppositetotheairwave．Ingeneral，
Sincepermittivityofrock（andwater）islargerthan Shows that the800−MHz GPR has a potentialto
identifythesubglacialreflectionfrom15mdepthinthat ofice，pOlarity of received voltage from subg−
1acialsurfaceisoppositetotheairwave．Next，itis temperateglaciers．Ontheotherhand，ificethickness
directions．Incase ofvalleyglaciers，We Can reCeive
SeVeralenglacialreflections were also found．For
reflections from mountains aroundtheglacier．How−
example，WeCanSeeaCOnVeX−Shapereflectionatthe
ever，Sincewesetantennasperpendiculartoiceflow， distance of22m nearby the bedrockItis probably
ice．Moreover，the previous study showed that bed−

VaSSeS．

rocktopographyaroundthisareaisgentleandwecan
expect thatitisinfrequent to observe side−looking
reflectionsinprlOrtOthebeneathreflection．
︵
＞
∈
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0
訪
望
○
＞
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U
D
で
P
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−
＄
￠
∝

2
1
1

0
5
0

0
0
0
0
0

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七
重
d
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凸

5

0
0
0

5

0 10 20 30 40 50 60

−
1
一
l

■
h
︶
0

Distancefromtheglaciertorminus（m）
0．0 0．5 1．0 1．5 2．0 2．5 3．0 3．5 4．O
D0laytim8仙S）

5
Fig．4．Timeseriesofreceivedvoltageat thesite shownwiththestarinFig．1a．

Water within the ice affects the propagation

Fig．5．Pseudo−CrOSS SeCtion of the glacier terminus
ObtainedwithGPR．Strongerandsma11erreceivedsig−
nalsrepresentwithdarkerandlightercolors．Acontinu−

OuSeChobetweenthelefttopandtherightbottomis
from the subglacialinterface．The circle shows thelocationofaconvex−Shapeenglacialreflection．

Gadesetal．（2000）showedthataone−halfsum−Of−

Speed（Macheretetalリ1993）．Ifweassumethatthere Squared voltage amplitude（V）within agiven time

is nointeraction betweenice and water and per−mittivityofamixtureofice andwateriscalculated

Windowisaproxyofreflectionpower．Then，V for
Subglacialreflections（t勺）is usefultoinvestigate
byLooyengaequation（ParenandRobin，1975），WeCan Subglacialconditions（CoplandandSharp，2001；Gadesetal．，2000）．Wecalculatedl布withthesamemanner，evaluatetheeffectofwateronthepropagationspeed．
Whend＞2m（Fig．6）．Sinceperiodof800→MHzradio
Asimplecalculationshowedthatthespeeddecreases

BulletinofGlaciologicalResearch

こラ・J

noiselevel（l万乙），WhicharealsoshowninFig．6．t勺isinverselyproportionaltotheicethicknessintherange

ゝ
﹂
○
事
O
d
p
O
＞
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じ
巴
・
〇
P
⊃
○
∽
d

1

0 4

1

0 3

1

0 2

Of2＜d＜5m．Moreover，Since smallerl句 can be
CauSedbylarger Ve，1句andl々hasroughanti−phase
COrrelationin the range of d＞4m．However，for
instance，l々decreaseswithdepthfor d＜4m，Where
l々alsodecreases．Then，featuresin Varemuchmore

COmplex than the previous study．Possible causes of
thisdiscrepancyareradarfrequencyandwaterexis−
tencewithintheice．Weobservedatemperateglacier

2

4

6

8

at800MHz．Instead，Gades et al．（2000）investigated

10 12

COldiceatseveralmegahertz．Sinceweobserveback
SCattering from targets，We Can nOt detect defuse

Dopth〟（m）Fig．6．Proxyofreceivedpowerfromenglacialandsubg−

reflectioncomponents．However，iffrequencyishigh，
thecomponents arerelativelysignificant．Moreover，

lacialreflectors（Veandl句）．Proxyofnoiselevel（l々）is also shown．Just for convenience，l々andl勺areif water exists not aslayers but as separately，theWatermayCauSelargedefusescatteringcomponents．

biased−10，000and＋10，000digits，reSpeCtively．1々and
l句for d＞4mweresampledat anintervaloflO data（approximately，0．5m）．

Then，WeCannOteValuate Vsimplywithdepthand／
Or anti−phase relation betweenl々 and 彷．This

WaVeisl．25nsinice，WeChoosethetimewindowas requires more detail studies to apply the method to
12ns．Variationsofl句arecausedbychangesofice high−frequencyradarsurveysintemperateglaciers．
thickness，basalcharacteristics，englacialstructures

andnoiseleveloftheinstruments．Toseparatetheseeffectsandtoknowthebasalcharacteristics，Wealso

4．2．3．上）g∂γ怨才カグc烏乃β550乃娩βgCg−COγぞd〃70γ㍑オ〝gResultsofGPRsurveysalongthelinesAand B

are shownin Fig．7．Since we confirmed with pit

Calculated V for englacialreflections（l々）and for
糾
︵
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○
∈
芋
ゝ
帽
■
○
凸

0

EfFectsofthetransmittion wave

4

8

RefIection什omthe

debris・iceinterbco

4

6

10

8

12

一二J；了、＼こ．・．− 、
㈲
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写
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0

E抒ectsofthe
tran9¶‖裏On WaVe

4だc；1ざはrh9

什om cobbles

8−∴：：ミミニ・…二andRef］ectionfromthe

debris．iceinte血c￠
5

0

10

15

20

25

30

35

こ〜ミュごこt？・侶

Di＄tanCOβ8（m）￣：＝≡：二ZOnO・lI

ZOn0．暮Fig．7．Pseudo−CrOSSSeCtionofice−COredmorainealongthelineA（a）andlineB（b）．
Signalchangesforthedelaytime＜4nsareaffectedbythetransmissionwave．
Continuousreflectionsinthepanelaandzone−IIinthepanelbarefromtheice／debrisinterface．

55

Matsuoka et al．

WOrks that there are no clear boundary within the

Tachikawa，Japan，forwhichwearegratefultoRyoji

debrisatDA＝DB＝6m，WeCOnCludedthatthecontinu− Saito．We also thank GarryClarke of Unlversity of
OuSClearreflectionwasfromthedebris／iceinterface．British Columbia，MichaelDemuth of Geological
SurveyofCanada，andCharlieRaymondofUniversity
Thereflectionfromthedebris／iceinterfacewasclear−

1yobtainedalongthelineA，Whereasitwasobtained

OnlyforO＜DB＜around8m alongtheline B．Zone−I
and−IIinthepanelb（shownatthebottom）indicatethat there are cobble at the top of debris or not，

OfWashingtonfor their valuable suggestions to thisfieldwork．ThisstudyispartlysupportedbyaGrant−
in・AidforScientific Research（B，2，No．12554015）of
the Ministry of Education，Culture，Sports，Science

respectively．AsshowninFig．2，therewerecobblesat andTechnologyofJapan．
the top of the debris for zone−Ⅰ．Thelocation ofReferencesdebris−COmpOnentStranSitioniscoincidentwithbound・

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450（Yamamoto，2002），WeCanCOnSiderthatscattering
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icein
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Sea．Level．Science226，1418−1421．
penetratingradar（GPR）inAthabascaGlacier，Jasper Moore，）．C．，PaDoalli，A．，Ludwig，F．，Blatter，H．，Ja
NationalPark，Alberta，CanadainSeptember，2001．Gadek，B．，Glowacki，P．，Mochnacki，D．，andIsaksson，（1999）：High−reSOlution hydrothermalstructure of Hans−
Bothinstrumentsworkedwellundersevereconditions
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Observedcontinuousinterface betweenice anddebris
iceinterface or not．The GPR detected the scattered

Withinice−COred moraine．However，mOre detailed

Studiesarerequiredtoevaluatereceivedpowerquan−titatively．

Acknowledgments
Wecouldnotcarryoutshort−termefficientopera−

tions without kind supports of Parks Canada andBrewsterCompany．SpecialthanksareduetoMatty

Gibson（supervisoroftheicefieldcenter），EdNewport（operationmanagerofsnocoach），andtheirstuff．The

novelglacier profiler systemwith the portablelow−
frequencyice−penetrating radar was developed
througha cooperative study with Walnut Company，

203−236．

Reynolds，J．R．，andYoung，G．J．（1997）：Changesinarealextent，elevation and volume of Athabasca Glacier，Alberta，Canada，aS eStimated from a series of maps produced
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SnOWCOVerSwith aground−penetratingradar．unpublished
Masterthesis，Hokkaido University．（inJapanese）