Remote Sensing in Northern Hydrology: Measuring Environmental Change

164 Pages·2005·7.116 MB·English

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Geophysical Monograph 163
Remote Sensing in Northern Hydrology:
Measuring Environmental Change
ClaudeR . Duguay
Alain Pietroniro
Editors
AmericanG eophysicaUl nion
Washington,
Publishedu ndert he aegiso f the AGU BooksB oard
Jean-LouisB ougeret,C hair, Gray E. Bebout,C ari T. Friedrichs,J amesL . Horwitz, Lisa A. Levin, W. Berry Lyons,
KennethR . Minschwaner,A ndy Nyblade,D arrell Strobel,a nd William R. Young,m embers.
Library of Congress Cataloging-in-Publication Data
Remotes ensingin northernh ydrology: measuringe nvironmental
change/ ClaudeR . Duguay, Alain Pietroniro,e ditors.
p. cm. -- (Geophysicaml onograph; 163)
Includesb ibliographicalr eferencesa nd index.
ISBN-13:978-0-87590-428-3 (alk. paper)
ISBN-10:0-87590-428-9 (alk. paper)
1. Snow--Remotes ensing. 2. Ice--Remote sensing. I. Duguay,
Claude R. II. Pietroniro, Alain. III. Series.
GB2401.72.R42R44 2005
551.4809181'3--dc22
2005031625
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CONTENTS
Preface
ClaudeR . Duguaya ndA lainP ietronir.o.. .....................................................................................................v..i.i.
Introduction
ClaudeR . Duguaya ndA lainP ietronir.o.. .......................................................................................................1.. ..
RemoteS ensingo f SnowC over
DieterS chererD, orothyK . Hall, VolkerH ochschildM, ax KOnigJ,a n-GunnaWr intherC, laudeR . Duguay,
Fr(cid:127)d(cid:127)riqueP ivot,C hristianM (cid:127)'tzler,F rankR au,K lausS eidel,R uneS olberga, ndA nneE . Walker. .......................7
RemoteS ensingo f Glaciersa nd Ice Sheets
Jan-GunnaWr inther,R obertB indschadleMr,a x KOniga, nd DieterS chere.r. ....................................................3. 9
Ice Characteristicasn d Processesa,n d RemoteS ensingo f FrozenR iversa nd Lakes
Martin O. Jeffries,K im Morris, and Nickolai Kozlenko. ..................................................................................... 63
SatelliteR emoteS ensingo f Permafrosat nd SeasonallFy rozenG round
ClaudeR . Duguay,T ingjunZ hang,D avid W. Leveringtona,n d VladimirE . Romanovsk..y.. ..............................9. 1
RemoteS ensingo f SurfaceW ater and SoilM oisture
Alain PietroniroJ,e ssikaT (cid:127)yr(cid:127), RobertL econtea, nd GeoffK ite.. .....................................................................1. 19
Evaporation/EvapotranspiratiEosnt imatesW ith RemoteS ensing
RaoulG rangera nd NormandB ussibre..s.. ....................................................................................................1..4. 3
Appendix:A cronyms.. ................................................................................................................................1..5. 5
SubjectI ndex. ................................................................................................................................................
PREFACE
The North, with its vast and varied landscapes,s parse researchersa, nd studentsi n the biophysicals ciencesw ho
population, and cold climate has always challenged its wish to learn aboutt he researchn ow being conductedw ill
explorers: physically, mentally, logistically, and techni- also benefit from this volume.
cally. The scientific community in particular has known The volumed erivesf rom a task forceo n "RemoteS ensing
suchc hallengesi n the past and does so today, especially in Northern Hydrology,"i nitially proposedb y international
in light of the projectedi ntensificationo f climate change delegateso f the Northern ResearchB asins( NRB) working
at high latitudes.I ndeed, there are clear signst hat change group.T he NRB working groupw as establishedin 1975 as
is already ongoingi n many environmentalv ariables:A ir part of the InternationalH ydrologicalP rogramme( IHP) to
temperaturea nd annual precipitation( including snowfall) promote researcho n river basinsa t northern latitudes. In
are increasingin many regions;s prings nowc overe xtenti s contrastt o other snow and ice conferences,N RB is intended
decreasingl;a ke and river ice freeze-upd atesa re occurring specifically for Arctic environments. Full membership,
later and breakupd atese arlier; glaciersa re retreatingr ap- therefore, is limited to countries with territory north of
idly; permafrostt emperaturesa re increasinga nd, in many the Arctic Circle. Founding members included Canada,
cases,t he permafrost is thawing; and sea-ice extent is at Denmark (Greenland),F inland,N orway, Sweden,t he USA,
recordm inimums and thinning. and the former USSR. Iceland joined in 1992 and Russia
Although someo f the documentedc hangeh as occurred has since taken over the role of the former USSR. Countries
over long periods of time, it appearst hat the processh as with polar researchp rogramsa re also eligible for associ-
accelerated since the mid-1970s. Field measurements have ate membership;c urrent associatem embersa re Germany,
provideds omeo f the evidencef or the observedc hangesA. Switzerland,t he UK, and Japan.
steadyd eclinei n severali n situ measuremenst iteso ver the A particularo bjectiveo f the NRB Working Group,w hich
last two or three decadesh, owever,h as left importantg eo- meetse very 2 yearsi n eitherE uropeo r North America, is to
graphicalg apsi n observationanl etworks.R emote sensing set up task forcest o promoter esearchi nitiatives on topics
observationsto, getherw ith numericalm odelsa ndt raditional of speciali nterestt o northernr esearchb asins.T he objective
measurementt echniques,h ave thus becomea n invaluable of an NRB Task Forcei s to continuel iaisona mongm ember
tool for studyingh ydrospherea nd cryospherec hangesi n countriesb etweenN RB meetingst hrough investigationo f
remote areas of the North. an area of mutual interest. One such task force was formed
As a result, we have focused this volume on remote sens- to review the stateo f the art on the use of remotes ensingi n
ing observationsa nd interpretationso f componentso f the northernh ydrology.
hydrologicalc ycle that are germanet o northern environ- This volumes pecificallyd erivesf rom the work of the orig-
ments,s ucha s glaciersa nd ice sheets,s nowc over,l ake and inal memberso f the taskf orce--Duguay (Chair), Pietroniro,
river ice, permafrost, and seasonallyf rozen ground. The Scherer,a nd Winther--and other international contributors
volume also coversd eterminations of soil moisture, surface (Jeffriesa nd Grangera s lead authors,a nd many collabora-
water, and evaporation/evapotranspirationfr om satellite tors) who enthusiasticallya greedt o contributem aterial on
remotes ensingF. or thesep arametersa, particulare ffort was subjectsf or which significant gaps were identified. The
madet o provider eferencesa nd summarizew ork conducted completion of this volume would not have been possible
at high latitudes. without their help and commitmentt o the project.
With new sensorsa nd methodsc onstantlyb eing devel- As editorsw, e are very gratefult o all authorsw, ho worked
oped,r emotes ensingin northern( andg lobal)h ydrologyh as hard to make this projecta successW. e are indebtedt o the
becomea quickly evolving field. This book thus provides many reviewers who devoted so much of their time and
readersa foundationfr om whicht o build on asd evelopments effort to improve the various chapterso f this volume. We
occur. Over this and the coming decadeC anada, Europe, extend our sinceret hanks to Jan Mydynski who provided
Japan, and the United States will place into orbit highly valuablee ditorial assistanceF. inally, we appreciateth e help,
capables ensopr ackagesth at will fostern ew advancese, spe- patience,a nd expertiseo f AGU staff who workedd iligently
cially in northernh ydrology. to publisht he book.
Scientists,r esearchers,a nd studentsw ith a direct interest
in the application of remote sensingi n northern hydrol- ClaudeR . Duguay
ogy will find this volumeo f immediatei nterest.S cientists, Universityo f Alaska, Fairbanks,A laska
Remote Sensingi n Northern Hydrology
Alain Pietroniro
GeophysicalM onograph Series 163
Copyright2 005 by the American GeophysicaUl nion National Water Research Institute,
10.1029/163GM01
vii
Introduction
Claude R. Duguay
GeophysicaInl stitute,U niversityo f Alaska,F airbanksA, laska
Alain Pietroniro
National Water Research Institute, Saskatoon, Saskatchewan, Canada
At northernl atitudes,i nstrumenteds itesa re often sparsea nd poorly distributed,
and their numberh asb een steadilyd ecliningo vert he last two to three decades.
Thish asb eena majori mpedimentto advancinogu rk nowledgoef northernh ydrol-
ogy.S atelliter emotes ensingis ideallys uitedt o complemenfite ld measurements.
In this chapter,s ummarieso f the main topicsc overedi n this book (i.e., snow
coverg, laciersa ndi ce sheetsl,a kea ndr iveri ce,p ermafrosatn ds easonallfyr ozen
ground,s urfacew atera nd soilm oisturee, vaporatioann de vapotranspiratioans)
well asc urrenta ndu pcomingc ontributionosf satelliter emotes ensingin northern
hydrologya re provided.
The North is looselyd efineda s the geographicaalr eao f nuityo f datac ollectedH. owevero, urg reatesnt eedl ies
theN orthernH emisphereth at encompassethse tundraa nd elsewherea, ndc oncernsa ccessto largeri nstrumented
taigae cosystemsT.h e North alsoi s identifieda st he region researchw atershedsw heren umerousc omplementary
mosts usceptiblteo the effectso f globalw arming.S incei t hydrologicaml easurementasr e madea t a scalet hat
is the variousw aterc omponentosf the cryospher(eg laciers canb e coupledw ith atmospheripcr ocessetsh atd rive
and ice sheets,s now cover, sea ice, lake and river ice, and the hydrologicacl ycle.I n fact, we needs everals uch
frozeng round)t hata rec onsideretdh ep rincipale xpressions watershedlso catedi n circumpolabr asinsw ith differ-
and instrumentso f climate change,n orthern hydrologists ent environmentals ettings( permafrostd istribution
haveb ecomea logicals cientificb odyt o pursuer esearcho n andt hicknessv, egetationt,o pographyg, lacierse, tc.)
thep redictiona nde valuationo f climate-changiem pacts. [Kane,2 005].
Nonetheless there remain Notwithstandingth is needf or mored ataa t largers cales,
...manyh urdlesto advancingo urk nowledgeo f north- instrumentedsi tesa re sparsea ndp oorlyd istributedin the
ern hydrology(a ll casti n a time of changingc limate). North, and their numberh asb een steadilyd ecliningi n the
Foremost is the need for better measurements of vari- last2 0-30 yearsA. s a result,t he definingc haracteristicosf
ousc omponentosf theh ydrologicacly cle( thisi s glob- remotes ensingte chnologrye nderit ideallys uitedto comple-
ally true)--a neede xpresseadt numerousw orkshops ment,i f not supercedem, anyo f the classicahl ydrological
throughoutm y career, now of 30 years. Potential fieldt echniqueuss edi n northernh ydrologyR. emotes ensing
improvemenot,f coursei,s possibleth roughim proved canf ill theg eographicagla pst hatf ieldm easuremenatslo ne
technologyf;o r examplet,h eu seo f solid-stateel ectron- cannot.I t is in this context,a nd with a view of remote sens-
icsi n extremelyc olde nvironmentcsa ni mprovec onti- inga sa ni nvaluablteo olf orn orthernh ydrologicarel search-
ers, that the idea for this book was conceived.
RemoteS ensingi n Northern Hydrology Thereh asb eens ignificanpt rogressin the applicationo f
GeophysicaMl onographS eries1 63
remotes ensinign hydrologsyi nceth e1 970sF. urthers ubstan-
Copyright2 005 by the AmericanG eophysicaUl nion
10.1029/163GM02 tive developmenatsre forthcomingo vert he nextd ecade
2 INTRODUCTION
next-generatiosnp acecraftasr el aunchedb y CanadaE, urope, ometera nd the more advancedA MSR-E systema boardt he
Japana, ndt heU nitedS tatesA. t thet ime of thisw riting,m any Aquap latforma re alsod escribedS. ubsequendti scussioinn
recentlyl auncheds atellitep latformsa rep rovidingim portant thisc haptepr resentasp plicationasn da lgorithmsfo r deriving
informationo nt hes tateo f thec ryospheraen dt heh ydrosphere, snowp ropertiesf rom the previouslyd efineds ystemsT. he
andn ew satellitesw ill soonf ollowt hatw ill significantlyc on- authorsil lustratet he developmenotf remotes ensinga pplica-
tributet o the field of northernh ydrology. tionsw ith specifice xamplesre levantt o the determinationo f
Earlier bookso n remotes ensingin hydrologyh avet ended snow-covereadr ea,s noww atere quivalent( SWE), deptha nd
to providea broado verviewo f the use of remotes ensing temperaturew, et snow,a nd snowr eflectanceT. he chapter
in hydrology and water management[ e.g., Engman and concludews ith a proposaflo r futurea pplicationasn df uture
Gurney,1 991;S chultza nd Engman,2 000] or have focused sensorsf or continuedm onitoring of snow propertiesb y
primarily on well-definedp arameterss ucha s snowc over remotes ensingT. hesei nclude( 1) the improvemenot f SWE
[e.g.,S eide!a ndM atinec,2 004]. This monographb uildso n retrievala lgorithmsa ndS WE determinatioant h ighers patial
thesep reviousw orksb y providinga review of the progress resolutions(;2 ) the exploitationo f data fusiont echniques
andp rospectos f remotes ensingin hydrologyfo cusedo n the for snowr esearch(;3 ) a greateru se of land coverd ata sets
North, a regionw hereh ydrologyi s dominatedb y snow,i ce, and digital elevationm odelsf or the retrievalo f snowc over
and frozen ground. propertiesp, articularlyi n mountainousa nd foresteda reas;
and (4) the developmento f physicallyb aseda nd spatially
OVERVIEW OF CONTENTS distributed snow models to overcome some of the limitations
of currente mpiricala nd conceptuaml odels.
This monographis organizedin to sevenc hapterso, rdered In Chapter 3, Winther and colleaguesd escriber emote
to reflect the relativei mportanceo f eacht opict o the recent sensinga s a useful tool for the studyo f glaciersa nd large
primaryl iterature.C learly,r emotes ensingo f the cryosphere ice masses,w hich, due to harsh climate and insufficiency
is of primaryi mportancein northernla ndscape(sfo rt hep ur- of daylight, in combinationw ith extensiveg eographical
poseo f thisp ublicationt,h e definitiono f cryospherien cludes coveragea, re largelyi naccessibleS. atellitesp rovideo ne of
snow,f rozen ground,g laciersa nd ice sheetsa, nd lake and the few methodsf or the studyo f theset ypes of landscapes
river ice) and is the focuso f Chapters2 through5 . The two at large spatials cales.T he authorsn ote that glaciersh ave
succeedincgh aptersc entero n wateri n the liquida ndv apor long been recognizeda s sensitivei ndicatorsf or climate
phasesa ndd emonstratseo meo f the challengetso character- change,s incet hey contain a considerablefr action of the
izing surfacew atersa nde vaporativep rocessesa,s w ell asi n world's freshwater. Becauseo f the nature of theset argets,
the applicationo f remotes ensingt echniquesin thesea reas. remotes ensings tudiesa re focusedo n changed etectiona nd
All of the chaptersp rovided iscussionos f the potentialf or monitoringo f glacialf eaturesM. oreover,d uet o thee ssential
future remotes ensinga pplicationsin the North. similaritieso f glaciersa nd ice sheetst o frozenr ivers and
Chapter2 presentsa thoroughr eview of snowc overa nd lakes, much of the theoreticalb ackgroundo n the optical,
the subsequenatp plicationo f remote sensingt o the deter- thermal,a ndm icrowavep ropertieso f snowa ndi ce contained
mination of snowc overp roperties.S cherera nd colleagues in Chapter 2 providest he essentialb ackgroundf or infor-
provide a comprehensives ynopsiso f the reflective and mation in Chapter3 . Winther and colleaguesfo cuso n the
thermalp ropertieso f snow.T hesea re describedw ithin the remotes ensinga pplicationsu sedi n mappingg laciere xtent,
contexto f existingr emotes ensings ystemsa ndp rovidet he glacierf aces,e quilibriuml ines,a ndg lacierv elocity. They
fundamentabl ackgroundfo r understandintgh e development identify a key role for interferometric synthetica perture
of remote sensinga lgorithmsi n snow-coveredre gions.A radar (InSAR) in monitoringg lacier velocity.T he process
detailed descriptiono f sensorsa nd systemsi s also given, for determiningg lacierv elocityi s describedin detail. The
which highlights the history of remote sensings ystems use of radar altimetry in the measuremenot f glaciere leva-
alongw ith their usesi n snowa lgorithmd evelopmentT. he tion is also describedin detail, with emphasiso n its use in
satellites described include visible and infrared-based sen- changed etection.O ther topicso f interesti ncludem ethods
sors such as the familiar AVHRR radiometer aboard the for estimatingg lacierp ropertiess ucha s surfacete mperature,
NOAA polar-orbitings atellitesa ndt he morer ecentA STER albedo/grains ize, and snowa ccumulationf or use in mass
platform aboard the Terra platform. Microwave sensors and energyb alancee stimates.
and the electromagneticin teractionb etweenm icrowaves Chapter 4 provides a comprehensiveo verview of ice
and snow surfacesa re describedi n detail. Active systems characteristicsa nd processesin northernr ivers and lakes
described include the RADARSAT, ERS, and ENVISAT focusingo n initial ice formation in autumn and ice-melt
satellites ystems.P assives ensorss ucha s the SSM/I radi- in spring.J effriesa nd colleaguesc oncentratep rimarily
DUGUAY AND PIETRONIRO 3
SAR systems( ERS-1, ERS-2, JERS-1, RADARSAT-l), Chapter 6 centers on surface water and soil moisture
supplementebdy aerialp hotographsp,a ssive-microwavsee n- remote sensing.T hese two important aspectso f the hydro-
sors,a nd Landsati magesa s a meanso f characterizingl ake logical cycle were combinedb ecauset hey both represent
and river ice covers.B ecauseo f the nature of these targets storage of the liquid phase of water within the northern
(both in terms of size and dynamic temporal characteris- hydrologicalc ycle. Surface water storages( lakes and wet-
tics), systemsw ith high temporala nd spatialr esolutiona re lands) are easily discriminatedb y using conventionalv is-
the mostp racticable. The authorsf ocuso n remote sensing ible and infrared sensors such as those flown on Landsat
applicationsth at assisti n determinings easonailc e charac- or SPOT. The utilization of active microwave sensors,s uch
teristics sucha s autumn freeze-up, ice growth, thickening as RADARSAT-1 or ERS-1/2, has lead to improvementsin
and grounding;f racturinga nd motion;a nd springt haw and the interpretationa nd classificationo f open-waterb odies.
breakup. They point out that mostn orthernf reshwateri ce Pietroniro and colleaguesd iscusso pen-water extent, and
is seasonailn nature and that characterizingi ce variability to a lesserd egreew ater surfacee levation,w ith particular
andc hangep, articularlyi n remotel ocationsu, nderscoretsh e emphasiso n applicationsw ithin the microwave frequen-
importanceo f frequentd ataa cquisitiona ndt he valueo f time cies.T he methodsd iscusseda re well establisheda nd easily
serieso f imagest o followt he courseo f eventsa ndp rocesses. operationalizedf or regular monitoring of these important
This chapter'se xtensivea nd holistica pproachto the remote hydrologicafle atures.I n contrastb, ecauseo f the notoriously
sensingo f lake and river ice providesa major contribution ubiquitousn atureo f soilm oisturet, he detectiona ndm apping
to the literature in this area. It affords easy accesst o an of water storagei n the vadosez one or soil profile are much
inclusive examination of the field that until now has been less straightforwardO. f the very few soil moisturee xperi-
conspicuousllya cking. ments that have been carried out in northern regimes, the
The remote sensingo f permafrost (perennially frozen chapters ummarizess oil moisturee xperimentsin areasw ith
ground)a nd seasonallyfr ozeng roundi s the focuso f Chapter seasonallyf rozen mineral soils. Theoretically,o ne should
5. Unlike most of the other terrestrial componentsc overed be able to extract soil moisture from the 1-10-cm depths;
in this book,p ermafrosti s a subsurfacep henomenonA. fter however, reliable and consistents ystematico bservations
providinga descriptiono f the factorst hat controlp ermafrost of soil moisture derived from microwave satellites are still
distributiona ndt he surfacef eaturesi ndicativeo f permafrost difficult to ascertain.
presence( e.g.,t haw lakes,p olygonalg round),D uguay and Chapter7 describesr ecenta dvancesi n the remote sens-
colleaguesr eview the applicationo f remotes ensingt o map ing of evaporationa nd transpiration.R elativelyf ew studies
permafroste xtent, active layer depth (i.e., the layer of soil have been directed specificallyt owardst he determination
abovep ermafrostt hat thawsa nd freezesa nnually),a nd sur- of evaporationo r evapotranspirationin northern environ-
face featuresi ndicativeo f permafrostp resenceT. he authors ments. However, becauset he evaporative componentso f
then describe some of the most recent advances on the use of the energy and water balancesc an be as high as 50% and
active and passivem icrowavei magery to map the seasonal 65%, respectivelyi,t is essentiatl hat the evapotranspirative
freeze/thaws tatuso f the landscapef rom the regionalt o the phaseo f the hydrologicalc ycle be understoodM. ethods of
continental and pan-Arctic scales.I n the final sectiono f estimatinge vapotranspirationd evelopedi n temperatec li-
this chapter,D uguay and colleaguesid entify areasi n which matesa re described.G rangera nd Bussi(cid:127)resn ote that these
researchis likely to take placei n the future: (1) mappingt he methodsm ay not be directly transferablet o northerna reas
evolutiono f permafrost-relatedf eatures( e.g., thaw lakes, becauseo f the different characteristicso f the vegetationa nd
patternedg round)b y usinga rchivedi mageryo r aerial pho- other physiographicc onditionss ucha s permafrosto r sur-
tographsa nd more recenth igh-resolutions atellitei magery; face ice that dominatet he northern landscape.S uggestions
(2) increasingth e useo f (and the developmenot f new) land for incorporatingr emotelys ensedi ce-coveri nformationi n
surfacet emperatured atap roductsfr om thermali nfrareda nd ordert o estimatel argel ake evaporationb y reformulatingt he
passivem icrowaves ensorsto examinet he impacto f climate parameterizationo f canopyc ontrolso n evapotranspiration
variability and changeo n permafrostt errain; (3) increasing are included.T he authorsc learlyi dentify currentd efectsa nd
the useo f (andt he developmenot f new) land surfacef reeze/ provided irectionf or future improvements.
thaw productsf rom active and passivem icrowaves atellite
sensorst o examine variability and trends in the onset of WHERE NEXT FOR REMOTE SENSING IN
freezinga ndt hawingi n relationt o climate;a nd( 4) integrat- NORTHERN HYDROLOGY?
ing the land surfacep roductsd erivedf rom remote sensing
data( e.g.,s urfacet emperaturev, egetations, nowc overv ari- Each chapteri n this volume includesa concludings ec-
ables)i n spatiallyd istributedp ermafrostm odels. tion that contains a discussion on future directions
4 INTRODUCTION
remotes ensingin northernh ydrology.S everalo perational of emitted microwave radiation around the frequencyo f
or researchp roducts derived from satellite sensorsc ur- 1.4 GHz (L-band). SMOS will carry the first-ever,p olar-
rently in orbit are availablet o northernh ydrologists(e .g., orbiting,s pace-borne2,- D interferometrirca diometerT. he
snow-covereda rea, SWE, surface albedo, soil moisture). satellitew ill achieveg lobalc overagee very3 daysw ith more
Data acquired by sensorso nboard NASA's Terra and frequentc overagea t northernl atitudes.
Aqua platforms, as well as by those on other U.S. satel- In December2 009,N ASA planst o launcht heH ydrosphere
lites (e.g., QuikSCAT) and satellitesf rom the Canadian StateM ission (Hydros) satellite,s pecificallyd esignedf or
(e.g., RADARSAT) and the European( e.g., ENVISAT) soil moisturer etrieval (t0-km resolutionw ith revisitso f 2
spacea genciesa, re alreadyp rovidings omev aluablep rod- to 3 days)a nd freeze/thawm apping( 3-km resolutionw ith
ucts. The numbera nd the quality of the productsc an only t- to 2-day revisits).A combinedr adara ndr adiometers ys-
increasea s new sensorsa re flown and new algorithmsa re tem, Hydrosw ill operatea t 1.26G Hz and 1.4G Hz, respec-
being developed. tively [Entekhabei t al., 2004]. Hydrosw ill providet he first
During this decadea lone, severalm issionsh ave been globalv iew of theE arth'sc hangings oilm oisturea nds urface
confirmeda nd othersa re plannedt hat will further advance freeze/thawc onditionst,h use nablingn ew scientifics tudies
the contribution of remote sensing to northern hydrol- of globalc hangea nda tmospheripcr edictabilitya ndm aking
ogy. Planned satellite missions such as the Advanced new hydrologicaal pplicationpso ssible.
Land ObservingS atellite (ALOS) of the JapanA erospace Recently,t he U.S. National Academy of Sciencesh as
ExplorationA gency (JAXA), due for launchi n 2005, and beena skedb y NASA to form a communitya ssessmenant d
RADARSAT-2 of the CanadianS paceA gency( CSA), sched- strategyf or the future of earth sciencea nd applications
uled for launchi n 2006, thoughn ot exclusivelyd esignedfo r from space.T his is referredt o as the National Research
hydrologicala pplicationsw, ill providei mportanti nforma- Council( NRC) DecadalS urveyT. he panelr equesteds ub-
tion to northern hydrologists( e.g., snow and ice, surface missionsf rom the communityr egardingp otential future
water, and soil moisture). satellite missions that addressed the NRC science themes.
Other missions,m ore specifically designedf or hydro- Severa(lc loseto tOO)f uturem issionc oncepthsa veb eenp ro-
logical applicationsw, ill also take place.F or example,t he poseda, few of directr elevancteo hydrologyt:h eC old-Land
EuropeanS paceA gency (ESA) launchedt he CryoSatp lat- ProcessesP athfinder( CLPP) mission[ Cline et al., 2005],
form on 8 October 2005. Unfortunately, the satellite was the Water ElevationR ecovery( WatER) satellitem ission
lost due to launch failure. CryoSat carried a sophisticated [Alsdorfe t al., 2005], the GlobalW aterR esourcems ission
radar altimeter called SIRAL (Synthetic Aperture Radar [Hildebrande t al., 2005], the Global HydrosphereM apper
InterferometricR adarA ltimeter)t o monitorp recisec hanges mission[ Fu andRodriguez2, 005], and the Glaciersa nd Ice
in the thicknesso f the polar ice sheetsa nd floating seai ce. SheetsM apping Orbiter (GISMO) mission [Jezeke t al.,
The observationst o be made over the 3-year lifetime of 2005]. Documentsd escribinge achs atellitem issionc oncept
the missionw ere expectedt o provide conclusivee vidence canb e founda t http: //qp.nas.edu/decadalsurvUelyti.m ately,
of rates at which ice cover may be diminishing. CryoSat perhapso nly oneo r a combinationo f the proposedm ission
was meant to be the first Earth Explorer missiono f ESA's conceptsw ill make it to orbit.
Living PlanetP rogramme.E SA has initiated an assessment In the meantime,c urrenta ndu pcomings atellitem issions
of ways to recoverf rom the CryoSat satellitel oss and will will providet echnologietsh atw ill permitt her outinem oni-
be exploringt he rangeo f optionst hat may be availables uch toring of many hydrologicasl tatev ariableso vern orthern
as rebuildingt he satellitef or a future launch. latitudes.T hese new developmentsw ill encourageg reater
The second Earth Explorer mission of ESA, the Soil integration(a ssimilationo) f remotes ensing-derivepdr od-
Moisturea nd OceanS alinity (SMOS) mission,w ill provide ucts into climate, weather forecasting,a nd hydrological
globalo bservationosf soilm oisturea ndo ceans alinity,w hich models.
are needed to advance our knowledge of the water cycle
and to contributet o better forecastingo f weather,e xtreme AcknowledgmenWt.e wisht o thankJ anM ydynskif orh ere dito-
eventsa, nds easonacl limates.S oilm oistured ataa reu rgently rial help.
required for hydrologicals tudies.D ue for launch in early
2007, SMOS will alsop rovideo bservationso verr egionso f REFERENCES
snowa nd ice, contributingt o studieso f the cryospherea nd
thus of the hydrologicalc yclea t northernl atitudes.A novel Alsdorf, D., E. Rodriguez,D . Lettenmaier,a nd J. Famiglietti,
instrumenth asb eend evelopedth at is capableo f observing WatER:T he WaterE levationR ecoveryS atelliteM ission,h ttp://
both soil moisturea nd oceans alinity by capturingi mages qp'nas'edu/decadalsurvey'