2010

Annual Report

Hydrospheric Atmospheric Research Center (HyARC)

Nagoya University

NAGOYAUNIVERSITY

2010

drospheric tmosphericesearch enter

(HyARC)

Contents

Foreword 2

Staff and Organization 3

Research Programme 6

Progress Reports Projects 8 DivisionofRegional–ScaleWaterCycleProcesses 12 LaboratoryofMeteorology 12 LaboratoryforClimateSystemStudy 18 LaboratoryforCloudandPrecipitationClimatology 22

DivisionofGlobal–ScaleWaterCycleVariations 24 LaboratoryofSatelliteMeteorology 24 LaboratoryofSatelliteBiologicalOceanography 26 LaboratoryofBio-PhysicalOceanography 30 List of Publications 32

2 Foreword

TheHydrosphericAtmosphericResearchCenter(HyARC)atNagoyaUniversity

wasestablished10yearsagotopromoteresearchontheglobalwatercycle,whichis

aprimarycomponentoftheearthsystem.Researchontheglobalwatercyclerequires

strongandextensivecollaborationamongscienceandapplicationcommunities.There-

fore,HyARCfunctionsasaninter-universitycollaborativesystem,whichisinmany

waysuniqueintheworld.InordertoensuretheactivityHyARChasbeenaccredited

asaJointUsage/ResearchCentersinceApril2010bytheMinistryofEducation,Cul-

ture,Sports,ScienceandTechnology,Japan.

HyARChasinitiatednumerousprojectsandactivities.Prominentamongtheseis

theInternationalProjectOfficefortheGlobalEnergyandWaterCycleExperiment

(GEWEX) Asian Monsoon Experiment (GAME) led by Prof. T. Yasunari, and its

various follow-onprojects.Additionalworkhasbeensupportedby the following:

Grants-in-Aid forScientificResearch;CoreResearch forEvolutionalScienceand

Technology (CREST)of JapanScienceandTechnologyCorporation (JST);Global

EnvironmentResearchFund;InnovativeProgramofClimateChangeProjectionfor

the21stCentury;andmore.Inaddition,fundingfromtheMinistryofEducation,

Culture, Sports, Science and Technology, Japan, supported the construction of a

multiparameterradarsystemtostudywatercirculation,andfundingfromtheInter-

UniversityProjectsupportedavirtuallaboratoryfordiagnosingtheearth’sclimate

system.

HyARChasalsocollaboratedwithnumerousinstitutionssuchasResearchInsti-

tute of Humanity and Nature (RIHN) and National Institute of Information and

CommunicationTechnology(NICT).AspartialcontributiontotheUNESCOInter-

nationalHydrologyProgramme(IHP),HyARChasconductedtrainingcoursessup-

portedbytheJapanTrustFund.Thisyear’scoursewasonsatelliteremotesensing

ofatmosphericconstituents.

Whileselectingprojectsandactivities,HyARCconsidersprojectfeasibility,sig-

nificance,andcollaborationrequirements.Itcurrentlyfundsthreeresearchprojects

andfourworkshops.AlthoughHyARChasonly10permanentstaffmembers(four

professors, threeassociateprofessors, and threeassistantprofessors), it supports

manypostdoctoralcandidatesinactiveresearch.Inaddition,HyARChasaccepted

graduatestudentsintheDepartmentofEnvironmentalStudies.

NagoyaUniversityhasadoptedaflexiblemanagementsystemthatemphasizes

accountability,yetencouragesresearchpublicationsandoutreachprograms.With

theencouragementprovidedbyanexternalevaluationcommittee,weherewithpro-

posetoestablishalarge-scalenational/internationalfacilityandaneworganization

foraddressingitssocialrequirements.

Uyeda HiroshiDirector

HydrosphericAtmosphericResearchCenter

3Staff and Organization

Research Division Division of Regional – Scale Water Cycle Processes

Professor

Assoc. Professor

Assist. Professor

Designated Assist. Professor

VL Promotion Unit

AdministrativeDirector

AdministrativeVice-Director

UYEDA Hiroshi

TSUBOKI Kazuhisa

SHINODA Taro

OHIGASHI Tadayasu

YASUNARI Tetsuzo

MASUNAGA Hirohiko

FUJINAMI Hatsuki

Division of Global – Scale Water Cycle Variations

Professor NAKAMURA Kenji

MORIMOTO Akihiko

Assist. Professor MINO Yoshihisa

ISHIZAKA Joji

Technical Office (Technical Center) MINDA Haruya

Secretary Office

Administrative Office

IWAMOTO Keiko

TANIGUCHI Tetsuya

SUGIE Osamu

General Affairs Section

Board of Councilors

Director

AdvisoryBoard

Board onResearch

Collaboration

Assoc. Professor

Designated Assist. Professor TANAKA Hiroki

Accounting Section

Research Promotion Section

Supplies Section

Student Affairs Section

4

Administration

UYEDA Hiroshi: Director, Prof., Hydrospheric Atmospheric Research Center, Nagoya University

NAKAMURA Kenji: Prof., Hydrospheric Atmospheric Research Center, Nagoya University

YASUNARI Tetsuzo: Prof., Hydrospheric Atmospheric Research Center, Nagoya University

ISHIZAKA Joji: Prof., Hydrospheric Atmospheric Research Center, Nagoya University

TANAKA Kentaro: Prof., Graduate School of Science, Nagoya University

TSUJIMOTO Tetsuro: Prof., Graduate School of Engineering, Nagoya University

TAKENAKA Chisato: Prof., Graduate School of Bioagricultural Sciences, Nagoya University

KANZAWA Hiroshi: Prof., Graduate School of Environmental Studies, Nagoya University

MATSUMI Yutaka: Prof., Solar-Terrestrial Environment Laboratory, Nagoya University

Advisory Board

lMembersfromNagoyaUnisversity

NAKAMURAKenji:Prof., Hydrospheric Atmospheric Research Center, Nagoya University

YASUNARITetsuzo:Prof., Hydrospheric Atmospheric Research Center, Nagoya University

ISHIZAKAJoji:Prof., Hydrospheric Atmospheric Research Center, Nagoya University

TSUBOKIKazuhisa:Assoc. Prof., Hydrospheric Atmospheric Research Center, Nagoya University

MASUNAGAHirohiko: Assoc. Prof., Hydrospheric Atmospheric Research Center, Nagoya University

MORIMOTOAkihiko: Assoc. Prof., Hydrospheric Atmospheric Research Center, Nagoya University

lMembersoutsideNagoyaUniversity

FUJIYOSHIYasushi:Prof., Institute of Low Temperature Science, Hokkaido University

HANAWAKimio:Prof., Graduate School of Science, Tohoku University

SUMIAkimasa: Prof., Integrated Research System for Sustainability Science,

The University of Tokyo

FUKUSHIMAYoshihiro:Designated Prof., Tottori University of Environmental Studies

YAMANAKAManabu: Principal Scientist, Research Institute for Global Change, Japan Agency for Marine-Earth Science and Technology

YAMANOUCHITakashi:Prof., National Institute of Polar Research

TANIGUCHIMakoto:Prof., Research Institute for Humanityand Nature

OKIRiko:Senior Researcher, Earth Observation Research Center, Japan Aerospace Exploration Agency

Board of Councilors

5

Board on Research Collaboration

lMembersfromNagoyaUniversity

NAKAMURAKenji:Prof., Hydrospheric Atmospheric Research Center, Nagoya University

ISHIZAKAJoji:Prof., Hydrospheric Atmospheric Research Center, Nagoya University

MORIMOTOAkihiko:Assoc. Prof., Hydrospheric Atmospheric Research Center, Nagoya University

lMembersoutsideNagoyaUniversity

FUJIYOSHIYasushi: Prof., Institute of Low Temperature Science, Hokkaido University

YAMANAKAManabu:Principal Scientist, Research Institute for Global Change, Japan Agency for Marine-Earth Science and Technology

TANIGUCHIMakoto:Prof., Research Institute for Humanityand Nature

OKIRiko:Senior Researcher, Earth Observation Research Center, Japan Aerospace Exploration Agency

6 Research Programme

Water circulation studies using new polarimetric radars

In2007,newpolarimetric(multiparameter)radarswereinstalledattheHydrosphericAtmosphericResearchCenter(HyARC),NagoyaUniversity.Sinceitsinstallation,thisequip-menthasbeenpromotingnewstudiesoncloudsandprecipitation,thusaidinginthedevelop-mentofnewobservationalandanalyticaltechniquesthatareessentialforstudiesonwatercirculation.Suchobservationalandanalyticaltechniquesaswellasdataassimilationmethodsarenecessaryforutilizingobservationaldatafromthenewradarsandforamalgamatingthedatawithacloud-resolvingmodel. Thisresearchprogramaimsatpromotingresearchonwatercirculationusingthenewpolarimetricradarsandexistingradarsets.Inparticular,weexamineandimplementobser-vationaldataofweatherphenomenaandphysicalprocessesofcloudandprecipitationsystems.Weaimatdevelopingnewparametersformultiparameterradarobservationsanddataanal-ysisandnewdisplaymethodsforradardata.Wewilldevelopsoftwareandoperationalroutinesfortheradarequipmentfromphysicalandengineeringviewpointsincollaborationwithre-searchersparticipatinginthisstudyproject.

Diurnal processes of convection/precipitation systems in the climate System

Diurnalvariationinconvectionandprecipitationisaprominentmeteorologicalfeature,particularlyinthetropics/subtropicsandmonsoonregions.Energy,water,andmomentumexchangesthroughthediurnalcyclebetweentheearthsurface,atmosphericboundarylayer,andfreeatmosphereplayacrucialrole inglobalclimatemodels(GCMs)andstillcannotreproducearealisticdiurnalcycleinconvection/precipitation,includingsystematicerrorsinthemodels. Thisresearchplanaimstoclarify theregionalityandseasonalityofdiurnalprocessesbasedonTRMM,otherremotesensingdata,andin-situobservationaldatafromraingaugestations.Cloudresolvingmodels(e.g.,CReSSandWRF)andotherregionalmodelsarealsousedtoelucidatesystematicerrorsintheclimatemodelduetothediurnalcycle.Thesestud-iescancontributetotheongoinginternationalproject“MAHASRI.”Weaimtopromotestud-iesonthediurnalprocessofconvection/precipitationintheclimatesysteminJapan. OnDecember19,2007,adomesticworkshop,co-hostedbyMAHASRI,washeldinHakone.Studiesonthediurnalvariationofcloud/precipitationsystems, includingtherelationshipwithterrain,synopticconditionsandintraseasonalvariation,werepresented.ThesestudiescoveredareasfromtheTibetanPlateautotheMaritimecontinents.Intotal,14participantspresentednewscientificresultsandtherewasalivelydiscussionwithmanyparticipantsintheworkshop.Futureissuesondiurnalcycleswerealsodiscussed.

7

Study of atmospheric and oceanic climates over Okinawa Island and its surroundings

TheOkinawaSubtropicalEnvironmentRemote-SensingCenter,anobservationfacilityinOkinawa,Japan,wasestablishedbytheTheNationalInstituteofInformationandCom-municationTechnology (NICT).These facilitiesoffer theuseof fullpolarimetricDopplerradar(COBRA),400MHzwindprofilerradar,Dopplersodar,disdrometers,raingauges,andoceanradars.In2005,aninteruniversitycollaborationwasformedbetweenNICT,Okinawa,andtheHydrosphericAtmosphericResearchCenteratNagoyaUniversity,Japan(HyARC). Severalinterestingphenomena,suchasacoldwaterappearanceinnorthernTaiwanafteratyphoon,havebeenreported.Newobservations,suchasadual-Karadarsystemobserva-tion,havealsobeenintroduced.Thedirectionofthenextstepwasdiscussed,andtwodirec-tionshavebeen identified: (a)flexibleocean radardevelopmentandapplicationsand (b)Ka-bandradarobservationwithaversatileC-bandDopplerradar. Thescientificobjectivesarenotalwaysconcrete;however, the technology toremotelyobserveatmosphericandoceanicphenomenaissimilar.NICTdevelopsradiowavessensors,andHyARCorganizestheexplorationofdeeperandwiderapplications.Theimportanceofthecollaborationiswellrecognized.

8 Projects

PROgReSS RePORtS

Formation of a virtual laboratory for diagnosing the earth’s climate sys-tem (VL)

Toconductcollaborativeresearchandprovideeducationinaddressinghigh-stressfactorssuchasglobalwarming,avirtuallaboratoryfordiagnosingtheEarth’sclimatesystem(VL)wasformedin2007byfouruniversityresearchcentersstudyingclimateandenvironment.HyARCsetuptheAtmosphericResearchPromotionTeam(VLPromotionTeam)toprogressthecollaborativeresearch.Wefocusourstudiesonwaterbudgetsassociatedwithcloudsandprecipitationanddevelopanobservationandanalysissystem.WeanalyzetwopolarimetricDopplerradardatatodiagnoseacategoryofhydrometeorparticles,developacloud-resolvingmodelknownasCloudResolvingStormSimulator(CReSS),validateitsresultsusingasatel-litesimulatorknownasSatelliteDataSimulationUnit(SDSU),andestablishadataassimila-tionmethodforamesoscaleprecipitationsystem. In2010,weperformedcontinuousobservationwithapolarimetricDopplerradarlocatedatNagoyaUniversity.AheavyrainfalleventoccurredinthesoutheasternregionofGifuPre-fectureonJuly15,2010.ThestructureoftheprecipitationsystemwasclarifiedusingthepolarimetricradarandwasaccuratelyreproducedusingCReSS.Inaddition,thelightningfrequencywasreproducedusingCReSSLightningSimulator.Moreover,weusedpolarimetricradardatatoconductstatisticalanalysisofprecipitationcellsovertheNobiPlain. Wecomparedbrightnesstemperatures(TBBs)ofinfraredandmicrowavebandsobtainedfromsatelliteobservationswiththosecalculatedbySDSUappliedtothedailysimulationresultsusingCReSS.SatellitedatawereprovidedbyCenterforEnvironmentalRemoteSens-ing(CEReS),ChibaUniversity,undertheframeworkofVL.Figureshowshorizontaldistribu-tionsofTBBforinfraredbandobtainedbysatelliteobservationandsimulationovertheTai-wan–Okinawaregion.Twowell-developedMesoscaleConvectiveSystems(MCSs)withmini-mumTBBlessthan200KdevelopedoverthesoutheastandsouthwestareasfarfromTaiwanIslandinsatelliteobservation.ThesoutheasternMCScanbereproducedinthesimulation.WewillconfirmbiasesandimprovetheaccuracyofthemicrophysicalprocessesofCReSSincomparisonsimulationresultswithsatelliteobservationsstatistically,.

Fig. HorizontaldistributionsofTBBfortheinfraredbandobtainedbysatelliteobservation(MTSAT-CH1:left)andsimulation(CReSS-SDSU:right)at17UTConMay29,2010overtheTaiwan–Okinawaregion.

9

the Innovative Program of Climate Change Projection for the 21st Cen-tury (KAKUSHIN Program)

lCloud Modeling and Typhoon Research

Cloudphysics isoneof thekeyprocesses formodelingclimatechange,especially forglobalwarming.Improvingcloudprocessesisessentialforaccuratesimulations.Cloudpro-cessesarealsocoreprocessesinsimulationsofhigh-impactweathersystemssuchasheavyrainfallsandtyphoons.Thecloudmodelingteamhasbeendevelopingacloud-resolvingmod-elcalledtheCloudResolvingStormSimulator(CReSS).Thecloudmicrophysicsandcom-putationschemeofCReSSareimprovedforaccurateandhigh-speedcalculation.Convectivecloudsinthetropicalregionandtyphoonsareimportantobjectsofourteam.TheCReSSmodelisalsocoupledwithglobalmodelstosimulateconvectiveregions.CReSSisusedfortyphoonresearch,whichaimstohelpverifytyphoonsimulationsmadebyglobalmodelsandtoproduceaccurateandquantitativeevaluationsoftyphooneffectsonhumansocietyunderthepresentandfutureclimates. Occasionally,typhoonscauseseveredisastersowingtoheavyrainfallandstrongwinds.Ontheotherhand,theybringalargeamountofwatertotheEastAsiancountries.Changesintyphoonswithglobalwarming,therefore,havealargeimpactonhumansociety.Becausetyphoonsarecomposedofintenseconvectivecloudsandassociatedstratiformclouds,acloud-resolvingsimulationisnecessarytoaccuratelypredicttheirintensity.Inthepresentstudy,wehavedevelopedanewtechniqueforperformingaparallelcomputationofthecloud-resolvingmodel in anarbitrary-shaped region,which isnamed the “TilingDomain Technique” forCReSS.Thefigureshowsathree-dimensionaldisplayofsimulatedcloudsassociatedwiththetyphoonoverTaiwanin2009.TheeyewallaroundtheeyeislocatedoverTaiwan.ThecloudbandtothesouthoftheeyecausedheavyrainfallinsouthernTaiwan.Thesimulationshowsthatthecloud-resolvingsimulationenablesustoquantitativelypredictthetyphoonintensity.BycollaboratingwiththeotherteamoftheKAKUSHINprogram,ourteamperformedsimu-lationexperimentsoftyphoonsintheglobalwarmingclimateandfoundthatextremelyintensetyphoons,whichhaveneveroccurredinthepresentclimate,willoccurinthefutureclimates.

Fig.Three-dimensionaldisplayofsimulatedtyphoonNo.8in2009usingPOV-Ray.Thewhiteshadingshowsthemixingratioofcloudwaterat02UTCAugust8,2009.

10

Study consortium for earth-Life Interactive System (SeLIS)

TheStudyconsortiumu forEarth-Life InteractiveSystem(SELIS)wasestablishedasavirtualinstituteinNagoyaUniversityinMarch2008,tofollowuptheresearchactivityofthe21stcenturyCOEProgramof“theSun-Earth-LifeInteractiveSystem”.ThememberinstateofSELISareHyARC,GraduateSchoolofEnvironmentalSciences(GSES),GraduateSchoolofBio-AgriculturalSciences(GSBS)andtheSolar-TerrestrialEnvironmentalLaboratory.TheSELISprojectofficeislocatedatthe5thflooroftheInstituteforAdvancedResearchHallofthiscampus,andtheHyARCismanagingthisofficeasamaininstituteofSELIS.ThemainobjectiveoftheSELISistopromotecoopearativestudiesandrelevantcapacitybuildingfortheEarth-LifeInteractionstudies,andtopromotecollaborationwithrelevantnationalandinternationalprogramsandprojects.SELISisalsoexpectedtocontributetoresearchprojectsproposedfromNagoyaUniversitytotheResearchInstituteforHumanityandNature(RIHN)inKyoto.Intheeducationprogram,SELIScontributestosomelecturecourseandseminars,e.g.,“Chikyu-gaku”(StudyfortheEarth)attheGSES. Inacademic year2010,SELISorganized seven interdisciplinary seminars.SELISalsocontributes tobasic environmental studiesandeducationunder theGlobalCOEProgram“FromEarthSystemSciencetoBasicandClinicalEnvironmentalStudies(BCES)”thatstart-edinJuly2009.InNovember,SELISco-sponsoredaninternationalworkshopon“Impactofsolar activity on climate variability and change”. Two faculty members of SELIS, with agraduate student,publishedone scientificpaper (Zhang,YasunariandOhta,2011)on theTaiga-parmafrostcoupledsysteminSiberiaanditsresponsetothefutureclimatechangeattheEnvironmentalResearchLetters(ERL),whichisaninternationally-renownedjournalontheenvironmentalsciences.

11

12 Division of Regional – Scale Water Cycle Processes

Laboratory of Meteorology

MaintenanceandenhancementmechanismsoftheprecipitationbandformedalongtheIbuki–SuzukaMountainsonSeptember2–3,2008

AheavyprecipitationeventoccurredalongtheIbuki–SuzukaMountainslocatedinthewestof theNobiPlain,JapanonSeptember2–3,2008.Themaximumtotalprecipitationamountobservedbyraingaugesfor18hwas425mm.Thiseventwascausedbyastationaryprecipitationbandthatformedalongthenorth–south-orientedmountainsandstagnatedforapproximately13hfrom12JSTonSeptember2to01JSTonSeptember3.Thelengthandwidthofthebandwereapproximately100kmand20km,respectively. AtimeseriesofhorizontalwindsinaverticalprofileobservedbyawindprofilerradarlocatedatNagoyaLocalMeteorologicalObservatoryshowninFig.1wascapturedonthewindwardsideoftheband.Thelow-levelsoutheasterlywindwaswarmandmoistwithequivalentpotential temperaturegreaterthan355Kandwasinducedbyasynopticcondition (not shown). It would impinge on theeasternslopeoftheMountainsandcontinuouslydevelopprecipitationcells.Thesecellswerepropa-gatednorthwardbysoutherlywindsaboveaheightof1km(Fig.1),correspondingtothealignmentoftheband.Themaintenanceofthebandwouldbeattributedtokeeptheverticalwindprofileforap-proximately13hthroughthesynopticcondition. Twosignificantheavyprecipitationareaswithhorizontalscalesofapproximately10kmappearedintheband.Oneoftheareaswasincludedintherangeofadual-DoppleranalysisobtainedbytwoX-bandpolarimetricDopplerradars.Thisanalysisshowthatalow-levelsoutheasterlywindataheightof1kmconvergedinawedge-shapedvalleyopeningsouthwardbetweentheIbuki-SuzukaMountainsanditsbranch,theYoroMountains,whichareorientednorth–northwesttosouth–southeast(Fig.2).Thelocationofthisvalleycorrespondstothewindwarddirectionofwarmandmoistinflow.Theprecipitationen-hancementmechanismofthisareacanbeattributedtothecontinuousupdraftsanddevelop-mentofprecipitationcellsformedbythelow-levelconvergenceoverthisvalley.

Fig. 1 Timeseriesofhorizontalwindsinaverticalpro-fileobservedfrom00JSTonSeptember2to06JSTonSeptember3,2008byawindprofilerradarlocatedatNagoyaLocalMeteorologicalObserva-tory.Fullandhalfbarbsdepict5and2.5ms–1,respectively.

Fig. 2 (a)Horizontaldistributionofreflectivityataheightof3km(shades)andhorizontalwindsat1km(arrows)at1730JSTonSeptember2,2008.Contourshowsaheightof300mabovesealevel.

(b)Verticalcrosssectionofreflectivity(shades)andwindvectorsalongtheA–Bplane(arrows)in(a).

13StructureandformationmechanismoftherainbandaroundthecenterofTyphoon0918atlandfall

Heavyrainfallproducedbylandfallingtyphoonsinteracted with the typhoon’s atmospheric environ-ment,underlyingsurfacecondition,andinternalme-soscalestructure.Althoughmanypreviousstudieshavereported the orographic effect on the heavy rainfallproducedbylandfallingtyphoons,additionalfactorshavenotbeenstudiedmuch.Typhoon0918(T0918)broughtheavyrainfalltotheKiiPeninsulaandAichiPrefecturefrom00to07JSTonOctober8,2009.Thepurposeof this study is to clarify the structureandformationmechanismoftherainbandaroundthecen-terofT0918atlandfallandstructurealterationtoanextratropicalcyclone. TheheavyrainfallareaproceedednorthwardovertheeasternslopeoftheKiiPeninsulawiththepropaga-tionofT0918from00to04JSTonOctober8.Strongeasterlywindsinthelowertropospherewereobservedinthenorthernsideofthetyphooncenterduringtheperiod.Equivalentpotentialtemperatureinthelow-leveleasterlywindwasgreaterthan350K,thusawarmandmoistairmassascendedovertheeasternslopeoftheKiiPeninsulaandbroughtheavyrainfall.Duringtheperiod,theobservedcloud-topheightwasnotsig-nificantlyhigh,andlightningwasnotobservedthroughLightningLocationSystem(LLS)operatedbyChubuElectricPowerCo.,Inc.Thefactthattheheavyrainfallwascausedbytherelativelyshallowprecipitationsys-temovertheKiiPeninsulacorrespondstoseveralpre-viousstudies. AsT0918propagatednorthward,heavyrainfallwasobservednearAichiPrefecture.Theheavyrainfallwascausedbyarainbandalignedfromsouth–southwesttonorth–northeastwhoseecho-topheightdefinedby20dBZewashigherthan12km(Fig.3).FrequentlightningwasalsoobservedbyLLSduringthepassageoftherainbandnearAichiPrefecture.Figure4showshorizontaldistributionsofreflectivityatheightsof2kmand7kmat0350,0410,and0450JSTonOctober8observedbytheDopplerradarlocatedatNagoyaLocalMeteorologicalObservatory.Thedeeprainbandobservedat0450JSTdevelopedthrough

themergingofashallowprecipitationre-gionthatformedneartheeasterncoastoftheShimaPeninsulaintoanothershallowprecipitationregionthatpropagatedovertheKiiPeninsula.Thisrainbandproceedednortheastwardandwasmaintainedbycon-vergence of a low-level warm and moistsoutheasterlywindintheeasternsideandarelativelylowequivalentpotentialtem-perature airmass with the northwesterlywind in the western side. Therefore, thestructure of the deep rainband differedfromthatoftheshallowprecipitationre-gionthatdevelopedovertheeasternslopeof the Kii Peninsula. The deep rainbandwasformedabruptlybythemergingoftwoshallowprecipitationregions.

Fig. 3 Horizontaldistributionofreflectivityataheightof2kmobservedat0442JSTonOctober8,2009byanX-bandpolarimetricradarlocatedatAnjyoCity(upper)andverticalcrosssectionofreflectivityalongtheA–Blineatthesametime(lower).

Fig. 4 Horizontaldistributionsofreflectivityatheightsof2km(upper)and7km(lower)at0350(left),0410(center),and0450(right)JSTonOctober8,2009observedbytheDopplerradarlocatedatNagoyaLocalMeteorologicalObservatory.

14RelationshipofpolarimetricparameterswithpropertiesofsolidprecipitationparticlesobservedintheHokurikudistrict,Japanduringthewinterseasonin2008–2009

Tounderstandthecharacteristicsofsolidprecipitationparticlesusingpolarimetricradars,itisfirstnecessarytoclarifytherelationshipbetweenthepropertiesoftheseparticlesandpolari-metric parameters. The purpose of this study is to examine the relationship of polarimetricparametersobtainedbyaradarandpropertiesofsolidprecipitationparticles(category,diameter,shape, and number concentration) observed by a ground-based particle-imaging system atKanazawaUniversityduringthewinterseasonin2008–2009. ThepolarimetricradarlocatedatOshimizu,IshikawaPrefecture,Japanyieldedparametersofradarreflectivity(Zh),differentialreflectivity(Zdr),specificdifferentialphase(Kdp),andcorrela-tion coefficient between horizontal and vertical polarization signals (ρhv). The ground-basedparticle-imagingsystematKanazawaUniversity locatedapproximately30kmfromthe radarrecordedphotographsofeachsolidparticleanddigitizeditbyanimage-processingtechniquetoachievetheshapeanddiameterofeachparticleandtheirnumberconcentrations.Thecomplex-ity,whichistheratioofthecircumferencelengthtothatoftheminimumarea,andnumberofholeswereusedtodetermineclassificationofparticleintosnowflakeorgraupel.Here,particleswithoutholesandwithcomplexitylessthan1.21aredefinedasgraupel,whileremainingparticlesaredefinedassnowflakes.Moreover,particlewithdiameterslessthan3mmwereexcludedfromtheanalysesbecausetheirsizemadeexaminationimpractical.Thetotalvolumeofsnowflakeandgraupelparticleswascalculatedasthesumofparticlevolumesachievedbyrotatingparticlearea.Categoryandtypicalcharacteristicsofpredominantparticlesweredeterminedin1-minintervals.Tomatchthetargetareabetweenthevolumesobtainedbybothmethods,thetargetvolumeontheradarbininthelowermostPlanPositionIndicator(PPI)scanwasprescribedthroughconsid-erationofcategory,fallvelocity,andhorizontalwinddirectionandspeed. Ourobservationperiodswere1900–2100JSTonJan13,1255–1500JSTonJan15,and2100–2130JSTonFeb16,2009.Figure5showsatimeseriesofpolarimetricparameters,number,andvolumeofeachcategoryfrom1255to1500JSTonJan15.Whenconicalorroundgraupelparticleswithdiametersfrom3to6mm(graupelperiod)werepredominantlyobserved,Zh,Zdr,Kdp,andρhvrangedfrom19.9to31.2dBZe,-0.6to-0.1dB,−0.3to−0.1°/km,and0.99to1.00,respectively.Whensnowflakeswithdiametersfrom6to15mm(snowperiod)werepredominantlyobserved,thesameparametersrangedfrom14.9to27.2dBZe,−0.5to−0.2dB,−0.2to0.3°/km,and0.99to1.00, respectively. During thegraupel period, Zh increased incorrelationwiththesameshiftinobserved particle diameters ornumberconcentrations.Inaddi-tion,Zdrdecreased(approached0dB)when thepredominantpar-ticleshapewasconical (round).Theseresultscorrespondtothoseshown in previous studies. Thelower threshold of Zh to detectgraupel should be reconsideredbecausetheminimumZhwasap-proximately20dBZeinthisstudy.Itisinterestingtonotethatduringthesnowperiod,ZdrandKdpval-ueswereclosetozero,whichil-lustrates that snowflake shapesshouldnotbeoblate;thatis,theverticalandhorizontaldiametersmatch.

Fig. 5 Timeseriesofpolarimetricparameters(upperandmiddlepanels),number,andtotalvolumeofsnow/graupelparticles(lowerpanel)observedfrom1255to1500JSTonJanuary15,2009.Zh(solidline)andZdr(brokenline)obtainedbyapolarimetricradarin5-minintervalsareshownintheupperpanel.Kdp(brokenline)andρhv(solidline)areshowninthemiddlepanel.Numberofsnowparticles(orangebargraph),graupelparticles(bluebargraph),andvolumeofsnow(brokenline)andgraupel(solidline)obtainedbytheground-basedparticle-imagingsystematevery1-minintervalsareshowninthelowerpanel.

15VerticalobservationoficeparticlesizedistributionsinastratiformregionofaMesoscaleCon-vectiveSystemduringtheBaiuperiod

Althoughmanypreviousstudiesdoc-umentedthedynamicstructureofMeso-scaleConvectiveSystems(MCSs),nore-searchisbasedonmicrophysicalinsituobservationoficeparticleswithdiame-terslessthan500µm.Weconductedanin site observation of ice particles in astratiformregionofaMCSonJune12,2008 using hydrometeor videosonde(HYVIS)atOkinawaIsland.This studyanalyzes the vertical distribution of iceparticle properties obtained by HYVISobservation, including shape, numberconcentration,andparticlesizedistribu-tions (PSDs), and discusses the iceparticlegrowingprocess. AMCSfocusedinthepresentstudydevelopedalongtheBaiufrontandprop-agatedeastwardovertheEastChinaSea.ItsstratiformregioncoveredOkinawaIsland.HYVISlaunchedat1426JSTonJune12showsthemeltinglevelataheightof4.5km.UsingimagesobtainedbyHYVIS,iceparticleswereclassifiedintosixcategoriesaccordingtotheirshape:needle,column,plate,columnandplate,aggregate,andundefined.TheverticalprofilesofnumberconcentrationsofeachcategoryandPSDswerealsoestimated. Figure6showsverticalprofilesofnumberconcentrationsofeachcategorydividedbytheirshape,whichwasdelimitedbyamaximumdiameterof100µm.Thelargestcategorywastheplatetype,whichsuggestedthattheiceparticleswereobtainedinlowsupersatura-tionconditionswithicelessthan10%.Theordersofnumberconcentrationwithdiameterssmallerorlargerthan100µmwere105m−3or104m−3,respectively.Almostundefinedcate-gorywasthesmallparticleswithdiametersrangingfrom10to20µm.NosupercooledliquidparticlesorrimediceparticlesweredetectedbyHYVIS. PSDisdefinedbyslopeparameter(Λ)andinterceptparameter(N0).PSDsateachheightwerecalculatedbyfittingontheregressioncurveoftheMarshall–Palmerdistribution.Figure7showsverticalprofilesofΛandN0calculatedusingPSDsateachheight.Thegrowthprocessoficeparticlesisassumedbytheverticalprofiles of these parameters. When theheightdecreasesbetween10and12km,between7and8km,andlessthan6km,bothΛandN0decrease.Thevariationsoftheseparametersshowadecreaseinthenumberconcentrationoficeparticlesandtheappearanceoflargeparticleswithadecrease inheight,whichsuggests thataggregationgrowthispredominant.Onthecontrary,whentheheightdecreasesbetween8and10kmandbetween6and7 km, Λ is constant and N0 increases,which suggests a predominant deposi-tionalgrowth.

Fig. 6 Verticalprofilesofnumberconcentrationsofeachcategorydividedbytheirshape(shadedbargraph),whichwasdelim-itedbyamaximumdiameterof100µm.Maximumparticlediameterlessthan100µm(left)andgreaterthanorequalto100µm(right)areshown.Solidandbrokenlinesrepresentthedegreesoficeandwaterofsaturation,respectively.

Fig. 7 VerticalprofilesofN0 (left)andΛ (right) fromthemeltinglevelatapproximately4.5km to12km.Theseparameterswere obtained by fitting on the regression curves of theMarshall-Palmerdistribution.

16CharacteristicsofprecipitationcellsobservedbyR/VMiraioverthetropicalwesternPacificOcean

Precipitation cells, which are fundamental elements of precipitation systems, requirestatisticalanalysestoclarifytheirgeneralfeatures.Thisstudyinvestigatesstatisticalcharac-teristicsofprecipitationcellsoverthetropicalwesternPacificOceanusingdatarecordedfromJune6toJune27byaship-borneDopplerradarandupper-airsoundingobservationsobtainedbyR/VMirai(MR08-02)ofJapanAgencyforMarine-EarthScienceandTechnology(JAMSTEC)at135.0E/12.0N.Theareaand30-dBZeecho-topheightofeachprecipitationcellwereanalyzedastheirhorizontalandverticalscales,respectively.Athree-dimensionaldetec-tionalgorithmdevelopedinapreviousstudydetected13,654precipitationcellsduringtheobservationperiod. Figure8showsanintegratedprobabilitydensityof30-dBZeprecipitationcellecho-topheight.Theratiooftheecho-topheightnotexceedingthemeltinglevel(4.9km)+1kmwas84%.Thefrequencyofprecipitationcellswithechotopshigherthan8kmwassubstantiallylower,whichisconsistentwiththecharacteristicsofoceaniccellsreportedinpreviousstud-ies.Figure9showstheprobabilitydensityofanareaofprecipitationcellsataheightof2kmwithanaverageandmaximumfrequencyof34.8km2and21km2,respectively,whichindicatesthatthelargestareaissmallerthantheaverage. Upper-airsoundingobservationsconductedevery3hduringstationaryobservationonR/VMiraishowachangeintheatmosphericenvironment;thatis,mid-leveldrynesswithalow-leveleasterlywindwascharacterizedintheformerperiod,andadeep,moistlayerwithalow-levelwesterlywinddevelopedinthelatter.Sensitivityofthecharacteristicsofprecipi-tationcellsonrelativehumidity(RH)atheightsof3,4,and5km;verticalgradientofequiv-alentpotentialtemperaturebetween0.5and6.0km;andconvectiveavailablepotentialen-ergy(CAPE)asindicesofatmosphericenvironmentswereexamined.Precipitationcellshavelower(higher)30-dBZeecho-topheightandsmaller(larger)areaataheightof2kminthelower(higher)RHataheightof3km.Inaddition,thosewithsmaller(larger)areaataheightof2kmcorrespondtotheatmosphericenvironmentwithlower(higher)RHatheightsof4and5kmandwithsteep(gentle)verticalgradientofequivalentpotentialtemperature.How-ever,lesssensitivitywasobservedon30-dBZeecho-topheightsinRHatheightsof4and5kmandverticalgradientsofequivalentpotentialtemperature.Moreover,lesssensitivityinprecipitationcellswasobservedforCAPEcharacteristics.

Fig. 8 Integrated probability density of 30 dBZe echo-topheightinprecipitationcellsobtainedbyaship-borneDopplerradaronR/VMirai(MR08-02).

Fig. 9 Probabilitydensityofareaofprecipitationcellsataheightof2km.

17SimulationoflightningactivityusingCReSSLightningSimulator

WesimulatedlightningactivityusingaLightningSimulatorbasedonCloudResolvingStormSimulator(CReSS).ThisLightningSimulatorfeaturestwoprocesses:accumulationofelectricchargebyhydrometeorparticlechargingandlightningdischarge.Thelightningdischargeprocess includes theextensionof lightningchannelsandchargeneutralization.Althoughtheparametersensitivitywasconfirmedinpreviousstudiesofthelightningchannelextensionprocess,uncertaintiesexistedforparametersofthechargeneutralizationprocess. Inthechargeneutralizationprocess,threeparametersareusedtoconductthesensitivityexperiment:minimumthresholdofchargedensitythatdeterminestheregionofchargeneu-tralization(ρchan);minimumthresholdofchargedensitythatremainsbehindchargeneutral-ization(ρneut);andratioofneutralization(fρ).Ifthechargedensityatacertaingrid(Qx)isgreaterthanρchan,thegridhasapossibilitytobeinlightningchannelsandneutralize.Here,theneutralizedchargedensityinthegridis(Qx-ρneut)×fρ.Thisstudyexaminessensitivityexperimentsonthethreeparametersinthechargeneutralizationprocessbycomparingfre-quenciesofcloud-to-groundlightninganditspolarityusingLLS. Figure10showstheratioofnegativepolaritycloud-to-groundlightningtoallcloud-to-groundlightningfrom2340to2350JSTonSeptember2,2008.Here,sensitivitywithvaryingfρandρchanareconfirmedwithconstantρneut.Almostsimulatedpolaritiesratiointhesesen-sitivity experiments corresponded to the observed one obtained by LLS; that is, negativepolaritywasapproximately74%.Thisresultsuggeststhatfρandρchanhavelesssensitivityonthepolarityofcloud-to-groundlightning. Anadditionalsensitivityexperimentrevealedthathighfρsignificantlydecreasedthefre-quencyofthecloud-to-groundlightning,althoughlesssensitivityforcloud-to-groundlightningfrequencywasobtainedbyvaryingρchanandρneut.Moreover,lesssensitivitywasobservedintheratioofthecloud-to-groundlightningtoalllightningincludingin-cloudlightningbyvary-ingthethreeparameters,whichsuggeststhatthechargeneutralizationprocessisnotsig-nificantlycritical for lightning simulation.Thus,wecanconfirm that it is crucial for theLightningSimulatortoreproducethunderstormdevelopmentandtheirelectricchargeac-cumulationprocess.

Fig. 10 Simulatedratioofnegativepolaritycloud-to-groundlightningtoallcloud-to-groundlightningfrom2340to2350JSTonSeptember2,2008.

Parametersfρ(horizontalaxis)andρchan(typeofline)arevariedwithconstantρneut. Observed ratio of negative polarity by LLS is approximately 74%indicatedbytheboldline.

18

Laboratory for Climate System Study

DynamicsofLarchTaiga–PermafrostCoupledSysteminSiberiaunderClimateChange Larchtaiga,alsoknownastheSiberianborealforest,playsanimportantroleinglobalandregionalwater–energy–carbon(WEC)cyclesandintheclimatesystem.Recentinsituobservationshavesuggestedthatlarch-dominatedtaigatogetherwithpermafrostbehaveasacoupledeco-climatesystemacrossthebroadborealzoneofSiberia.However,neitherfield-basedobservationsnormodelingexperimentshaveclarifiedthesynthesizeddynamicsofthissystem.Here,usinganewdynamicvegetationmodelcoupledwithapermafrostmodel,werevealtheinteractiveprocessesbetweentaigaandpermafrost.ThemodeldemonstratesthatunderthepresentclimateconditionsineasternSiberia,larchtreesmaintainpermafrostbycontrollingitsseasonalthawing,whichinturnmaintainsthetaigabyprovidingsufficientwatertolarchtrees.Theexperimentwithoutpermafrostprocessesshowedthatlarchtreescandecreaseitsbiomassandbereplacedbyaprevalenceofpineandotherspeciesthatareexposed to drier hydro-climatic conditions. In the coupled system, fire, although usuallydestructive,canpreservethe larchdominationintheforests.Climate-warmingsensitivityexperimentsshowthatthiscoupledsystemcannotbemaintainedifthetemperaturerisesabove2°C.Undertheseconditions,aforestwithtypicaldeciduousanddarkconiferborealtreespecieswouldbealternativelydominatedanddecoupledfromthepermafrostprocesses.This study thus suggests that future global warming could dramatically alter the larch-dominatedtaiga–permafrostcoupledsysteminSiberiathroughassociatedchangesinWECcyclesandfeedbacktoclimate.

Fig. 1Schematicdiagramofsoil,vegetation,andfirefeedbackintheSiberiantaiga–permafrostsystemconsideredinthisstudy(right-sidediagram);spatialdistributionoflarchtaiga(bottomleft)andboundaryofpermafrost(bottomleft,dashedlines); location(bottomleftstar)andclimateofYakutsk(topleft).Intheschematicdia-gram, arrows show forcedirectionsbetweeneach factor. Symbols “+”and “–” indicate apositive andnegativecorrelationbetweentwofactors,repectively;“±”indicatesanunclearcorrelation.Thethickerar-rowsindicateprocessesthatwerebetterconsideredinmodelsimulation.Dashedarrowindicatesaprocessnotconsideredinthisstudy.Thewordsbesideeacharrowidentifythevariablesthatcontroleachprocess.

19Reference:Zhang,N.-N.,,T.YasunariandT.Ohta.2011:Dynamicsofthelarchtaiga-permafrostcoupledsystem

inSiberiaunderclimatechange,Environ.Res.Lett.6,2,doi:10.1088/1748-9326/6/2/024003

Fig. 2 Timesequenceofsimulatedforestsuccessionandactivelayerthickness(ALT)ofpermafrost.Coloredareasindicatetheassembledsimulationofabove-groundforestsuccessionfrombareground(first300yearsof1000-yearrun);dashedlinerepresentsassembledresultofsimulatedannualmaximumALT’“+”symbolsindicate observed biomass above ground at different forest stages; pie charts show observed (left) andsimulated(right)forestcompositions.

Fig. 3 Above-groundtotalbiomassincludingfractionalcomponentsofmajorspeciesforCNTLrun(leftbar)andNPrun(rightbar)simulatedunderfivevariousclimateconditions.Thefivebargroups,fromlefttoright,representthepresentclimateconditions;temperatureconditionsof1.12°Cabovethepresent;+2.25°C,+4.5°C,and+4.5°Cplusprecipitationof20%abovethepresent.Theexperimentnamesareshownaboveeachbar.Thetwodashedlinesintheupperpartof thefigureshowchangesinsummer(JJA)meansoilwaterforCNTLandNPrunsindicatedbysquareanddiamondmarks,respectively.Notethechangesofmajorspeciescontributingtothetotalbiomassunderthevariousclimateconditions.

20Long-termvariabilityofAsiansummermonsoonanditsseasonality

Anthropogenicclimatechangeduetoincreaseingreenhousegasesandaerosolhasbecomeamajorissueinrecentdecades.Assessmentofsuchclimatechangebasedonobservationaldataandsensitivityexperimentswithclimatemodelsisstronglyrequiredforbetterunder-standingof itsprocessandmechanism. In this study,wehave investigated the long-termtrendsoftheAsiansummermonsoonrainfallandthecirculationfieldduring1979–2008onamonthlymeanbasisbyusingtherainfalldataset(CMAP),reanalysiswindcirculationdata(NCEP/NCAR),HadISST(UKMetoffice),andinterpolatedOLRdata(NOAA).Thenon-para-metricMann–Kendalltestisappliedforevaluatingthetrends.Inparticular,wefocusedontheseasonaldependenceoflong-termclimatechange. InMay,asignificantincreasingtrendofmonsoonrainfallisobservedovertheArabianSea,theBayofBengal,andtheSouthChinaSea(Fig.4a).Trendsofstrongwesterlywindappearalong10N,whichcorrespondtoenhancedconvectionwithrainfall.Incontrast,therainfallovertheabovementionedareasshowsasignificantdecreasingtrendinJune(Fig.4b).TheincreasingtrendoverSouthernChinaisalsoremarkableinJune.Theserainfalltrendsareconsistentwiththemonsooncirculationandwatervaporfluxtrendsinthelowertropo-sphere.Inaddition,weexaminedthevariabilityinmonsoononsetduring1979–2008onthebasisoftheclimatologicalpentadmeanrainfalldata.ThemonsoononsetdatedefinedbyWangandLinHo(2002)isfollowed.Inrecentdecades,themonsoononsetdatesforsoutheasternandeasternAsiahasbeenshiftedapproximatelyto10–15daysearly(Fig.5),whichreflectstherainfalltrendsinMayandJune.Interestingly,theAsianmonsoonrainfallinJulyandAugustdoesnothaveanyclearsignificanttrend.Thus,theAsianmonsoonhasasignifi-canttrendonlyduringthetransientphasefromborealspringtosummer.

Fig. 4 (a) Lineartrendofrainfall(CMAP;Shading:mm/day)and850hPawind(NCEP/NCARReanalysis;vector:m/s)inMayduring1979–2008.Allvaluesaremultipliedby30(years)fortheperiod1979–2008.Onlythosethataresignificantat95%levelbytheMann–kendalltestareplotted.

(b) SameastheLeftpanel,butforJune.

(a)

(b)

21 Itissuggestedthatthesetrendsofearlymonsoononsetarecloselyrelatedtotheincreas-ingtrendsofSSToverthetropicalPacificandIndianOceanaswellastheincreasingtrendsofthelandsurfacetemperatureintheAsiancontinent.However,theseSSTwarmingtrendslastthroughouttheyearwithlesssignificantseasonalvariations.GCMsimulationssuggeststrongseasonalityintheeffectofincreaseinanthropogenicornaturalaerosolforcingontheAsianmonsoonclimate. ThisstudyispartiallysupportedbytheresearchfundforglobalwarmingundertheMinistryofEnvironment(A0902)titled“IntegratedImpactofVegetationandAerosolChangesonAsianMonsoonClimate.”

Fig. 5 Dateofmonsoononsetobtainedbyclimatologicalpentadmeanrainfallduring1979–1993(Digit).TheonsetpentadisdeterminedasinWangandLinho(2002).TheJulianpentadinwhichtherelativerainfallratesubtractedbytheJanuarymeanexceeds5mm/dayisdefinedastheonsetpentad.Shadingdenotesthedifferencebetweenthemonsoononsetfor1994–2008and1979–1993.

22

Laboratory for Cloud and Precipitation Climatology

EquatorialAsymmetryofEastPacificinter-tropicalconvergencezone(ITCZ) ThelocationoftheeastPacificinter-tropicalconvergencezone(ITCZ),abandof area covered with convective clouds,exclusivelytothenorthoftheequator(Fig.1)hasbeenalong-standingmystery.Whilemany theories explain this north–southITCZ asymmetry, observational verifica-tion is still required. Therefore, theproposed hypotheses are quantitativelyexamined.Toachievethis,theequatorialasymmetry of the east Pacific ITCZ isexploredonthebasisofanoceansurfaceheatbudgetanalysisperformedusingvarioussatellitedataproducts. TheannualmeanclimatologyofabsorbedshortwavefluxexhibitsamarkedmeridionalasymmetrybecauseofthereductionofinsolationbyhighcloudsinthenorthITCZ.Oceanmixed-layeradvectionhasthegreatesteffectofcounteractingthisshortwave-exertedasym-metry.Althoughotherheatfluxes,inparticularlatentheatflux,predominateovertheadvec-tiveheatfluxinmagnitude,theyaresecondaryfactorswithrespecttoequatorialasymmetry(Fig.2).TheasymmetryintheadvectiveheatfluxoriginatesfromawarmpoolofftheCentralAmericancoastand,toalesserextent,theNorthEquatorialCounterCurrent,neitherofwhichexistsinthesouthernhemisphere.Theirregularcontinentalgeographypresumablycomesintoplaybygeneratingawarmpoolnorthoftheequator,andbringingcoldwatertothesouthinthefareasternPacific. Inadditiontotheannualclimatology,thenorth–southcontrastintheseasonalcycleofthesurfaceheatfluxisinstrumentalinsustainingthenorthITCZthroughouttheyear.ThenortheastPacificisexposedtoaseasonalcycleconsiderablyweakerthanthatinthesoutheastPacific.ThisiscausedbymultiplephenomenaincludingthefiniteeccentricityoftheEarth’sorbitandthemeridionalgradientinmixedlayerabsorptivity.Simpleexperimentsgeneratingsyntheticseasurfacetemperature(SST)illus-tratethatthemutedseasonalcycleofheatfluxforcingmoderatesSSTseasonalvariability inthenortheastPacific, thusallowingthenorthITCZtosustainthroughouttheyear. Existing theories on the ITCZ asymmetryare briefly examined considering the presentfindings:1)Thewind-evaporative-SST(WES)feedbackisactivebutconsiderablyweaktoen-tirely cause the equatorial asymmetry; 2) thestratus-SSTfeedbackisalocalizedeffectneartheSouthAmericancoast;and3)theupwelling-SSTfeedbackislimitedtotheequatorialcoldtongue and is unlikely to help maintain theITCZ.

Fig. 2 North–southcontrastinzonal-meanheatfluxes:absorbed shortwave (shaded), latent heat(solid),upwelling(dotted),longwave(dashed),andadvectiveheat(dot-dashed).

Fig. 1 Geographicalmapofannualmeandeepconvectivecloudcover(shaded)andSST(contour).

23SatelliteStudyofAtmosphericForcingandResponsetoMoistConvectionoverTropicalandSubtropicalOceans

Tropicalconvectivecloudsareoftendescribedas“mediators”actingagainstlarge-scaleforcingthatdestabilizestheatmosphere,suchasmoisturecon-vergence and surface heat flux. This neutralizingeffectofconvectionwasformulatedbyDrs.AarakawaandSchubertintothequasi-equilibriumhypothesis,whichhasbeenwidelyacceptedasthebasisformanycumulusparameterization schemes.On theotherhand,somerecentstudiesdiscoveredobservationalevidence that necessitates updating the quasi-equilibriumhypothesisasoriginallypostulated. Satellitedataareanalyzedtoexplorethether-modynamicevolutionoftropicalandsubtropicalatmospherespriorandsubsequenttomoistconvec-tioninordertoofferanobservationaltestbedforconvectiveadjustment,whichisimportanttothequasi-equilibriumhypothesis.MeasurementsbytheTropicalRainfallMeasuringMission(TRMM)andAquasatellitesareprojectedonacompositetem-poralsequenceoveranhourlytodailytimescale.Thisisdonebyexploitingthetemporalgapbetweenthelocalsatelliteoverpassesthatchangesdaily(Fig.3).Theatmosphericforcingandresponsetoconvectionareinvestigatedseparatelyfordeepconvectiveandcongestusclouds.ConvectiveadjustmentisquickandefficientinthedeepTropicsduringtimeswhendeepconvectionisactive.Moisturetransportfromtheatmosphericboundarylayer(ABL)tothefreetroposphereisevidentinassociationwithdeepconvection.However,theevolutionofconvectiveavailablepotentialenergy(CAPE)iscontrollednotonlybyABLmoisturebutalsoextensivelybycoin-cidentABLcooling.CAPEexhibitsarapiddropfor12hpriortoconvectionandasubsequentrestoringphaselasting1–2daysasthecoolanomalyrecovers(Fig4a).ABLcoolingisaccom-panied180°outofphasebymid-toupper-troposphericwarmingtogethercomprisingabipo-lartemperatureanomaly.ThebehaviorofCAPEisconsiderablydifferentwhenmoistconvec-tioniscausedbycongestuscloudswithnodeepconvectionnearby.CAPEgentlyincreasesoverape-riodof1–2daysuntilcongestusclouds appear, then slowly de-clinestotheinitiallevel(Fig.4b).Convectiveadjustmentisnotef-ficientlyatworkeveninthedeepTropics when convective cloudsarenotdevelopedsodeepinorderto penetrate the entire tropo-sphere. The subtropical atmo-sphereshowsnosignofconvec-tiveadjustment regardlesof thepresenceofvigorousconvection.

Fig. 3 Schematic representation of compositeanalysis.TRMMandAquaobservationsaremarkedbycloudsandlinegraphs,respec-tively.

Fig. 4 CompositeCAPEfordeepconvection(a)andcongestusclouds(b).

24 Division of global – Scale Water Cycle Variations

Loboratory of Satellite Meteorology

DualKa-bandradarsystemobservationforthefutureGlobalPrecipitationMeasurementMission AdualKa-bandradarsystemwasdevelopedbytheJapanAerospaceExplorationAgency(JAXA)fordevelopingtheglobalprecipitationmeasurement–dual-frequencyprecipitationradar(GPM–DPR)algorithm.ThedualKa-radar system,whichconsistsof two identicalKa-bandradars,canmeasurespecificattenuationandequivalentradarreflectivityattheKaband;boththeseparametersareimportant,particularlyforsnowmeasurement.UsingthisdualKa-radarsystem along with other instruments such as ground-based rain measurement systems andpolarimetricprecipitationandwindprofilerradars,parameteruncertaintiesintheDPRalgorithmcanbereduced.VerificationofimprovementinrainretrievalusingtheDPRalgorithmisalsoincludedasanobjective. Thebasicconceptofthemeasurementistocomparethesameprecipitationsystemintworadarsplaced10–20kmapart.Thebeamofthefirstradarisdirectedtomatchthatofthesecondradar.Ingeneral,theprecipitationechointensitydecreaseswithrangebecauseofrainattenua-tion,whichappearssymmetricallyinbothradars.Throughthismethod,theseparationofequiv-alentradarreflectvitivyofprecipitationandrainattenuationcanbeattained. ThedualKa-bandradarsystemisinstalledattheOkinawaSubtropicalEnvironmentRemoteSensingCenter,theNationalInstituteofInformationandCommunicationsTechnology(NICT),wheresimultaneousobservationofrainwithaC-bandpolarimetricDopplerradarandgroundrainobservationinstrumentsiscurrentlyunderway.Thisradarisafrequencymodulatedcon-tinuouswave(FMCW)systemwitharelativelylowtransmittingpowerof100Wandtwooffsetparabolicantennasthatenablesimultaneoustransmissionandreception.Thissystemishighlydigitizedwithflexibilitytoadjustsystemparameterswithobservationsandisequippedwiththreeobservationmodes:(1)nominal,witha15kmobservationrangeand50mrangeresolu-tion;(2)long-range,witha30kmobservationrange;and(3)high-sensitivity,with250mrangeresolution. Figure1showstheobservationconfigurationinOkinawaIsland.Thetworadarbeamsarenotanexactmatchbecauseoftheinterferencecausedbyasmallmountainthatexistsbetweenthetworadars.Nearthemiddlepoint,instrumentsareinstalledtomeasuregroundrain.Figure2showsanexampleoftheprecipitationechoesrecordedbythetwoKa-bandradarsonJanuary15,2011.Thetwopatternsappearsymmetricalbecausebothradarsobserveprecipitationin

Fig. 2 PrecipitationechoesobtainedfromdualKa-radarsystem.

Fig. 1ConfigurationofdualKa-radarsystemobservation.

25oppositedirections.StrongrainattenuationintheKabandcausesastrongechonearoneradarandaratherweakdetectionnearthesecond.ThisfiguresuggeststhefeasibilityofspecificrainattenuationestimatesobtainedfromthisdualKa-bandradarsystem.

StudyofKuroshio’simpactonprecipitatonusingsatellitedata TheKuroshioisawarmcurentwiththeseasurfacetemperature(SST)warmerthanthatofthesurroundingoceanthroughouttheyear.PrecipitationgenerallyoccursoverwarmSSTareasasaresultofincreasedwater-vaporandsensible-heatfluxesfromtheseasurface.Inthisstudy,theKuroshio’sinfluenceonprecipitationisinvestigatedusingtheGlobalSatelliteMappingofPrecipitation_MVK+(GSMaP_MVK+)productanddataobtainedfromprecipita-tion radar (PR) onboard the Tropical Rainfall Measuring Mission (TRMM) satellite. TheprecipitationbandalongtheKuroshioappearsafteraveragingGSMaP_MVK+for2003–2006.ToidentifythetypeofprecipitationsystemmostoftenattributedtotheKuroshio,GSMaP_MVK+dataaredividedintoseveraltypesaccordingtosynopticscaledisturbances.Compos-iteanalysis reveals that rainappears tobeenhancedby theKuroshioand that thisbandmainly consists of precipitation associated with atmospheric fronts. Little precipitationappearsduringcold-airoutbreaksdespitethestrongatmosphere–oceancontrastintempera-tures. PRdataprovidevariousprecipitationdetailsincludingconvectiveorstratiformprecipita-tiontypes,stormheight,andtheverticalprecipitationprofile,inadditiontonearsurfacerainrate,whichallowustostudyprecipitationcharacteristicsingreaterdetail.Thisanalysisre-vealsthattheKuroshioplaysamoresignificantroleinthefrequencyofconvectiveprecipita-tionthanthatofprecipitationintensityforconvectiveorstratiformpreciptation(Figs.3and4).ThefrequencyofconvectionateachaltitudeisinvestigatedtoobservethescopeoftheKuroshio’seffect,whichispresentupto9kmanddisappearsat10km.Aninterstingfeatureis that thestormheightovertheKuroshioappears lower inthewinter.ThesurfacewindvelocityisalsohigheroverorslightlynorthwestoftheKuroshio,whichcanbeexplainedbyverticalmixing.However, therapidsurfacewindareadoesnotexactlycorrespond to thelowerstormheightregion.

Fig. 4 Distributionofconvectiverainfrequency.

Fig. 3LocationoftheKuroshio.

26

Laboratory of Satellite Biological Oceanography

SeasonalandSpringInterannualVariationsofChlorophyll-aintheYellowSeaandEastChinaSeaUsingaNewSatelliteDataSetwithReducedInfluenceofSuspendedSediment

IncreaseinredtideandmassiveoutbreakofgiantjellyfishareknownproblemsintheYellowSeaandEastChinaSea(YECS).Itisspeculatedthateutrophicationisoneoftheirpossiblecauses.TheoccurrencesindicatedthattheenvironmentalconditionsinYECSmaybechanging.Furthermore,theconstructionofThreeGorgesDamintheupperstreamofChangjiangRiverissuspectedofinfluencingtheenvironmentoftheYECS.Oceancolorremotesensingdataaccu-mulatedovermorethan10-years,whichcanmeasuresurfacechlorophyll-a(Chl)asanindexoftheamountofphytoplankton,isagoodtoolforexamininginterannualvariationsofChlintheYECS.However,itissuggestedthattheaccuracyofthestandardsatelliteChl(standardSCHL)ispoorbecauseofthehighconcentrationofsuspendedsedimentintheYECS.Inthisstudy,anewSCHLalgorithm,withreducedinfluenceofsuspendedsediment,hasbeendeveloped,andtheseasonalandspringinterannualvariationsofnewSCHLwasexaminedwithcomparingsatellite-estimatedtotalsuspendedmatter(TSM)intheYECS. ThemonthlynewSCHLwaslowerthanthestandardSCHLatcoastalareasandaroundtheChangjiangHillock,wherethebottomtopographyisshallow(<50m),fromfalltoearlyspring.Insummer,theareaofthelowernewSCHLwaslimitedalongthecoast.TheselowernewSCHLareascorrespondedtohighTSMareas. TSMwaslowthroughouttheyearinthemiddleofYellowSeaandsouthoffthehillock,andmaximumSCHLwasobservedinApril(Figs.1bandb).Itisconsideredthatspringbloomsoccurredintheseareas.CorrelationbetweenSCHLandTSMwashigh,andtheratioofSCHLinTSMwashigh.ThisindicatedthatvariationofTSMmostlydependedonconcentrationofphytoplanktonandthatinorganicmatterintheTSMwaslowattheseareas(Figs.2aandb).

Fig. 1 Seasonal variation of monthly newSCHL (black circle) and TSM (whitecircle)averagedover10-yearsineacharea.(a)middleofYellowSea,(b)southoffChangjiangHillock,(c)offshoreofChangjiangRivermouth, (d)Changji-angHillock,and(e)eastoffChangjiangHillock.

Fig. 2 Scatter diagram of 10-year averagedmonthlynewSCHLandTSMineacharea.(a)middleofYellowSea,(b)southoffChangjiangHillock,(c)offshoreofChangjiangRivermouth, (d)Changji-angHillock,and(e)eastoffChangjiangHillock. Lines indicate the regressionlineatthemiddleofYellowSea.

27 Ontheotherhand,onthehillockthemonthlySCHLwaslowwithhighTSMinwinterandincreasedwithdecreaseofTSMstartingfromApril,andmaximumofSCHLwasobservedinMay(Fig.1d).ItisconsideredthatspringbloomsoccurredfollowingdecreaseoftheTSMbecausegrowthofphytoplanktonmaybelimitedbylowlightconditionsduetothehighTSMinthatarea.Insummer,maximumSCHLwasobservedandwasprobablyduetotheinfluenceofChangji-angDilutedWater.Inaddition,theratioofSCHLinTSMwasashighasthatinthemiddleofYellowSeaandsouthoffthehillock(Fig.2d).Atoffshoreofthemouth,themonthlySCHLwaslowwithhighTSMinwinteranditincreasedwithdecreaseofTSMinspring.However,maximumSCHLwasnotobserved,andmaximumSCHLwasobservedinsummerandtheratioofSCHLinTSMwasashighasthatinthemiddleofYellowSeaandsouthoffthehillock(Figs.1cand2c) SpringSCHLsignificantly increasedatoffshoreof themouth,andthe increasemightcorrespondtotheincreaseintheoccurrenceandmagnitudeofredtides.InthemiddleofYellowSea,springmaximumofSCHLgraduallyincreasedsignificantly,anditseemstobecausedbyeutrophication. FromthenewSCHLandTSMdata,itisclearthatspringbloomsoccurredatthehighTSMareasaswellaslowTSMareasasaresultoffavorablelightconditionsduetodecreaseofTSM.TheincreasingtrendofthespringSCHLaswellassummerinthemiddleofYellowSeaindicatesthepossibilityofeutrophication.

ModificationofVerticallyGeneralizedProductionModelforTurbidWatersofAriakeBay,South-westernJapan

Remotely-sensedoceancolorcannotprovideadequateinformationaboutoceanicprimaryproductivity(PP)withoutthesupportofmodelsandseatruthdata.SeveralmodelsarebeingusedforderivingPPintheocean.Theverticallygeneralizedproductionmodel(VGPM)formu-latedbyBehrenfeldandFalkowski(1997a;henceforthBF)isoneofthesimplestandmostcom-monlyusedmodels forestimatingPPfromsatellite-basedchlorophylla (Chla), seasurfacetemperature(SST)andphotosyntheticallyactiveradiation(PAR)data.Despiteofconsiderableunderstandingofthephotosyntheticprocessandknowledgeoftheoceanopticsthatdetermineoceancolorsignals,satellite-basedPPoftenhave limited success in reproducing theobservedvariabilityofPPdataspecificallyin coastal environments. This study at-temptstodevelopamodifiedversionoftheVGPMforaturbidcoastalwater. TheVGPM,basicallydesignedforopenoceanwaters,wasevaluatedwithinsitumeasurementsofPPintheturbidcoastalwaters of Ariake Bay. The VGPM-basedeuphoticdepth(Zeu)-integratedPP(IPP)significantlyoverestimated(x1-3)usinginsituChlaandSST,anditexplainedonly52%oftheobservedvariability(Fig.3a).This largeerrorcouldbepartlybecausetheestimatesfromthesub-modelsforZeuand optimal Chl a-normalized PP (PB

opt)suggestedbyBFoverestimateandshowedweak correlations with in situ data. BysubstitutingPB

optandZeuwithinsituvalues;the modeled IPP significantly improvedaccounting84%ofvariabilityandshowedlessoverestimation(Fig.3b).

Fig. 3 ScatterplotsofinsituandVGPM-basedIPPobtainedbyusing(a)modeledPB

optandZeu,(b)insituPBoptand

Zeu,(c)insituPBoptandmodeledZeu,and(d)modified

VGPMmodel.Thesolidanddottedlinerepresentstheregressionlineandthe1:1line,respectively.

28 TheZeuwasthemostimportantparameterinfluencingthemodeledIPPvariationinAriakeBay.BFsuggestedopenoceanZeumodelbasedonsurfaceChla,largelyoverestimated(x2-3)(Fig.3c).AbetterestimationofZeuinthisturbidwatercouldbeobtainedfrominsituremotesensingreflectance(Rrs)byemployingaquasi-analyticalalgorithm(QAA).Amongtheparam-etersofthePPmodels,PB

optisconsideredtobethemostimportant.However,inthisstudy,PB

optwasfoundtobeofsecondaryimportanceandwasdifficulttobeestimatedfromSST.TheestimationofChlawasimprovedbyoptimizingacoastalalgorithmwithinsituRrsdata. By incorporating the QAA-based Zeu, optimizing algorithm Chl a and using constant(median)PB

opt;theperformanceofVGPMwassignificantlyimprovedinthestudyarea(Fig.3d).Thus,althoughVGPMisaglobalopenoceanmodel,whencoupledwithturbidwateralgo-rithmsforZeuandChla,itprovidedrealisticestimatesofIPPintheturbidwaterecosystem.

PhotoadaptiveResponseofPhytoplanktontoLightVariationCausedbyWindandTide:ACaseStudyofTurbidAriakeBay

Intheocean,lightisoneofthemostimportantvariablescontrollingprimaryproduction.Tomaintainhighphotosyntheticefficiencyinavariablelightenvironment,phytoplanktoncellsareknowntorespondtothevariationsoflight.ThisstudyexaminestheinfluenceoftemporallightvariationscausedbyverticalmixingonphotosyntheticpigmentandefficiencyinAriakeBay,Japan.AriakeBayisknownforitshighturbiditycausedbythelargetidalam-plitude,anditcouldbeasuitablesiteforexaminingtheinfluenceofthelightvariationsonphytoplankton.Changesofphotosyntheticpigmentandtheassociatedphotosyntheticeffi-ciencyofphytoplanktonundervaryinglightconditionswereexaminedunderatdifferenttimescalesoftheverticalmixingcausedbywindandtide. ObservationswereconductedbyT/VKakuyoMaruofNagasakiUniversityonNovember8(Cruise1)and15(Cruise2),2008andNovember8(Cruise3)and15(Cruise4),2009.Thetimescaleoflightvariationsforphytoplanktonwasevaluatedbyverticalmixingtimecoveringtheeuphoticzone(teu)estimatedbythediffusioncoefficient(Kz)andtheeuphoticzonedepth(Zeu).

Z2euteu=

2×Kz×602　

Effectsofdifferenttimescalesoflightvariationsonmeanchlorophylla(Chla)-specificdiadinoxanthin(DD)anddiato-xanthin(DT)poolsize[(DD+DT)/Chla]andonmaximumquantumyieldofpho-tosystem(PS)II(Fv/Fm)wereexamined. Theshortest(4h)andlongest(27d)teuwereobservedathigh(8.6±0.5ms–1)andlow(2.2±0.8ms–1)windspeedsdur-ingCruises1and3,respectively.Despiteoflowwindspeed,theintermediatevalues(10hours)ofteuwerealsofoundasare-sultsofshallowerZeucausedbythetidalcurrent mixing during Cruises 2 and 4.(DD+DT)/Chlavariedwithdiurnalcycleand the average was higher for long teu(>10h)comparedwiththatforshortteu(<5h)(Fig.4).Theseresultsindicatedthatphoto-protective response could be ac-tivelyoccurredduringthelongestteu.TheFv/Fminupperlayerswashigherduringlongteu(>10h)comparedwiththatduring

Fig. 4 Timevariationof(DD+DT)/ChlaandPhotosyntheticallyActiveRadiation(PAR)forCruise1(a),Cruise2(b),Cruise3(c)andCruise4(d).Openedrhombussymbolsrepresentphytoplank-tonat thesurface.Openedcycleandclosedcyclesymbolsrepresenttheincubatedphytoplanktonunderhighlightcondi-tion(100%PAR)andlowlightcondition(1%PAR),respec-tively.Thinlinesrepresent1minute-averagedincidentPAR.

29shortteu(<5h).Theseresultsindicatedthatphoto-damagetotheFv/Fmunderhighlightcondi-tionswascausedbyaninactivephoto-protectiveresponseduringshortteu(<5h). Therefore,thevariationintheshorttimescale(teu<5h)inthelightenvironmentduetostrongwindmayinhibitthephoto-protectiveresponseandthephotosynthesisofphytoplank-ton.Tounderstandtheprimaryproduction,itisnecessarytoexaminehowphotosynthesischangeswithshorttimelightvariationscausedbywind.

VariationsofPhytoplanktonPhoto-physiologyandProductivityinaDynamicEutrophicEcosystem Incoastalwatersrelativelyhighprimaryproduc-tionoccursasaresultofthesupplyofnutrientsfromland.Localproductivityusuallyshowsalarge,com-plexvariationsinbothtemporalandspatialscalesinresponsetochangesintheavailabilityofresourc-es(lightandnutrients)duetotidalmovementsandthe inflowof freshwater. Inparticular,underan-thropogenicallyeutrophicconditionswithtypicallythinopticallayersduetoastrongattenuation,cellsundergopronounced,short-termchangesinalightenvironment due to vertical mixing. Therefore, astrategytoacclimatizetoagivenlightregimeiscru-ciallyimportantfortheirgrowthandsuccess.Inthisstudy, using a fast repetition rate fluorometer(FRRF),weinvestigatedthephoto-acclimationstateofphytoplanktonassemblagesandtheproductivityin the upper Gulf of Thailand (UGOT) which ishighlyeutrophiedduetoanthropogenicloading. Two onboard observations on November 2005andJuly2006revealed theregionaldifferences inthephotosystem(PS)IIparameters,FV/FM,σPSIIandthemaximumratesofQareoxidation(1/τQA).Inpar-ticular,theprofilesof1/τQAapparentlyreflectedtheregional differences in water column structures,which corresponded to the photoacclimation re-sponse. These PS II parameterswereused to estimate normalizedproductivity (PB)with aphotosyntheticmodel,andfrominsituPBprofiles;inaddition,thephotosynthesis-irradiance(P-E)curvesandtheinstantaneouseuphoticzone(EZ)-averagedPB(PB

EZ)weredetermined.ThederivedP-EparametersshowedlargedifferencesbetweentheupperstratifiedwatersinStn.1andwell-mixedwatercolumnofStn.5;ahigherαwasfoundinStn.5whilePB

maxandtheEkwerehigherintheStn.1(Fig.5;Table1).Thisindicatedthatrelativelyhighlight-acclimated(oradapted)cellsweredominantinStn.1,wheretheyweresustainedunderbrighterconditionsduetoastronghalocline.Ontheotherhand,cellsinStn.5hadacclimatedtoalowerlightlevelasaresultofdeepermixing.Asignificant(logarithmic)relationshipwasfoundbetweenPB

EZandthesurfacePARfromthedataforallprofilesdata,whichsuggestedthatthecolumnproductivityintheUGOTwasprincipallycontrolledbylightavailability.Inaddition,this implied that, although cells wereexposedtodifferent lightregimesunderlessnutrient-stress,cellsatdifferentsitesmight achieve a comparable potentialproductivity due to adequate photo-acclimation.

Fig. 5 Relationships between underwater PARandinstantaneousFRRF_basedPB(a)forStn.1,(b)forStn.5intheupperGulfofThailand.

table 1 TheestimatedP-EparametersforStn.1and5.

30

Laboratory of Bio-Physical Oceanography

StudyoftheKuroshioaxismovementassociatedwithtyphoonpassagebyusingatmosphere–oceancoupledmodel

WereproducedoceanicandmetrologicalstatesaroundTaiwanbeforeandafterTyphoonHaitang’spassagein2005forinvestigatingthemechanismoftheKuroshioaxismovement,whichwasobservedbylong-rangeoceanradar(LROR)developedbytheNationalInstituteofInforma-tionandCommunicationsTechnology(NICT),Japan.WeusedtheCloudResolvingStormSim-ulator(CReSS)developedbyTsubokiandSakakibara(2002)asameteorologicalmodelandtheNonhydrostaticOceanmodelforEarthSimulator(NHOES)developedbyAikiandYamagata(2004)asanoceanmodel,andcoupledboththemodels.Thehorizontalgridsizeofboththemodelswas0.04°,andtheverticallayersweredividedinto100layersbytheNHOESwithdepthsrangingfrom2mto100mbelowthesurface.Thecalculationperiodwas10daysfrom0:00UTCJuly14,2005,thedaywhenTyphoonHaitangspawned,to0:00UTCJuly24,2005;TyphoonHaitangmadelandfallonJuly18,2005.Thecalculatedpathofthetyphoonwasconsistentwiththatoftheobservedpath.ThemodelwindatYonaguniIslandwasslightlystrongerthantheoneobserved;however,thevariationtendencywasnearlyidentical.TheKuroshioflowednortheast-wardalongtheshelfedgeinthemodelbeforethetyphoonapproached,asobservedbyLROR(Fig.1aandb).Southerlywindassociatedwiththetyphoon’sapproachdominatednortheastTaiwanforonedayuntiltheKuroshioaxischangedthewinddirectiontonortherly.Themodelcurrentpatternat1:00UTCJuly21coincideswellwiththatoftheLROR(Fig.1candd). Volumetransportacrosstheshelfedgeincreasedby4Svwhenthewinddirectionchangedfromnortherlytosoutherlyandthenananti-cycloniceddyemergedontheshelf.Thegenerationofananti-cycloniceddyisconsideredsuchthatthewatercolumnobtainednegativevorticityasaresultofconservationofpotentialvorticitycausedbythemovementoftheKuroshiowatersfromdeeptoshallowerarea.Becausethevolumetransportacrosstheshelfedgeincreasedperi-odicallyaftertheeddyformation,negativevorticitycouldbesuppliedcontinuously.Itis,therefore,suggestedthattheanti-cycloniceddiesontheshelfcausedthechangeinKuroshioaxisdirection.

MeanfieldandseasonalvariationofseasurfacecurrentintheEastChinaSea Weobtaineddetailed,high-resolutionspatiotemporalinformationoftheseasurfacecurrentfieldintheEastChinaSea(ECS)bycombiningsatellitealtimeterandsurfacedrifterdata,andinvestigateditstemporalmeanfieldandseasonalvariationbyanalyzingthisdata. TheKuroshio’snortheastwardcurrentwithspeedsgreaterthan50cms−1alongthecontinentalshelfslope;theTaiwanWarmCurrentflowingnorthwardwithspeedsof20–30cms−1,extendingfromTaiwanStraitwithanorthwardintrusion(~30cms−1)northeastofTaiwan;andtheKuroshio

Fig. 1 Surfacecurrentfieldbeforetyphoonpassage:(a)calculatedbythemodel;(b)observedbyLROR.Surfacecurrentfieldaftertyphoonpassage:(c)calcu-latedby themodel; (d)observedbyLROR.

31branch’snorthwardcurrentwithspeedsof10–20cms−1westofKyushuweresteady(Fig.2a).Ontheotherhand,anannualvariationcausedbythedevelopmentoftwodifferentdisturbances,whichpropagatedalongtheisobathsonthecontinentalshelffromthenortheastTaiwanStraitandneartheTsushimaStrait(TS)towestofKyushu,waspredominant in the seasonal disturbance. Thespatiotemporalscaleandthepropagationofthesedisturbancescanbeexplainedbythedispersionrelationship of barotropic topographic Rossbywavespropagatinginasteadyflow.Thesedistur-bances also caused differences in the annualvariationsofcurrentspeedandaxialpositionoftheKuroshiobranchbetweenitssouthernandnorthern(linesSandNinFig.2a,respectively)parts(Fig.2bandc). Insummary,theannualvariationwaspredominantintheseasonaldisturbanceofthesurfacecurrentfield.Thisannualvariationwascausedbythepropagationofthedisturbance,whichbehavedliketopographicwavesinasteadyflowfromthevicinityofthetwostraits.Thesea-sonalvariationwestofKyushuwasespeciallyinfluencedbythesepropagationsintheECS.

TsushimawarmcurrentpathsinthesouthwesternpartoftheJapanSea TheTsushimaWarmCurrent (TWC)pathshavebeenpreviously investigatedbynumerousoceanographers;however,thecorrectcurrentpathswereunclear.Inthepresentstudy,wecreatedseasurfacecurrentanddynamicalheightfieldinformationusingsatellitealtimeterandArgosbuoytrajectorydatarecordedfromMay1995toJanuary2009.WethencomparedourseasurfacecurrentdatawithgeostrophiccurrentcomponentsoftheArgosbuoytrajectoriestoreproduceandevaluatetheaccuracyofourdataset.WeexaminedtheTWCpathsinthesouthwesternpartoftheSeaofJapan/EastSea,whereTWCpathsdisplayhighvariability,usingthedataset. Inthemeanseasurfacecurrentfield,thefirstbranchoftheTWC(FBTWC)throughtheeast-ernchannelofTSflowsalongtheJapanesecoastandthroughnorthofMishimaIsland.ThesecondbranchoftheTWC(SBTWC)flowsalongthecontinentalshelfedge,andthethirdbranchoftheTWC(TBTWC)throughthewesternchannelofTSflowsnorthwardalongtheKoreancoast. WeexaminedseasonalvariationintheTWCpaths.ItisclearthattheFBTWCandTBTWCexistthroughouttheyearwithspeedsgreaterthan15cms−1.TheSBTWCappearsinAugust,continuingthroughOctober.Inothermonths,theSBTWCflowsalongthecontinentalshelfedgewithasmallcurrentvelocity.Twocurrentaxesarepresentnearshoreandoffshoreofthecontinentalshelfeastof131°Ethroughouttheyear.TheoffshorecurrentpathappearsfromApriltoSeptember.ItisconsideredthatthiscurrentaxisoriginatedfromtheSBTWCandFBTWC,whichcouldhavebeenbifur-catedafterpassingnorthofMishimaIsland.Thenear-shorecurrentflowsthroughthewestsideofOkiwithameancurrentspeedof20cms−1,andthecurrentwithaspeedgreaterthan15cms−1appearsfromJanuarytoMayandfromAugusttoDecember. OurschematicviewoftheTWCpathsinthesouth-westernpartoftheSeaofJapan/EastSea,showninFig.3,isthefirstofitstypetobedocumented.

Fig. 2 Horizontaldistributionoftemporalmeansurfacecurrentvectors from May 1995 to January 2010: (a) annualvariationinnorthwardsurfacecurrentsalong(b)linesSand(c)N.Shadedareasin(b)and(c)representcurrentspeedwithvaluesgreaterthan15cms−1.Contourin-tervalsfornorthwardsurfacecurrentare1cms−1.

Fig. 3 SchematicviewofTsushimaWarmCurrentpathsinthesouthwesternpartoftheSeaofJapananalyzedfromMay1995toJanuary2009.

32 List of Publications*:Staffs,studentsandresearchfellowsintheHyARC.

01. Akter,N.*andK.Tsuboki* CharacteristicsofsupercellsintherainbandofnumericallysimulatedCycloneSidr.Scientific

OnlineLettersontheAtmosphere(SOLA),6A,25-28,doi:10.2151/sola.6A-007,2010.02. Bhatt,B.C.,T.-Y.Koh,M.YamamotoandK.Nakamura* ThediurnalcycleofconvectiveactivityoverSouthAsiaasdiagnosedfromMETEOSAT-5and

TRMM data. Terrestrial, Atmospheric and Oceanic Sciences, 21(5), 841-854, doi:10.3319/TAO.2010.02.04.01(A),2010.

03. Hossen,M.S.,T.HiyamaandH.Tanaka* EstimationofnighttimeecosystemrespirationoverapaddyfieldinChina.BiogeosciencesDiscus-

sions,7(1),1201-1232,doi:10.5194/bgd-7-1201-2010,2010.04. Hutahaean,A.A.*,J.Ishizaka*,A.Morimoto*,J.Kanda,N.HorimotoandT.Saino Developmentofalgorithmsforestimatingtheseasonalnitrateprofilesintheupperwatercolumn

oftheSagamiBay,Japan.Lamer,48(2),71-86,2010.05. Islam,M.N.,S.DasandH.Uyeda* CalibrationofTRMMderivedrainfalloverNepalduring1998-2007.TheOpenAtmosphericSci-

enceJournal,4,12-23,doi:10.2174/1874282301004010012,2010.06. Karev,A.R.,D.-I.Lee,C.-H.YouandH.Uyeda* Variationsinraindropsizedistributionsobservedinmid-latitudeoceancloudsduringtheEast-

Asiansummermonsoon.AtmosphericResearch,96(1),65-78,doi:10.1016/j.atmosres.2009.11.014,2010.

07. Lee,K.-O.,S.Shimizu,M.Maki,C.-H.You,H.Uyeda*andD.-I.Lee Enhancementmechanismofthe30June2006precipitationsystemobservedoverthenorthwest-

ernslopeofMt.Halla,JejuIsland,Korea.AtmosphericResearch,97(3),343-358,doi:10.1016/j.atmosres.2010.04.008,2010.

08. Li,X.,W.-K.Tao,T.Matsui,C.LiuandH.Masunaga* ImprovingaspectralbinmicrophysicalschemeusingTRMMsatelliteobservations.Quarterly

JournaloftheRoyalMeteorologicalSociety,136(647),382-399,doi:10.1002/qj.569,2010.09. Ma,X.,Y.Fukushima,T.Yasunari*,M.Matsuoka,Y.Sato,F.KimuraandH.Zheng ExaminationofthewaterbudgetinupstreamandmidstreamregionsoftheYellowRiver,China.

HydrologicalProcesses,24(5),618-630,doi:10.1002/hyp.7556,2010.10. Masunaga,H.*,T.Matsui,W.-K.Tao,A.Y.Hou,C.D.Kummerow,T.Nakajima,P.Bauer,W.S.

Olson,M.SekiguchiandT.Y.Nakajima SatelliteDataSimulatorUnit:Amultisensor,multispectralsatellitesimulatorpackage.Bulletin

of theAmericanMeteorologicalSociety,91(12),1625-1632,doi:10.1175/2010BAMS2809.1,2010.

11. Masunaga,H.*andT.S.L’Ecuyer The southeast Pacific warm band and double ITCZ. Journal of Climate, 23(5), 1189-1208,

doi:10.1175/2009JCLI3124.1,2010.12. Minda,H.*,F.A.Furuzawa*,S.SatohandK.Nakamura* ConvectiveboundarylayeraboveasubtropicalislandobservedbyC-bandradarandinterpreta-

tionusingacloudresolvingmodel.JournaloftheMeteorologicalSocietyofJapan,88(3),285-312,doi:10.2151/jmsj.2010-303,2010.

13. Oue,M.*,H.Uyeda*andY.Shusse TwotypesofprecipitationparticledistributioninconvectivecellsaccompanyingaBaiufrontal

rainband around Okinawa Island, Japan. Journal of Geophysical Research, 115, D02201,doi:10.1029/2009JD011957,2010.

14. Rafiuddin,M.,H.Uyeda*andM.N.Islam CharacteristicsofmonsoonprecipitationsystemsinandaroundBangladesh.InternationalJour-

nalofClimatology,30(7),1042-1055,doi:10.1002/joc.1949,2010.15. Saba,V.S.,M.A.M.Friedrichs,D.Antoine,R.A.Armstrong,I.Asanuma,M.J.Behrenfeld,A.M.

Ciotti,M.Dowell,N.Hoepffner,K.J.W.Hyde,J. Ishizaka*,T.Kameda,J.Marra,F.Mélin,A.Morel,J.O’Reilly,M.Scardi,W.O.SmithJr.,T.J.Smyth,S.Tang,J.Uitz,K.WatersandT.K.Westberry

Anevaluationofoceancolormodelestimatesofmarineprimaryproductivity incoastaland

33pelagicregionsacrosstheglobe.BiogeosciencesDiscussions,7(5),6749-6788,doi:10.5194/bgd-7-6749-2010,2010.

16. Saba,V.S.,M.A.M.Friedrichs,M.-E.Carr,D.Antoine,R.A.Armstrong,I.Asanuma,O.Aumont,N.R.Bates,M.J.Behrenfeld,V.Bennington,L.Bopp,J.Bruggeman,E.T.Buitenhuis,M.J.Church,A.M.Ciotti,S.C.Doney,M.Dowell,J.Dunne,S.Dutkiewicz,W.Gregg,N.Hoepffner,K.J.W.Hyde,J.Ishizaka*,T.Kameda,D.M.Karl,I.Lima,M.W.Lomas,J.Marra,G.A.McKinley,F.Mélin,J.K.Moore,A.Morel,J.O’Reilly,B.Salihoglu,M.Scardi,T.J.Smyth,S.Tang,J.Tjiputra,J.Uitz,M.Vichi,K.Waters,T.K.WestberryandA.Yool

Challengesofmodelingdepth-integratedmarineprimaryproductivityovermultipledecades:AcasestudyatBATSandHOT.GlobalBiogeochemicalCycles,24(3),GB3020,doi:10.1029/2009GB003655,2010.

17. Shibata,T.*,S.C.Tripathy*andJ.Ishizaka* Phytoplanktonpigmentchangeasaphotoadaptiveresponsetolightvariationcausedbytidal

cycle inAriakeBay,Japan.JournalofOceanography,66(6),831-843,doi:10.1007/s10872-010-0067-z,2010.

18. Short,D.A.andK.Nakamura* EffectofTRMMorbitboostonradarreflectivitydistributions.JournalofAtmosphericandOce-

anicTechnology,27(7),1247-1254,doi:10.1175/2010JTECHA1426.1,2010.19. Singh,P.*andK.Nakamura* Diurnalvariationinsummermonsoonprecipitationduringactiveandbreakperiodsovercentral

India and southern Himalayan foothills. Journal of Geophysical Research, 115, D12122,doi:10.1029/2009JD012794,2010.

20. Sojisuporn,P.,A.Morimoto*andT.Yanagi SeasonalvariationofseasurfacecurrentintheGulfofThailand.CoastalMarineScience,34(1),

91-102,2010.21. Son,Y.B.,T.Lee,D.-L.Choi,S.-T.Jang,C.-H.Kim,Y.H.Ahn,J.H.Ryu,M.Kim,S.-K.Jungand

J.Ishizaka* Spatialandtemporalvariationsofsatellite-derived10-yearsurfaceParticulateOrganicCarbon

(POC)intheEastChinaSea.KoreanJournalofRemoteSensing,26(4),421-437,2010.22. Takahashi,D.*,H.Miyake,T.Nakayama,N.Kobayashi,K.KidoandY.Nishida ResponseofasummertimeanticycloniceddytowindforcinginFunkaBay,Hokkaido,Japan.

ContinentalShelfResearch,30(13),1435-1449,doi:10.1016/j.csr.2010.05.003,2010.23. Takahashi,H.G.,H.Fujinami*,T.Yasunari*andJ.Matsumoto DiurnalrainfallpatternobservedbyTropicalRainfallMeasuringMissionPrecipitationRadar

(TRMM-PR)around the Indochinapeninsula.JournalofGeophysicalResearch,115,D07109,doi:10.1029/2009JD012155,2010.

24. Takahashi,H.G.,T.Yoshikane,M.Hara,K.TakataandT.Yasunari* High-resolutionmodellingofthepotentialimpactoflandsurfaceconditionsonregionalclimate

overIndochinaassociatedwiththediurnalprecipitationcycle.InternationalJournalofClimatol-ogy,30(13),2004-2020,doi:10.1002/joc.2119,2010.

25. Tripathy,S.C.*,J.Ishizaka*,T.Fujiki,T.Shibata*,K.Okamura,T.HosakaandT.Saino Assessmentofcarbon-andfluorescence-basedprimaryproductivityinAriakeBay,southwestern

Japan.Estuarine,CoastalandShelfScience,87(1),163-173,doi:10.1016/j.ecss.2010.01.006,2010.26. You,C.-H.,D.-I.Lee,S.-M.Jang,M.Jang,H.Uyeda*,T.Shinoda*andF.Kobayashi CharacteristicsofrainfallsystemsaccompaniedwithChangmafrontatChujadoinKorea.Asia-

PacificJournalofAtmosphericSciences,46(1),41-51,doi:10.1007/s13143-010-0005-1,2010.27. Zhao,X.,Y.Liu,H.Tanaka*andT.Hiyama Acomparisonoffluxvarianceandsurfacerenewalmethodswitheddycovariance.IEEEJournal

ofSelectedTopicsinAppliedEarthObservationsandRemoteSensing,3(3),345-350,doi:10.1109/JSTARS.2010.2060473,2010.

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2010

Annual Report

Hydrospheric Atmospheric Research Center (HyARC)

Nagoya University