城市气象学（杭建）ppt课件 05-3城市热岛-影响

Ch5UrbanHeatIslands

（UHIs）三、UHIs影响四、UHIs减缓措施五、UHI的文献评述三、UHIs影响城市中由于在天气条件适宜时，经常会出现热岛效应，这就直接或间接地对当时当地有关气候要素，居民生活和城市经济产生多种影响。有有利的一面，也有不利的一面。空调（取暖）度日数、积雪、霜冻健康影响对能源消耗的影响对风云雨的影响（以后介绍）1、度日数2、健康盛夏高温会降低工作效率。据统计如以气温15℃时的工效为100％，则25℃时为92.5％，35℃时为84.3％。据武汉气象台统计当最高气温大于37℃时，则中署病人急剧增多。WithintheUnitedStatesalone,anaverageof1,000peopledieeachyearduetoextremeheat.3、能源消耗Anotherconsequenceofurbanheatislandsistheincreasedenergyrequiredforairconditioningandrefrigerationincitiesthatareincomparativelyhotclimates.TheHeatIslandGroupestimatesthattheheatislandeffectcostsLosAngelesaboutUS$100millionperyearinenergy.Conversely,thosethatareincoldclimatessuchasMoscow,Russiawouldhavelessdemandforheating.However,throughtheimplementationofheatislandreductionstrategies,significantannualnetenergysavingshavebeencalculatedfornorthernlocationssuchasChicago,SaltLakeCity,andToronto.四、UHIs减缓措施减缓热岛强度的主要措施：屋顶、地面的材料和颜色绿化10绿化降温效应11数值模式试验的几种情况1214:00时温度差（反照率0.12-0.25)

14:00时10m高处水平面位温差分布（℃）等值线数字＝建筑物反照率0.12时位温－建筑物反照率0.25时位温建筑物反照率0.12树木叶面指数5.0草地叶面指数2.0无屋顶绿化

14:00时温度差（屋顶绿化有-无）14:00时10m高处水平面位温差分布（℃）等值线数字＝屋顶绿化时位温－屋顶无绿化时位温建筑物反照率0.12树木叶面指数5.0草地叶面指数2.0屋顶绿化叶面指数2.014:00时温度差（叶面指数10.0-5.0)

14:00时10m高处水平面位温差分布（℃）等值线数字＝树木叶面指数为10.0时位温－树木叶面指数为5.0时位温建筑物反照率0.12树木叶面指数10.0

草地叶面指数2.0无屋顶绿化

五、关于UHI的文献评述介绍一篇比较“另类”的文章Inthemoderneraofurbanclimatology,muchemphasishasbeenplacedonobservinganddocumentingheatislandmagnitudesincitiesaroundtheworld.Urbanclimateliteratureconsequentlyboastsaremarkableaccumulationofobservationalheatislandstudies.Throughtime,however,methodologistshaveraisedconcernsabouttheauthenticityofthesestudies,especiallyregardingthemeasurement,definitionandreportingofheatislandmagnitudes….AbstractThispapersubstantiatestheseconcernsthroughasystematicreviewandscientificcritiqueofheatislandliteraturefromtheperiod1950–2007.Thereviewusesninecriteriaofexperimentaldesignandcommunicationtocriticallyassessmethodologicalqualityinasampleof190heatislandstudies.Resultsofthisassessmentarediscouraging:themeanqualityscoreofthesampleisjust50percent,andnearlyhalfofallurbanheatislandmagnitudesreportedinthesamplearejudgedtobescientificallyindefensible.Twoareasofuniversalweaknessintheliteraturesamplearecontrolledmeasurementandopennessofmethod:one-halfofthesamplestudiesfailtosufficientlycontroltheconfoundingeffectsofweather,reliefortimeonreported‘urban’heatislandmagnitudes,andthree-quartersfailtocommunicatebasicmetadataregardinginstrumentationandfieldsitecharacteristics.Alargeproportionofobservationalheatislandliteratureisthereforecompromisedbypoorscientificpractice.Thispaperconcludeswithrecommendationsforimprovingmethodandcommunicationinheatislandstudiesthroughbetterscrutinyoffindingsandmorerigorousreportingofprimaryresearch.Thefollowingscientificcriteriaweredevelopedforthepurposeofassessingmethodologicalqualityintheheatislandliteraturesample:Operationaltestandconceptualmodelarealigned;Operationaldefinitionsareexplicitlystated;Instrumentspecificationsareexplicitlystated;Sitemetadataareappropriatelydetailed;Fieldsitesarerepresentativeofthelocal-scalesurroundings;Numberofreplicateobservationsissufficientlylarge;Weathereffectsarepassivelycontrolled;Surfaceeffectsarepassivelycontrolled;Temperaturesaremeasuredsynchronously.1.OperationaltestandconceptualmodelarealignedTheoperationaltestoftheinvestigationisalignedwiththeconceptualmodelofacanopy-layerUHI.Thetestforthismodelinvokesairtemperaturemeasurementbelowrooflevelinurbanenvironments,andintheturbulentsurfacelayerofruralenvironments.2.Operationaldefinitionsareexplicitlystated

OperationaldefinitionsofUHImagnitudeorintensityareexplicitlystatedinthereport,ormadeimplicitthroughitsdiscussionorpresentationofdata.OperationaldefinitionsrevealthemeasurementvariablesandfieldsitesusedtoquantifyUHImagnitude.3.InstrumentspecificationsareexplicitlystatedInstrumentspecificationsareexplicitlystatedinthereport,ormadeimplicitthroughdiscussionorpresentationofdata.Instrumentspecificationsincludetype,mountingandmeasurement4.SitemetadataareappropriatelydetailedSitemetadataareappropriatelydetailedinthereport.Metadataincludealocal-orregional-scalemap,sketchorphotographofthestudyarea,andoneormorequantitativeindicatorsofmicro-orlocal-scalesurfaceexposure,roughnessorcoveratthefieldsitesusedtoquantifyUHImagnitude.5.Fieldsitesarerepresentativeofthelocal-scalesurroundings;

Themicro-scalesettingsofthefieldsitesusedtoquantifyUHImagnitudeareapproximatelyrepresentative,insurfacematerials,geometryandhumanactivity,ofthelocal-scalesurroundings.6.NumberofreplicateobservationsissufficientlylargeThenumberofreplicateheatislandobservationsinareportissufficientlylargetomeetthestatedaimsofthestudyandtoyieldrepresentativeandreliableestimatesofUHImagnitude.7.Weathereffectsarepassivelycontrolled

TheextraneouseffectsofweatheronUHImagnitudearepassivelycontrolled.ComputationsofUHImagnitudeusetemperaturesmeasuredinrelativelysteady-stateweather:nopassingfronts,strongadvection,orprecipitation.8.SurfaceeffectsarepassivelycontrolledTheextraneouseffectsofsurfacerelief,elevationandwaterbodiesonUHImagnitudearemadesufficientlysmallthroughplannedsamplingdesign,ormadesufficientlyknownthroughdiscussionandrecognitionoftheirinfluencesonobservedheatislandmagnitudes.9.TemperaturesaremeasuredsynchronouslyTemperaturesusedtoquantifyUHImagnitudearemeasuredsynchronously.Inhomogeneitiesresultingfromnon-synchronousmeasurementareacknowledgedassuchandadjustedtoacommonbasetime.Geographicdistributionofheatislandobservationsintheliteraturesample.Theheatislandobservationsreportedintheliteraturesamplearedistributedacross11continentalrealmsand221citiesandtownsFrequencydistributionoftheheatislandliteraturesample(N=190)byscientificcriterionandaggregatepass/failratios.Discussion1、Thefirstareaforgeneralisationisoperationalisationofconcepts.Theliteratureisreasonablysuccessfulinthisregard,asmoststudiesdemonstrategoodconceptualunderstandingoftheheatislandeffectandestablishappropriatedefinitionstotesttheseconcepts.2、Thesecondareaforgeneralisationiscontrolledmeasurement.Theliteratureisgenerallypoorinthisregard.Approximatelyhalfofallheatislandstudiesfailtosufficientlycontroltheirmeasurementsfortheconfoundingeffectsofweather,reliefortime.3、Thethirdareaforgeneralisationisopennessofmethod.Theliteratureishighlyinadequateinthisarea,withthree-quartersofthesamplefailingtocommunicate,inmostbasicterms,theprecisionofinstrumentsusedtomeasureUHImagnitudeandthephysicalnatureofthesurfacessurroundingthoseinstrumentsatthetimeofmeasurement.Recommendationsandclosingremarks1、Reducethespatialandtemporalresolutionofyourdata.ForthepurposeofquantifyingUHImagnitude,fewerfieldsitesinrepresentativelocationsispreferabletomoresitesinunrepresentativelocations.Likewise,asmallerdatasetofcontrolledmeasurementsispreferabletoalargerdatasetofuncontrolledmeasurements.AsimplecomparisonoftworepresentativesiteswillprovideareasonablygoodmeasureofUHImagnitude,providedthatthemeasurementssufficientlyregulatetheeffectsofweather,relief,timeandrandomvariation.2、Followstandardisedguidelinesforsitereporting.GuidelinesinAguilaretal.(2003)andOke(2004)includedescriptivetemplatesforreportingthemicro-,local-andmeso-scalesettingsoftemperaturemeasurementsinurbanandruralenvironments.TheinformationcontainedinthesetemplatesisessentialtoanyheatislandpaperandtoproperinterpretationandcomparisonofitsreportedUHImagnitudes.3、Disclosethelimitsofyourdata.Observationaldatainenvironmentalsciencearelimitedintheircertaintyandreliability.Likeallclimateobservations,UHImeasurementsarelimitedbythecomplexitiesofthesurface–atmospheresystemandbythetechnicalcapacityofourinstrumentstosamplethatsystem.PublicstatementsclaimingexactandabsolutevaluesofUHImagnitudeareunjustifiedbecausethephenomenonbeingmeasuredisinherentlycomplexanddifficulttoaccess.HonestreportingoflimitationsanderrorsinobservationisthebestpracticeforsharingandadvancingknowledgeofUHIs.Publicstatementsshouldinsteadclaim‘reasonableestimates’ofUHImagnitude,andcouchtheseestimatesinroundfigures,withinmarginsofinstrumentalerror,andwithatoneofcaution.4、Useterminologywithdiscretion.Theterm“urbanheatisland”isusedirresponsiblyintheliteraturetodescribeallobservedcity-countrytemperaturedifferencesregardlessofthecausesbehindthosedifferences.Ifthetemperaturedifferencesinaparticularcityarecausedprimarilybyweatherortopographicinterferences,thentheperceivedheatislandshouldnotbedescribedasanurban-inducedone.5、NeveracceptUHImagnitudesatfacevalue.BehindeveryreportedestimateofUHImagnitudeisanextenuatingsetofcircumstances.Thesecircumstancesarebothexperim