Designation:D5741−96(Reapproved2011)StandardPracticeforCharacterizingSurfaceWindUsingaWindVaneandRotatingAnemometer1ThisstandardisissuedunderthefixeddesignationD5741;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope1.1Thispracticecoversamethodforcharacterizingsurfacewindspeed,winddirection,peakone-minutespeeds,peakthree-secondandpeakone-minutespeeds,andstandarddevia-tionsoffluctuationaboutthemeansofspeedanddirection.1.2Thispracticemaybeusedwithotherkindsofsensorsiftheresponsecharacteristicsofthesensors,includingtheirsignalconditioners,areequivalentorfasterandthemeasure-mentuncertaintyofthesystemisequivalentorbetterthanthosespecifiedbelow.1.3Thecharacterizationprescribedinthispracticewillprovideinformationonwindacceptableforawidevarietyofapplications.NOTE1—ThispracticebuildsonaconsensusreachedbytheattendeesataworkshopsponsoredbytheOfficeoftheFederalCoordinatorforMeteorologicalServicesandSupportingResearchinRockville,MDonOct.29–30,1992.1.4Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappro-priatesafetyandhealthpracticesanddeterminetheapplica-bilityofregulatorylimitationspriortouse.2.ReferencedDocuments2.1ASTMStandards:2D1356TerminologyRelatingtoSamplingandAnalysisofAtmospheresD5096TestMethodforDeterminingthePerformanceofaCupAnemometerorPropellerAnemometerD5366TestMethodforDeterminingtheDynamicPerfor-manceofaWindVane3.Terminology3.1DefinitionsofTermsSpecifictoThisStandard:3.1.1aerodynamicroughnesslength(z0,m)—acharacter-isticlengthrepresentingtheheightabovethesurfacewhereextrapolationofwindspeedmeasurements,belowthelimitofprofilevalidity,wouldpredictthewindspeedwouldbecomezero(1).3Itcanbeestimatedfordirectionsectorsfromalandscapedescription.3.1.2dampednatural...
