ASTM_D_5527_-_00_2011.pdf

Designation:D552700(Reapproved 2011)Standard Practices forMeasuring Surface Wind and Temperature by AcousticMeans1This standard is issued under the fixed designation D5527;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 These practices cover procedures for measuring one-,two-,or three-dimensional vector wind components and sonictemperature by means of commercially available sonicanemometer/thermometers that employ the inverse time mea-surement technique.These practices apply to the measurementof wind velocity components over horizontal terrain usinginstruments mounted on stationary towers.These practices alsoapply to speed of sound measurements that are converted tosonic temperatures but do not apply to the measurement oftemperature by the use of ancillary temperature devices.1.2 The values stated in SI units are to be regarded as thestandard.1.3 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2D1356 Terminology Relating to Sampling and Analysis ofAtmospheresD3631 Test Methods for Measuring Surface AtmosphericPressureD4230 Test Method of Measuring Humidity with Cooled-Surface Condensation(Dew-Point)HygrometerE337 Test Method for Measuring Humidity with a Psy-chrometer(the Measurement of Wet-and Dry-Bulb Tem-peratures)IEEE/ASTM SI-10 American National Standard for Use ofthe International System of Units(SI):The Modern MetricSystem3.Terminology3.1 DefinitionsRefer to Terminology D1356 for commonterminology.3.2 Definitions of Terms Specific to This Standard:3.2.1 acceptance angle(6,deg)the angular distance,centered on the array axis of symmetry,over which thefollowing conditions are met:(a)wind components are unam-biguously defined,and(b)flow across the transducers isunobstructed or remains within the angular range for whichtransducer shadow corrections are defined.3.2.2 acoustic pathlength(d,(m)the distance betweentransducer transmitter-receiver pairs.3.2.3 sampling period(s)the record length or time intervalover which data collection occurs.3.2.4 sampling rate(Hz)the rate at which data collectionoccurs,usually presented in samples per second or Hertz.3.2.5 sonic anemometer/thermometeran instrument con-sisting of a transducer array containing paired sets of acoustictransmitters and receivers,a system clock,and microprocessorcircuitry to measure intervals of time between transmission andreception of sound pulses.3.2.5.1 DiscussionThe fundamental measurement unit istransit time.With transit time and a known acoustic pathlength,velocity or speed of sound,or both,can be calculated.Instrument output is a series of quasi-instantaneous velocitycomponent readings along each axis or speed of sound,or both.The speed of sound and velocity components may be used tocompute sonic temperature(Ts),to describe the mean windfield,or to compute fluxes,variances,and turbulence intensi-ties.3.2.6 sonic temperature(Ts),(K)an equivalent tempera-ture that accounts for the effects of temperature and moistureon acoustic wavefront propagation through the atmosphere.3.2.6.1 DiscussionSonic temperature is related to thevelocity of sound c,absolute temperature T,vapor pressure ofwater e,and absolute pressure P by(1).31These practices are under the jurisdiction of ASTM Committee D22 on AirQuality and are the direct responsibility of Subcommittee D22.11 on Meteorology.Current edition approved Oct.1,2011.Published October 2011.Originallyapproved in 1994.Last previous edition approved in 2007 as D5527 00(2007).DOI:10.1520/D5527-00R11.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.3The boldface numbers in parentheses refer to the list of references at the end ofthese practices.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 c25 403T110.32e/P!5 403Ts(1)(Guidance concerning measurement of P and e are con-tained in Test Methods D3631,D4230,and E337.)3.2.7 transducer shadow correctionthe ratio of the truealong-axis velocity,as measured in a wind tunnel or by anotheraccepted method,to the instrument along-axis wind measure-ment.3.2.7.1 DiscussionThis ratio is used to compensate foreffects of along-axis flow shadowing by the transducers andtheir supporting structure.3.2.8 transit time(t,(s)the time required for an acousticwavefront to travel from the transducer of origin to thereceiving t