BS 7843-3-2012 Acquisition and management of meteorological precipitation data from a gauge network Code of practice for the design and manufacture of storage and automatic collect.pdf

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1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationBS 7843-3:2012Acquisition andmanagement ofmeteorological precipitationdata from a gauge networkPart 3: Code of practice for thedesign and manufacture of storageand automatic coll

2、ecting raingaugesPublishing and copyright informationThe BSI copyright notice displayed in this document indicates when the documentwas last issued. The British Standards Institution 2012Published by BSI Standards Limited 2012.ISBN 978 0 580 71311 8ICS 07.060The following BSI references relate to th

3、e work on this standard:Committee reference CPI/113Draft for comment 11/30219645 DCPublication historyBS 7843-3.1 first published November 1999BS 7843-3.2 first published January 2005First published as BS 7843-3, February 2012Amendments issued since publicationDate Text affectedBS 7843-3:2012 BRITIS

4、H STANDARDContentsForeword iiIntroduction 11 Scope 12 Normative references 13 Terms and definitions 24 The UK reference storage raingauge 35 Main components of a collecting raingauge 36 The collecting device 47 The measurement device 68 Automatic raingauge heaters 149 Data conditioning, data logging

5、 and data transmission 1410 Facilitating maintenance 1411 Automatic raingauge environmental considerations 1512 Calibration of automatic raingauges 1513 Other technologies for the measurement component of automaticraingauges 17AnnexesAnnex A (normative) The UK reference storage raingauge 18Annex B (

6、informative) An example tipping bucket Class B calibrationcalculation 22Biblography 25List of figuresFigure1Tipvolume corresponding to 0.2 mm increment of rainfall 5Figure 2 Accumulated monthly collected rainfall as a function of raingaugediameter 6Figure 3 Raingauge: Example frost protector 7Figure

7、410mmrain measure 10Figure550mmrain measure 11Figure 6 Raingauge: Example dip rod 12Figure7Tipping bucket operation 13Figure A.1 Reference daily raingauge: General assembly 19Figure A.2 Reference daily raingauge: General assembly 19Figure A.3 Reference daily raingauge: Can outer 20Figure A.4 Referen

8、ce daily raingauge: Can inner 21Figure A.5 Reference daily raingauge: Funnel 22Summary of pagesThis document comprises a front cover, an inside front cover, pages i to ii,pages 1 to 26, an inside back cover and a back cover.BRITISH STANDARD BS 7843-3:2012 The British Standards Institution 2012 iFore

9、wordPublishing informationThis part of BS 7843 is published by BSI Standards Limited, under licence fromThe British Standards Institution, and came into effect on 29 February 2012. Itwas prepared by Technical Committee CPI/113, Hydrometry. A list oforganizations represented on this committee can be

10、obtained on request to itssecretary.SupersessionTogether with BS 7843-1:2012, BS 7843-3:2012 supersedes BS 7843-3.1:1999 andBS 7843-3.2:2005, which are withdrawn.Relationship with other publicationsBS 7843, Acquisition and management of meteorological precipitation data froma raingauge network, comp

11、rises four parts. Part 1: Guide for design, development and review of a raingaugenetwork. Part 2: Code of practice for operating raingauges and managingprecipitation data. Part 3: Code of practice for the design and manufacture of storage andautomatic collecting raingauges. Part 4: Guide for the est

12、imation of areal rainfall.Information about this documentThis is a full revision of the standard.Use of this documentAs a code of practice, this British Standard takes the form of guidance andrecommendations. It should not be quoted as if it were a specification andparticular care should be taken to

13、 ensure that claims of compliance are notmisleading.Any user claiming compliance with this British Standard is expected to be able tojustify any course of action that deviates from its recommendations.Presentational conventionsThe provisions in this standard are presented in roman (i.e. upright) typ

14、e. Itsrecommendations are expressed in sentences in which the principal auxiliaryverb is “should”.Commentary, explanation and general informative material is presented insmaller italic type, and does not constitute a normative element.Contractual and legal considerationsThis publication does not pur

15、port to include all the necessary provisions of acontract. Users are responsible for its correct application.Compliance with a British Standard cannot confer immunity from legalobligations.BRITISH STANDARDBS 7843-3:2012ii The British Standards Institution 2012IntroductionRainfall totals and intensit

16、y rates are measured at frequencies ranging fromseconds to months, and the data are required by the user on timescales rangingfrom the immediate to several weeks in arrears. Measurements are made bymany different organizations and individuals using various types of raingaugesand techniques.This Brit

17、ish Standard covers instrumentation that measures rainfall by collectingthe volume of water that falls on a fixed area. The collected volume of water isdivided by the fixed area of the colleting device to give a value for volume perunit area, termed rainfall depth, and measured in millimetres. Raing

18、auges mayalso be used to measure solid precipitation, although their performance for thispurpose is generally poor and other measurement methods ought to beconsidered if accurate measurements are required. Unlike many othermeteorological instruments, there is no absolute physical standard against wh

19、icha raingauge can be compared 1. It is important to recognize that differentraingauge instruments and different technologies can yield a range of indicatedmeasures of rainfall.Many different types, shapes and sizes of raingauge are acceptable for themeasurement of rainfall, each reflecting a specif

20、ic requirement. Most consist ofa circular collecting device, delineating the fixed area of the sample, and afunnel leading into a storage reservoir and/or measuring system. Some types ofautomatic gauge do not require a funnel.The amount of rainfall collected in a raingauge is affected by the speed o

21、f theairflow over the gauge collecting device and the proximity of obstructions suchas trees or buildings. In addition, the shape of the collecting device causes anobstruction to the wind flow pattern and the increase in air speed across thegauge orifice can result in the smallest raindrops being sw

22、ept away from thecollecting device and not being measured.NOTE For the purposes of this standard the thermal expansion coefficient for wateris not considered due to its negligible effect on rainfall measurement when all otheruncertainties are considered.1 ScopeThis part of BS 7843 gives recommendati

23、ons for the design and manufacture ofstorage and automatic collecting raingauges to be deployed at ground level, orclose to the ground, for measuring the amount of rainfall in millimetres ofwater equivalent, either for a dedicated purpose at a specific location or as partof a network covering a larg

24、e area. It is not applicable to remote sensing devicesthat detect the presence of precipitation particles or to weather radars.BS 7843-1 provides information on the selection of raingauges depending onuser requirements.2 Normative referencesThe following referenced documents are indispensable for th

25、e application ofthis document. For dated references, only the edition cited applies. For undatedreferences, the latest edition of the referenced document (including anyamendments) applies.BS 7843-1, Acquisition and management of meteorological precipitation datafrom a raingauge network Part 1: Guide

26、 for design, development and reviewof a raingauge networkBRITISH STANDARD BS 7843-3:2012 The British Standards Institution 2012 1BS 7843-2, Acquisition and management of meteorological precipitation datafrom a raingauge network Part 2: Code of practice for operating raingaugesand managing precipitat

27、ion dataBS EN ISO 772:2001, Hydrometric determinations Vocabulary and symbolsBS ISO 385, Laboratory glassware BurettesCEN/TC 318 N 320, Hydrometry Measurement of the rainfall intensity (liquidprecipitation) requirements, calibration methods and field measurementsOIML R111:2004, Weights of classes E1

28、, E2, F1, F2, M1, M12, M2, M23 and M33 Terms and definitionsFor the purposes of this part of BS 7843, the terms and definitions given inBS EN ISO 772:2001 and the following apply.3.1 calibrationprocess which establishes, under specified conditions, the relationship betweenthe values indicated by a r

29、aingauge and the corresponding known valuesindicated by a measurement standard with associated measurementuncertainties3.2 dip rodcalibrated marked rod used to measure rainfall from the measurement of thedepth of water in the collecting vessel3.3 maintenanceprocess that ensures that the site and equ

30、ipment continue to function correctlyfor the measurement of precipitation3.4 manual readingmeasurements of precipitation made by an observer using a storage raingaugeand a rain measure3.5 observerperson who makes a manual reading3.6 precipitationwater or ice derived from the atmosphere and deposited

31、 at ground levelNOTE Measured in terms of the depth in mm of its liquid equivalent.3.7 rainfalltotal liquid component of precipitation, including condensation from theatmosphere collected and measured by a raingauge3.8 rainfall collecting vesselcontainer that stores collected rainfall3.9 rainfall in

32、tensityaccumulated precipitation in unit time3.10 rain measuregraduated measuring cylinder made of clear glass or plastic, used by theobserver for measuring the volume of collected liquid and melted solidprecipitationBRITISH STANDARDBS 7843-3:20122 The British Standards Institution 20123.11 raingaug

33、e3.11.1 automatic raingaugecollecting raingauge that measures rainfall by automatic meansNOTE This may include data processing and logging capability.3.11.2 collecting raingaugeinstrument that collects precipitation falling through an orifice of knowncross-sectional area for the measurement of its w

34、ater equivalent volume, massor weight accumulated over a measured period3.11.3 storage raingaugecollecting raingauge that accumulates rainfall and melted solid precipitation in acollecting vessel for manual measurement of its volume3.12 real-time datadata obtained while the precipitation event to wh

35、ich it relates is occurring3.13 sitearea of ground where a raingauge is deployed for measurement or has beendeployed in the pastNOTE Other instruments for measuring the environment may also be deployed atthe site.4 The UK reference storage raingaugeA storage raingauge should be constructed in accord

36、ance with Annex A, whichgives recommendations for the UK reference gauge.NOTE Over the last 100 years or so, storage rainfall measurements in the UK havebeen made using a basic design (or close variants) having a level circular collectingdevice 127 mm (5 in) in diameter, exposed at 305 mm (12 in) ab

37、ove the ground. Thelong record of rainfall data and extensive raingauge field trials have resulted in thistype of storage gauge being established as the reference daily raingauge.5 Main components of a collecting raingaugeFunctionally, all collecting raingauges should comprise the following twocompo

38、nent subsystems.a) The collecting device (see Clause 6), which acts to intercept and capture aportion of the incident precipitation.b) The measurement device (see Clause 7), which measures the collectedrainfall.Automatic raingauges may be optionally fitted with heaters (see Clause 8).An automatic ra

39、ingauge should have an additional component sub-systemcomprising the following elements: signal processing, data logging and datatransmission.BRITISH STANDARD BS 7843-3:2012 The British Standards Institution 2012 36 The collecting device6.1 Design criteria for the collecting device: manually read an

40、dautomatic raingauges6.1.1 The rainfall capture component should be constructed such that theincident rainfall captured is independent of the direction of wind over theraingauge (a round orifice satisfies this recommendation).6.1.2 The design of the gauge should minimize the vertical component ofair

41、flow over the raingauge orifice.6.1.3 The upper part of the collecting device that delineates the collecting areashould have a sharp edge, formed by an external bevel and with the inner facevertical. The material of which it is manufactured should be sufficiently robustto retain the sharp edge for t

42、he intended lifetime of the raingauge.6.1.4 An automatic raingauge should be provided with a mechanism to allowthe rim edge to be adjusted to be horizontal while in service or the designshould maintain plane of rim level to within 2 of the base plane. Thismechanism should be designed and constructed

43、 to retain this setting for theintended duration of deployment.NOTE Storage raingauges need to be installed in a level and stable manner. SeeBS 7843-2 for further information.6.1.5 The diameter of the edge of the collecting device should not differ bymore than 0.2% of the stated diameter in any dire

44、ction. The gauge diametershould be greater than 100 mm to minimize unacceptable impacts due to thewind flow 2. The selected cross-sectional area should be based on aconsideration of the expected annual or seasonal precipitation and therequirements of the measurement mechanism.6.1.6 The raingauge sho

45、uld be constructed in a material that is durable and canendure natural weathering without changes to its surface characteristics.6.1.7 Sound watertight seams should be used throughout. If a gauge stores therainfall then the storage volume should remain isolated from external flooding,up to a depth o

46、f 100 mm above ground level.6.1.8 If a funnel forms part of the design, it should be constructed of durablestable materials, such that water droplets are not retained by surface tensionbut run freely towards the orifice and pass into the measurement mechanism.The surface of the funnel should remain

47、in this state for the expected lifetime ofthe raingauge.NOTE Experience has shown that painted surfaces are unlikely to meet thisrecommendation.6.1.9 The collecting device should fit firmly over the top of the outer but shouldbe removable without undue force.6.1.10 If a funnel forms part of the desi

48、gn, the funnel spout internal diametershould be large enough to allow free flow into the measurement device at themaximum specified rainfall intensity.6.1.11 The collecting device should be designed to prevent rain from splashingout. This can be achieved by designing the internal surfaces of the col

49、lectingdevice such that a line drawn perpendicular to any point on any surfaceintercepts the internal face of the gauge below the rim 2.BRITISH STANDARDBS 7843-3:20124 The British Standards Institution 20126.2 Additional design criteria for automatic raingauge collectingdevice6.2.1 Tipping bucket raingauge (TBR) collecting deviceThe collecting device should have a funnel spout entering the measurementdevice. A filter may be provided to prevent small particles entering the bucketmechanism. If a filter is provided then the mesh s