1、BSI Standards Publication Manual measurement of snow water equivalent PD CEN/TR 16588:2014National foreword This Published Document is the UK implementation of CEN/TR 16588:2014. The UK participation in its preparation was entrusted to Technical Committee CPI/113, Hydrometry. A list of organizations
2、 represented on this committee can be obtained on request to its secretary. This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. The British Standards Institution 2014. Published by BSI Standards Limited 2014 ISBN
3、 978 0 580 77502 4 ICS 07.060 Compliance with a British Standard cannot confer immunity from legal obligations. This Published Document was published under the authority of the Standards Policy and Strategy Committee on 31 March 2014. Amendments/corrigenda issued since publication Date Text affected
4、 PUBLISHED DOCUMENT PD CEN/TR 16588:2014 TECHNICAL REPORT RAPPORT TECHNIQUE TECHNISCHER BERICHT CEN/TR 16588 March 2014 ICS 07.060 English Version Manual measurement of snow water equivalent Mesure manuelle de lquivalent en eau de la neige Manuelle Messung des Schneewasserquivalents This Technical R
5、eport was approved by CEN on 3 September 2013. It has been drawn up by the Technical Committee CEN/TC 318. CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany,
6、Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORM
7、UNG CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels 2014 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. CEN/TR 16588:2014 E PD CEN/TR 16588:2014CEN/TR 16588:2014 (E) 2 Contents Page Foreword 4 Introduction .5 1 Scope
8、 6 2 Terms and definitions .6 3 Symbols . 10 4 Objective 10 4.1 Spatial estimation of SWE . 10 4.2 Snow load assessment 11 4.3 Snow profile 11 4.4 Water content in newly fallen snow 11 4.5 Reference to automatic SWE measurements 12 5 Principle of manual SWE measurements . 12 6 Measurement sites 12 6
9、.1 General . 12 6.2 Manual measurements . 13 7 Measurements . 14 7.1 General . 14 7.2 Snow density . 14 7.3 Snow depth 15 7.3.1 Manual probing . 15 7.3.2 Manual readings on fixed snow stakes 15 7.3.3 Automatic recording . 15 7.3.4 Remote sensing 16 8 Manual SWE sampling methods . 16 8.1 General . 16
10、 8.2 Snow tubes 16 8.3 Core drills 17 8.4 Density cutters 17 9 Spatial estimation . 18 9.1 General . 18 9.2 Interpolation methods 18 9.3 Snow courses 19 9.4 Regression modelling 19 9.5 Hydrologic and land surface modelling . 20 9.6 Remote sensing systems for snow monitoring . 20 10 Maintenance 21 11
11、 Uncertainties . 21 11.1 Environmental factors 21 11.2 Technical factors 21 11.3 Human factors . 22 12 Assessment of quality 22 13 Measurement uncertainty 22 PD CEN/TR 16588:2014CEN/TR 16588:2014 (E) 3 14 Recommendations 22 Annex A (informative) List of methods for determination of SWE in total snow
12、pack . 24 Annex B (informative) Manual SWE measuring bodies in Europe . 25 Annex C (informative) Determination of mass of snow sample . 26 Annex D (informative) Determination of water volume in snow sample . 27 Annex E (informative) Snow stakes 28 Annex F (informative) List of samplers for detection
13、 of SWE 29 Annex G (informative) Snow tubes . 30 Annex H (informative) Core drills 31 Annex I (informative) Density cutters 32 Annex J (informative) On-line glossaries . 33 Bibliography 34 PD CEN/TR 16588:2014CEN/TR 16588:2014 (E) 4 Foreword This document (CEN/TR 16588:2014) has been prepared by Tec
14、hnical Committee CEN/TC 318 “Hydrometry”, the secretariat of which is held by BSI. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN and/or CENELEC shall not be held responsible for identifying any or all such patent rights. PD
15、CEN/TR 16588:2014CEN/TR 16588:2014 (E) 5 Introduction Snow water equivalent (SWE) measurements Snow water equivalent (SWE), also called “water equivalent of snow”, is the depth of water that would be obtained by melting the snowpack in a given area, and is normally expressed in millimetres. In other
16、 words, SWE corresponds to the mass of snow over a given area. Measurements of SWE in snowpack, and new snow, improve the estimation of winter precipitation, especially in areas with a sparse network of meteorological stations. The measurements are mainly made for the purpose of estimating the spati
17、al distribution of the total water content in catchment areas, as knowledge of the SWE in river basins is fundamental for estimating the expected snowmelt runoff. Information about snow accumulation and daily melt rate is essential in flood forecasting during the snowmelt season. SWE is also used in
18、 avalanche theory and forecasting, as well as for risk assessment of heavy snow loads. Furthermore, the data is important in glaciological mass balance studies and climate monitoring. The melt from polar ice sheets is a major factor in sea level rise. Methods and instruments, which have been develop
19、ed for determination of SWE, are listed in Annex A. Manual SWE measurements The first station networks with manual SWE measurements were established in the early 20th century at meteorological institutes in North America and Europe. Today the measurements are made routinely at federal and national m
20、eteorological and hydrological institutes, within the hydropower industry, and by universities, in cold climate countries all over the world. Annex B shows a list of manual SWE measuring bodies in Europe. Automized methods have been developed to be used in remote areas, as well as to enable continuo
21、us recording, but manual measurements are still more common, as they can provide high quality data for a relatively low capital cost. The importance of manual measurements is also reflected in their use as reference to other SWE measuring methods. PD CEN/TR 16588:2014CEN/TR 16588:2014 (E) 6 1 Scope
22、This Technical Report defines the requirements for manual measurements of SWE over land, see ice and glaciers, under natural environmental conditions, and shows methods for calculating the spatial distribution of the data. It includes measurements with snow tubes, core drills and density cutters. 2
23、Terms and definitions For the purposes of this document, the following terms and definitions apply. Note 1 to entry Primarily The International Classification for Seasonal Snow on the Ground (UNESCO), Cryospheric Glossary (NSIDC) and Glossary of Meteorology (AMS) has been used as reference. 2.1 abla
24、tion removal of material from the surface of an object by vaporization, chipping, or other erosive processes. In this case the opposite of snow accumulation 2.2 blowing snow an ensemble of snow particles raised by the wind to moderate or great heights above the ground; the horizontal visibility at e
25、ye level is generally very poor Note 1 to entry See also drifting snow. 2.3 condensation the change of the physical state of matter from gaseous phase into liquid phase (opposite of evaporation) 2.4 deposition (1) a process by which water vapour is deposited as ice without first forming liquid water
26、 (opposite of sublimation) (2) the process by which snow is deposited on the ground either with or without wind action Note 1 to entry As a result, stationary snow deposits such as snow dunes, snowdrifts, or the snow cover itself may form. 2.5 drifting snow snow raised from the snow surface by the w
27、ind to a height of less than 2 metres; it does not restrict horizontal visibility at 2 metres or more above the surface Note 1 to entry See also blowing snow. 2.6 evaporation vaporization of a liquid that only occurs on the surface of a liquid, at temperatures below the boiling point (opposite of co
28、ndensation) 2.7 firn well-bonded and compacted snow that has survived the summer season, but has not been transformed to glacier ice PD CEN/TR 16588:2014CEN/TR 16588:2014 (E) 7 Note 1 to entry Typical densities are 400 - 830 kgm 3 . Thus firn is the intermediate stage between snow and glacial ice wh
29、ere the pore space is at least partially interconnected. Firn usually results from both melt-freeze cycles and compaction by overload, or from compaction alone, as in inland Antarctic snow. 2.8 glacier a mass of land ice formed by the further recrystallization of firn, normally flowing continuously
30、from higher to lower elevations 2.9 new snow recently fallen snow in which the original form of the ice crystals can be recognized Note 1 to entry This is usually the snow which has accumulated on a snow board during the standard observing period of 24 hours. 2.10 old snow deposited snow whose trans
31、formation into firn is so far advanced that the original form of the ice crystals can no longer be recognized 2.11 recrystallize to crystallize again, i.e., to form into new crystals 2.12 redistribution distribution of previously deposited snow that was eroded and transported by the wind Note 1 to e
32、ntry Redistribution features such as snowdrifts are usually formed from densely packed and friable snow. 2.13 perennial snow snow persisting for an indefinite time longer than one year Note 1 to entry See also seasonal snow. 2.14 seasonal snow snow that accumulates during one season and does not las
33、t for more than one year Note 1 to entry See also perennial snow. 2.15 snow accumulation all processes that add mass to the snow cover, i.e. typically solid and liquid precipitation, ice deposition from atmospheric water vapour, and snow deposited by wind, avalanches, etc. (opposite of ablation) 2.1
34、6 snow avalanche mass of snow which becomes detached and slides swiftly down a slope Note 1 to entry Large snow avalanches may contain rocks, soil, vegetation, and/or ice. 2.17 snow board in this case a specially constructed board used to identify the surface of snow that has been recently covered b
35、y snowfall PD CEN/TR 16588:2014CEN/TR 16588:2014 (E) 8 2.18 snow core a sample of snow, either just the freshly fallen snow or the combined old and new snow on the ground, obtained by pushing, or drilling, a cylinder down through the snow layer and extracting it 2.19 snow course an established line,
36、 or transect, of measurements of SWE across a snow covered area in a representative terrain, where appreciable amounts of snow accumulates 2.20 snow cover in general, the accumulation of snow on the ground surface, and in particular, the areal extent of snow- covered ground; term to be preferably us
37、ed in conjunction with the climatologic relevance of snow on the ground Note 1 to entry See also snowpack. 2.21 snow creep a continuous, slow downhill movement of a snow layer 2.22 snow density the mass per unit volume of snow Note 1 to entry Sometimes total and dry snow densities are measured separ
38、ately. Total snow density encompasses all constituents of snow (ice, liquid water, and air) while dry snow density refers to the ice matrix and air only. 2.23 snow depth the total height of the snowpack, measured vertically from the base to the snow surface Note 1 to entry The slope-perpendicular eq
39、uivalent of snow depth is the snowpack thickness. 2.24 snow distribution spatial and temporal variability of snow cover affected by snowfall, wind speed, elevation, topography, vegetation and ablation 2.25 snow erosion the process by which the surface of the snow cover is worn away, primarily by the
40、 action of wind Note 1 to entry Wind erosion is a very important factor in the redistribution of snow. 2.26 snow height the vertical distance from a base to a specific level in the snow, or to the snow surface Note 1 to entry Ground surface is usually taken as the base, but on firn fields and glacie
41、rs it refers to the level of either the firn surface or glacier ice. Height is used to denote the locations of layer boundaries but also of measurements such as snow temperatures relative to the base. Where only the upper part of the snowpack is of interest, the snow surface may be taken as the refe
42、rence. This should be indicated by using negative coordinate values. Snow depth is the total height of the snowpack. 2.27 snow layer PD CEN/TR 16588:2014CEN/TR 16588:2014 (E) 9 a layer of ice crystals with similar size and shape 2.28 snow load the downward force on an object or structure caused by t
43、he weight of accumulated snow 2.29 snow metamorphism the transformation that the snow undergoes in the period from deposition to either melting or passage to glacial ice Note 1 to entry Meteorological conditions as well as mechanical or gravitational stresses are the primary external factors that af
44、fect snow metamorphism. 2.30 snow pit in this case a pit dug vertically into the snowpack where snowpack stratigraphy and characteristics of the individual snow layers are observed Note 1 to entry See also snow profile. 2.31 snow profile a stratigraphic record of the snowpack including characteristi
45、cs of individual snow layers, usually performed in snow pits 2.32 snow sample in this case a sample of snow with a defined volume extracted from the snowpack 2.33 snow sampler an instrument used for the collection of snow samples in an undisturbed snowpack 2.34 snow season the time period when the g
46、round usually is covered by snow 2.35 snow surface the uppermost part of the snow cover, forming the interface to the atmosphere 2.36 snow survey the process of determining snow parameters, most often depth and density, at representative points, usually along a snow course 2.37 snow water equivalent
47、 (SWE) the depth of water that would result if a certain amount of snow melted completely Note 1 to entry It can represent the snow cover over a given region or a confined snow sample over the corresponding area. The snow water equivalent is the product of the snow height and the snow density divide
48、d by the density of water. It is typically expressed in millimetres of water equivalent, which is equivalent to kilograms per square metre or litres of water per square metre. 2.38 snowdrift PD CEN/TR 16588:2014CEN/TR 16588:2014 (E) 10 a mound or bank of snow deposited as sloping surfaces and peaks,
49、 often behind obstacles, irregularities, and on lee slopes, due to eddies in the wind field. (See also deposition) 2.39 snowfall the quantity of snow falling within a given area in a given time 2.40 snowpack the accumulation of snow on the ground at a given site and time; term to be preferably used in conjunction with the physical and mechanical properties of the snow Note 1 to entry See also snow cover. 2.41 snowpack stratigraphy the definition and description of the stratified, i.e. layered snowpack Note 1 to entry See also snow profile. 2.42 snowpack thickness the
