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Sundström, Nils
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Publications (10 of 19) Show all publications
Feiccabrino, J., Graff, W., Lundberg, A., Sundström, N. & Gustafsson, D. (2015). Meteorological Knowledge Useful for the Improvement of Snow Rain Separation in Surface Based Models (ed.). Paper presented at . Hydrology, 2(4), 266-288
Open this publication in new window or tab >>Meteorological Knowledge Useful for the Improvement of Snow Rain Separation in Surface Based Models
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2015 (English)In: Hydrology, ISSN 2306-5338, Vol. 2, no 4, p. 266-288Article in journal (Refereed) Published
Abstract [en]

An accurate precipitation phase determination—i.e., solid versus liquid—is of paramount importance in a number of hydrological, ecological, safety and climatic applications. Precipitation phase can be determined by hydrological, meteorological or combined approaches. Meteorological approaches require atmospheric data that is not often utilized in the primarily surface based hydrological or ecological models. Many surface based models assign precipitation phase from surface temperature dependent snow fractions, which assume that atmospheric conditions acting on hydrometeors falling through the lower atmosphere are invariant. This ignores differences in phase change probability caused by air mass boundaries which can introduce a warm air layer over cold air leading to more atmospheric melt energy than expected for a given surface temperature, differences in snow grain-size or precipitation rate which increases the magnitude of latent heat exchange between the hydrometers and atmosphere required to melt the snow resulting in snow at warmer temperatures, or earth surface properties near a surface observation point heating or cooling a shallow layer of air allowing rain at cooler temperatures or snow at warmer temperatures. These and other conditions can be observed or inferred from surface observations, and should therefore be used to improve precipitation phase determination in surface models.

National Category
Geochemistry
Research subject
Applied Geology
Identifiers
urn:nbn:se:ltu:diva-8054 (URN)10.3390/hydrology2040266 (DOI)67eff2de-28be-4745-86dc-772d81f5e82b (Local ID)67eff2de-28be-4745-86dc-772d81f5e82b (Archive number)67eff2de-28be-4745-86dc-772d81f5e82b (OAI)
Note
Godkänd; 2015; 20151201 (andbra)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2017-11-24Bibliographically approved
Villain, L., Sundström, N., Perttu, N., Alakangas, L. & Öhlander, B. (2014). Evaluation of the effectiveness of backfilling and sealing at an open-pit mine using ground penetrating radar and geoelectrical surveys, Kimheden, northern Sweden (ed.). Paper presented at . Environmental Earth Sciences, 73(8), 4495-4509
Open this publication in new window or tab >>Evaluation of the effectiveness of backfilling and sealing at an open-pit mine using ground penetrating radar and geoelectrical surveys, Kimheden, northern Sweden
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2014 (English)In: Environmental Earth Sciences, ISSN 1866-6280, E-ISSN 1866-6299, Vol. 73, no 8, p. 4495-4509Article in journal (Refereed) Published
Abstract [en]

At Kimheden, a small copper mine in northern Sweden, reclamation of the two open pits was investigated using ground penetrating radar and geoelectrical multiple-gradient array measurements. The pits had been backfilled with waste rock, with a dry cover being applied on top in 1996 in order to reduce the influx of oxygen to the sulphidic mine waste and the subsequent production of acid mine drainage. The dry cover consists of a sealing layer of clayey till and a protective layer of unsorted till. As geochemical sampling in the drainage from the pits had previously revealed the continued release of contaminating oxidation products, the purpose of the geophysical survey undertaken in 2010 was to identify deficiencies in the cover or other pathways for oxygen to reach the waste rock. The radar images did not reveal any damage in the sealing layer but risks of deterioration of the cover in the long term were identified with both the radar and geoelectrical data. The radar localised regions of thinner protective layer where the sealing layer could be exposed to frost action. The geoelectrical measurements indicated the existence of seepage through the dry cover that presented a risk of erosion of the sealing layer. 2-D inversion of geoelectrical data also imaged some pathways of groundwater around the main pit. The results from the geophysical investigations were used together with other site data in order to show that both deficiencies in the cover and superficial fractures in the pit walls may explain an ongoing influx of oxygen to the mine waste.

Keywords
Earth sciences - Exogenous eart sciences, geofysik, georadar, geoelektriska mätningar, gruvavfall, Geovetenskap - Exogen geovetenskap
National Category
Geochemistry Geophysics
Research subject
Applied Geology; Applied Geophysics
Identifiers
urn:nbn:se:ltu:diva-14661 (URN)10.1007/s12665-014-3737-0 (DOI)000351453600044 ()2-s2.0-84924943216 (Scopus ID)e13b367e-0a72-4aa9-9cf6-3a5ed0852a28 (Local ID)e13b367e-0a72-4aa9-9cf6-3a5ed0852a28 (Archive number)e13b367e-0a72-4aa9-9cf6-3a5ed0852a28 (OAI)
Note
Validerad; 2014; 20141127 (lucvyl)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2019-11-22Bibliographically approved
Sundström, N., Lundberg, A., Gustafsson, D. & Kruglyak, A. (2013). Field evaluation of a new method for estimation of liquid water content and snow water equivalent of wet snowpacks with GPR (ed.). Paper presented at . Hydrology Research, 44(4), 600-613
Open this publication in new window or tab >>Field evaluation of a new method for estimation of liquid water content and snow water equivalent of wet snowpacks with GPR
2013 (English)In: Hydrology Research, ISSN 1998-9563, Vol. 44, no 4, p. 600-613Article in journal (Refereed) Published
Abstract [en]

Estimates of snow water equivalent (SWE) with ground-penetrating radar can be used to calibrate and validate measurements of SWE over large areas conducted from satellites and aircrafts. However, such radar estimates typically suffer from low accuracy in wet snowpacks due to a built-in assumption of dry snow. To remedy the problem, we suggest determining liquid water content from path-dependent attenuation. We present the results of a field evaluation of this method which demonstrate that, in a wet snowpack between 0.9 and 3 m deep and with about 5 vol% of liquid water, liquid water content is underestimated by about 50% (on average). Nevertheless, the method decreases the mean error in SWE estimates to 16% compared to 34% when the presence of liquid water in snow is ignored and 31% when SWE is determined directly from two-way travel time and calibrated for manually measured snow density.

National Category
Geochemistry Embedded Systems
Research subject
Applied Geology; Embedded System
Identifiers
urn:nbn:se:ltu:diva-2580 (URN)10.2166/nh.2012.182 (DOI)000321953200003 ()2-s2.0-84884479665 (Scopus ID)0367e137-8ef8-4514-abe9-6d4a2c275393 (Local ID)0367e137-8ef8-4514-abe9-6d4a2c275393 (Archive number)0367e137-8ef8-4514-abe9-6d4a2c275393 (OAI)
Note
Validerad; 2013; 20120919 (nilgra)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Gustafsson, D., Ahlberg, J., Feiccabrino, J., Lindström, G., Lundberg, A., Sundström, N. & Wetterhall, F. (2012). Distribuerade system för förbättrade snö- och avrinningsprognoser: Integration i hydrologiska modeller. Slutrapport (ed.). Paper presented at . Stockholm: Elforsk
Open this publication in new window or tab >>Distribuerade system för förbättrade snö- och avrinningsprognoser: Integration i hydrologiska modeller. Slutrapport
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2012 (Swedish)Report (Other academic)
Abstract [sv]

Det övergripande målet med projektet har varit att minska totala volymfelet i prognoser för vårflödesavrinningen samt att förbättra tids- och volym-bestämningen av flödespikarna för dessa. Projektet har fokuserat på att kombinera utveckling av modell- och mätteknik för att studera hur modellstrukturer och metoder för att integrera mätinformation (data-assimilering) kan optimeras i förhållande till tillgänglig snöinformation. Ett syfte har också varit att de utvecklade metoderna skall vara operationellt användbara och baserade på kostnads- och tidseffektiva mättekniker och modelleringsverktyg, samtidigt som de skall ge en betydande förbättring av prognoserna. I projektet har en rad mättekniker testats och vidareutvecklas (tex snökuddar, automatiska sensorer för snödjup- och densitet, samt markradartekniker). Störst fokus har varit på vidareutveckling av radarteknik för linjemätning av snötäckets djup, densitet och fuktighet. För torr snö har djup och densitet uppskattats med hjälp av radarvågornas snöutbredningshastighet direkt från radardata med ett flerkanalradarsystem, [så kallad ”common-mid point” (CMP) metod)]. För blöt snö krävs förutom utbrednings-hastigheten också information om snöns fuktighet för korrigering av uppskattningen av snöns densitet. Inom projektet har därför en ny metod utvecklats för bestämning av snös fuktighet baserad på det faktum att utsläckningen av radarsignalens amplitud beror på snöns fuktighet. Två olika hydrologiska modeller har använts inom projektet: SMHI:s nya vattenbalans- och vattenkvalitetsmodell HYPE samt en egenutvecklad modell. Den senare modellen har utvecklats för att kunna jämföra tillrinnings-prognosernas känslighet för val av snömodellstruktur (representation av processer och distribution i tid och rum). Modellen består av en rumsligt distribuerad snömodell kopplad till en odistribuerad avrinningsmodell (en förenklad variant av HBV-modellen). Modellen utvecklades inom det hydrologiska modelleringssystemet HYSS utvecklat på SMHI, men kan i princip kopplas till vilken modellplattform som helst. Snö-smältningen kan beräknas antingen med temperatur- och strålnings-indexmetod eller med energibalansmetod. Den rumsliga distribueringen kan göras antingen med ett 2-dimensionellt nät eller genom uppdelning av avrinningsområdet i representativa enheter baserad på klassificering av topografi (höjd, lutning väderstreck) och vegetation. HYPE-modellen har för närvarande en enklare snömodell än den egenutvecklade modellen, men erbjuder istället hög rumslig uppdelning, öppen källkod (HYPE Open Source Community) och en enkel hantering av drivdata och modelluppsättningar för nya områden genom den operationella sverigeapplikationen (S-HYPE). HYPE-modellen har därför använts för att göra projektets modellutveckling lättare tillgänglig för andra. Den har också använts för att jämföra värdet av assimilering av snödata med värdet av val av prognosdata för nederbörd och temperatur. På sikt kan den egenutvecklade snömodellen göras tillgänglig som en valbar modul i HYPE. En dataassimileringsrutin baserad på Ensemble Kalmanfilter (EnKF) har utvecklats för integrering av snöinformation i simuleringarna och har implementerats som en modul i HYPE. Med EnKF metoden uppdateras modelltillstånd som funktion av kovariansen mellan modelltillstånd och modellfel. Uppdateringen sker sekventiellt, det vill säga under simuleringens gång vartefter nya observationer tillkommer. Kovariansen mellan modelltillstånd och modellfel uppskattas genom att skapa en ensemble av modeller med en viss spridning i modelltillstånden. Spridningen genereras genom att köra flera parallella modeller med slumpmässiga avvikelser i drivvariabler och parametervärden. En styrka med metoden är att osäkerheter i observationer, modellparametrar och indata kan uppskattas var för sig och användas för en automatisk uppdatering av modelltillstånden. Resterande spridning i den uppdaterade prognosen nyttjas för skattning av osäkerheten i resultaten. Beräkningsbördan ökar jämfört med en enskild simulering (ca 100 ensemblemedlemmar behövs), men jämfört med andra dataassimileringsmetoder är EnKF metoden mycket effektiv. De flesta hydrologiska modeller använder samma tröskeltemperatur för att skilja på regn och snö för alla nederbördstillfällen Förhållanden högre upp i atmosfären påverkar emellertid också hur stor andel av nederbörden som faller som snö respektive regn vid en viss markytetemperatur. Situationen i atmosfären beror i sin tur till stor del på vilken typ av front (gräns mellan luftmassor med olika temperatur) som producerar nederbörden. Vi har visat att man kan minska andelen felklassad nederbörd genom att identifiera vilken typ av front (varm- eller kall) som orsakar nederbörden vid ett specifikt tillfälle och anpassa tröskeltemperaturen efter fronttypen. Simuleringar med det nyutvecklade modellsystemet för testområdet Kultsjön i Västerbotten visar att assimilering med EnKF av distribuerade snödata förbättrade vårflodsprognoserna samtliga 4 år i delområdet Kultsjön och 3 av 4 år i delområdet Ransarn. Den relativa förbättringen var i medel 10-15 % beroende på vilka drivdata som användes. Störst förbättring av vårflodsprognosen, jämfört med den traditionella metoden med ensembler av historiska år, erhölls emellertid genom att använda säsongsprognoser från ECMWF (European Centre for Medium Range Weather Forecasts) som drivdata. Det var överraskande att dessa simuleringar gav bättre resultat än simuleringar med stationsmätningar. En möjlig förklaring kan vara att den interpolation av stationsdata som ligger till grund för SMHIs operationella drivdata (nederbörd och temperatur, PTHBV) kan ge både över- och underskattning av nederbörd i fjällområden beroende på om vädersystemen kommer från väster eller öster. Medelvolymfelet för Kultsjön förbättrades från 17 % till 8 % för de undersökta åren när en kombination av säsongsprognoser från ECMWF och assimilering av snöradardata användes istället för en deterministisk PTHBV-simulering. Den utvecklade dataassimileringstekniken har således visats sig vara ett effektivt sätt att automatiskt uppdatera modellerna inför vårflodsprognosen, och bör enkelt kunna anpassas för operationell användning. Det är också tydligt att assimilering av väderprognosdata från ECWMF gav en bättre prognos för Kultsjöns avrinningsområde än nuvarande PTHBV data. Mer arbete med att förstå hur osäkerheter och korrelationer i såväl snödata som modelldata krävs dock för att med säkerhet slå fast att målsättningarna i projektet har uppnåtts. Användningen av väderprognosdata som input i kombination med assimilering av snödata var mycket lovande och bör vidareutvecklas.

Place, publisher, year, edition, pages
Stockholm: Elforsk, 2012. p. 70
Series
Elforsk rapport, ISSN 1401-5706 ; 12:53
National Category
Geochemistry
Research subject
Applied Geology
Identifiers
urn:nbn:se:ltu:diva-22451 (URN)2e75ab28-5e5d-491c-a707-ae0e7e830b96 (Local ID)2e75ab28-5e5d-491c-a707-ae0e7e830b96 (Archive number)2e75ab28-5e5d-491c-a707-ae0e7e830b96 (OAI)
Note
Godkänd; 2012; 20121001 (nilgra)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2017-11-24Bibliographically approved
Sundström, N. (2012). Improving snow water equivalent estimates with ground penetrating radar by measuring on multiple channels (ed.). (Doctoral dissertation). Paper presented at . Luleå: Luleå tekniska universitet
Open this publication in new window or tab >>Improving snow water equivalent estimates with ground penetrating radar by measuring on multiple channels
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Snow water equivalent (SWE) of a snowpack is often measured along well-chosen transects representative of an area of interest, such as a drainage basin, to capture spatial distribution of SWE, which is of great interest for many applications. For example, it is a useful input to the new generation of hydrological models used for snow melt run-off predictions. A time-effective method to perform such measurements is to conduct them along one or several transects using a ground penetrating radar (GPR) operated from e.g. a snowmobile. Traditionally, a single-channel radar system has been used to estimate SWE from the radar wave two-way travel time via a linear formula, which can be calibrated for a particular snowpack with one or several manual measurements of snow density; this method typically relies on the assumption of a dry snowpack. However, if an unknown amount of liquid water is present in the snow, or if the snow density or the liquid water content varies substantially along the transect, SWE estimates are likely to be inaccurate.A different approach is to use a multi-channel GPR system with an array of antennas that makes it possible to simultaneously measure two-way travel time of several radar pulses that form a common mid-point (CMP) gather. Then the snow depth and the radar wave propagation velocity can be determined at each point with the CMP method under the assumption of a single-layer snowpack with parallel snow and ground surfaces. With liquid water content known or assumed to be zero, the snow density can be estimated from the propagation velocity via an empirical formula for mixtures, thus solving the problem of spatial variation in snow density. Finally, SWE is calculated from the snow depth and density. However, the CMP method is known to be sensitive to measurement errors in two-way travel time and to violations of its assumptions; and for a wet snowpack, the need to know the liquid water content at each measurement point to accurately estimate snow density presents a problem if the liquid water content varies along the transect.In this thesis, two methods that improve SWE estimates obtained with GPR are presented, both of which rely on measuring on multiple channels to obtain a CMP gather at each measurement point. The first method mitigates the impact of errors in CMP calculations on density estimates by establishing a depth-to-density function from the CMP data for all measurement points along a transect. This function, specific for each transect, is then used to determine snow density from snow depth. The second method (the PDA method) improves SWE estimates of wet snowpacks by determining liquid water content at each measurement point from path-dependent attenuation of two radar signals in the CMP gather. Both methods have been tested in field experiments and the sensitivity of the PDA method to built-in assumptions and measurement errors has been investigated in simulations.The field experiment conducted to test the first method has demonstrated that by applying a depth-to-density function, the accuracy of SWE estimates for a dry snowpack can be improved substantially. For the transect in the experiment, snow density and SWE estimated directly with the CMP method were overestimated by 34% and 36% on average; and when a depth-to-density function was used, snow density was underestimated by 2% and SWE was overestimated by less than 1%. The error was determined by comparison with manual measurements.In the field experiment conducted to test the PDA method, for a snowpack with the mean liquid water content of about 5 vol.%, the mean error in SWE was 16%, compared to 34% and 31% for two reference methods that both assumed liquid water content to be zero. Separately, the performed simulations suggest that the PDA method is very sensitive to measurement errors when liquid water content is close to zero; in such cases, one of the methods that assume dry snow should be used instead of the PDA method.

Place, publisher, year, edition, pages
Luleå: Luleå tekniska universitet, 2012. p. 184
Series
Doctoral thesis / Luleå University of Technology 1 jan 1997 → …, ISSN 1402-1544
National Category
Geochemistry
Research subject
Applied Geology
Identifiers
urn:nbn:se:ltu:diva-26398 (URN)e193e777-6e16-4107-a81a-cebe5566053e (Local ID)978-91-7439-524-2 (ISBN)e193e777-6e16-4107-a81a-cebe5566053e (Archive number)e193e777-6e16-4107-a81a-cebe5566053e (OAI)
Note

Godkänd; 2012; 20121112 (nilgra); DISPUTATION Ämne: Tillämpad geofysik/Applied Geophysics Opponent: Professor Robert W. Jacobel, Director of Environmental Studies, St Olafs College, Minnesota, U.S.A. Ordförande: Docent Angela Lundberg, Institutionen för samhällsbyggnad och naturresurser, Luleå tekniska universitet Tid: Måndag den 17 december 2012, kl 10.00 Plats: F531, Luleå tekniska universitet

Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2017-11-24Bibliographically approved
Sundström, N., Kruglyak, A. & Friborg, J. (2012). Modeling and simulation of GPR wave propagation through wet snowpacks: testing the sensitivity of a method for snow water equivalent estimation (ed.). Paper presented at . Cold Regions Science and Technology, 74-75, 11-20
Open this publication in new window or tab >>Modeling and simulation of GPR wave propagation through wet snowpacks: testing the sensitivity of a method for snow water equivalent estimation
2012 (English)In: Cold Regions Science and Technology, ISSN 0165-232X, E-ISSN 1872-7441, Vol. 74-75, p. 11-20Article in journal (Refereed) Published
Abstract [en]

Snow water equivalent (SWE) of a snowpack is an important input to the distributed snow hydrological models used for runoff predictions in areas with annual snowpacks. Since the conventional method of manually measuring SWE is very time-consuming, more automated methods are being adopted, such as using ground penetrating radar operated from a snowmobile with SWE estimated from radar wave two-way travel time. However, this method suffers from significant errors when liquid water is present in the snow.In our previous work, a new method for estimating SWE of wet snowpacks from radar wave travel times and amplitudes was proposed, with both these parameters obtained from a common mid-point survey. Here we present a custom ray-based model of radar wave propagation through wet snowpacks and results of MATLAB simulations conducted to investigate the method's sensitivity to measurement errors and snowpack properties. In particular, for a single-layer snowpack up to 2.1 m deep and with liquid water content up to 4.5% (by volume), the simulations indicate that SWE can be estimated with an error of ± 5% or less if (a) the noise (measurement errors) in the resulting amplitude has a standard deviation less than 15% and(b) the noise in two-way travel time has a standard deviation less than 0.075 ns (22.5% and 0.15 ns for a snowpack less than 1.3 m deep).

National Category
Geochemistry Embedded Systems
Research subject
Applied Geology; Embedded System
Identifiers
urn:nbn:se:ltu:diva-10124 (URN)10.1016/j.coldregions.2012.01.006 (DOI)000302507300002 ()2-s2.0-84857912531 (Scopus ID)8de777d9-2930-4f95-bced-6d71c18c0d0b (Local ID)8de777d9-2930-4f95-bced-6d71c18c0d0b (Archive number)8de777d9-2930-4f95-bced-6d71c18c0d0b (OAI)
Note
Validerad; 2012; 20120126 (ysko)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Sundström, N. & Gustafsson, D. (2012). Testing the accuracy of electrical permittivity estimation from angle-dependent reflectivity with ground penetrating radar (ed.). Paper presented at . Luleå: Luleå tekniska universitet
Open this publication in new window or tab >>Testing the accuracy of electrical permittivity estimation from angle-dependent reflectivity with ground penetrating radar
2012 (English)Report (Other academic)
Place, publisher, year, edition, pages
Luleå: Luleå tekniska universitet, 2012. p. 17
Series
Research report / Luleå University of Technology, ISSN 1402-1528
National Category
Geochemistry
Research subject
Applied Geology
Identifiers
urn:nbn:se:ltu:diva-25208 (URN)e3405d52-2324-4c76-ba95-0950374058d8 (Local ID)978-91-7439-482-5 (ISBN)e3405d52-2324-4c76-ba95-0950374058d8 (Archive number)e3405d52-2324-4c76-ba95-0950374058d8 (OAI)
Note
Godkänd; 2012; 20120921 (nilgra)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2017-11-24Bibliographically approved
Villain, L., sundström, N., Perttu, N., Alakangas, L. & Öhlander, B. (2011). Geophysical investigations to identify groundwater pathways at a small open-pit copper mine reclaimed by backfilling and sealing (ed.). In: (Ed.), Thomas R. Rüde; Antje Freund; Christian Wolkersdorfer (Ed.), Mine Water – Managing the Challenges: Proceedings of the International Mine Water Association (IMWA) Congress 2011, RWTH Aachen, Germany, 4 — 11 September 2011. Paper presented at International Mine Water Association Congress : Mine Water - Managing the Challenges : 04/09/2011 - 11/09/2011 (pp. 71-76). Aachen, Germany: RWTH Aachen University, Institute of Hydrogeology
Open this publication in new window or tab >>Geophysical investigations to identify groundwater pathways at a small open-pit copper mine reclaimed by backfilling and sealing
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2011 (English)In: Mine Water – Managing the Challenges: Proceedings of the International Mine Water Association (IMWA) Congress 2011, RWTH Aachen, Germany, 4 — 11 September 2011 / [ed] Thomas R. Rüde; Antje Freund; Christian Wolkersdorfer, Aachen, Germany: RWTH Aachen University, Institute of Hydrogeology , 2011, p. 71-76Conference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
Aachen, Germany: RWTH Aachen University, Institute of Hydrogeology, 2011
Keywords
Earth sciences - Exogenous eart sciences, Ground Penetrating Radar, DC resistivity, groundwater pathways, open pit, backfilling and sealing, Geovetenskap - Exogen geovetenskap
National Category
Geochemistry Geophysics
Research subject
Applied Geology; Applied Geophysics
Identifiers
urn:nbn:se:ltu:diva-30612 (URN)4797cc22-88bd-444f-8e03-ce20c4c7c06d (Local ID)978-3-00-035543-1 (ISBN)4797cc22-88bd-444f-8e03-ce20c4c7c06d (Archive number)4797cc22-88bd-444f-8e03-ce20c4c7c06d (OAI)
Conference
International Mine Water Association Congress : Mine Water - Managing the Challenges : 04/09/2011 - 11/09/2011
Note
Godkänd; 2011; 20120926 (nilgra)Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2019-11-22Bibliographically approved
Granlund, N., Lundberg, A. & Gustafson, D. (2010). Laboratory study of the influence of salinity on the relationship between electrical conductivity and wetness of snow (ed.). Paper presented at . Hydrological Processes, 24(14), 1981-1984
Open this publication in new window or tab >>Laboratory study of the influence of salinity on the relationship between electrical conductivity and wetness of snow
2010 (English)In: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 24, no 14, p. 1981-1984Article in journal (Refereed) Published
Abstract [en]

Snow water equivalent of a snowpack can be estimated using ground-penetrating radar from the radar wave two-way travel time. However, such estimates often have low accuracy when the snowpack contains liquid water. If snow wetness is known, it is possible to take it into account in the estimates; it is therefore desirable to be able to determine snow wetness from already available radar data. Our approach is based on using radar wave attenuation, and it requires that the relationship between electrical conductivity and wetness of snow should be known. This relationship has been tentatively established in previous laboratory experiments, but only for a specific liquid water salinity and radar frequency. This article presents the results of new laboratory experiments conducted to investigate if and how this relationship is influenced by salinity. In each experiment, a certain amount of snow was melted and a known amount of salt (different for different experiments) was added to the water. Water salinity was measured, and the water was added step-wise to a one-meter thick snowpack, with radar measurements taken between additions of water. Our experiments have confirmed the earlier established linear relationship between electrical conductivity and wetness of snow, and they allow us to suggest that the influence of liquid water salinity on electrical conductivity is negligible when compared to the influence of liquid water content in snow

National Category
Geochemistry
Research subject
Applied Geology
Identifiers
urn:nbn:se:ltu:diva-12395 (URN)10.1002/hyp.7659 (DOI)000280140700006 ()2-s2.0-77954363684 (Scopus ID)b8835030-948c-11df-8806-000ea68e967b (Local ID)b8835030-948c-11df-8806-000ea68e967b (Archive number)b8835030-948c-11df-8806-000ea68e967b (OAI)
Note
Validerad; 2010; 20100721 (andbra)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Lundberg, A., Granlund, N. & Gustafsson, D. (2010). Towards automated 'ground truth' snow measurements: a review of operational and new measurement methods for Sweden, Norway, and Finland (ed.). Paper presented at . Hydrological Processes, 24(14), 1955-1970
Open this publication in new window or tab >>Towards automated 'ground truth' snow measurements: a review of operational and new measurement methods for Sweden, Norway, and Finland
2010 (English)In: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 24, no 14, p. 1955-1970Article in journal (Refereed) Published
Abstract [en]

Manual snow measurements are becoming increasingly expensive and climate-change-imposed snow alterations are affecting run-off and frost patterns; snow observations are included in run-off modelling, making reliable snow observations of utmost importance. Multiple new and modified ground-based techniques for monitoring snow depth, density, snow water equivalent (SWE), wetness, and layering have been tested over the last decade, justifying a review of such methods. Techniques based on snow mass, electrical properties, attenuation of radioactivity, and other miscellaneous properties are reviewed. The following sensors seem suitable for registration of temporal variations: ultrasonic (depth) and terrestrial laser scanning (depth), several snow pillows at the same location (SWE), Cold Regions Research and Engineering Laboratory/Natural Resources Conservation Service weighing sensor (SWE), Snowpower (depth, density, SWE, and wetness), active and passive (cosmic) γ-ray attenuation (SWE), and adjusted time domain reflectometry probes (density and wetness). Ground-penetrating radar (GPR) is, depending on the design and operation modes, suitable for different purposes; when arrays of antennas are pulled by a snowmobile, the technique is suitable for monitoring of spatial variations in depth, density, and SWE for dry snow. Techniques are under development, which will hopefully improve the accuracy for wet snow measurements. Frequency-modulated continuous wave GPRs seem fit for measurement of snow layering. Some suggested techniques are not operational yet. Copyright

National Category
Geochemistry
Research subject
Applied Geology
Identifiers
urn:nbn:se:ltu:diva-6338 (URN)10.1002/hyp.7658 (DOI)000280140700004 ()2-s2.0-77954377479 (Scopus ID)491501d0-948c-11df-8806-000ea68e967b (Local ID)491501d0-948c-11df-8806-000ea68e967b (Archive number)491501d0-948c-11df-8806-000ea68e967b (OAI)
Note
Validerad; 2010; Bibliografisk uppgift: 66th Annual Eastern Snow Conference Niagara on the Lake, CANADA, JUN 09-11, 2009; 20100721 (andbra)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
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