Change search
ReferencesLink to record
Permanent link

Direct link
Time series analysis of ground frost conditionsat Abisko, sub-Arctic Sweden, 1985-2010
Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
2012 (English)Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesisAlternative title
Tidserieanalys av marktemperatur i Abisko,Norra Sverige, under perioden 1985-2010 (Swedish)
Abstract [en]

Observed climatic change may result in modification of the ground thermal regime.The causes of shallow ground temperature variability, however, are not well documented.This thesis reports ground temperatures from Absiko Scientific Research Station, measured ata site currently not underlain by permafrost to illustrate the response of shallow groundtemperatures to changes in climatic parameters. Both air temperature and precipitationincreased at Abisko from 1985-2010. The strongest increase in air temperature occurred inwinter, whereas the precipitation increased mainly during the summer months. There was asignificant trend towards later onset of permanent snow cover, as well as a steadily earlierdisappearance of permanent snow cover in spring, resulting in reduced snow cover duration.Also the snow thickness decreased at Abisko during the study period. The ground experiencedapproximately five months of frost at 5 and 20 cm depth and approx. four, respectively two,months at 50 and 100 cm depth. Annual ground temperatures were found to be increasingfrom 1985-2010 with approx. 0.31 °C, 0.64 °C, 0.82 °C and 0.94 °C at 5, 20, 50, respectively100 cm depth from the surface. The duration and intensity of the seasonal frost cycles weredecreasing, which would reflect the increasing ground temperatures. Changes in short-termfrost cycles were not found to be significant. The changes in mean annual and winter groundtemperature were significantly correlated to the changes in mean annual and winter airtemperature, but surprisingly not to the changes in snow cover. However, seasonally theincreasing trend of ground temperatures was found in autumn and winter, whereas thesummer ground temperatures were decreasing. The cooling of ground temperature in summerat increasing air temperatures may be explained by increased precipitation totals and henceincreased soil moisture due to the so called soil-moisture feedback. From this fact, it can bededuced that the changes in air temperature alone cannot explain all variances in groundtemperatures. However, the results of the study may suggest that in sub-Arctic Swedenchanges in air temperatures may be used as indicator for changes in shallow groundtemperatures.

Abstract [sv]

perioden 1985-2010 ökade både lufttemperatur och nederbörd i Abiskoområdet. Denstörsta ökningen av lufttemperatur skedde under vinterhalvåret medan nederbörden ökademest under sommarhalvåret. En signifikant förkortning i längden av vintersnötäckets existensunder året observerades under studieperioden. Reduceringen av vintesnötäcket skedde genomatt den första snön kom senare och bortsmältningen på våren skedde tidigare. Snötäcketstjocklek minskade också under studieperioden. Marktemperaturmätningarna visar frysgraderpå 5 och 20 cm djup fem månader och fyra respektive två månader på 50 och 100cm djup.Den årliga medeltemperaturen i marken ökade under perioden med 0.31 °C, 0.64 °C, 0.82 °Coch 0.94 °C vid 5, 20, 50 och 100 cm djup. Den årliga längden och intensiteten avfrysförhållandena i marken minskade vilket förmodligen är en konsekvens av de ökandemarktemperaturerna. Ingen trend i förekomsten av kortare svängningar i frysförhållandenakunde observeras. Förändringarna i årsmedetemperaturen i marken är signifikant korrelerademed förändringen i den årliga medeltemperaturen och vintertemperaturen i luften, men ingenkorrelation mellan marktemperaturen och förändringar i snötäckets tjocklek och längdobserverades. Studien avslöjade också att temperaturen i marken ökade under vinternhalvåretmedan den sjönk under sommaren. Avkylningen av marken under sommaren kan förklaras avökad nederbörd under sommaren som ger högre markfuktighet som ger en kylande effektgenom den så kallade jord-fuktighets återkopplingsmekanismen (soil-moisture feedback).Från detta kan vi dra slutsatsen att förändringar i enbart lufttemperatur inte kan förklara denhela observerade variansen av marktemperatur men att lufttemperaturen har en domineranderoll. Resultaten från denna studie indikerar således att förändringar lufttemperatur kananvändas som en indikator på marktemperaturförändringar i Abisko området.

Place, publisher, year, edition, pages
2012. , 86 p.
Series
Examensarbete vid Institutionen för geovetenskaper, ISSN 1650-6553 ; 233
Keyword [en]
marktemperatur, subarktiska Sverige, Abisko forskningstation, frost cykler, snötäcke, lufttemperatur, Ground temperatures, subarctic Sweden, Abisko research station, frost cycle, snow cover, air temperature
National Category
Physical Geography
Identifiers
URN: urn:nbn:se:uu:diva-301910OAI: oai:DiVA.org:uu-301910DiVA: diva2:955616
Educational program
Master Programme in Earth Science
Presentation
, Uppsala (English)
Supervisors
Examiners
Available from: 2016-08-26 Created: 2016-08-25 Last updated: 2016-08-26Bibliographically approved

Open Access in DiVA

fulltext(1673 kB)9 downloads
File information
File name FULLTEXT01.pdfFile size 1673 kBChecksum SHA-512
a4b77b2dc85d76cdcdd3472e3b55b4721d98c501998733633f0a477223c5a94a30eb59faed1f33c7d289d4a260e880b01d54a6e234ee3762e61d9f52ba5c05e6
Type fulltextMimetype application/pdf

By organisation
Department of Earth Sciences
Physical Geography

Search outside of DiVA

GoogleGoogle Scholar
Total: 9 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Total: 21 hits
ReferencesLink to record
Permanent link

Direct link