In this study, near-surface stratigraphy was measured in snowpits and shallow ice cores across all snow facies of a High Arctic ice cap in order to examine variability at different spatial (metre to > kilometre) and temporal (seasonal and inter-annual) resolutions. Additionally, dye tracing was employed to investigate processes controlling meltwater percolation and refreezing. <i>Pre-melt </i>snowpack densities were low at all spatial scales, whilst different inter-annual <i>post-melt </i>stratigraphies at > 1 km scales showed high variability. This is attributed to different extrinsic conditions generating dissimilar surface melt and percolation regimes. Variability at small spatial scales is related to the intrinsic stratigraphic properties of the pre-melt snowpack. A snowpack model was applied to a single point at 1400 m.a.s.l. over the course of two summers, to assess its simulation of the observed dissimilar annular density evolution. The model performed poorly due to an inability to simulate ice layers in the near surface snowpack, which are the main property controlling variability. Modelled thermal regimes and densification were also unrealistic and found to be highly sensitive to albedo. The model may be improved by incorporating diurnal Albedo variations; known to be a strong control on surface melting at high latitudes. Overall, combined <i>in-situ</i> measurements and modelling results show that the relationship between near-surface densification and air temperature is not straightforward. Extrapolation of generalised trends between the two, across large spatial and temporal scales, should be avoided since spatial and temporal variability can be high. This should be considered when up-scaled modelling of surface mass balance and firm densification is utilised during interpretations of SRA-based estimates of elevation change across large ice masses over several years.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:509226 |
| Date | January 2008 |
| Creators | Bell, Christina |
| Publisher | University of Aberdeen |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=53367 |
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