{"title":"Constraining regional glacier reconstructions using past ice thickness of deglaciating areas – a case study in the European Alps","authors":"C. Sommer, J. Fürst, M. Huss, M. Braun","doi":"10.5194/tc-17-2285-2023","DOIUrl":null,"url":null,"abstract":"Abstract. In order to assess future glacier evolution and\nmeltwater runoff, accurate knowledge on the volume and the ice thickness\ndistribution of glaciers is crucial. However, in situ observations of\nglacier thickness are sparse in many regions worldwide due to the difficulty\nof undertaking field surveys. This lack of in situ measurements can be\npartially overcome by remote-sensing information. Multi-temporal and\ncontemporaneous data on glacier extent and surface elevation provide past\ninformation on ice thickness for retreating glaciers in the newly\ndeglacierized regions. However, these observations are concentrated near the\nglacier snouts, which is disadvantageous because it is known to introduce\nbiases in ice thickness reconstruction approaches. Here, we show a strategy\nto overcome this generic limitation of so-called retreat thickness\nobservations by applying an empirical relationship between the ice viscosity\nat locations with in situ observations and observations from digital elevation model (DEM) differencing at the glacier margins. Various datasets from the European\nAlps are combined to model the ice thickness distribution of Alpine glaciers\nfor two time steps (1970 and 2003) based on the observed thickness in regions\nuncovered from ice during the study period. Our results show that the\naverage ice thickness would be substantially underestimated (∼ 40 %) when relying solely on thickness observations from previously\nglacierized areas. Thus, a transferable topography-based viscosity scaling\nis developed to correct the modelled ice thickness distribution. It is shown\nthat the presented approach is able to reproduce region-wide glacier\nvolumes, although larger uncertainties remain at a local scale, and thus might\nrepresent a powerful tool for application in regions with sparse\nobservations.\n","PeriodicalId":56315,"journal":{"name":"Cryosphere","volume":null,"pages":null},"PeriodicalIF":4.4000,"publicationDate":"2023-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"1","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Cryosphere","FirstCategoryId":"89","ListUrlMain":"https://doi.org/10.5194/tc-17-2285-2023","RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"GEOGRAPHY, PHYSICAL","Score":null,"Total":0}
引用次数: 1
Abstract
Abstract. In order to assess future glacier evolution and
meltwater runoff, accurate knowledge on the volume and the ice thickness
distribution of glaciers is crucial. However, in situ observations of
glacier thickness are sparse in many regions worldwide due to the difficulty
of undertaking field surveys. This lack of in situ measurements can be
partially overcome by remote-sensing information. Multi-temporal and
contemporaneous data on glacier extent and surface elevation provide past
information on ice thickness for retreating glaciers in the newly
deglacierized regions. However, these observations are concentrated near the
glacier snouts, which is disadvantageous because it is known to introduce
biases in ice thickness reconstruction approaches. Here, we show a strategy
to overcome this generic limitation of so-called retreat thickness
observations by applying an empirical relationship between the ice viscosity
at locations with in situ observations and observations from digital elevation model (DEM) differencing at the glacier margins. Various datasets from the European
Alps are combined to model the ice thickness distribution of Alpine glaciers
for two time steps (1970 and 2003) based on the observed thickness in regions
uncovered from ice during the study period. Our results show that the
average ice thickness would be substantially underestimated (∼ 40 %) when relying solely on thickness observations from previously
glacierized areas. Thus, a transferable topography-based viscosity scaling
is developed to correct the modelled ice thickness distribution. It is shown
that the presented approach is able to reproduce region-wide glacier
volumes, although larger uncertainties remain at a local scale, and thus might
represent a powerful tool for application in regions with sparse
observations.
期刊介绍:
The Cryosphere (TC) is a not-for-profit international scientific journal dedicated to the publication and discussion of research articles, short communications, and review papers on all aspects of frozen water and ground on Earth and on other planetary bodies.
The main subject areas are the following:
ice sheets and glaciers;
planetary ice bodies;
permafrost and seasonally frozen ground;
seasonal snow cover;
sea ice;
river and lake ice;
remote sensing, numerical modelling, in situ and laboratory studies of the above and including studies of the interaction of the cryosphere with the rest of the climate system.