The glaciological and the geodetic approaches both have inherent uncertainties (e.g.
Tidewater physicians multispec full#
Full details on both methods are available in the Glossary of Glacier Mass Balance (Cogley and others, Reference Cogley2011). Increasingly, glacier and ice-cap mass balance is being assessed using the geodetic approach involving measurement of surface elevation and therefore volume change. Glacier and ice-cap mass balance has traditionally been monitored using the glaciological method based on point stake, pit and probe measurements. Glacier and ice-cap mass balance is the key variable that must be monitored because it is changing mass balance that affects global sea levels and regional and local river regimes. Radić and Hock, Reference Radić and Hock2011 Marzeion and others, Reference Marzeion, Jarosch and Hofer2012 Chen and others, Reference Chen, Wilson and Tapley2013) and the effects on regional and local hydrology, including flooding (Dahlke and others, Reference Dahlke, Lyon, Stedinger, Rosqvist and Jansson2012), river biodiversity (Jacobsen and others, Reference Jacobsen, Milner, Brown and Dangles2012) and water supply to large populations (Hopkinson and Demuth, Reference Hopkinson and Demuth2006 Björnsson and Pálsson, Reference Björnsson and Pálsson2008 Baraer and others, Reference Baraer2011 Barry, Reference Barry2011 Bolch and others, Reference Bolch2012). Oerlemans, Reference Oerlemans1994), the implications for global sea-level rise (e.g.
Monitoring their changes is key to understanding the impacts of global and regional climate change (e.g. a −1) from 1993 to 2009, to the global oceans (IPCC, Reference Stocker2013). Glaciers and ice caps are important components of the world's hydrological cycle. Nevertheless, the study was ultimately able to investigate dynamic surge behaviour in the absence of in situ measurements during the surge. While mass balances are largely in good agreement, discrepancies between modelled and geodetic mass balance may be explained by inaccurate estimates of precipitation, saturated adiabatic lapse rate or degree-day factors. mass transfer from the accumulation area to the ablation area followed by recharge of the source area), we see peripheral areas where the surge impinged upon an adjacent ridge and subsequently retreated. In addition to observing the extent of traditional surge behaviour (i.e. Maps of emergence and submergence velocity successfully highlight the 1998 surge and subsequent quiescence of one of Langjökull's outlets by visualizing both source and sink areas. Thus, we not only compare the geodetic, modelled and glaciological mass balances, but also map spatial variations in glacier dynamics. We use DEMs, in situ stake measurements, regional reanalyses and a mass-balance model to calculate the vertical ice velocity. By differencing elevation change with surface mass balance, we estimate the contribution of ice dynamics to elevation change. Here, we study Iceland's second largest ice cap, Langjökull, which has both surge- and non-surge-type outlets. Glaciers and ice caps around the world are changing quickly, with surge-type behaviour superimposed upon climatic forcing.
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