Deriving mass balance and calving variations from reanalysis data and sparse observations, Glaciar San Rafael, northern Patagonia, 1950–2005

Koppes, Michèle; Conway, H.; Rasmussen, L. A.; Chernos, M.

doi:10.5194/tc-5-791-2011

Cited by 26 publications

(38 citation statements)

References 48 publications

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“…For the validation of the modeled climate data, several sources of measured meteorological data were available (here, the term‘modeled climate data’ is used to refer to the climate data that were used as input data for the mass balance modeling after the statistical downscaling detailed in section 2.1 and the subgrid parametrization explained in section 2.2): the Chilean Weather Service (DMC): Continuous data of temperature and precipitation with long‐time records although there are problems at some stations in the 2000s, the Chilean Water Directory (DGA): Precipitation data of mixed quality and record length, other sources: Including the Chilean Navy, the Argentine Weather Service and the measurements of Koppes et al [].…”

Section: Results and Validation Of The Downscalingmentioning

confidence: 99%

“…This can be explained by the different time span that was analyzed by Escobar et al [] (data from the 1960s to the 1980s) and the increase of accumulation that we observe in the 1990s in our modeled data (Figure ). An increase of accumulation in the 1990s and 2000s as compared to the second half of the 1970s and the 1980s has also been found by Koppes et al [] on the San Rafael Glacier.…”

Section: Discussionmentioning

confidence: 99%

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Modeling past and future surface mass balance of the Northern Patagonia Icefield

et al. 2013

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Glaciers are strongly retreating and thinning in Patagonia. We present new inferences about the climatic situation and the surface mass balance on the Northern Patagonia Icefield in the past and the future using a combined modeling approach. The simulations are driven by NCAR/NCEP Reanalysis and ECHAM5 data, which were physically downscaled using the Weather Research and Forecasting regional climate model and simple sub‐grid parameterizations. The surface mass balance model was calibrated with geodetic mass balance data of three large non‐calving glaciers and with point mass balance measurements. An increase of accumulation on the Northern Patagonia Icefield was detected from 1990–2011 as compared to 1975–1990. Using geodetic mass balance data, calving losses from the Northern Patagonia Icefield could be inferred, which doubled in 2000–2009 as compared to 1975–2000. The 21st century projection of future mass balance of the Northern Patagonia Icefield shows a strong increase in ablation from 2050 and a reduction of solid precipitation from 2080, both due to higher temperatures. The total mass loss in the 21st century is estimated to be 592±50 Gt with strongly increasing rates towards the end of the century. The prediction of the future mass balance of the Northern Patagonia Icefield includes several additional sources of errors due to uncertainties in the prediction of future climate and due to possible variations in ice dynamics, which might modify the geometry of the icefield and change the rate of mass losses due to calving.

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Section: Results and Validation Of The Downscalingmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Modeling past and future surface mass balance of the Northern Patagonia Icefield

et al. 2013

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“…Among other results, the paper reported higher amounts of ablation on the glacier tongues along the eastern side of Patagonia, and accumulation in excess of 20 mwe on the highest sections of the icefield. They also found that 50%–80% of calving fluxes were due to dynamics in the San Rafael glacier, broadly agreeing to previous studies [ Koppes et al ., ]. Schaefer et al .…”

Section: Modeling Andean Glaciers and Climate Changes At Specific Locmentioning

confidence: 99%

“…Schaefer et al [2013Schaefer et al [ , 2015 NPI and SPI Not used 6.5 Lapse rate used only for redistribution of temperature inside each 5 km gird-cell. Koppes et al [2011] San Rafael glacier 3.9 (snow) 6.6 (ice) After reviewing global approaches, we examined modeling studies incorporating all Andean glaciers as a regional entity. These studies are important because they allow adequate identification of heterogeneous glacier responses to changes in climate.…”

Section: Findings and Open Challengesmentioning

confidence: 99%

Modeling modern glacier response to climate changes along the Andes Cordillera: A multiscale review

Fernández

Mark

2016

J Adv Model Earth Syst

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Here we review the literature preferentially concerned with modern glacier-climate modeling along the Andes. We find a diverse range of modeling approaches, from empirical/statistical models to relatively complex energy balance procedures. We analyzed these models at three different spatial scales. First, we review global approaches that have included the Andes. Second, we depict and analyze modeling exercises aimed at studying Andean glaciers as a whole. Our revision shows only two studies dealing with glacier modeling at this continental scale. We contend that this regional approach is increasingly necessary because it allows for connecting the ''average-out'' tendency of global studies to local observations or models, in order to comprehend scales of variability and heterogeneity. Third, we revise small-scale modeling, finding that the overwhelming number of studies have targeted glaciers in Patagonia. We also find that most studies use temperature-index models and that energy balance models are still not widely utilized. However, there is no clear spatial pattern of model complexity. We conclude with a discussion of both the limitations of certain approaches, as for example the use of short calibration periods for long-term modeling, and also the opportunities for improved understanding afforded by new methods and techniques, such as climatic downscaling. We also propose ways to future developments, in which observations and models can be combined to improve current understanding of volumetric glacier changes and their climate causes.

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“…Flow velocity at Bridge Glacier is moderate due to gentle gradients in the lower reaches of the glacier, as well as a relatively narrow cross-sectional area. A gentle surface slope reduces the gravitational stresses, while narrow valley sidewalls constrict glacier flow by providing substantial lateral drag (Benn et al, 2007a;Koppes et al, 2011), both of which limit flow speeds. Near-terminus flow speeds at Bridge Glacier are 1 to 2 orders of magnitude smaller than those observed at larger tidewater calving glaciers in Patagonia and Alaska (Rivera et al, 2012;Koppes et al, 2011;Meier and Post, 1987;Motyka et al, 2003) and reflect a smaller mass turnover, similar to lake-terminating glaciers Mendenhall and Tasman (Boyce et al, 2007;Dykes et al, 2011).…”

Section: Controls On Calvingmentioning

confidence: 99%

Ablation from calving and surface melt at lake-terminating Bridge Glacier, British Columbia, 1984–2013

Chernos¹,

Koppes²,

Moore³

2016

The Cryosphere

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Abstract. Bridge Glacier is a lake-calving glacier in the Coast Mountains of British Columbia and has retreated over 3.55 km since 1972. The majority of this retreat has occurred since 1991. This retreat is substantially greater than what has been inferred from regional climate indices, suggesting that it has been driven primarily by calving as the glacier retreated across an overdeepened basin. In order to better understand the primary drivers of ablation, surface melt (below the equilibrium line altitude, ELA) and calving were quantified during the 2013 melt season using a distributed energy balance model (DEBM) and time-lapse imagery. Calving, estimated using areal change, velocity measurements, and assuming flotation were responsible for 23 % of the glacier's ablation below the ELA during the 2013 melt season and were limited by modest flow speeds and a small terminus cross-section. Calving and surface melt estimates from 1984 to 2013 suggest that calving was consistently a smaller contributor of ablation. Although calving was estimated to be responsible for up to 49 % of the glacier's ablation for individual seasons, averaged over multiple summers it accounted between 10 and 25 %. Calving was enhanced primarily by buoyancy and water depths, and fluxes were greatest between 2005 and 2010 as the glacier retreated over the deepest part of Bridge Lake. The recent rapid rate of calving is part of a transient stage in the glacier's retreat and is expected to diminish within 10 years as the terminus recedes into shallower water at the proximal end of the lake. These findings are in line with observations from other lake-calving glacier studies across the globe and suggest a common large-scale pattern in calving-induced retreat in lake-terminating alpine glaciers. Despite enhancing glacial retreat, calving remains a relatively small component of ablation and is expected to decrease in importance in the future. Hence, surface melt remains the primary driver of ablation at Bridge Glacier and thus projections of future retreat should be more closely tied to climate.

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Deriving mass balance and calving variations from reanalysis data and sparse observations, Glaciar San Rafael, northern Patagonia, 1950–2005

Cited by 26 publications

References 48 publications

Modeling past and future surface mass balance of the Northern Patagonia Icefield

Modeling past and future surface mass balance of the Northern Patagonia Icefield

Modeling modern glacier response to climate changes along the Andes Cordillera: A multiscale review

Ablation from calving and surface melt at lake-terminating Bridge Glacier, British Columbia, 1984–2013

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