scholarly journals High-resolution modeling of glacier mass balance and surface runoff in western Norway driven by bias-corrected climate forcing

2021 ◽  
Author(s):  
Yongmei Gong ◽  
Irina Rogozhina
Keyword(s):  
Mass Balance ◽  
Surface Runoff ◽  
Unit Area ◽  
Climate Forcing ◽  
Glacier Mass Balance ◽  
Surface Mass Balance ◽  
Drainage Basins ◽  
Climatic Forcing ◽  
Surface Mass ◽  
Western Norway

Abstract. Western Norway hosts many glacierized drainage basins with complex terrain and local climate. These drainage basins face challenges related to long-term planning of hydropower production and flood risk mitigation under global warming. To enable forward vision of such efforts, bias-corrected outputs from state-of-the-art regional climate models and reanalysis provide climatic forcing for impact simulations. We utilize a distributed, process-based snow evolution model with a daily temporal and 100 m × 100 m spatial resolution to investigate the applicability of different bias-corrected climate forcing data for multidecadal reconstructions of glacier surface mass balance and surface runoff regimes in western Norway. These simulations are driven by climatic forcing from the bias-corrected NORA10 hindcast in 2000–2014, which has been produced specifically for western Norway and treated as a benchmark dataset, as well as ten bias-corrected and uncorrected CORDEX outputs under different Representative Concentration Pathway scenarios in 2000–2020. Downscaled drainage basin-wide air temperature, precipitation and glacier-wide surface mass balance are then validated against observations. The variables mentioned above produced by the benchmark simulation match available observations well. The mean annual surface mass balance of glaciers in most glacierized basins is negative in 2001–2014, and its evolution is mainly correlated with trends in annual snowfall. There is a general negative west to east gradient in seasonal and annual unit area runoff, which peaks between 2005 and 2008 in most drainage basins. Snow meltwater is the largest contributor to both seasonal and annual runoff in all drainage basins except for two of the westernmost ones. Drainage basins with denser glacier coverage turn out to have a later peak runoff discharge date. The correction applied to the CORDEX forcing reversed the cold bias in the original datasets, while the agreement between bias-corrected and observed precipitation rates varies strongly from basin to basin. As a result, simulations driven by bias-corrected CORDEX datasets produce lower annual surface mass balance in the most and least glacierized drainage basins, i.e., Basin 1 and 17, respectively. They all produce more unit area runoff in Basin 1 and less in Basin 17 both seasonally and annually, with only a few exceptions. We conclude that the identified errors will likely be inherited by the results of the future projections, casting doubts on the applicability of bias-corrected CORDEX forcing to directly drive local scale projections and the modeled outputs in developing climate change adaptation strategies.

scholarly journals Long-range terrestrial laser scanning measurements of annual and intra-annual mass balances for Urumqi Glacier No. 1, eastern Tien Shan, China

2019 ◽  
Vol 13 (9) ◽  
pp. 2361-2383 ◽  
Author(s):  
Chunhai Xu ◽  
Zhongqin Li ◽  
Huilin Li ◽  
Feiteng Wang ◽  
Ping Zhou
Keyword(s):  
Mass Balance ◽  
Long Range ◽  
Tien Shan ◽  
Glacier Mass Balance ◽  
Surface Mass Balance ◽  
Mass Balances ◽  
Surface Mass ◽  
Mass Conversion ◽  
Geodetic Mass Balance

Abstract. The direct glaciological method provides in situ observations of annual or seasonal surface mass balance, but can only be implemented through a succession of intensive in situ measurements of field networks of stakes and snow pits. This has contributed to glacier surface mass-balance measurements being sparse and often discontinuous in the Tien Shan. Nevertheless, long-term glacier mass-balance measurements are the basis for understanding climate–glacier interactions and projecting future water availability for glacierized catchments in the Tien Shan. Riegl VZ®-6000 long-range terrestrial laser scanner (TLS), typically using class 3B laser beams, is exceptionally well suited for repeated glacier mapping, and thus determination of annual and seasonal geodetic mass balance. This paper introduces the applied TLS for monitoring summer and annual surface elevation and geodetic mass changes of Urumqi Glacier No. 1 as well as delineating accurate glacier boundaries for 2 consecutive mass-balance years (2015–2017), and discusses the potential of such technology in glaciological applications. Three-dimensional changes of ice and firn–snow bodies and the corresponding densities were considered for the volume-to-mass conversion. The glacier showed pronounced thinning and mass loss for the four investigated periods; glacier-wide geodetic mass balance in the mass-balance year 2015–2016 was slightly more negative than in 2016–2017. Statistical comparison shows that agreement between the glaciological and geodetic mass balances can be considered satisfactory, indicating that the TLS system yields accurate results and has the potential to monitor remote and inaccessible glacier areas where no glaciological measurements are available as the vertical velocity component of the glacier is negligible. For wide applications of the TLS in glaciology, we should use stable scan positions and in-situ-measured densities of snow–firn to establish volume-to-mass conversion.

scholarly journals Measurements and modeling of snow albedo at Alerce Glacier, Argentina: effects of volcanic ash, snow grain size, and cloudiness

2020 ◽  
Vol 14 (12) ◽  
pp. 4581-4601
Author(s):  
Julián Gelman Constantin ◽  
Lucas Ruiz ◽  
Gustavo Villarosa ◽  
Valeria Outes ◽  
Facundo N. Bajano ◽  
...  
Keyword(s):  
Grain Size ◽  
Mass Balance ◽  
Volcanic Ash ◽  
Impurity Content ◽  
Field Measurements ◽  
Glacier Mass Balance ◽  
Surface Mass Balance ◽  
Surface Mass ◽  
Snow Albedo ◽  
The Impact

Abstract. The impact of volcanic ash on seasonal snow and glacier mass balance has been much less studied than that of carbonaceous particles and mineral dust. We present here the first field measurements on the Argentinian Andes, combined with snow albedo and glacier mass balance modeling. Measured impurity content (1.1 mg kg−1 to 30 000 mg kg−1) varied abruptly in snow pits and snow and firn cores, due to high surface enrichment during the ablation season and possibly local or regional wind-driven resuspension and redeposition of dust and volcanic ash. In addition, we observed high spatial heterogeneity, due to glacier topography and the prevailing wind direction. Microscopic characterization showed that the major component was ash from recent Calbuco (2015) and Cordón Caulle (2011) volcanic eruptions, with a minor presence of mineral dust and black carbon. We also found a wide range of measured snow albedo (0.26 to 0.81), which reflected mainly the impurity content and the snow and firn grain size (due to aging). We updated the SNow, ICe, and Aerosol Radiation (SNICAR) albedo model to account for the effect of cloudiness on incident radiation spectra, improving the match of modeled and measured values. We also ran sensitivity studies considering the uncertainty in the main measured parameters (impurity content and composition, snow grain size, layer thickness, etc.) to identify the field measurements that should be improved to facilitate the validation of the snow albedo model. Finally, we studied the impact of these albedo reductions on Alerce Glacier using a spatially distributed surface mass balance model. We found a large impact of albedo changes on glacier mass balance, and we estimated that the effect of observed ash concentrations can be as high as a 1.25 m water equivalent decrease in the annual surface mass balance (due to a 34 % increase in the melt during the ablation season).

scholarly journals The contrasting response of outlet glaciers to interior and ocean forcing

2020 ◽  
Author(s):  
John Erich Christian ◽  
Alexander Robel ◽  
Cristian Proistosescu ◽  
Gerard Roe ◽  
Michelle Koutnik ◽  
...  
Keyword(s):  
Mass Balance ◽  
Fast Response ◽  
Climate Forcing ◽  
Reduced Model ◽  
Surface Mass Balance ◽  
Anthropogenic Influences ◽  
Outlet Glacier ◽  
Surface Mass ◽  
Oceanic Forcing ◽  
The Impact

Abstract. The dynamics of marine-terminating outlet glaciers are of fundamental interest in glaciology, and affect mass loss from ice sheets in a warming climate. In this study, we analyze the response of outlet glaciers to different sources of climate forcing. We find that outlet glaciers have a characteristically different transient response to surface-mass-balance forcing applied over the interior than to oceanic forcing applied at the grounding line. A recently developed reduced model represents outlet glacier dynamics via two widely-separated response timescales: a fast response associated with grounding-zone dynamics, and a slow response of interior ice. The reduced model is shown to emulate the behavior of a more complex numerical model of ice flow. Together, these models demonstrate that ocean forcing first engages the fast, local response, and then the slow adjustment of interior ice, whereas surface-mass-balance forcing is dominated by the slow interior adjustment. We also demonstrate the importance of the timescales of stochastic forcing for assessing the natural variability of outlet glaciers, highlighting that decadal persistence in ocean variability can affect the behavior of outlet glaciers on centennial and longer timescales. Finally, we show that these transient responses have important implications for: attributing observed glacier changes to natural or anthropogenic influences; the future change already committed by past forcing; and the impact of past climate changes on the preindustrial glacier state, against which current and future anthropogenic influences are assessed.

scholarly journals Climate and surface mass balance of Mocho Glacier, Chilean Lake District, 40°S

2016 ◽  
Vol 63 (238) ◽  
pp. 218-228 ◽  
Author(s):  
MARIUS SCHAEFER ◽  
JOSE LUIS RODRIGUEZ ◽  
MATTHIAS SCHEITER ◽  
GINO CASASSA
Keyword(s):  
Mass Balance ◽  
Mean Annual Precipitation ◽  
Mean Annual Temperature ◽  
Glacier Mass Balance ◽  
Surface Mass Balance ◽  
Climate Data ◽  
Lake District ◽  
Surface Mass ◽  
Annual Variations ◽  
Snow Drift

ABSTRACTWe present climate data, direct surface mass balance (SMB) observations and model results for Mocho Glacier in the Chilean Lake District. Mean annual temperature on a nunatak of Mocho Glacier at an elevation of ~2000 m was +2.6°C in 2006–15 and mean annual precipitation in Puerto Fuy (13 km from the glacier, at an elevation of 600 m) was 4000 mm for the same period. High interannual variations in the SMB of Mocho Glacier were observed. A simple SMB model is able to reproduce the observed annual variations in SMB, but fails to predict the steep observed mass-balance gradient. The average of the measured annual glacier mass balances in the four hydrological years 2009/10–2012/13 was −0.90 m w.e. a−1and the average modelled annual glacier mass balance 2006/07–2014/15 was −1.05 m w.e. a−1. The observed distributed ablation shows a clear altitudinal dependency, while accumulation is determined by patterns of snow drift as well. These patterns are only poorly represented in the model and have to be included in order to be able to reproduce a realistic SMB map of the glacier.

scholarly journals The surface albedo of the Greenland Ice Sheet between 1982 and 2015 from the CLARA-A2 dataset and its relationship to the ice sheet's surface mass balance

2019 ◽  
Vol 13 (10) ◽  
pp. 2597-2614 ◽  
Author(s):  
Aku Riihelä ◽  
Michalea D. King ◽  
Kati Anttila
Keyword(s):  
Time Series ◽  
Mass Balance ◽  
Surface Runoff ◽  
Surface Albedo ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Early Summer ◽  
Surface Mass Balance ◽  
Surface Mass ◽  
Surface Melt

Abstract. The Greenland Ice Sheet is losing mass at a significant rate, driven in part by increasing surface-melt-induced runoff. Because the ice sheet's surface melt is closely connected to changes in the surface albedo, studying multidecadal changes in the ice sheet's albedo offers insight into surface melt and associated changes in its surface mass balance. Here, we first analyse the CM SAF Cloud, Albedo and Surface Radiation dataset from AVHRR data second edition (CLARA-A2) Surface Albedo (SAL), covering 1982–2015, to obtain decadal albedo trends for each summer month. We also examine the rates of albedo change during the early summer, supported with atmospheric reanalysis data from MERRA-2 (Modern-Era Retrospective analysis for Research and Applications, version 2), to discern changes in the intensity of early summer melt, and their likely drivers. We find that rates of albedo decrease during summer melt have accelerated during the 2000s relative to the early 1980s and that the surface albedos now often decrease to values typical of bare ice at elevations 50–100 m higher on the ice sheet. The southern margins exhibit the opposite behaviour, though, and we suggest this is due to increasing snowfall over the area. We then subtract ice discharge from the mass balance estimates observed by the Gravity Recovery and Climate Experiment (GRACE) satellite mission to estimate surface mass balance. The CLARA-A2 albedo changes are regressed with these data to obtain a summer-aggregated proxy surface mass balance time series for the summer periods 1982–2015. This proxy time series is compared with latest regional climate model estimates from the MAR model to perform an observation-based test on the dominance of surface runoff in the magnitude and variability of the summer surface mass balance. We show that the proxy time series agrees with MAR through the analysed period within the associated uncertainties of the data and methods, demonstrating and confirming that surface runoff has dominated the rapid surface mass loss period between the 1990s and 2010s. Finally, we extend the analysis to the drainage basin scale to examine discharge–albedo relationships. We find little evidence of surface-melt-induced ice flow acceleration at annual timescales.

scholarly journals Brief communication: CESM2 climate forcing (1950–2014) yields realistic Greenland ice sheet surface mass balance

2020 ◽  
Vol 14 (4) ◽  
pp. 1425-1435 ◽  
Author(s):  
Brice Noël ◽  
Leonardus van Kampenhout ◽  
Willem Jan van de Berg ◽  
Jan T. M. Lenaerts ◽  
Bert Wouters ◽  
...  
Keyword(s):  
Mass Loss ◽  
Mass Balance ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Earth System Model ◽  
Climate Forcing ◽  
System Model ◽  
Surface Mass Balance ◽  
Earth System ◽  
Surface Mass

Abstract. We present a reconstruction of historical (1950–2014) surface mass balance (SMB) of the Greenland ice sheet (GrIS) using a high-resolution regional climate model (RACMO2; ∼11 km) to dynamically downscale the climate of the Community Earth System Model version 2 (CESM2; ∼111 km). After further statistical downscaling to 1 km spatial resolution, evaluation using in situ SMB measurements and remotely sensed GrIS mass change shows good agreement. Comparison with an ensemble of previously conducted RACMO2 simulations forced by climate reanalysis demonstrates that the current product realistically represents the long-term average and variability of individual SMB components and captures the recent increase in meltwater runoff that accelerated GrIS mass loss. This means that, for the first time, climate forcing from an Earth system model (CESM2), which assimilates no observations, can be used without additional corrections to reconstruct the historical GrIS SMB and its recent decline that initiated mass loss in the 1990s. This paves the way for attribution studies of future GrIS mass loss projections and contribution to sea level rise.

scholarly journals The contrasting response of outlet glaciers to interior and ocean forcing

2020 ◽  
Vol 14 (7) ◽  
pp. 2515-2535
Author(s):  
John Erich Christian ◽  
Alexander A. Robel ◽  
Cristian Proistosescu ◽  
Gerard Roe ◽  
Michelle Koutnik ◽  
...  
Keyword(s):  
Mass Balance ◽  
Fast Response ◽  
Climate Forcing ◽  
Reduced Model ◽  
Surface Mass Balance ◽  
Anthropogenic Influences ◽  
Outlet Glacier ◽  
Surface Mass ◽  
Oceanic Forcing ◽  
The Impact

Abstract. The dynamics of marine-terminating outlet glaciers are of fundamental interest in glaciology and affect mass loss from ice sheets in a warming climate. In this study, we analyze the response of outlet glaciers to different sources of climate forcing. We find that outlet glaciers have a characteristically different transient response to surface-mass-balance forcing applied over the interior than to oceanic forcing applied at the grounding line. A recently developed reduced model represents outlet-glacier dynamics via two widely separated response timescales: a fast response associated with grounding-zone dynamics and a slow response of interior ice. The reduced model is shown to emulate the behavior of a more complex numerical model of ice flow. Together, these models demonstrate that ocean forcing first engages the fast, local response and then the slow adjustment of interior ice, whereas surface-mass-balance forcing is dominated by the slow interior adjustment. We also demonstrate the importance of the timescales of stochastic forcing for assessing the natural variability in outlet glaciers, highlighting that decadal persistence in ocean variability can affect the behavior of outlet glaciers on centennial and longer timescales. Finally, we show that these transient responses have important implications for attributing observed glacier changes to natural or anthropogenic influences; the future change already committed by past forcing; and the impact of past climate changes on the preindustrial glacier state, against which current and future anthropogenic influences are assessed.

scholarly journals Glacier-wide summer surface mass-balance calculation: hydrological balance applied to the Argentière and Mer de Glace drainage basins (Mont Blanc)

2018 ◽  
Vol 64 (243) ◽  
pp. 119-131 ◽  
Author(s):  
A. VIANI ◽  
T. CONDOM ◽  
C. VINCENT ◽  
A. RABATEL ◽  
B. BACCHI ◽  
...  
Keyword(s):  
Mass Balance ◽  
Surface Mass Balance ◽  
Mass Balances ◽  
Drainage Basins ◽  
Mass Balance Calculation ◽  
Surface Mass ◽  
Hydrological Balance ◽  
Good Agreement

ABSTRACTWe present the glacier-wide summer surface mass balances determined by a detailed hydrological balance (sSMBhydro) and the quantification of the uncertainties of the calculations on the Argentière and Mer de Glace-Leschaux drainage basins, located in the upper Arve watershed (French Alps), over the period 1996–2004. The spatial distribution of precipitation within the study area was adjusted using in situ winter mass-balance measurements. The sSMBhydro performance was assessed via a comparison with the summer surface mass balances based on in situ glaciological observations (sSMBglacio). Our results show that the sSMBhydro has an uncertainty of ± 0.67 m w.e. a−1 at Argentière and ± 0.66 m w.e. a−1 at Mer de Glace-Leschaux. Estimates of the Argentière sSMBhydro values are in good agreement with the sSMBglacio values. These time series show almost the same interannual variability. From the marked difference between the sSMBhydro and sSMBglacio values for the Mer de Glace-Leschaux glacier, we suspect a significant role of groundwater fluxes in the hydrological balance. This study underlines the importance of taking into account the groundwater transfers to represent and predict the hydro-glaciological behaviour of a catchment.

scholarly journals An approach to remotely monitor glacier mass balance at seasonal to annual time scales, Columbia and Rocky Mountains, Canada.

2020 ◽  
Author(s):  
◽  
Ben Mauri Pelto
Keyword(s):  
Mass Balance ◽  
Rocky Mountains ◽  
Large Scale ◽  
Mass Change ◽  
Ice Thickness ◽  
Glacier Mass Balance ◽  
Surface Mass Balance ◽  
Study Region ◽  
Surface Mass ◽  
Global Database

My dissertation investigates glacier mass change in the Columbia and Rocky Mountains of British Columbia. In chapter one I discuss the importance of the cryosphere and glaciers, introduce the climate and glaciers of the study region, and outline the objectives and structure of this dissertation. Previous work established the feasibility of geodetic methods to accurately produce winter glacier mass balance and annual glacier mass balance. These studies demonstrate that geodetic surveys can be used to estimate mass balance during the accumulation season or for one glacier over a number of years. In chapter two, I refine these published methods to measure seasonal and annual mass balance for six glaciers within two mountain ranges from 2014–2018. I use synchronous field-based glaciological measurements, airbornelaser scanningsurveys (ALS) and satelliteimagery to quantify seasonal glacier mass change from 2014–2018. Chapter three reports on radar surveys I completed of the study glaciers, adding important observations to the global database of ice thickness. I use these observations and an existing flowline model, driven with observations of surface mass balance and glacier elevation to bias-correct ice thickness estimates for each glacier. Finally, I use the model to estimate ice thickness for all glaciers in the Columbia Basin and estimate total ice volume. Chapter four builds upon previous work which used surface topography, glacier mass balance, ice thickness, and ice velocity data to estimate ice flux at discrete glacier cross-sections. Previous efforts to infer the spatial distribution of mass balance have focused on glacier tongues. I expand upon this method, calculating surface mass balance between flux gates over the entire elevation range of three glaciers, over three years. I derive the altitude-mass balance relation and demonstrate that the relation can be accurately described with high-resolution elevation and ice flux data, and suggest that this method can be expanded for large-scale estimates. Chapter five summarizes the study’s major findings, highlights its limitations and discussed its broader implications. Finally, I make recommendations that will address knowledge gaps, and improve our understanding of changing glacier conditions and ability to model glacier dynamics.

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