scholarly journals Relationships between interannual variability of glacier mass balance and climate

1999 ◽  
Vol 45 (151) ◽  
pp. 456-462 ◽  
Author(s):  
Roger J. Braithwaite ◽  
Yu Zhang
Keyword(s):  
Standard Deviation ◽  
Mass Balance ◽  
Interannual Variability ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
The Arctic ◽  
Glacier Mass Balance ◽  
Strongly Correlated ◽  
Calculated Mass ◽  
The Difference

AbstractThe interannual variability of glacier mass balance is expressed by the standard deviation of net balance, which varies from about ±0.1 to ±1.4 m a−1 for a sample of 115 glaciers with at least 5 years of record. The standard deviation of net balance is strongly correlated with the mass-balance amplitude (half the difference between winter and summer balances) for 60 glaciers, so the amplitude can be estimated from net balance standard deviation for the other 55 glaciers where winter and summer balances are unavailable. The observed and calculated mass-balance amplitudes for the 115 glaciers show contrasts between the Arctic and lower latitudes, and between maritime and continental regions. The interannual variability of mass balance means that balances must be measured for at least a few years to determine a statistically reliable mean balance for any glacier. The net balance of the Greenland ice sheet is still not accurately known, but its standard deviation is here estimated to be about ±0.24 m a−1, in agreement with other Arctic glaciers. Mass-balance variability of this magnitude implies that the ice sheet can thicken or thin by several metres over 20–30 years without giving statistically significant evidence of non-zero balance under present climate.

scholarly journals Relationships between interannual variability of glacier mass balance and climate

1999 ◽  
Vol 45 (151) ◽  
pp. 456-462 ◽  
Author(s):  
Roger J. Braithwaite ◽  
Yu Zhang
Keyword(s):  
Standard Deviation ◽  
Mass Balance ◽  
Interannual Variability ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
The Arctic ◽  
Glacier Mass Balance ◽  
Strongly Correlated ◽  
Calculated Mass ◽  
The Difference

AbstractThe interannual variability of glacier mass balance is expressed by the standard deviation of net balance, which varies from about ±0.1 to ±1.4 m a−1for a sample of 115 glaciers with at least 5 years of record. The standard deviation of net balance is strongly correlated with the mass-balance amplitude (half the difference between winter and summer balances) for 60 glaciers, so the amplitude can be estimated from net balance standard deviation for the other 55 glaciers where winter and summer balances are unavailable. The observed and calculated mass-balance amplitudes for the 115 glaciers show contrasts between the Arctic and lower latitudes, and between maritime and continental regions. The interannual variability of mass balance means that balances must be measured for at least a few years to determine a statistically reliable mean balance for any glacier. The net balance of the Greenland ice sheet is still not accurately known, but its standard deviation is here estimated to be about ±0.24 m a−1, in agreement with other Arctic glaciers. Mass-balance variability of this magnitude implies that the ice sheet can thicken or thin by several metres over 20–30 years without giving statistically significant evidence of non-zero balance under present climate.

The effect of latent heat transport by waves on Greenland Surface Mass Balance

2020 ◽  
Author(s):  
Tuomas Ilkka Henrikki Heiskanen ◽  
Rune Grand Graversen
Keyword(s):  
Mass Balance ◽  
Heat Transport ◽  
Latent Heat ◽  
Energy Transport ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
The Arctic ◽  
Surface Mass Balance ◽  
Surface Mass ◽  
Circulation Patterns

<p>The Arctic region shows some of the world's most significant signs of climate change. The atmospheric energy transport plays an important role for the Arctic climate; the atmospheric transport contributes an amount of energy into the Arctic that is comparable to that provided directly by the sun. From recently developed Fourier and wavelet based methods it has been found that the planetary component of the latent heat transport affects that Arctic surface temperatures stronger than the decomposed dry-static energy transport and the synoptic scale component of the latent heat transport. </p><p>A large concern for humanity is that the climate change in polar regions will lead to significant melting of the ice sheets and glaciers. In fact the discharge water from the Greenland ice sheet has recently increased to the extent that this ice sheet is one of the major contributorsto sea-level rise. Here we test the hypothesis that the recent rapid increase in melt of the Greenland ice sheet is linked to a shift of planetary-scale waves transporting warm and humid air over the ice sheet.</p><p>The effect of the atmospheric energy transport is investigated by correlating the divergence of energy over the Greenland ice sheet with the surface mass balance of this ice sheet. The divergence of latent heat transport is found to correlate positively with the surface mass balance along the edges of the ice sheet, and negatively in the interior. This indicates that a convergence of latent at the edges of the ice sheet lead to a increased mass discharge from the ice sheet, whilst in the interior converging latent heat indicates an accumulation of mass to the ice sheet. </p><p>To investigate the effect of transport by planetary and synoptic scale waves on the Greenland ice sheet surface mass balance the mass flux component of the transport divergence is decomposed into wavenumbers through the application of a Fourier series. The divergences of transport contributions of each wavenumber are then correlated with the surface mass balance of the Greenland ice sheet. The correlations between the surface-mass balance and divergence of transport contributions by different wavenumbers reveals the relative impact of atmospheric circulation systems, such as Rossby waves and cyclones, on the Greenland ice sheet mass balance. Further, identifying shifts in the circulation patterns over Greenland by applying self organizing maps, or similar methods, and investigations of how these circulation patterns affect the energy transport over Greenland by atmospheric waves of different scales are also pursued.<br> <br>  </p>

scholarly journals Annual Greenland accumulation rates (2009–2012) from airborne snow radar

2016 ◽  
Vol 10 (4) ◽  
pp. 1739-1752 ◽  
Author(s):  
Lora S. Koenig ◽  
Alvaro Ivanoff ◽  
Patrick M. Alexander ◽  
Joseph A. MacGregor ◽  
Xavier Fettweis ◽  
...  
Keyword(s):  
Mass Balance ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Ice Cores ◽  
Snow Accumulation ◽  
Ultra Wideband ◽  
The Arctic ◽  
Surface Mass Balance ◽  
Accumulation Rates ◽  
Surface Mass

Abstract. Contemporary climate warming over the Arctic is accelerating mass loss from the Greenland Ice Sheet through increasing surface melt, emphasizing the need to closely monitor its surface mass balance in order to improve sea-level rise predictions. Snow accumulation is the largest component of the ice sheet's surface mass balance, but in situ observations thereof are inherently sparse and models are difficult to evaluate at large scales. Here, we quantify recent Greenland accumulation rates using ultra-wideband (2–6.5 GHz) airborne snow radar data collected as part of NASA's Operation IceBridge between 2009 and 2012. We use a semiautomated method to trace the observed radiostratigraphy and then derive annual net accumulation rates for 2009–2012. The uncertainty in these radar-derived accumulation rates is on average 14 %. A comparison of the radar-derived accumulation rates and contemporaneous ice cores shows that snow radar captures both the annual and long-term mean accumulation rate accurately. A comparison with outputs from a regional climate model (MAR) shows that this model matches radar-derived accumulation rates in the ice sheet interior but produces higher values over southeastern Greenland. Our results demonstrate that snow radar can efficiently and accurately map patterns of snow accumulation across an ice sheet and that it is valuable for evaluating the accuracy of surface mass balance models.

scholarly journals Impact of Atmospheric Circulation on Temperature, Clouds, and Radiation at Summit Station, Greenland, with Self-Organizing Maps

2018 ◽  
Vol 31 (21) ◽  
pp. 8895-8915 ◽  
Author(s):  
Michael R. Gallagher ◽  
Matthew D. Shupe ◽  
Nathaniel B. Miller
Keyword(s):  
Mass Balance ◽  
Atmospheric Circulation ◽  
Radiative Forcing ◽  
Large Scale ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Cloud Formation ◽  
The Arctic ◽  
Self Organizing Maps ◽  
Self Organizing

The Greenland Ice Sheet (GrIS) plays a crucial role in the Arctic climate, and atmospheric conditions are the primary modifier of mass balance. This analysis establishes the relationship between large-scale atmospheric circulation and principal determinants of GrIS mass balance: moisture, cloud properties, radiative forcing, and temperature. Using self-organizing maps (SOMs), observations from the Integrated Characterization of Energy, Clouds, Atmospheric State, and Precipitation at Summit (ICECAPS) project are categorized by daily sea level pressure (SLP) gradient. The results describe in detail how southerly, northerly, and zonal circulation regimes impact observations at Summit Station, Greenland. This southerly regime is linked to large anomalous increases in low-level liquid cloud formation, cloud radiative forcing (CRF), and surface warming at Summit Station. An individual southerly pattern relates to the largest positive anomalies, with the most extreme 25% of cases leading to CRF anomalies above 21 W m−2 and temperature anomalies beyond 8.5°C. Finally, the July 2012 extreme melt event is analyzed, showing that the prolonged ice sheet warming was related to persistence of these southerly circulation patterns, causing an unusually extended period of anomalous CRF and temperature. These results demonstrate a novel methodology, connecting daily atmospheric circulation to a relatively brief record of observations.

scholarly journals Increasing mass loss from Greenland's Mittivakkat Gletscher

2011 ◽  
Vol 5 (2) ◽  
pp. 341-348 ◽  
Author(s):  
S. H. Mernild ◽  
N. T. Knudsen ◽  
W. H. Lipscomb ◽  
J. C. Yde ◽  
J. K. Malmros ◽  
...  
Keyword(s):  
Mass Loss ◽  
Mass Balance ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Winter Precipitation ◽  
The Arctic ◽  
Surface Mass ◽  
Glacier Changes ◽  
Temperature Records ◽  
Current Area

Abstract. Warming in the Arctic during the past several decades has caused glaciers to thin and retreat, and recent mass loss from the Greenland Ice Sheet is well documented. Local glaciers peripheral to the ice sheet are also retreating, but few mass-balance observations are available to quantify that retreat and determine the extent to which these glaciers are out of equilibrium with present-day climate. Here, we document record mass loss in 2009/10 for the Mittivakkat Gletscher (henceforth MG), the only local glacier in Greenland for which there exist long-term observations of both the surface mass balance and glacier front fluctuations. We attribute this mass loss primarily to record high mean summer (June–August) temperatures in combination with lower-than-average winter precipitation. Also, we use the 15-yr mass-balance record to estimate present-day and equilibrium accumulation-area ratios for the MG. We show that the glacier is significantly out of balance and will likely lose at least 70% of its current area and 80% of its volume even in the absence of further climate changes. Temperature records from coastal stations in Southeast Greenland suggest that recent MG mass losses are not merely a local phenomenon, but are indicative of glacier changes in the broader region. Mass-balance observations for the MG therefore provide unique documentation of the general retreat of Southeast Greenland's local glaciers under ongoing climate warming.

scholarly journals Improved GRACE regional mass balance estimates of the Greenland ice sheet cross-validated with the input–output method

2016 ◽  
Vol 10 (2) ◽  
pp. 895-912 ◽  
Author(s):  
Zheng Xu ◽  
Ernst J. O. Schrama ◽  
Wouter van der Wal ◽  
Michiel van den Broeke ◽  
Ellyn M. Enderlin
Keyword(s):  
Mass Balance ◽  
Climate Model ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Mass Change ◽  
Input Output ◽  
Surface Mass ◽  
Ice Cloud ◽  
The Difference ◽  
Gravity Recovery

Abstract. In this study, we use satellite gravimetry data from the Gravity Recovery and Climate Experiment (GRACE) to estimate regional mass change of the Greenland ice sheet (GrIS) and neighboring glaciated regions using a least squares inversion approach. We also consider results from the input–output method (IOM). The IOM quantifies the difference between the mass input and output of the GrIS by studying the surface mass balance (SMB) and the ice discharge (D). We use the Regional Atmospheric Climate Model version 2.3 (RACMO2.3) to model the SMB and derive the ice discharge from 12 years of high-precision ice velocity and thickness surveys. We use a simulation model to quantify and correct for GRACE approximation errors in mass change between different subregions of the GrIS, and investigate the reliability of pre-1990s ice discharge estimates, which are based on the modeled runoff. We find that the difference between the IOM and our improved GRACE mass change estimates is reduced in terms of the long-term mass change when using a reference discharge derived from runoff estimates in several subareas. In most regions our GRACE and IOM solutions are consistent with other studies, but differences remain in the northwestern GrIS. We validate the GRACE mass balance in that region by considering several different GIA models and mass change estimates derived from data obtained by the Ice, Cloud and land Elevation Satellite (ICESat). We conclude that the approximated mass balance between GRACE and IOM is consistent in most GrIS regions. The difference in the northwest is likely due to underestimated uncertainties in the IOM solutions.

scholarly journals Towards an assessment of the balance state of the Greenland Ice Sheet

2004 ◽  
Vol 4 ◽  
pp. 81-84
Author(s):  
Carl E. Bøggild ◽  
Christoph Mayer ◽  
Steffen Podlech ◽  
Andrea Taurisano ◽  
Søren Nielsen
Keyword(s):  
Mass Balance ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Factors Affecting ◽  
Snow Covered Area ◽  
Covered Area ◽  
Balance State ◽  
Freshwater Budget

The climate of Europe is strongly influenced by heat transport by ocean currents flowing from equatorial regions towards the Arctic (Clark et al. 2002). During recent years, research has been increasingly focused on factors affecting this circulation, e.g. the freshwater budget of the Arctic which is influenced by glacial meltwater from North and East Greenland outlet glaciers (Linthout et al. 2000, Mayer et al. 2000). Furthermore, the climate is affected by snow cover that, apart from its contribution to the freshwater budget, provides feedback effects in that it reflects most of the solar radiation. Apart from Arctic sea-ice cover, the Greenland Ice Sheet is the largest permanent ice- and snow-covered area in the northern hemisphere, with an area of 1.67 ×106 km2 and by far the largest storage of ice with a volume of 2.93 × 106 km3 (Bamber et al. 2001). Most of the mass loss from the Greenland Ice Sheet (the least known mass-balance parameter) occurs in the marginal region of the ice sheet, which is also the area where the largest changes in albedo occur. The Geological Survey of Denmark and Greenland (GEUS) has for many years carried out research along the Greenland Ice Sheet margin to monitor changes of mass balance and melt conditions.

scholarly journals Improved GRACE regional mass balance estimates of the Greenland Ice Sheet cross-validated with the input-output method

2015 ◽  
Vol 9 (5) ◽  
pp. 4661-4699 ◽  
Author(s):  
Z. Xu ◽  
E. Schrama ◽  
W. van der Wal ◽  
M. van den Broeke ◽  
E. M. Enderlin
Keyword(s):  
Mass Balance ◽  
Climate Model ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Mass Change ◽  
Input Output ◽  
Surface Mass ◽  
Ice Cloud ◽  
The Difference ◽  
Gravity Recovery

Abstract. In this study, we use satellite gravimetry data from the Gravity Recovery and Climate Experiment (GRACE) to estimate regional mass changes of the Greenland ice sheet (GrIS) and neighbouring glaciated regions using a least-squares inversion approach. We also consider results from the input-output method (IOM) that quantifies the difference between mass input and output of the surface mass balance (SMB) components from the Regional Atmospheric Climate Model version 2 (RACMO2) and ice discharge (D) from 12 years of high-precision ice velocity and thickness surveys. We use a simulation model to quantify and correct for GRACE approximation errors in mass changes between different sub-regions of GrIS and investigate the reliability of pre-1990s ice discharge estimates based on modelled runoff. We find that the difference between IOM and our improved GRACE mass change estimates is reduced in terms of the long-term mass changes when using runoff-based discharge estimates in several sub-areas. In most regions our GRACE and IOM solutions are consistent with other studies, but differences remain in the northwestern GrIS. We verify the GRACE mass balance in that region by considering several different GIA models and mass change estimates derived from the Ice, Cloud and land Elevation satellite (ICEsat). We conclude that the remaining differences between GRACE and IOM are likely due to underestimated uncertainties in the IOM solutions.

Contemporary (1960–2012) Evolution of the Climate and Surface Mass Balance of the Greenland Ice Sheet

2013 ◽  
Vol 35 (5) ◽  
pp. 1155-1174 ◽  
Author(s):  
J. H. van Angelen ◽  
M. R. van den Broeke ◽  
B. Wouters ◽  
J. T. M. Lenaerts
Keyword(s):  
Mass Balance ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Surface Mass Balance ◽  
Surface Mass
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