Greenland ice sheet surface temperature, melt and mass loss: 2000–06

AbstractA daily time series of ‘clear-sky’ surface temperature has been compiled of the Greenland ice sheet (GIS) using 1 km resolution moderate-resolution imaging spectroradiometer (MODIS) land-surface temperature (LST) maps from 2000 to 2006. We also used mass-concentration data from the Gravity Recovery and Climate Experiment (GRACE) to study mass change in relationship to surface melt from 2003 to 2006. The mean LST of the GIS increased during the study period by ∼0.27°C a−1. The increase was especially notable in the northern half of the ice sheet during the winter months. Melt-season length and timing were also studied in each of the six major drainage basins. Rapid (<15 days) and sustained mass loss below 2000 m elevation was triggered in 2004 and 2005 as recorded by GRACE when surface melt begins. Initiation of large-scale surface melt was followed rapidly by mass loss. This indicates that surface meltwater is flowing rapidly to the base of the ice sheet, causing acceleration of outlet glaciers, thus highlighting the metastability of parts of the GIS and the vulnerability of the ice sheet to air-temperature increases. If air temperatures continue to rise over Greenland, increased surface melt will play a large role in ice-sheet mass loss.

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Analysis of the Spatiotemporal Changes of Ice Sheet Mass and Driving Factors in Greenland

Remote Sensing ◽

10.3390/rs11070862 ◽

2019 ◽

Vol 11 (7) ◽

pp. 862 ◽

Cited By ~ 2

Author(s):

Yankai Bian ◽

Jianping Yue ◽

Wei Gao ◽

Zhen Li ◽

Dekai Lu ◽

...

Keyword(s):

Surface Temperature ◽

Mass Loss ◽

Land Surface Temperature ◽

Land Surface ◽

Ice Sheet ◽

Phase Relationship ◽

Greenland Ice Sheet ◽

Driving Factors ◽

Mk Test ◽

Relative Change

With the warming of the global climate, the mass loss of the Greenland ice sheet is intensifying, having a profound impact on the rising of the global sea level. Here, we used Gravity Recovery and Climate Experiment (GRACE) RL06 data to retrieve the time series variations of ice sheet mass in Greenland from January 2003 to December 2015. Meanwhile, the spatial changes of ice sheet mass and its relationship with land surface temperature are studied by means of Theil–Sen median trend analysis, the Mann–Kendall (MK) test, empirical orthogonal function (EOF) analysis, and wavelet transform analysis. The results showed: (1) in terms of time, we found that the total mass of ice sheet decreases steadily at a speed of −195 ± 21 Gt/yr and an acceleration of −11 ± 2 Gt/yr2 from 2003 to 2015. This mass loss was relatively stable in the two years after 2012, and then continued a decreasing trend; (2) in terms of space, the mass loss areas of the Greenland ice sheet mainly concentrates in the southeastern, southwestern, and northwestern regions, and the southeastern region mass losses have a maximum rate of more than 27 cm/yr (equivalent water height), while the northeastern region show a minimum rate of less than 3 cm/yr, showing significant changes as a whole. In addition, using spatial distribution and the time coefficients of the first two models obtained by EOF decomposition, ice sheet quality in the southeastern and northwestern regions of Greenland show different significant changes in different periods from 2003 to 2015, while the other regions showed relatively stable changes; (3) in terms of driving factors temperature, there is an anti-phase relationship between ice sheet mass change and land surface temperature by the mean XWT-based semblance value of −0.34 in a significant oscillation period variation of 12 months. Meanwhile, XWT-based semblance values have the largest relative change in 2005 and 2012, and the smallest relative change in 2009 and 2010, indicating that the influence of land surface temperature on ice sheet mass significantly varies in different years.

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Ice sheet mass loss caused by dust and black carbon accumulation

The Cryosphere Discussions ◽

10.5194/tcd-9-2563-2015 ◽

2015 ◽

Vol 9 (2) ◽

pp. 2563-2596

Author(s):

T. Goelles ◽

C. E. Bøggild ◽

R. Greve

Keyword(s):

Mass Loss ◽

Black Carbon ◽

Ice Sheet ◽

Greenland Ice Sheet ◽

Carbon Accumulation ◽

Model Framework ◽

Ice Dynamics ◽

Ablation Area ◽

Ice Surface ◽

Surface Melt

Abstract. Albedo is the dominating factor governing surface melt variability in the ablation area of ice sheets and glaciers. Aerosols such as mineral dust and black carbon (soot) accumulate on the ice surface and cause a darker surface and therefore a lower albedo. The dominant source of these aerosols in the ablation area is melt-out of englacial material which has been transported via ice flow. The darkening effect on the ice surface is currently not included in sea level projections, and the effect is unknown. We present a model framework which includes ice dynamics, aerosol transport, aerosol accumulation and the darkening effect on ice albedo and its consequences for surface melt. The model is applied to a simplified geometry resembling the conditions of the Greenland ice sheet, and it is forced by several temperature scenarios to quantify the darkening effect of aerosols on future mass loss. The effect of aerosols depends non-linearly on the temperature rise due to the feedback between aerosol accumulation and surface melt. The effect of aerosols in the year 3000 is up to 12% of additional ice sheet volume loss in the warmest scenario.

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Firn temperature and meltwater refreezing in the lower accumulation area of the Greenland ice sheet, Pâkitsoq, West Greenland

Rapport Grønlands Geologiske Undersøgelse ◽

10.34194/rapggu.v159.8218 ◽

1993 ◽

Vol 159 ◽

pp. 109-114

Author(s):

R.J Braithwaite

Keyword(s):

Sea Level ◽

Ice Sheet ◽

Greenland Ice Sheet ◽

International Project ◽

Sea Level Changes ◽

West Greenland ◽

Degree Day ◽

Air Temperatures ◽

Surface Melt ◽

High Degree

Firn temperatures and meltwater refreezing are studied in the lower accumulation area of the Greenland ice sheet as part of an international project on sea level changes. In the study area, 1440–1620 m a.s.l., meltwater penetrates several metres into the firn and refreezes, warming the firn by 5–7°C compared with annual air temperatures. This firn warming is closely related to surface melt which can be estimated by several methods. A relatively high degree-day factor is needed to account for the melt rates found.

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Melt probabilities and surface temperature trends on the Greenland ice sheet using a Gaussian mixture model

10.5194/tc-2021-259 ◽

2021 ◽

Author(s):

Daniel Clarkson ◽

Emma Eastoe ◽

Amber Leeson

Keyword(s):

Surface Temperature ◽

Gaussian Mixture Model ◽

Mixture Model ◽

Ice Sheet ◽

Greenland Ice Sheet ◽

Gaussian Mixture ◽

Ice Surface ◽

Moderate Resolution Imaging Spectroradiometer ◽

Ice Surface Temperature ◽

Model Components

Abstract. The Greenland ice sheet has experienced significant melt over the past six decades, with extreme melt events covering large areas of the ice sheet. Melt events are typically analysed using summary statistics, but the nature and characteristics of the events themselves are less frequently analysed. Our work examines melt events from a statistical perspective by modelling 19 years of Moderate Resolution Imaging Spectroradiometer (MODIS) ice surface temperature data using a Gaussian mixture model. We use a mixture model with separate model components for ice and meltwater temperatures at 1139 locations spaced across the ice sheet. By considering the uncertainty of the ice surface temperature measurements, we use the two categories of model components to define a probability of melt for a given observation rather than using a fixed melt threshold. This probability can then be used to estimate the expected number of melt events at a given location. Furthermore, the model can be used to estimate temperature quantiles at a given location, and analyse temperature and melt trends over time by fitting the model to subsets of time. Fitting the model to data from 2001–2009 and 2010–2019 shows increases in melt probability for significant portions of the ice sheet, as well as the yearly expected maximum temperatures.

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Wintertime storage of water in buried supraglacial lakes across the Greenland Ice Sheet

The Cryosphere Discussions ◽

10.5194/tcd-8-3999-2014 ◽

2014 ◽

Vol 8 (4) ◽

pp. 3999-4031 ◽

Cited By ~ 2

Author(s):

L. S. Koenig ◽

D. J. Lampkin ◽

L. N. Montgomery ◽

S. L. Hamilton ◽

J. B. Turrin ◽

...

Keyword(s):

Mass Loss ◽

Total Mass ◽

Ice Sheet ◽

Greenland Ice Sheet ◽

Subsurface Water ◽

Blue Color ◽

Total Mass Loss ◽

Supraglacial Lakes ◽

Hydrologic System ◽

Surface Melt

Abstract. Surface melt over the Greenland Ice Sheet (GrIS) is increasing and estimated to account for half or more of the total mass loss. Little, however, is known about the hydrologic pathways that route surface melt within the ice sheet. In this study, we present over-winter storage of water in buried supraglacial lakes as one hydrologic pathway for surface melt, referred to as buried lakes. Airborne radar echograms are used to detect the buried lakes that are distributed extensively around the margin of the GrIS. The subsurface water can persist through multiple winters and is, on average, ~4.2 + 0.4 m below the surface. The few buried lakes that are visible at the surface of the GrIS have a~unique visible signature associated with a darker blue color where subsurface water is located. The volume of retained water in the buried lakes is likely insignificant compared to the total mass loss from the GrIS but the water will have important implications locally for the development of the englacial hydrologic network, ice temperature profiles and glacial dynamics. The buried lakes represent a small but year-round source of meltwater in the GrIS hydrologic system.

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Analyzing Near Surface Temperature Inversions Across the Greenland Ice Sheet Using In-situ, Remote Sensing, and Reanalysis Data

10.5194/egusphere-egu2020-10670 ◽

2020 ◽

Author(s):

Alden Adolph ◽

Wesley Brown ◽

Karina Zikan ◽

Robert Fausto

Keyword(s):

Surface Temperature ◽

Energy Exchange ◽

Ice Sheet ◽

Greenland Ice Sheet ◽

Near Surface ◽

Surface Temperatures ◽

Air Temperatures ◽

Exchange Processes ◽

Temperature Inversions

As Arctic temperatures have increased, the Greenland Ice Sheet has exhibited a negative mass balance, with a substantial and increasing fraction of mass loss due to surface melt. Understanding surface energy exchange processes in Greenland is critical for our ability to predict changes in mass balance. In-situ and remotely sensed surface temperatures are useful for monitoring trends, melt events, and surface energy balance processes, but these observations are complicated by the fact that surface temperatures and near surface air temperatures can significantly differ due to the presence of inversions that exist across the Arctic. Our previous work shows that even in the summer, very near surface inversions are present between the 2m air and surface temperatures a majority of the time at Summit, Greenland. In this study, we expand upon these results and combine a variety of data sources to quantify differences between surface snow/ice temperatures and 2m air temperatures across the Greenland Ice Sheet and investigate controls on the magnitude of these near surface temperature inversions. In-situ temperatures, wind speed, specific humidity, and albedo data are provided from automatic weather stations operated by the Programme for Monitoring of the Greenland Ice Sheet (PROMICE). We use the Clouds and the Earth's Radiant Energy System (CERES) cloud area fraction data to analyze effects of cloud presence on near surface temperature gradients. The in-situ temperatures are compared to Modern-Era Retrospective analysis for Research and Applications Version 2 (MERRA-2) and Moderate Resolution Imaging Spectrometer (MODIS) ice surface temperature data to extend findings across the ice sheet. Using PROMICE in-situ data from 2015, we find that these 2m temperature inversions are present 77% of the time, with a median strength of 1.7&#176;C. The data confirm that the presence of clouds weakens inversions. Initial results indicate a RMSE of 3.9&#176;C between MERRA-2 and PROMICE 2m air temperature, and a RMSE of 5.6&#176;C between the two datasets for surface temperature. Improved understanding of controls on near surface inversions is important for use of remotely sensed snow surface temperatures and for modeling of surface mass and energy exchange processes.

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The ocean response to changes of the Greenland Ice sheet in a warming climate

10.5194/egusphere-egu2020-21261 ◽

2020 ◽

Author(s):

Marianne S. Madsen ◽

Shuting Yang ◽

Christian Rodehacke ◽

Guðfinna Aðalgeirsdóttir ◽

Synne H. Svendsen ◽

...

Keyword(s):

Mass Loss ◽

Ocean Circulation ◽

Large Scale ◽

Climate Model ◽

Variable Mass ◽

Ice Sheet ◽

Greenland Ice Sheet ◽

Model System ◽

Meridional Overturning Circulation ◽

The Arctic

During recent decades, increased and highly variable mass loss from the Greenland ice sheet has been observed, implying that the ice sheet can respond to changes in ocean and atmospheric conditions on annual to decadal time scales. Changes in ice sheet topography and increased mass loss into the ocean may impact large scale atmosphere and ocean circulation. Therefore, coupling of ice sheet and climate models, to explicitly include the processes and feedbacks of ice sheet changes, is needed to improve the understanding of ice sheet-climate interactions.Here, we present results from the coupled ice sheet-climate model system, EC-Earth-PISM. The model consists of the atmosphere, ocean and sea-ice model system EC-Earth, two-way coupled to the Parallel Ice Sheet Model, PISM. The surface mass balance (SMB) is calculated within EC-Earth, from the precipitation, evaporation and surface melt of snow and ice, to ensure conservation of mass and energy. The ice sheet model, PISM, calculates ice dynamical changes in ice discharge and basal melt as well as changes in ice extent and thickness. Idealized climate change experiments have been performed starting from pre-industrial conditions for a) constant forcing (pre-industrial control); b) abruptly quadrupling the CO2 concentration; and c) gradually increasing the CO2 concentration by 1% per year until 4xCO2 is reached. &#160;All three experiments are run for 350 years.Our results show a significant impact of the interactive ice sheet component on heat and fresh water fluxes into the Arctic and North Atlantic Oceans. The interactive ice sheet causes freshening of the Arctic Ocean and affects deep water formation, resulting in a significant delay of the recovery of the Atlantic Meridional Overturning Circulation (AMOC) in the coupled 4xCO2 experiments, when compared with uncoupled experiments.

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Comparison of satellite, thermochron and air temperatures at Summit, Greenland, during the winter of 2008/09

Journal of Glaciology ◽

10.3189/002214310793146269 ◽

2010 ◽

Vol 56 (198) ◽

pp. 735-741 ◽

Cited By ~ 31

Author(s):

Lora S. Koenig ◽

Dorothy K. Hall

Keyword(s):

Surface Temperature ◽

Air Temperature ◽

Satellite Data ◽

Ice Sheet ◽

Greenland Ice Sheet ◽

Seasonal Temperature ◽

Temperature Trends ◽

Air Temperatures ◽

Winter Time ◽

Arctic Surface

AbstractCurrent trends show a rise in Arctic surface and air temperatures, including over the Greenland ice sheet where rising temperatures will contribute to increased sea-level rise through increased melt. We aim to establish the uncertainties in using satellite-derived surface temperature for measuring Arctic surface temperature, as satellite data are increasingly being used to assess temperature trends. To accomplish this, satellite-derived surface temperature, or land-surface temperature (LST), must be validated and limitations of the satellite data must be assessed quantitatively. During the 2008/09 boreal winter at Summit, Greenland, we employed data from standard US National Oceanic and Atmospheric Administration (NOAA) air-temperature instruments, button-sized temperature sensors called thermochrons and the Moderate Resolution Imaging Spectroradiometer (MODIS) satellite instrument to (1) assess the accuracy and utility of thermochrons in an ice-sheet environment and (2) compare MODIS-derived LSTs with thermochron-derived surface and air temperatures. The thermochron-derived air temperatures were very accurate, within 0.1 ± 0.3°C of the NOAA-derived air temperature, but thermochron-derived surface temperatures were ∼3°C higher than MODIS-derived LSTs. Though surface temperature is largely determined by air temperature, these variables can differ significantly. Furthermore, we show that the winter-time mean air temperature, adjusted to surface temperature, was ∼11°C higher than the winter-time mean MODIS-derived LST. This marked difference occurs largely because satellite-derived LSTs cannot be measured through cloud cover, so caution must be exercised in using time series of satellite LST data to study seasonal temperature trends.

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A Satellite-Derived Climate-Quality Data Record of the Clear-Sky Surface Temperature of the Greenland Ice Sheet

Journal of Climate ◽

10.1175/jcli-d-11-00365.1 ◽

2012 ◽

Vol 25 (14) ◽

pp. 4785-4798 ◽

Cited By ~ 40

Author(s):

Dorothy K. Hall ◽

Josefino C. Comiso ◽

Nicolo E. DiGirolamo ◽

Christopher A. Shuman ◽

Jeffrey R. Key ◽

...

Keyword(s):

Surface Temperature ◽

Accuracy Assessment ◽

Ice Sheet ◽

Greenland Ice Sheet ◽

Quality Data ◽

Climate Data ◽

Clear Sky ◽

Data Record ◽

Moderate Resolution Imaging Spectroradiometer ◽

Ice Surface Temperature

Abstract The authors have developed a climate-quality data record of the clear-sky surface temperature of the Greenland Ice Sheet using the Moderate-Resolution Imaging Spectroradiometer (MODIS) ice-surface temperature (IST) algorithm. Daily and monthly quality-controlled MODIS ISTs of the Greenland Ice Sheet beginning on 1 March 2000 and continuing through 31 December 2010 are presented at 6.25-km spatial resolution on a polar stereographic grid along with metadata to permit detailed accuracy assessment. The ultimate goal is to develop a climate data record (CDR) that starts in 1981 with the Advanced Very High Resolution Radiometer (AVHRR) Polar Pathfinder (APP) dataset and continues with MODIS data from 2000 to the present, and into the Visible Infrared Imager Radiometer Suite (VIIRS) era (the first VIIRS instrument was launched in October 2011). Differences in the APP and MODIS cloud masks have thus far precluded merging the APP and MODIS IST records, though this will be revisited after the APP dataset has been reprocessed with an improved cloud mask. IST of Greenland may be used to study temperature and melt trends and may also be used in data assimilation modeling and to calculate ice sheet mass balance. The MODIS IST climate-quality dataset provides a highly consistent and well-characterized record suitable for merging with earlier and future IST data records for climate studies. The complete MODIS IST daily and monthly data record is available online.

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Large-scale ice-sheet modelling as a means of dating deep ice cores in Greenland

Journal of Glaciology ◽

10.1017/s0022143000003257 ◽

1997 ◽

Vol 43 (144) ◽

pp. 307-310 ◽

Cited By ~ 13

Author(s):

Ralf Greve

Keyword(s):

Surface Temperature ◽

Large Scale ◽

Piecewise Linear ◽

Three Dimensional ◽

Ice Sheet ◽

Greenland Ice Sheet ◽

Ice Cores ◽

Temperature History ◽

Geothermal Heat ◽

Annual Layer

Abstract The three-dimensional ice-sheet model SICOPOLIS is used to simulate the dynamic/thermody namic behaviour of the entire Greenland ice sheet from 250 000 a BP until today. External forcing consists of a surface-temperature history constructed from δ18O data of the GRIP core, a snowfall history coupled linearly to that of the surface temperature, a piecewise linear sea-level scenario and a constant geothermal heat flux. The simulated Greenland ice sheet is investigated in the vicinity of Summit, the position where the maximum elevation is taken, and where the two drill sites GRIP and GISP2 are situated 28km apart from each other. In this region, the agreement between modelled and observed topography and ice temperature turns out to be very good. Computed age-depth profiles for GRIP and GISP2 are presented, which can he used to complete the dating of these cores in the deeper regions where annual-layer counting is not possible. However, artificial diffusion influences the computed ages in a near-basal boundary layer of approximately 15% of the ice thickness, so that the age at the bottom of the cores cannot be predicted yet.

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