scholarly journals Supplementary material to "The impact of climate oscillations on the surface energy budget over the Greenland Ice Sheet in a changing climate"

2022 ◽  
Author(s):  
Tiago Silva ◽  
Jakob Abermann ◽  
Brice Noël ◽  
Sonika Shahi ◽  
Willem Jan van de Berg ◽  
...  
Keyword(s):  
Surface Energy ◽  
Energy Budget ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Surface Energy Budget ◽  
Climate Oscillations ◽  
Changing Climate ◽  
Supplementary Material ◽  
The Impact

Is the impact of climate oscillations changing over the Greenland Ice Sheet?

2021 ◽  
Author(s):  
Tiago Silva ◽  
Jakob Abermann ◽  
Sonika Shahi ◽  
Wolfgang Schöner ◽  
Brice Nöel
Keyword(s):  
North Atlantic ◽  
General Circulation ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Surface Energy Budget ◽  
Climate Indices ◽  
Near Surface ◽  
Climate Oscillations ◽  
Regional Climate Model Output ◽  
The Impact

<p>Greenland Block Index (GBI) and North Atlantic Oscillation (NAO) are climate indices widely used for climatological studies especially over the Greenland Ice Sheet (GrIS). Particularly in summer, they are highly and negatively correlated; both have a strong relationship to near surface processes around the GrIS; their magnitude creates non-linear feedbacks and influences the low troposphere, shaping spatial accumulation and ablation patterns.</p><p>NAO is a measure of the surface pressure difference over the North Atlantic, providing insight of intensity and location of the jet stream. GBI denotes the general circulation over Greenland at the 500-hPa level and depending on its signal promotes heat and moist advection towards inland.</p><p>Based on the 1959-2019 period, the extreme summer melt of 2019 recorded the highest mean summer GBI while the extreme summer melt of 2012 recorded the lowest mean summer NAO. Their impact, however, goes beyond the melting season since the inter-seasonal phase change of these two indices may enhance/ postpone early melt/late refreezing and vice-versa.</p><p>Supported by 62 years of high-resolution regional climate model output (RACMO2.3p2), this work uses a statistical approach to analyze inter-seasonal variability of climate oscillations and their impact on the surface energy budget components over the GrIS. Also, teleconnection changes in a changing climate are hypothesized.</p>

The Impact of Extratropical Cyclones on the Greenland Ice Sheet

2020 ◽  
Author(s):  
Luca Maffezzoni ◽  
Laura Edwards ◽  
Tom Matthews
Keyword(s):  
Surface Energy ◽  
Sensible Heat Flux ◽  
Ice Sheet ◽  
Warm Season ◽  
Greenland Ice Sheet ◽  
Surface Energy Budget ◽  
Extratropical Cyclones ◽  
Positive Contribution ◽  
Surface Mass ◽  
The Impact

<p>The Greenland Ice Sheet (GrIS) stores enough freshwater to raise global sea level by more than 7 m, so its response to climate variability and change is of considerable societal significance. In this context, extratropical cyclones are known to impact the surface mass budget (SMB) via their influence on precipitation and the surface energy budget (SEB). However, there has so far been limited research on these pathways. We address this by expanding process-based knowledge of cyclones and their influence on the GrIS. Using a 58-year integration of the Model Atmospherique Regional (MAR) along with a cyclones`dataset covering the Northern Hemisphere for the same period, we show the mean standardized anomalies of SMB and SEB over the GrIS when cyclones are in close proximity. Overall, our results, show a positive contribution of extratropical cyclones to the SMB during warm and cold seasons alike, especially via snowfall. In both winter and summer, cyclones enhance the downwelling longwave radiative flux due to higher temperatures and increased humidity. In summer an increase (decrease) of long-wave downward and relative humidity (sensible heat flux and temperature) is observed. In winter the impact on these surface energy variables is similar, apart for temperature which have an opposite sign. Overall, cyclones suppress melt and run-off, especially in the ablation zone and peripherals areas of the Ice Sheet during the warm season. Results from this study will contribute to better understanding of how the GrIS may respond in terms of SMB and SEB to changes in the North Atlantic storm tracks under global warming scenarios.</p>

scholarly journals Measuring the impact of a new snow model using surface energy budget process relationships

2020 ◽  
Author(s):  
Jonathan Day ◽  
Gabriele Arduini ◽  
Irina Sandu ◽  
Linus Magnusson ◽  
Anton Beljaars ◽  
...  
Keyword(s):  
Surface Energy ◽  
Energy Budget ◽  
Surface Energy Budget ◽  
Budget Process ◽  
Snow Model ◽  
The Impact

scholarly journals Impact of updated radiative transfer scheme in RACMO2.3p3 on the surface mass and energy budget of the Greenland ice sheet

2020 ◽  
Author(s):  
Christiaan T. van Dalum ◽  
Willem Jan van de Berg ◽  
Michiel R. van den Broeke
Keyword(s):  
Radiative Transfer ◽  
Energy Budget ◽  
Climate Model ◽  
Regional Climate ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Snow Melt ◽  
Transfer Scheme ◽  
Surface Mass ◽  
The Impact

Abstract. This study evaluates the impact of a new snow and ice albedo and radiative transfer scheme on the surface mass and energy budget for the Greenland ice sheet in the latest version of the regional climate model RACMO2, version 2.3p3. We also evaluate the modeled (sub)surface temperature and snow melt, as subsurface heating by radiation penetration now occurs. The results are compared to the previous model version and are evaluated against stake measurements and automatic weather station data of the K-transect and PROMICE projects. In addition, subsurface snow temperature profiles are compared at the K-transect, Summit and southeast Greenland. The surface mass balance is in good agreement with observations, and only changes considerably with respect to the previous RACMO2 version around the ice margins and in the percolation zone. Snow melt and refreezing, on the other hand, are changed more substantially in various regions due to the changed albedo representation, subsurface energy absorption and melt water percolation. Internal heating leads to considerably higher snow temperatures in summer, in agreement with observations, and introduces a shallow layer of subsurface melt.

The extreme Greenland melt season of 2019 in a 16-year time series of surface energy balance at the Kangerlussuaq transect

2020 ◽  
Author(s):  
Peter Kuipers Munneke ◽  
Carleen Reijmer ◽  
Paul Smeets ◽  
Michiel van den Broeke
Keyword(s):  
Time Series ◽  
Surface Energy ◽  
Energy Budget ◽  
High Surface ◽  
Greenland Ice Sheet ◽  
Surface Energy Budget ◽  
Strong Increase ◽  
Near Surface ◽  
Ablation Area ◽  
Surface Melt

<p>In 2019, the Kangerlussuaq transect has experienced a record surface melt season at some stations, exceeding even the melt seasons of 2010 and 2012. We demonstrate that net radiation has been driving the high surface melt rates especially in the higher parts of the transect.</p><p>Since 2003, continuous measurements of the surface energy budget are made in a transect of four automatic weather stations, spanning the ablation area close to the ice edge to the accumulation are of the Greenland Ice Sheet. All available data have been homogenized and corrected, and an unprecedented time series of surface energy budget is presented here, including meltwater production. In this contribution, the melt season of 2019 is put into the longer-term context, and precise atmospheric drivers of the melt are exposed.</p><p>Sixteen years of data clearly reveal the inland and upward expansion of the ablation area. The weather station closest to the equilibrium line (S9) shows a clear and distinct reduction in albedo, and a relatively strong increase in surface melt, which has started to exceed accumulation during the period of observation. Photographs of the area around S9 show that the surface has undergone major changes between 2003 and 2019, now featuring many surface hydrological features that were completely absent in 2003.</p><p>These changes have important implications for the hydrology of the surface, the near-surface, and the underlying firn. A firn model calculation reveals that the entire firn column has been heating by several degrees Celsius in the percolation zone, due to refreezing of meltwater. Sudden, stepwise warming is seen in extreme melt seasons like 2019.</p>

scholarly journals Near-surface climate and surface energy budget of Larsen C ice shelf, Antarctic Peninsula

2012 ◽  
Vol 6 (2) ◽  
pp. 353-363 ◽  
Author(s):  
P. Kuipers Munneke ◽  
M. R. van den Broeke ◽  
J. C. King ◽  
T. Gray ◽  
C. H. Reijmer
Keyword(s):  
Surface Energy ◽  
Antarctic Peninsula ◽  
Energy Budget ◽  
Heat Fluxes ◽  
Surface Energy Budget ◽  
Shortwave Radiation ◽  
Sensible Heat ◽  
Ice Shelf ◽  
Near Surface ◽  
The Impact

Abstract. Data collected by two automatic weather stations (AWS) on the Larsen C ice shelf, Antarctica, between 22 January 2009 and 1 February 2011 are analyzed and used as input for a model that computes the surface energy budget (SEB), which includes melt energy. The two AWSs are separated by about 70 km in the north–south direction, and both the near-surface meteorology and the SEB show similarities, although small differences in all components (most notably the melt flux) can be seen. The impact of subsurface absorption of shortwave radiation on melt and snow temperature is significant, and discussed. In winter, longwave cooling of the surface is entirely compensated by a downward turbulent transport of sensible heat. In summer, the positive net radiative flux is compensated by melt, and quite frequently by upward turbulent diffusion of heat and moisture, leading to sublimation and weak convection over the ice shelf. The month of November 2010 is highlighted, when strong westerly flow over the Antarctic Peninsula led to a dry and warm föhn wind over the ice shelf, resulting in warm and sunny conditions. Under these conditions the increase in shortwave and sensible heat fluxes is larger than the decrease of net longwave and latent heat fluxes, providing energy for significant melt.

Measuring model improvement using surface energy budget process relationships: the impact of a new snow model

2020 ◽  
Author(s):  
Jonathan Day ◽  
Gabriele Arduini ◽  
Linus Magnusson ◽  
Irina Sandu ◽  
Anton Beljaars ◽  
...  
Keyword(s):  
Surface Energy ◽  
Energy Budget ◽  
Energy Exchange ◽  
Weather Prediction ◽  
Surface Energy Budget ◽  
Diagnostic Tools ◽  
Holistic View ◽  
Skill Scores ◽  
Model Improvement ◽  
The Impact

<p>Energy exchange at the snow-atmosphere interface in winter governs the evolution of temperature at the surface and within the snow, preconditioning the snowpack for melt during spring. This study illustrates a set of diagnostic tools that are useful for evaluating the energy exchange at the Earth surface in a numerical weather prediction model from a process-based perspective using in-situ observations. In particular, a new way to measure model improvement using relationships between different terms in the surface energy budget (SEB) is presented. These process-oriented diagnostics provide a holistic view the realism of the balance of terms in the SEB, ensuring that improvements in headline skill scores, such as 2m temperature, are happening for the right reasons. Correctly capturing such process relationships is a necessary step to achieve reliable weather forecasts.</p><p>These diagnostic techniques are applied to assess the impact of a new multi-layer snow scheme in the ECMWF-Integrated Forecast System at two high-Arctic sites (Summit, Greenland and Sodankylä, Finland). The multi-layer scheme is expected to replace a single layer snow scheme enhancing the 2m temperature forecast accuracy and reliability across the northern hemisphere in boreal winter. </p>

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