scholarly journals Sensitivity of the surface energy budget to drifting snow as simulated by MAR in coastal Adelie Land, Antarctica

2020 ◽  
Author(s):  
Louis Le Toumelin ◽  
Charles Amory ◽  
Vincent Favier ◽  
Christoph Kittel ◽  
Stefan Hofer ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Surface Energy ◽  
Energy Budget ◽  
Radiative Forcing ◽  
Climate Models ◽  
Surface Energy Budget ◽  
Near Surface ◽  
Surface Atmosphere ◽  
Drifting Snow ◽  
The Impact

Abstract. In order to understand the evolution of the climate of Antarctica, dominant processes that control surface and low-atmosphere meteorology need to be accurately captured in climate models. We used the regional climate model MAR (v3.11) at 10 km horizontal resolution, forced by ERA5 reanalysis over a 9-year period (2010–2018), to study the impact of drifting snow (designing here the wind-driven transport of snow particles below and above 2 m) on the near-surface atmosphere and surface in Adelie Land, East Antarctica. Two model runs were performed, respectively with and without drifting snow, and compared to half-hourly in situ observations at D17, a coastal and windy location of Adelie Land. We show that sublimation of drifting-snow particles in the atmosphere drives the difference between model runs and is responsible for significant impacts on the near-surface atmosphere. By cooling the low atmosphere and increasing its relative humidity, drifting snow also reduces sensible and latent heat exchanges at the surface (−5.9 W m−2 on average). Moreover, large and dense drifting-snow layers act as near-surface cloud by interacting with incoming radiative fluxes, enhancing incoming longwave radiations and reducing incoming shortwave radiations in summer (net radiative forcing: 5.9 W m−2). Even if drifting snow modifies these processes involved in surface-atmosphere interactions, the total surface energy budget is only slightly modified by introducing drifting snow, because of compensating effects in surface energy fluxes. The drifting-snow driven effects are not prominent near the surface but peak higher in the boundary layer (fifth vertical level, 38 m) where drifting snow sublimation is the most pronounced. Accounting for drifting snow in MAR generally improves the comparison at D17, more especially for the representation of relative humidity (mean bias reduced from −11.1 % to 2.9 %) and incoming longwave radiation (mean bias reduced from −7.6 W m−2 to −1.5 W m−2). Consequently, our results suggest that a detailed representation of drifting-snow processes is required in climate models to better capture the near–surface meteorology and surface–atmosphere interactions in coastal Adelie Land.

scholarly journals Sensitivity of the surface energy budget to drifting snow as simulated by MAR in coastal Adelie Land, Antarctica

2021 ◽  
Vol 15 (8) ◽  
pp. 3595-3614
Author(s):  
Louis Le Toumelin ◽  
Charles Amory ◽  
Vincent Favier ◽  
Christoph Kittel ◽  
Stefan Hofer ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Surface Energy ◽  
Energy Budget ◽  
Climate Models ◽  
Longwave Radiation ◽  
Surface Energy Budget ◽  
Near Surface ◽  
Surface Atmosphere ◽  
Drifting Snow ◽  
The Impact

Abstract. In order to understand the evolution of the climate of Antarctica, dominant processes that control surface and low-atmosphere meteorology need to be accurately captured in climate models. We used the regional climate model MAR (v3.11) at 10 km horizontal resolution, forced by ERA5 reanalysis over a 9-year period (2010–2018) to study the impact of drifting snow (designating here the wind-driven transport of snow particles below and above 2 m) on the near-surface atmosphere and surface in Adelie Land, East Antarctica. Two model runs were performed, one with and one without drifting snow, and compared to half-hourly in situ observations at D17, a coastal and windy location of Adelie Land. We show that sublimation of drifting-snow particles in the atmosphere drives the difference between model runs and is responsible for significant impacts on the near-surface atmosphere. By cooling the low atmosphere and increasing its relative humidity, drifting snow also reduces sensible and latent heat exchanges at the surface (−5.7 W m−2 on average). Moreover, large and dense drifting-snow layers act as near-surface cloud by interacting with incoming radiative fluxes, enhancing incoming longwave radiation and reducing incoming shortwave radiation in summer (net radiative forcing: 5.7 W m−2). Even if drifting snow modifies these processes involved in surface–atmosphere interactions, the total surface energy budget is only slightly modified by introducing drifting snow because of compensating effects in surface energy fluxes. The drifting-snow driven effects are not prominent near the surface but peak higher in the boundary layer (fourth vertical level, 12 m) where drifting-snow sublimation is the most pronounced. Accounting for drifting snow in MAR generally improves the comparison at D17, especially for the representation of relative humidity (mean bias reduced from −14.0 % to −0.7 %) and incoming longwave radiation (mean bias reduced from −20.4 W m−2 to −14.9 W m−2). Consequently, our results suggest that a detailed representation of drifting-snow processes is required in climate models to better capture the near-surface meteorology and surface–atmosphere interactions in coastal Adelie Land.

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.

scholarly journals Near-surface meteorology during the Arctic Summer Cloud Ocean Study (ASCOS): evaluation of reanalyses and global climate models

2014 ◽  
Vol 14 (1) ◽  
pp. 427-445 ◽  
Author(s):  
G. de Boer ◽  
M. D. Shupe ◽  
P. M. Caldwell ◽  
S. E. Bauer ◽  
O. Persson ◽  
...  
Keyword(s):  
Surface Energy ◽  
Energy Budget ◽  
Climate Models ◽  
Global Climate ◽  
Global Climate Models ◽  
Surface Energy Budget ◽  
The Arctic ◽  
Near Surface ◽  
Ocean Study ◽  
Arctic Summer

Abstract. Atmospheric measurements from the Arctic Summer Cloud Ocean Study (ASCOS) are used to evaluate the performance of three atmospheric reanalyses (European Centre for Medium Range Weather Forecasting (ECMWF)-Interim reanalysis, National Center for Environmental Prediction (NCEP)-National Center for Atmospheric Research (NCAR) reanalysis, and NCEP-DOE (Department of Energy) reanalysis) and two global climate models (CAM5 (Community Atmosphere Model 5) and NASA GISS (Goddard Institute for Space Studies) ModelE2) in simulation of the high Arctic environment. Quantities analyzed include near surface meteorological variables such as temperature, pressure, humidity and winds, surface-based estimates of cloud and precipitation properties, the surface energy budget, and lower atmospheric temperature structure. In general, the models perform well in simulating large-scale dynamical quantities such as pressure and winds. Near-surface temperature and lower atmospheric stability, along with surface energy budget terms, are not as well represented due largely to errors in simulation of cloud occurrence, phase and altitude. Additionally, a development version of CAM5, which features improved handling of cloud macro physics, has demonstrated to improve simulation of cloud properties and liquid water amount. The ASCOS period additionally provides an excellent example of the benefits gained by evaluating individual budget terms, rather than simply evaluating the net end product, with large compensating errors between individual surface energy budget terms that result in the best net energy budget.

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

2011 ◽  
Vol 5 (5) ◽  
pp. 2665-2697
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), including 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 reduction of net longwave and latent heat fluxes, providing energy for significant melt.

scholarly journals Near-surface meteorology during the Arctic Summer Cloud Ocean Study (ASCOS): evaluation of reanalyses and global climate models

2013 ◽  
Vol 13 (7) ◽  
pp. 19421-19470 ◽  
Author(s):  
G. de Boer ◽  
M. D. Shupe ◽  
P. M. Caldwell ◽  
S. E. Bauer ◽  
P. O. G. Persson ◽  
...  
Keyword(s):  
Surface Energy ◽  
Energy Budget ◽  
Climate Models ◽  
Global Climate ◽  
Global Climate Models ◽  
Surface Energy Budget ◽  
The Arctic ◽  
Near Surface ◽  
Ocean Study ◽  
Arctic Summer

Abstract. Atmospheric measurements from the Arctic Summer Cloud Ocean Study (ASCOS) are used to evaluate the performance of three reanalyses (ERA-Interim, NCEP/NCAR and NCEP/DOE) and two global climate models (CAM5 and NASA GISS ModelE2) in simulation of the high Arctic environment. Quantities analyzed include near surface meteorological variables such as temperature, pressure, humidity and winds, surface-based estimates of cloud and precipitation properties, the surface energy budget, and lower atmospheric temperature structure. In general, the models perform well in simulating large scale dynamical quantities such as pressure and winds. Near-surface temperature and lower atmospheric stability, along with surface energy budget terms are not as well represented due largely to errors in simulation of cloud occurrence, phase and altitude. Additionally, a development version of CAM5, which features improved handling of cloud macro physics, is demonstrated to improve simulation of cloud properties and liquid water amount. The ASCOS period additionally provides an excellent example of the need to evaluate individual budget terms, rather than simply evaluating the net end product, with large compensating errors between individual surface energy budget terms resulting in the best net energy budget.

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 Arctic Cloud Fraction and Radiative Fluxes in Atmospheric Reanalyses

2009 ◽  
Vol 22 (9) ◽  
pp. 2316-2334 ◽  
Author(s):  
John E. Walsh ◽  
William L. Chapman ◽  
Diane H. Portis
Keyword(s):  
Surface Energy ◽  
Energy Budget ◽  
Radiative Forcing ◽  
Cloud Fraction ◽  
Surface Energy Budget ◽  
Japan Meteorological Agency ◽  
Central Research ◽  
Radiative Fluxes ◽  
Arctic Clouds ◽  
Cloud Radiative Forcing

Abstract Arctic radiative fluxes, cloud fraction, and cloud radiative forcing are evaluated from four currently available reanalysis models using data from the North Slope of Alaska (NSA) Barrow site of the Atmospheric Radiation Measurement Program (ARM). A primary objective of the ARM–NSA program is to provide a high-resolution dataset of direct measurements of Arctic clouds and radiation so that global climate models can better parameterize high-latitude cloud radiative processes. The four reanalysis models used in this study are the 1) NCEP–NCAR global reanalysis, 2) 40-yr ECMWF Re-Analysis (ERA-40), 3) NCEP–NCAR North American Regional Reanalysis (NARR), and 4) Japan Meteorological Agency and Central Research Institute of Electric Power Industry 25-yr Reanalysis (JRA25). The reanalysis models simulate the radiative fluxes well if/when the cloud fraction is simulated correctly. However, the systematic errors of climatological reanalysis cloud fractions are substantial. Cloud fraction and radiation biases show considerable scatter, both in the annual mean and over a seasonal cycle, when compared to those observed at the ARM–NSA. Large seasonal cloud fraction biases have significant impacts on the surface energy budget. Detailed comparisons of ARM and reanalysis products reveal that the persistent low-level cloud fraction in summer is particularly difficult for the reanalysis models to capture creating biases in the shortwave radiation flux that can exceed 160 W m−2. ERA-40 is the best performer in both shortwave and longwave flux seasonal representations at Barrow, largely because its simulation of the cloud coverage is the most realistic of the four reanalyses. Only two reanalyses (ERA-40 and NARR) capture the observed transition from positive to negative surface net cloud radiative forcing during a 2–3-month period in summer, while the remaining reanalyses indicate a net warming impact of Arctic clouds on the surface energy budget throughout the entire year. The authors present a variable cloud radiative forcing metric to diagnose the erroneous impact of reanalysis cloud fraction on the surface energy balance. The misrepresentations of cloud radiative forcing in some of the reanalyses are attributable to errors in both simulated cloud amounts and the models’ radiative response to partly cloudy conditions.

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 Quantification of the radiative impact of light-absorbing particles during two contrasted snow seasons at Col du Lautaret (2058 m a.s.l., French Alps)

2020 ◽  
Author(s):  
François Tuzet ◽  
Marie Dumont ◽  
Ghislain Picard ◽  
Maxim Lamare ◽  
Didier Voisin ◽  
...  
Keyword(s):  
Radiative Forcing ◽  
Near Infrared ◽  
Measurement Techniques ◽  
Meteorological Conditions ◽  
Surface Energy Budget ◽  
Near Surface ◽  
French Alps ◽  
Snow Season ◽  
Snow Metamorphism ◽  
The Impact

Abstract. The presence of light-absorbing particles (LAPs) in snow leads to a decrease in shortwave albedo, affecting the surface energy budget. Precisely quantifying the impacts of LAPs on snowpack evolution is crucial to characterise the spatio-temporal variability of snowmelt and assess snow albedo feedbacks in detail. However, the understanding of the impacts of LAPs is hampered by the lack of dedicated datasets, as well as the scarcity of models able to represent the interactions between LAPs and snow metamorphism. The present study aims to address both these limitations by introducing a survey of LAP concentrations over two snow seasons in the French Alps, as well as an estimation of their impacts based on the Crocus snowpack model that represents the complex interplays between LAP dynamics and snow metamorphism. First, we present a unique dataset collected at the Col du Lautaret (2058 m a.s.l; French Alps) for the two snow seasons 2016–2017 and 2017–2018. This dataset consists of spectral albedo measurements (manual and automated), vertical profiles of snow specific surface area (SSA), density, and concentrations of refractive Black Carbon (rBC), Elemental Carbon (EC) and mineral dust. Spectral albedo data are processed to estimate near-surface SSA and LAP absorption-equivalent concentrations near the surface of the snowpack. These estimates are then compared to chemical measurements of dust and BC concentrations, as well as to SSA measurements acquired by near-infrared reflectometry. Our dataset highlights large discrepancies between the two measurement techniques of BC concentrations, with EC concentrations being one order of magnitude higher than rBC measurements. In view of LAP absorption inferred from albedo measurements, the mass absorption efficiency (MAE) of BC used in our study (11.25 g m−2 at 550 nm) is more appropriate for EC measurements than for rBC ones. Second, we present ensemble snowpack simulations of ESCROC – the multi-physics version of the detailed snowpack model Crocus – forced with in-situ meteorological data as well as dust and BC deposition fluxes from the ALADIN-Climate atmospheric model. The results of these simulations are compared to the near-surface properties estimated from automatic albedo measurements, showing that the temporal variations of near-surface LAP concentration and SSA are correctly reproduced. The impact of dust and BC on our simulations is estimated by comparing this ensemble to a similar ensemble that does not account for LAPs. The seasonal radiative forcing of LAPs is 1.33 times higher for the 2017–2018 snow season than for the 2016–2017 one, highlighting a strong variability between these two seasons. However, the shortening of the snow season caused by LAPs are similar with 10 ± 5 and 11 ± 1 days for the first and the second snow seasons respectively. This counter-intuitive result is attributed to two small snowfalls at the end of the first season and highlights the importance to account for meteorological conditions to correctly predict the impact of LAPs. The strong variability of season shortening caused by LAPs in the multi-physics ensemble for the first season also points out the sensitivity of model-based estimations of LAP impact to modelling uncertainties of other processes. Finally, the indirect impact of LAPs (i.e. the enhancement of energy absorption due to acceleration of the metamorphism by LAPs) is negligible for the two years considered here, contrary to what was found in previous studies for other sites. This finding is mainly attributed to the meteorological conditions of the two studied snow seasons.

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