scholarly journals Analysis of meteorological data and the surface energy balance of McCall Glacier, Alaska, USA

2005 ◽  
Vol 51 (174) ◽  
pp. 451-461 ◽  
Author(s):  
E.J. Klok ◽  
M. Nolan ◽  
M.R. Van Den Broeke
Keyword(s):  
Energy Balance ◽  
Surface Energy ◽  
Mass Balance ◽  
Forest Fires ◽  
Surface Energy Balance ◽  
Meteorological Data ◽  
Heat Fluxes ◽  
Turbulent Heat ◽  
Net Radiation ◽  
Specific Mass

AbstractWe report on analysis of meteorological data for the period 27 May–20 August 2004, from two automatic weather stations on McCall Glacier, Alaska, USA, aimed at studying the relationship between climate and ablation. One station is located on a mountain ridge and the other in the ablation area where we also analyzed the energy balance. The weather station on the glacier measured an average temperature of 5.3°C (at 2 m height above surface) and wind speed of 3.1 m s−1 (at 3 m height). A sonic height ranger and ablation stakes indicate a specific mass balance of –1.94 ± 0.09 m w.e between 15 June and 20 August. The specific mass balance calculated from the surface energy balance, –2.06 ± 0.18 m w.e., is in close correspondence to this. The latter is the sum of 0.12 m w.e. of snowfall, 0.003 m w.e. of deposition and –2.18 m w.e. of melt. Net radiation contributes 74% of the melt energy. Compared to ablation measurements in the early 1970s, summer ablation was large. This increase is explained by a combination of a relatively higher net radiation, a lower albedo and larger turbulent heat fluxes that led to more energy being available for melting. No single meteorological variable can be isolated as being the principal reason for the high ablation, however. The lower ice albedo (0.19) is possibly due to ash deposits from forest fires.

scholarly journals Water tracks intensify surface energy and mass exchange in the Antarctic McMurdo Dry Valleys

2019 ◽  
Vol 13 (8) ◽  
pp. 2203-2219 ◽  
Author(s):  
Tobias Linhardt ◽  
Joseph S. Levy ◽  
Christoph K. Thomas
Keyword(s):  
Climate Change ◽  
Energy Balance ◽  
Surface Energy ◽  
Surface Energy Balance ◽  
Heat Fluxes ◽  
Dry Valleys ◽  
Sensible Heat ◽  
Net Radiation ◽  
Taylor Valley ◽  
The Antarctic

Abstract. The hydrologic cycle in the Antarctic McMurdo Dry Valleys (MDV) is mainly controlled by surface energy balance. Water tracks are channel-shaped high-moisture zones in the active layer of permafrost soils and are important solute and water pathways in the MDV. We evaluated the hypothesis that water tracks alter the surface energy balance in this dry, cold, and ice-sheet-free environment during summer warming and may therefore be an increasingly important hydrologic feature in the MDV in the face of landscape response to climate change. The surface energy balance was measured for one water track and two off-track reference locations in Taylor Valley over 26 d of the Antarctic summer of 2012–2013. Turbulent atmospheric fluxes of sensible heat and evaporation were observed using the eddy-covariance method in combination with flux footprint modeling, which was the first application of this technique in the MDV. Soil heat fluxes were analyzed by measuring the heat storage change in the thawed layer and approximating soil heat flux at ice table depth by surface energy balance residuals. For both water track and reference locations over 50 % of net radiation was transferred to sensible heat exchange, about 30 % to melting of the seasonally thawed layer, and the remainder to evaporation. The net energy flux in the thawed layer was zero. For the water track location, evaporation was increased by a factor of 3.0 relative to the reference locations, ground heat fluxes by 1.4, and net radiation by 1.1, while sensible heat fluxes were reduced down to 0.7. Expecting a positive snow and ground ice melt response to climate change in the MDV, we entertained a realistic climate change response scenario in which a doubling of the land cover fraction of water tracks increases the evaporation from soil surfaces in lower Taylor Valley in summer by 6 % to 0.36 mm d−1. Possible climate change pathways leading to this change in landscape are discussed. Considering our results, an expansion of water track area would make new soil habitats accessible, alter soil habitat suitability, and possibly increase biological activity in the MDV. In summary, we show that the surface energy balance of water tracks distinctly differs from that of the dominant dry soils in polar deserts. With an expected increase in area covered by water tracks, our findings have implications for hydrology and soil ecosystems across terrestrial Antarctica.

scholarly journals The Surface Energy Balance System (SEBS) for estimation of turbulent heat fluxes

2002 ◽  
Vol 6 (1) ◽  
pp. 85-100 ◽  
Author(s):  
Z. Su
Keyword(s):  
Energy Balance ◽  
Surface Energy ◽  
Surface Energy Balance ◽  
Heat Fluxes ◽  
Physical Parameters ◽  
Turbulent Heat ◽  
Evaporative Fraction ◽  
Balance System ◽  
Turbulent Heat Fluxes

Abstract. A Surface Energy Balance System (SEBS) is proposed for the estimation of atmospheric turbulent fluxes and evaporative fraction using satellite earth observation data, in combination with meteorological information at proper scales. SEBS consists of: a set of tools for the determination of the land surface physical parameters, such as albedo, emissivity, temperature, vegetation coverage etc., from spectral reflectance and radiance measurements; a model for the determination of the roughness length for heat transfer; and a new formulation for the determination of the evaporative fraction on the basis of energy balance at limiting cases. Four experimental data sets are used to assess the reliabilities of SEBS. Based on these case studies, SEBS has proven to be capable to estimate turbulent heat fluxes and evaporative fraction at various scales with acceptable accuracy. The uncertainties in the estimated heat fluxes are comparable to in-situ measurement uncertainties. Keywords: Surface energy balance, turbulent heat flux, evaporation, remote sensing

scholarly journals The surface energy balance of a polygonal tundra site in northern Siberia – Part 1: Spring to fall

2011 ◽  
Vol 5 (1) ◽  
pp. 151-171 ◽  
Author(s):  
M. Langer ◽  
S. Westermann ◽  
S. Muster ◽  
K. Piel ◽  
J. Boike
Keyword(s):  
Heat Flux ◽  
Energy Balance ◽  
Surface Energy ◽  
Snow Cover ◽  
Latent Heat ◽  
Latent Heat Flux ◽  
Surface Energy Balance ◽  
Heat Fluxes ◽  
Net Radiation ◽  
Ground Heat Flux

Abstract. In this article, we present a study on the surface energy balance of a polygonal tundra landscape in northeast Siberia. The study was performed during half-year periods from April to September in each of 2007 and 2008. The surface energy balance is obtained from independent measurements of the net radiation, the turbulent heat fluxes, and the ground heat flux at several sites. Short-wave radiation is the dominant factor controlling the magnitude of all the other components of the surface energy balance during the entire observation period. About 50% of the available net radiation is consumed by the latent heat flux, while the sensible and the ground heat flux are each around 20 to 30%. The ground heat flux is mainly consumed by active layer thawing. About 60% of the energy storage in the ground is attributed to the phase change of soil water. The remainder is used for soil warming down to a depth of 15 m. In particular, the controlling factors for the surface energy partitioning are snow cover, cloud cover, and the temperature gradient in the soil. The thin snow cover melts within a few days, during which the equivalent of about 20% of the snow-water evaporates or sublimates. Surface temperature differences of the heterogeneous landscape indicate spatial variabilities of sensible and latent heat fluxes, which are verified by measurements. However, spatial differences in the partitioning between sensible and latent heat flux are only measured during conditions of high radiative forcing, which only occur occasionally.

scholarly journals Strong Summer Atmospheric Rivers Trigger Greenland Ice Sheet Melt through Spatially Varying Surface Energy Balance and Cloud Regimes

2020 ◽  
Vol 33 (16) ◽  
pp. 6809-6832 ◽  
Author(s):  
Kyle S. Mattingly ◽  
Thomas L. Mote ◽  
Xavier Fettweis ◽  
Dirk van As ◽  
Kristof Van Tricht ◽  
...  
Keyword(s):  
Energy Balance ◽  
Surface Energy ◽  
Surface Energy Balance ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Heat Fluxes ◽  
Water Vapor Transport ◽  
Turbulent Heat ◽  
Atmospheric Rivers ◽  
Turbulent Heat Fluxes

ABSTRACTMass loss from the Greenland Ice Sheet (GrIS) has accelerated over the past two decades, coincident with rapid Arctic warming and increasing moisture transport over Greenland by atmospheric rivers (ARs). Summer ARs affecting western Greenland trigger GrIS melt events, but the physical mechanisms through which ARs induce melt are not well understood. This study elucidates the coupled surface–atmosphere processes by which ARs force GrIS melt through analysis of the surface energy balance (SEB), cloud properties, and local- to synoptic-scale atmospheric conditions during strong summer AR events affecting western Greenland. ARs are identified in MERRA-2 reanalysis (1980–2017) and classified by integrated water vapor transport (IVT) intensity. SEB, cloud, and atmospheric data from regional climate model, observational, reanalysis, and satellite-based datasets are used to analyze melt-inducing physical processes during strong, >90th percentile “AR90+” events. Near AR “landfall,” AR90+ days feature increased cloud cover that reduces net shortwave radiation and increases net longwave radiation. As these oppositely signed radiative anomalies partly cancel during AR90+ events, increased melt energy in the ablation zone is primarily provided by turbulent heat fluxes, particularly sensible heat flux. These turbulent heat fluxes are driven by enhanced barrier winds generated by a stronger synoptic pressure gradient combined with an enhanced local temperature contrast between cool over-ice air and the anomalously warm surrounding atmosphere. During AR90+ events in northwest Greenland, anomalous melt is forced remotely through a clear-sky foehn regime produced by downslope flow in eastern Greenland.

scholarly journals The recent retreat of Mexican glaciers on Citlaltépetl Volcano detected using ASTER data

2012 ◽  
Vol 6 (4) ◽  
pp. 3149-3176 ◽  
Author(s):  
J. Cortés-Ramos ◽  
H. Delgado-Granados
Keyword(s):  
Energy Balance ◽  
Surface Energy ◽  
Satellite Imagery ◽  
Surface Energy Balance ◽  
Meteorological Data ◽  
Radiation Balance ◽  
Net Radiation ◽  
Glacial Retreat ◽  
Radiation Data ◽  
Close Relationship

Abstract. Satellite imagery and net radiation data collected between 2001 and 2007 for Citlaltépetl Volcano confirm the dramatic shrinkage of Glaciar Norte and the elimination of Jamapa and Chichimeco glacier tongues. The Glaciar Norte rapidly retreated between 2001 and 2002 while for 2007 this retreat decreases considerably. Jamapa and Chichimeco tongues disappeared by 2001 as compared to the geometry shown for 1958. The Glaciar Norte lost about 72% of its surface area between 1958 and 2007. Recently, the ice loss appears to be accelerating as evidenced by the 33% areal loss in just 6 yr between 2001 and 2007. At this shrinkage rate the glaciers would be gone from the volcano by the year 2020, which is decades earlier than previously estimated. The net radiation from ASTER images and the energy fluxes calculated via the meteorological data at the glacial surface show the close relationship between glacial shrinkage and surface energy balance. The magnitude of changes in the net radiation balance allows improved understanding of glacial retreat in Mexico.

scholarly journals Diurnal land surface energy balance partitioning estimated from the thermodynamic limit of a cold heat engine

2018 ◽  
Author(s):  
Axel Kleidon ◽  
Maik Renner
Keyword(s):  
Energy Balance ◽  
Surface Energy ◽  
Thermodynamic Limit ◽  
Land Surface ◽  
Radiative Forcing ◽  
Surface Energy Balance ◽  
Heat Engine ◽  
Turbulent Fluxes ◽  
Heat Fluxes ◽  
Turbulent Heat

Abstract. Turbulent fluxes strongly shape the conditions at the land surface, yet they are typically formulated in terms of semi-empirical parameterisations that make it difficult to derive theoretical estimates of how global change impacts land surface functioning. Here, we describe these turbulent fluxes as the result of a thermodynamic process that generates work to sustain convective motion and thus maintains the turbulent exchange between the land surface and the atmosphere. We first derive a limit from the second law of thermodynamics that is equivalent to the Carnot limit, but which explicitly accounts for diurnal heat storage changes in the lower atmosphere. We then use this limit of a cold heat engine together with the surface energy balance to infer the maximum power that can be derived from the turbulent fluxes for a given solar radiative forcing. The surface energy balance partitioning estimated from this thermodynamic limit requires no empirical parameters and compares very well with the observed partitioning of absorbed solar radiation into radiative and turbulent heat fluxes across a range of climates, with correlation coefficients r2 ≥ 95 % and slopes near one. These results suggest that turbulent heat fluxes on land operate near their thermodynamic limit on how much convection can be generated from the local radiative forcing. It implies that this type of approach can be used to derive first-order estimates of global change that are solely based on physical principles.

scholarly journals Surface-Energy-Balance Closure over Land: A Review

2020 ◽  
Vol 177 (2-3) ◽  
pp. 395-426 ◽  
Author(s):  
Matthias Mauder ◽  
Thomas Foken ◽  
Joan Cuxart
Keyword(s):  
Energy Balance ◽  
Surface Energy ◽  
Surface Energy Balance ◽  
Transport Processes ◽  
Heat Fluxes ◽  
Future Research ◽  
Turbulent Heat ◽  
Energy Balance Closure ◽  
Airborne Measurements ◽  
Open Questions

Abstract Quantitative knowledge of the surface energy balance is essential for the prediction of weather and climate. However, a multitude of studies from around the world indicate that the turbulent heat fluxes are generally underestimated using eddy-covariance measurements, and hence, the energy balance is not closed. This energy-balance-closure problem, which has been heavily covered in the literature for more than 25 years, is the topic of the present review, in which we provide an overview of the potential reason for the lack of closure. We demonstrate the effects of the diurnal cycle on the energy balance closure, and address questions with regard to the partitioning of the energy balance residual between the sensible and the latent fluxes, and whether the magnitude of the flux underestimation can be predicted based on other variables typically measured at micrometeorological stations. Remaining open questions are discussed and potential avenues for future research on this topic are laid out. Integrated studies, combining multi-tower experiments and scale-crossing, spatially-resolving lidar and airborne measurements with high-resolution large-eddy simulations, are considered to be of critical importance for enhancing our understanding of the underlying transport processes in the atmospheric boundary layer.

scholarly journals Diurnal land surface energy balance partitioning estimated from the thermodynamic limit of a cold heat engine

2018 ◽  
Vol 9 (3) ◽  
pp. 1127-1140 ◽  
Author(s):  
Axel Kleidon ◽  
Maik Renner
Keyword(s):  
Energy Balance ◽  
Surface Energy ◽  
Thermodynamic Limit ◽  
Land Surface ◽  
Radiative Forcing ◽  
Surface Energy Balance ◽  
Heat Engine ◽  
Turbulent Fluxes ◽  
Heat Fluxes ◽  
Turbulent Heat

Abstract. Turbulent fluxes strongly shape the conditions at the land surface, yet they are typically formulated in terms of semiempirical parameterizations that make it difficult to derive theoretical estimates of how global change impacts land surface functioning. Here, we describe these turbulent fluxes as the result of a thermodynamic process that generates work to sustain convective motion and thus maintains the turbulent exchange between the land surface and the atmosphere. We first derive a limit from the second law of thermodynamics that is equivalent to the Carnot limit but which explicitly accounts for diurnal heat storage changes in the lower atmosphere. We call this the limit of a “cold” heat engine and use it together with the surface energy balance to infer the maximum power that can be derived from the turbulent fluxes for a given solar radiative forcing. The surface energy balance partitioning estimated from this thermodynamic limit requires no empirical parameters and compares very well with the observed partitioning of absorbed solar radiation into radiative and turbulent heat fluxes across a range of climates, with correlation coefficients r2≥95 % and slopes near 1. These results suggest that turbulent heat fluxes on land operate near their thermodynamic limit on how much convection can be generated from the local radiative forcing. It implies that this type of approach can be used to derive general estimates of global change that are solely based on physical principles.

Surface energy balance closure – the role dispersive fluxes induced by submesoscale secondary circulations

2021 ◽  
Author(s):  
Matthias Mauder
Keyword(s):  
Energy Balance ◽  
Surface Energy ◽  
Eddy Covariance ◽  
Large Scale ◽  
Surface Energy Balance ◽  
Heat Fluxes ◽  
Turbulent Heat ◽  
Energy Balance Closure ◽  
Secondary Circulations ◽  
Dispersive Fluxes

<p>Quantitative knowledge of the surface energy balance is essential for the prediction of weather and climate. However, a multitude of studies from around the world indicates that the turbulent heat fluxes are generally underestimated using eddy-covariance measurements, and hence, the surface energy balance is not closed. This energy balance closure problem has been heavily covered in the literature for more than 25 years, and as a result, several instrumental and methodological aspects have been reconsidered and partially revised. Nevertheless, a non-negligible energy imbalance remains, and we demonstrate that a major portion of this imbalance can be explained by dispersive fluxes in the surface layer, which are associated with submesoscale secondary circulations. Such large-scale organized structures are a very common phenomenon in the convective boundary layer, and depending on static stability, they can either be roll-like or cell-like and occur even over homogeneous surfaces. Over heterogeneous surfaces, thermally-induced mesoscale circulations can occur in addition to those. Either way, the associated dispersive heat fluxes can inherently not be captured by single-tower measurements, since the ergodicity assumption is violated. As a consequence, energy transported non-turbulently will not be sensed by eddy-covariance systems and a bias towards lower energy fluxes will result. The objective of this research is to develop a model that can be used to correct single-tower eddy-covariance data. As a first step towards this goal, we will present a parametrisation for dispersive fluxes, which was developed based on an idealized high-resolution LES study for homogeneous surfaces, as a function of non-local scaling variables. Secondly, we explore how well this parametrisation works for a number of real-world eddy-covariance sites.</p>

scholarly journals Using climate reanalysis data in conjunction with multi-temporal satellite thermal imagery to derive supraglacial debris thickness changes from energy-balance modelling

2021 ◽  
pp. 1-19
Author(s):  
Rebecca L. Stewart ◽  
Matthew Westoby ◽  
Francesca Pellicciotti ◽  
Ann Rowan ◽  
Darrel Swift ◽  
...  
Keyword(s):  
Energy Balance ◽  
Surface Energy ◽  
Surface Energy Balance ◽  
Current Knowledge ◽  
Meteorological Data ◽  
Reanalysis Data ◽  
Balance Model ◽  
Thermal Imagery ◽  
Thickness Estimation ◽  
Miage Glacier

Abstract Surface energy-balance models are commonly used in conjunction with satellite thermal imagery to estimate supraglacial debris thickness. Removing the need for local meteorological data in the debris thickness estimation workflow could improve the versatility and spatiotemporal application of debris thickness estimation. We evaluate the use of regional reanalysis data to derive debris thickness for two mountain glaciers using a surface energy-balance model. Results forced using ERA-5 agree with AWS-derived estimates to within 0.01 ± 0.05 m for Miage Glacier, Italy, and 0.01 ± 0.02 m for Khumbu Glacier, Nepal. ERA-5 data were then used to estimate spatiotemporal changes in debris thickness over a ~20-year period for Miage Glacier, Khumbu Glacier and Haut Glacier d'Arolla, Switzerland. We observe significant increases in debris thickness at the terminus for Haut Glacier d'Arolla and at the margins of the expanding debris cover at all glaciers. While simulated debris thickness was underestimated compared to point measurements in areas of thick debris, our approach can reconstruct glacier-scale debris thickness distribution and its temporal evolution over multiple decades. We find significant changes in debris thickness over areas of thin debris, areas susceptible to high ablation rates, where current knowledge of debris evolution is limited.

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