scholarly journals Long-term energy balance measurements at three different mountain permafrost sites in the Swiss Alps

2021 ◽  
Author(s):  
Martin Hoelzle ◽  
Christian Hauck ◽  
Tamara Mathys ◽  
Jeannette Noetzli ◽  
Cécile Pellet ◽  
...  
Keyword(s):  
Energy Balance ◽  
Air Temperature ◽  
Thermal Regime ◽  
Surface Energy Balance ◽  
Heat Fluxes ◽  
Swiss Alps ◽  
Net Radiation ◽  
Ground Heat Flux

Abstract. The surface energy balance is a key factor influencing the ground thermal regime. With ongoing climate change, it is crucial to understand the interactions of the individual heat fluxes at the surface and within the subsurface layers as well as their relative impacts on permafrost thermal regime. A unique set of high-altitude meteorological measurements has been analysed to determine the energy balance at three mountain permafrost sites in the Swiss Alps (Murtèl-Corvatsch, Schilthorn and Stockhorn), where data is being collected since the late 1990s in collaboration with the Swiss Permafrost Monitoring Network (PERMOS). All stations are equipped with sensors for four-component radiation, air temperature, humidity, wind speed and direction as well as ground temperatures and snow height. The three sites differ considerably in their surface and ground material composition as well as their ground ice contents. The energy fluxes are calculated based on two decades of field measurements. While the determination of the radiation budget and the ground heat flux is comparatively straightforward (by the four-component radiation sensor and thermistor measurements within the boreholes), larger uncertainties exist for the determination of turbulent sensible and latent heat fluxes. Our results show that mean air temperature at Murtèl-Corvatsch (1997–2018, 2600 m asl.) is −1.66 °C and has increased by about 0.7 °C during the measurement period. At the Schilthorn site (1999–2018, 2900 m asl.) a mean air temperature of −2.60 °C with a mean increase of 1.0 °C was measured. The Stockhorn site (2003–2018, 3400 m asl.) recorded lower air temperatures with a mean of −6.18 °C and an increase of 0.7 °C. Measured net radiation, as the most important energy input at the surface, shows substantial differences with mean values of 30.59 W m−2 for Murtèl-Corvatsch, 32.40 W m−2 for Schilthorn and 6.91 W m−2 for Stockhorn. The calculated turbulent fluxes show values of around 7 to 13 W m−2 using the Bowen ratio method and 3 to 15 W m−2 using the bulk method at all sites. Large differences are observed regarding the energy used for melting of the snow cover: at Schilthorn a value of 8.46 W m−2, at Murtèl-Corvatsch of 4.17 W m−2 and at Stockhorn of 2.26 W m−2 is calculated reflecting the differences in snow height at the three sites. In general, we found considerable differences in the energy fluxes at the different sites. These differences may help to explain and interpret the causes of the varying reactions of the permafrost thermal regime at the three sites to a warming atmosphere. We recognize a strong relation between the net radiation and the ground heat flux. Our results further demonstrate the importance of long-term monitoring in order to better understand the impacts of changes in the surface energy balance components on the permafrost thermal regime. The dataset presented can be used to improve permafrost modelling studies aiming at e.g. advancing knowledge about permafrost thaw processes. The data presented and described in this study is available for download at the following site http://dx.doi.org/10.13093/permos-meteo-2021-01 (Hoelzle et al., 2021).

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.

Long-term energy balance measurements at three different mountain permafrost sites in the Swiss Alps

2020 ◽  
Author(s):  
Martin Hoelzle ◽  
Christian Hauck ◽  
Jeannette Noetzli ◽  
Cécile Pellet ◽  
Martin Scherler
Keyword(s):  
Energy Balance ◽  
Air Temperature ◽  
Bowen Ratio ◽  
Heat Fluxes ◽  
Swiss Alps ◽  
Ratio Method ◽  
Fine Grained ◽  
Mountain Permafrost ◽  
Ice Content

<p>The surface energy balance is one of the most important influencing factors for the ground thermal regime. It is therefore crucial to understand the interactions of the individual heat fluxes at the surface and within the subsurface layers as well as their relative impacts. A unique set of high-altitude meteorological measurements has been analysed to determine the energy balance at three mountain permafrost sites in the Swiss Alps, where data is being collected since the late 1990s in collaboration with the Swiss Permafrost Monitoring (PERMOS). The three stations have a standardized equipment with sensors for four-component radiation, air temperature, humidity, wind speed and direction as well as ground temperatures and snow height. The three sites differ considerably by their surface and ground material composition ranging from a coarse blocky active layer above ice supersaturated permafrost at rock glacier Murtèl-Corvatsch to deeply weathered micaceous shales, which are covered by fine grained debris of sandy and silty material with a low ice content at the Northern slope of Schilthorn summit. The third site at the Stockhorn plateau shows intermediate ice contents and heterogeneous surface conditions with medium-size debris, fine grained material and outcropping bedrock. Ice content estimation and general ground characterisation are based on geophysical surveying and borehole drilling.</p><p> </p><p>The energy fluxes are calculated based on around two decades of field measurements. While the determination of the radiation budget and the ground heat flux is comparatively straightforward (by the four-component radiation sensor and thermistor measurements within the boreholes, respectively), larger uncertainties exist for the determination of sensible and latent turbulent heat fluxes. They are therefore determined on the one hand by the bulk aerodynamic method using the bulk Richardson number to describe the stability of the surface layer relating the relative effects of buoyancy to mechanical forces and on the other hand by the bowen ratio method.</p><p> </p><p>Results show that mean air temperature at Murtèl-Corvatsch (1997–2018, elevation 2600 m asl.) is –1.66°C and has increased by about 0.7°C during the observation period. The Schilthorn (1999–2018, elevation 2900 m asl.) site shows a mean air temperature of –2.48°C with a mean increase of 1.0°C and the Stockhorn (2003–2018, elevation 3400 m asl.) site shows lower air temperatures with a mean of –5.99°C with an increase of 0.6°C. Measured net radiation, as the most important energy input at the surface, shows substantial differences with mean values of 33.41 Wm<sup>-2</sup> for Murtèl-Corvatsch, 40.65 Wm<sup>-2</sup> for Schilthorn and 24.88 Wm<sup>-2</sup> for Stockhorn. The calculated turbulent fluxes show values of around 7 to 12 Wm<sup>-2</sup> using the bowen ratio method and 8 to 18 Wm<sup>-2</sup> using the bulk method at all sites. Large differences are observed regarding the energy used for melting of the snow cover: at Schilthorn a value of 12.41 Wm<sup>-2</sup>, at Murtèl-Corvatsch of 7.31 Wm<sup>-2</sup> and at Stockhorn of 3.46 Wm<sup>-2</sup> is calculated reflecting the differences in snow height at the three sites.</p>

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 Permafrost and surface energy balance of a polygonal tundra site in northern Siberia – Part 1: Spring to fall

2010 ◽  
Vol 4 (3) ◽  
pp. 901-947 ◽  
Author(s):  
M. Langer ◽  
S. Westermann ◽  
S. Muster ◽  
K. Piel ◽  
J. Boike
Keyword(s):  
Heat Flux ◽  
Energy Balance ◽  
Surface Energy ◽  
Latent Heat ◽  
Latent Heat Flux ◽  
Surface Energy Balance ◽  
Heat Fluxes ◽  
Dominant Factor ◽  
Wave Radiation ◽  
Ground Heat Flux

Abstract. Permafrost thawing is essentially determined by the surface energy balance, which potentially triggers the activation of a massive carbon source, if previously frozen organic soils are exposed to microbial decomposition. In this article, we present the first part of a comprehensive annual surface energy balance study performed at a polygonal tundra landscape in northeast Siberia, realized between spring 2007 and winter 2009. This part of the study focuses on the half year period from April to September 2007–2008, during which the surface energy balance is obtained from independent measurements of the radiation budget, the turbulent heat fluxes and the ground heat flux at several sites. The short-wave radiation is the dominant factor in the surface energy balance during the entire observation period. About 50% of the available net radiation is consumed by latent heat flux, while the sensible and the ground heat flux are both on the order of 20 to 30%. The ground heat flux is mainly consumed by active layer thawing, where 60% of soil energy storage are attributed to. The remainder is used for soil warming down to a depth of 15 m. The controlling factors for the surface energy partitioning are in particular the snow cover, the cloud cover and the soil temperature gradient. Significant surface temperature differences of the heterogeneous landscape indicate spatial variabilities of sensible and latent heat fluxes, which are verified by measurements at different locations. However, differences in the partition between sensible and latent heat flux for the different sites only exist during conditions of high radiative forcing, which only occur occasionally.

scholarly journals Surface Temperature and Heat Fluxes: Comparison between Natural Forest and Oil Palm Plantation in Jambi Province Using Surface Energy Balance Algorithm for Land (SEBAL)

Agromet ◽  
2019 ◽  
Vol 33 (2) ◽  
pp. 62-70
Author(s):  
Salis Deris Artikanur ◽  
Tania June
Keyword(s):  
Heat Flux ◽  
Energy Balance ◽  
Surface Temperature ◽  
Oil Palm ◽  
Surface Energy Balance ◽  
Sensible Heat Flux ◽  
Canopy Cover ◽  
Heat Fluxes ◽  
Net Radiation ◽  
Oil Palm Plantation

One of the leading commodities that has contributed a lot of income for Indonesia is oil palm. Oil palm plantations in Jambi are widespread, affecting the energy balance and surface temperature. This study aims to compare surface temperature and heat fluxes of oil palm plantation with different ages, how is the difference between forest and oil palm plantation, and to analyze the effect of oil palm planting on micro-climate change in Jambi. Using the Surface Energy Balance Algorithm for Land (SEBAL), it was found that in Jambi, young oil palm (2 years old) had higher surface temperatures of 2oC compared with adult oil palm (19 years old). While the surface temperature of the adult oil palm plant is slightly higher than natural forest that is 0.5oC. The increase of the age of oil palm followed by the increase of plant height (h), Canopy Cover (CC), and surface roughness which resulted in the increase of NDVI value and the cooling effect around the plantation so that the surface temperature (Ts) decreased as indicated by equation TS = 27.00 - 0.1581h - 0.0317CC and NDVI = 0.1335 + 0.00892h + 0.00096CC. The sensible heat flux (H) is affected by surface temperature, roughness length, friction velocity, and aerodynamic resistance of the plant. The highest H value is in the oil palm plantation near Brimob which is 282 W/m2. Latent heat flux (LE) is the remainder of the net radiation minus the flux of the soil and the flux feels. The highest LE value is in the oil palm plantation of Pompa Air Village which is 710 W/m2. Substantially ground heat flux (G) is affected by net radiation, NDVI, surface temperature, and albedo. The highest value of G is in PT Pisifera Persada oil palm plantation of 98 W/m2.Keywords: NDVI, net radiation, sensible heat flux, latent heat flux, Canopy Cover

scholarly journals The surface energy balance of a polygonal tundra site in northern Siberia – Part 2: Winter

2011 ◽  
Vol 5 (2) ◽  
pp. 509-524 ◽  
Author(s):  
M. Langer ◽  
S. Westermann ◽  
S. Muster ◽  
K. Piel ◽  
J. Boike
Keyword(s):  
Heat Flux ◽  
Energy Balance ◽  
Surface Energy ◽  
Latent Heat ◽  
Latent Heat Flux ◽  
Surface Energy Balance ◽  
Sensible Heat ◽  
Net Radiation ◽  
Northern Siberia ◽  
Ground Heat Flux

Abstract. In this study, we present the winter time surface energy balance at a polygonal tundra site in northern Siberia based on independent measurements of the net radiation, the sensible heat flux and the ground heat flux from two winter seasons. The latent heat flux is inferred from measurements of the atmospheric turbulence characteristics and a model approach. The long-wave radiation is found to be the dominant factor in the surface energy balance. The radiative losses are balanced to about 60 % by the ground heat flux and almost 40 % by the sensible heat fluxes, whereas the contribution of the latent heat flux is small. The main controlling factors of the surface energy budget are the snow cover, the cloudiness and the soil temperature gradient. Large spatial differences in the surface energy balance are observed between tundra soils and a small pond. The ground heat flux released at a freezing pond is by a factor of two higher compared to the freezing soil, whereas large differences in net radiation between the pond and soil are only observed at the end of the winter period. Differences in the surface energy balance between the two winter seasons are found to be related to differences in snow depth and cloud cover which strongly affect the temperature evolution and the freeze-up at the investigated pond.

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 Analysing surface energy balance closure and partitioning over a semi-arid savanna FLUXNET site in Skukuza, Kruger National Park, South Africa

2017 ◽  
Vol 21 (7) ◽  
pp. 3401-3415 ◽  
Author(s):  
Nobuhle P. Majozi ◽  
Chris M. Mannaerts ◽  
Abel Ramoelo ◽  
Renaud Mathieu ◽  
Alecia Nickless ◽  
...  
Keyword(s):  
Heat Flux ◽  
Energy Balance ◽  
Surface Energy ◽  
Latent Heat ◽  
Surface Energy Balance ◽  
Sensible Heat Flux ◽  
Dry Season ◽  
Energy Balance Closure ◽  
Net Radiation ◽  
Wet Season

Abstract. Flux towers provide essential terrestrial climate, water, and radiation budget information needed for environmental monitoring and evaluation of climate change impacts on ecosystems and society in general. They are also intended for calibration and validation of satellite-based Earth observation and monitoring efforts, such as assessment of evapotranspiration from land and vegetation surfaces using surface energy balance approaches. In this paper, 15 years of Skukuza eddy covariance data, i.e. from 2000 to 2014, were analysed for surface energy balance closure (EBC) and partitioning. The surface energy balance closure was evaluated using the ordinary least squares regression (OLS) of turbulent energy fluxes (sensible (H) and latent heat (LE)) against available energy (net radiation (Rn) less soil heat (G)), and the energy balance ratio (EBR). Partitioning of the surface energy during the wet and dry seasons was also investigated, as well as how it is affected by atmospheric vapour pressure deficit (VPD), and net radiation. After filtering years with low-quality data (2004–2008), our results show an overall mean EBR of 0.93. Seasonal variations of EBR also showed the wet season with 1.17 and spring (1.02) being closest to unity, with the dry season (0.70) having the highest imbalance. Nocturnal surface energy closure was very low at 0.26, and this was linked to low friction velocity during night-time, with results showing an increase in closure with increase in friction velocity. The energy partition analysis showed that sensible heat flux is the dominant portion of net radiation, especially between March and October, followed by latent heat flux, and lastly the soil heat flux, and during the wet season where latent heat flux dominated sensible heat flux. An increase in net radiation was characterized by an increase in both LE and H, with LE showing a higher rate of increase than H in the wet season, and the reverse happening during the dry season. An increase in VPD is correlated with a decrease in LE and increase in H during the wet season, and an increase in both fluxes during the dry season.

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