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 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 Comparison of Aerodynamic, Bowen-Ratio, and Penman-Monteith Methods in Estimating Evapotranspiration of Oil Palm Plantation

Agromet ◽  
2018 ◽  
Vol 32 (1) ◽  
pp. 11
Author(s):  
Tania June ◽  
Ni Wayan Srimani Puspa Dewi ◽  
Ana Meijide
Keyword(s):  
Oil Palm ◽  
Economic Value ◽  
Global Radiation ◽  
Reference Method ◽  
Bowen Ratio ◽  
Ratio Method ◽  
Agricultural Commodity ◽  
Evapotranspiration Rate ◽  
Oil Palms

<p>Oil palm is one important agricultural commodity that has high economic value. Oil palm productivity is significantly influenced by its water use (needs). Measurement and estimation of oil palm evapotranspiration is needed for determination of its water needs. Various methods are available and this study compare three methods, consisting of aerodynamic, Bowen-Ratio and Penman-Monteith methods in analyzing water needs/use of oil palms plantation located in PTPN VI Jambi.  Peak of evapotranspiration rate occured in the afternoon around 13.00 and 14.00 local time. Bowen-Ratio method has higher estimation value of evapotranspiration than the other two methods. Ratio between evapotranspiration and global radiation of two and ten-years old oil palm plantations remain similar, around 47%. Penman Monteith method has the nearest estimation value to reference method (aerodynamic method) showed by the smallest RMSE value, 0.087 for two years oil palm and 0.157 for ten-years old oil palm.<strong> </strong></p>

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 Avaliação da Evapotranspiração de Pastagem pelo Método do Domo (Evaluation of Grassland Evapotranspiration by Dome Method)

2014 ◽  
Vol 7 (4) ◽  
pp. 716
Author(s):  
Irami Buarque Amazonas ◽  
Antônio Celso Dantas Antonino ◽  
Willames Albuquerque Sores ◽  
José Romualdo Sousa Lima ◽  
Suzana Maria Gico Lima Montenegro
Keyword(s):  
Experimental Data ◽  
Energy Balance ◽  
Bowen Ratio ◽  
Botanical Garden ◽  
Ratio Method ◽  
Satisfactory Performance ◽  
De Se ◽  
Para Determinar ◽  
The Town ◽  
Semi Arid

A região semiárida nordestina necessita de formas alternativas confiáveis economicamente e viáveis de se estimar a evaporação (E) ou a evapotranspiração (ET), uma vez que apresenta um regime de chuvas irregular e a ET se constitui na principal perda de água no sistema solo-planta-atmosfera. Dentre os vários métodos de se determinar a ET, o domo tem sido comparado com outros métodos, apresentando desempenho satisfatório e, por ser mais barato do que os demais, pode se tornar uma alternativa viável para medidas rápidas e pontuais. O domo consiste em uma cúpula de acrílico colocada sobre o solo, onde se determina a E ou ET a partir de medidas de temperatura e umidade no seu interior. Neste trabalho o domo foi usado para determinar a ET de uma pastagem, no município de São João-PE, e os resultados foram confrontados com os obtidos pelo balanço de energia-razão de Bowen. Verificou-se que o método do domo apresentou resultados satisfatórios na determinação da ET, sendo a média diária de 3,33 e 4,05 mm d-1, obtidas pelo domo e pela razão de Bowen, respectivamente. A metodologia do domo possui a desvantagem de não ser automatizada e subestimar a ET nos horários de maior incidência de radiação.    A B S T R A C T The semi-arid northeastern need of alternative reliable and economically feasible to estimate evaporation (E) or evapotranspiration (ET), since it presents an irregular rainfall and ET constitutes the main loss of water in the soil-plant-atmosphere. Among the various methods of determining the ET, the dome has been compared with other methods, showing satisfactory performance, and because it is cheaper than the others, it can become a viable alternative for rapid and punctual measures. The dome consists of an acrylic dome placed over the soil, where it determines the E or ET from measurements of temperature and humidity inside. In this work, the dome was used to determine the ET of grassland in the town of São João, in the Pernambuco state, and the results were compared with experimental data obtained from the energy balance-Bowen ratio method. It has been found that the method of the dome was satisfactory in determining ET of the grassland and the average daily ET was 3.33 and 4.05 mmd-1, obtained by the dome and by Bowen ratio, respectively. The methodology of the dome has the disadvantage of not being automated and underestimates the evapotranspiration in times of highest incidence of radiation. Keywords: Native fruits, Flora of Brazil, Phenology, Botanical Garden 

scholarly journals A field study on Ground Energy Balance calculation for typical communities in South China

2020 ◽  
Vol 172 ◽  
pp. 25003
Author(s):  
Riyi Li ◽  
Yufeng Zhang ◽  
Chongyun Huang ◽  
Chundian He
Keyword(s):  
Energy Balance ◽  
Solar Radiation ◽  
Latent Heat ◽  
South China ◽  
Convective Heat Transfer Coefficient ◽  
Bowen Ratio ◽  
Ground Temperature ◽  
Ratio Method ◽  
Subtropical Climate ◽  
Ground Energy

Urban heat island (UHI) greatly influences human health, comfort and building energy. The ground temperature plays an important role in understanding UHI, and the method based on the ground energy balance (GEB) is fundamental in the predictions of urban ground temperature and UHI. South China is fast developed and highly urbanized, with special humid subtropical climate and particular urban design characteristics. Although amounts of methods or formulas have been previously proposed for urban GEB calculation, few of them has been testified in field in South China. In this study, two typical urban communities in South China in the aligned and enclosed layout were measured during the summer sunny days in Aug. 2017, with the focus on incident solar radiation, sensible heat, and latent heat of the ground. The measured data were compared with the calculated ones by various methods. The results show that the two calculation methods, i.e., with and without reflections, showed comparable performances (difference on RMSE 3-13 W/m2) in the prediction of solar radiation incident into the community ground. The previously proposed formulas performed poorly in the prediction of surface convective heat transfer coefficient for the community hard pavement, and the power function regressed by using the measuring data performed well, with the air speed at the reference height of 0.13 m as variable and R2 of 0.74. The Bowen ratio method performed better in the prediction of latent heat for the community permeable sidewalk, with RMSE of 156 W/m2 and the consistency index of 0.93. This study provides the field evidences and reliable methods for urban GEB calculation, and potentially contributes to the UHI prediction and mitigation in South China.

scholarly journals Observations of daytime surface energy balance in cloudy tropical conditions at Ile-Ife, Nigeria

MAUSAM ◽  
2022 ◽  
Vol 53 (3) ◽  
pp. 359-366
Author(s):  
O. O. JEGEDE
Keyword(s):  
Energy Balance ◽  
Surface Energy ◽  
Surface Energy Balance ◽  
Cloud Amount ◽  
Soil Surface ◽  
Bowen Ratio ◽  
Heat Fluxes ◽  
Sensible Heat ◽  
Average Value ◽  
Tropical Conditions

Daytime energy balance at the surface in cloudy tropical conditions for Ile-Ife; Nigeria (7°33'N, 4°34'E) is investigated based on a series of micrometeorological measurements performed in October/November of 1998. For the humid environment that it is (mixing ratio, 17 -25 g / kg), magnitudes of the latent heat flux were much larger than the values for the sensible heat. Of the morning hours the average value for the Bowen ratio obtained was 0.36, while for the afternoons it was 0.74. As the soil surface became dried up in the afternoons, magnitudes of both sensible heat and ground heat fluxes were found to be comparable.   Fluctuations in the magnitudes of the terms of the surface energy balance correlated well to the cloud amount, degree of soil wetness, air temperature and humidity. But of all these factors, the variation in the amount of cloudiness appeared most dominant.

scholarly journals Large area land surface simulations in heterogeneous terrain driven by global datasets: application to mountain permafrost

2013 ◽  
Vol 7 (6) ◽  
pp. 5853-5887 ◽  
Author(s):  
J. Fiddes ◽  
S. Endrizzi ◽  
S. Gruber
Keyword(s):  
Surface Temperature ◽  
Air Temperature ◽  
Land Surface ◽  
Snow Depth ◽  
Ground Surface ◽  
Swiss Alps ◽  
Large Area ◽  
Heterogeneous Terrain ◽  
Ground Surface Temperature ◽  
Mountain Permafrost

Abstract. Numerical simulations of land-surface processes are important in order to perform landscape-scale assessments of earth-systems. This task is problematic in complex terrain due to: (i) high resolution grids required to capture strong lateral variability, (ii) lack of meteorological forcing data where it is required. In this study we test a topography and climate processor, which is designed for use with large area land surface simulation, in complex and remote terrain. The scheme is driven entirely by globally available datasets. We simulate air temperature, ground surface temperature, snow depth and test the model with a large network of measurements in the Swiss Alps. We obtain RMSE values of 0.64 °C for air temperature, 0.67–1.34 °C for non-bedrock ground surface temperature, and 44.5 mm for snow depth, which is likely affected by poor input precipitation field. Due to this we trial a simple winter precipitation correction method based on melt-dates of the snow-pack. We present a test application of the scheme in the context of simulating mountain permafrost. The scheme produces a permafrost estimate of 2000 km2 which compares well to published estimates. We suggest that this scheme represents a good first effort in application of numerical models over large areas in heterogeneous terrain.

20 years of mountain permafrost monitoring in the Swiss Alps: key results and major challenges

2020 ◽  
Author(s):  
Jeannette Noetzli ◽  
Cécile Pellet
Keyword(s):  
Monitoring Network ◽  
Warming Trend ◽  
Phase Changes ◽  
Swiss Alps ◽  
High Mountain ◽  
The Past ◽  
Heat Effects ◽  
Mountain Permafrost ◽  
Ice Content

&lt;p&gt;Permafrost is a widespread thermal subsurface phenomenon in polar and high mountain regions and was defined as an essential climatic variable (ECV) by the Global Climate Observing System (GCOS). The Swiss Permafrost Monitoring Network was started in the year 2000 as an unconsolidated network of sites from research projectsand as the first national long-term observation network for permafrost it is an early component of the Global Terrestrial Network for Permafrost (GTN-P). After 20 years of operation, development and evaluation, PERMOS holds the largest and most diverse collection of mountain permafrost data worldwide and has a role model regarding its structure and organization. PERMOS aims at the systematic long-term documentation of the state and changes of mountain permafrost in the Swiss Alps. The scientific monitoring strategy is now based on three observation elements: ground-surface and subsurface temperatures, changes in subsurface ice content, and permafrost creep velocities. These three elements complement each other in a landform-based approach to capture the influence of the topography as well as the surface and subsurface conditions of different landforms on the ground thermal regime. These influences are considered to be more relevant than regional climatic conditions in the small country.&lt;/p&gt;&lt;p&gt;Over the past 20 years, all observation elements indicate a clear warming trend of mountain permafrost in the Swiss Alps. Borehole temperatures generally increase at 10 and 20 m depth. This warming trend was intensified after 2009 and temporarily interrupted following winters with a thin and late snow cover, particularly winter 2016. Further, the trend is more pronounced at cold permafrost sites like rock glacier Murt&amp;#232;l-Corvatsch, where an increase of +0.5&amp;#176;C has been observed at 20 m over the past 30 years. For permafrost temperatures close to 0 &amp;#176;C, climate warming does not result in significant temperature increase but is masked by phase changes and latent heat effects. These result in significant changes in ice content, which can be registered by electrical resistivity tomography (ERT). Further, the warming trend of mountain permafrost in the Swiss Alps is corroborated by increasing creep rates of rock glaciers, which follow an exponential relationship with ground temperatures. In this contribution, we present and discuss the key results from two decades of mountain permafrost monitoring within the PERMOS network. In addition to the measurement data, we identified considerable challenges for long-term monitoring network of mountain permafrost based on experience collected over two decades. The acquisition of reliable data at a limited number of stations in extreme environments with difficult access requires robust strategies, standards and traceability for the entire data acquisition chain: installation &gt; measurement &gt; raw data &gt; processing &gt; archiving and, finally, reporting.&lt;/p&gt;

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