scholarly journals Review of 'Avalanches and micrometeorology driving mass and energy balance of the lowest perennial ice field of the Alps: a case study'

2019 ◽  
Author(s):  
Noel Fitzpatrick
Keyword(s):  
Energy Balance ◽  
Ice Field ◽  
The Alps ◽  
Perennial Ice

scholarly journals Avalanches and micrometeorology driving mass and energy balance of the lowest perennial ice field of the Alps: a case study

2019 ◽  
Vol 13 (4) ◽  
pp. 1247-1265 ◽  
Author(s):  
Rebecca Mott ◽  
Andreas Wolf ◽  
Maximilian Kehl ◽  
Harald Kunstmann ◽  
Michael Warscher ◽  
...  
Keyword(s):  
Heat Exchange ◽  
Energy Balance ◽  
Mass Balance ◽  
Snow Accumulation ◽  
Near Surface ◽  
Rock Face ◽  
Katabatic Flows ◽  
Ice Field ◽  
The Alps ◽  
Perennial Ice

Abstract. The mass balance of very small glaciers is often governed by anomalous snow accumulation, winter precipitation being multiplied by snow redistribution processes (gravitationally or wind driven), or suppressed snow ablation driven by micrometeorological effects lowering net radiation and/or turbulent heat exchange. In this case study, we analysed the relative contribution of snow accumulation and ablation processes governing the long- and short-term mass balance of the lowest perennial ice field of the Alps, the Ice Chapel, located at 870 m a.s.l. in the Berchtesgaden National Park (Germany). This study emphasizes the importance of the local topographic setting for the survival of a perennial ice field located far below the climatic snow line. Although long-term mass balance measurements of the ice field surface showed a dramatic mass loss between 1973 and 2014, the ice field mass balance was rather stable between 2014 and 2017 and even showed a strong mass gain in 2017/2018 with an increase in surface height by 50 %–100 % relative to the ice field thickness. Measurements suggest that the winter mass balance clearly dominated the annual mass balance. At the Ice Chapel surface, 92 % of snow accumulation was gained by snow avalanching, thus clearly governing the 2017/2018 winter mass balance of the ice field with mean snow depths of 32 m at the end of the accumulation period. Avalanche deposition was amplified by preferential deposition of snowfall in the wind-sheltered rock face surrounding the ice field. Detailed micrometeorological measurements combined with a numerical analysis of the small-scale near-surface atmospheric flow field identified the micrometeorological processes driving the energy balance of the ice field. Measurements revealed a katabatic flow system draining down the ice field throughout the day, showing strong temporal and spatial dynamics. The spatial origin of the thermal flow system was shown to be of particular importance for the ice field surface energy balance. Numerical simulation indicates that deep katabatic flows, which developed at higher-elevation shaded areas of the rock face and drained down the ice field, enhance sensible heat exchange towards the ice field surface by enhancing turbulence close to the ice surface. Conversely, the shallow katabatic flow developing at the ice field surface appeared to laterally decouple the local near-surface atmosphere from the warmer adjacent air suppressing heat exchange. Numerical results thus suggest that shallow katabatic flows driven by the cooling effect of the ice field surface are especially efficient in lowering the climatic sensitivity of the ice field to the surrounding rising air temperatures. Such micrometeorological phenomena must be taken into account when calculating mass and energy balances of very small glaciers or perennial ice fields at elevations far below the climatic snow line.

scholarly journals Avalanches and micrometeorology driving mass and energy balance of the lowest perennial ice field of the Alps: a case study

2018 ◽  
Author(s):  
Rebecca Mott ◽  
Andreas Wolf ◽  
Maximilian Kehl ◽  
Harald Kunstmann ◽  
Michael Warscher ◽  
...  
Keyword(s):  
Heat Exchange ◽  
Energy Balance ◽  
Mass Balance ◽  
Snow Accumulation ◽  
Near Surface ◽  
Rock Face ◽  
Katabatic Flows ◽  
Ice Field ◽  
The Alps ◽  
Perennial Ice

Abstract. The mass balance of very small glaciers is often governed either by anomalous snow accumulation, winter precipitation being multiplied by snow redistribution processes (gravitationally or wind-driven), or by suppressed snow ablation driven by micrometeorological effects lowering net radiation and/or turbulent heat exchange. In this case study, we analysed the relative contribution of snow accumulation and ablation processes governing the long- and short-term mass balance of the lowest perennial ice field of the Alps, the Ice Chapel, located at 870 m ASL in the Berchtesgaden National Park (Germany). This study emphasizes the importance of the local topographic setting for the survival of a perennial ice field located far below the climatic snow line. Although long-term mass balance measurements of the ice field surface showed a dramatic mass loss between 1973 and 2014, the ice field mass balance was rather stable between 2014 and 2017 and even showed a strong mass gain in 2017/2018 with an increase in surface height by 50–100 % relative to the ice field thickness. Measurements suggest that the winter mass balance clearly dominated the annual mass balance with 3000 % of winter snow accumulation compared to a near-by flat field station. At the Ice Chapel surface, 92 % of snow accumulation was gained by snow avalanching, thus clearly governing the 2017/2018 winter mass balance of the ice field with mean snow depths of 32 m at the end of the accumulation period. Avalanche deposition was amplified by preferential deposition of snowfall in the wind-sheltered rock face surrounding the ice field. Detailed micrometeorological measurements combined with a numerical analysis of the small-scale near-surface atmospheric flow field identified the micrometeorological processes driving the energy balance of the ice field. Measurements revealed a katabatic flow system draining down the ice field throughout the day, showing strong temporal and spatial dynamics. The spatial origin of the onset of the thermal flow system, was shown to be of particular importance for the ice field surface energy balance. Deep katabatic flows, that developed at higher-elevated shaded areas of the rock face and drained down the ice field appeared to enhance sensible heat exchange towards the ice field surface by enhancing turbulence close to the ice surface. Contrary, the shallow katabatic flow developing at the ice field surface appeared to laterally decouple the local near-surface atmosphere from the warmer adjacent air supressing heat exchange. Results thus suggest that shallow katabatic flows driven by the cooling effect of the ice field surface are especially efficient in lowering the climatic sensitivity of the ice field to the surrounding rising air temperatures. Such micrometeorological phenomena must be taken into account when calculating mass and energy balances of very small glaciers or perennial ice fields at elevations far below the climatic snow line.

scholarly journals Energy Balance in Wastewater Systems with Energy Recovery: A Portuguese Case Study

2021 ◽  
Vol 6 (10) ◽  
pp. 141
Author(s):  
Catarina Jorge ◽  
Maria do Céu Almeida ◽  
Dídia Covas
Keyword(s):  
Energy Efficiency ◽  
Energy Balance ◽  
Energy Recovery ◽  
Real Life ◽  
Wet Season ◽  
Current Case ◽  
Total Input ◽  
Wastewater Systems ◽  
Regional Reference

This paper presents and discusses the application of a novel energy balance scheme for assessing energy efficiency in wastewater systems. The energy balance is demonstrated with a Portuguese real-life case study, using mathematical modelling to estimate the different energy components and to compute two energy efficiency indices. The total inflow intrinsic energy can represent a significant amount (>95%) of the total energy used in systems mainly composed of gravity sewers. The total input energy is significantly (four-times) higher in the wet season than in the dry season, mostly due to undue inflows (e.g., direct rainfall and infiltration). The potential for energy recovery strongly depends on the available head and flow rate at the delivery point, being 0.01 kWh/m3 in the current case, with a project payback period of 4 years. The energy balance components and the respective energy efficiency indices strongly depend on the considered reference elevation. Thus, a unique regional reference elevation is recommended in the calculations.

Investigating energy balance and carbon footprint in saffron cultivation – a case study in Iran

2016 ◽  
Vol 115 ◽  
pp. 162-171 ◽  
Author(s):  
Majid Khanali ◽  
Mehran Movahedi ◽  
Marziye Yousefi ◽  
Sanaz Jahangiri ◽  
Benyamin Khoshnevisan
Keyword(s):  
Energy Balance ◽  
Carbon Footprint

scholarly journals Biogas from Anaerobic Digestion: Power Generation or Biomethane Production?

Energies ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 743 ◽  
Author(s):  
Gianluca Caposciutti ◽  
Andrea Baccioli ◽  
Lorenzo Ferrari ◽  
Umberto Desideri
Keyword(s):  
Anaerobic Digestion ◽  
Energy Balance ◽  
Combustion Engine ◽  
Electric Energy ◽  
Optimal Level ◽  
Strong Impact ◽  
Co2 Absorption ◽  
External Energy ◽  
Biomethane Production

Biogas is a fuel obtained from organic waste fermentation and can be an interesting solution for producing electric energy, heat and fuel. Recently, many European countries have incentivized the production of biomethane to be injected into natural gas grids or compressed and used as biofuel in vehicles. The introduction of an upgrading unit into an existing anaerobic digestion plant to convert biogas to biomethane may have a strong impact on the overall energy balance of the systems. The amount of biomethane produced may be optimized from several points of view (i.e., energy, environmental and economic). In this paper, the mass and energy fluxes of an anaerobic digestion plant were analyzed as a function of the biogas percentage sent to the upgrading system and the amount of biomethane produced. A numerical model of an anaerobic digestion plant was developed by considering an existing case study. The mass and energy balance of the digesters, cogeneration unit, upgrading system and auxiliary boiler were estimated when the amount of produced biomethane was varied. An internal combustion engine was adopted as the cogeneration unit and a CO2 absorption system was assumed for biogas upgrading. Results demonstrated that the energy balance of the plant is strictly dependent on the biomethane production and that an excess of biomethane production makes the plant totally dependent on external energy sources. As for the environmental impact, an optimal level of biomethane production exists that minimizes the emissions of equivalent CO2. However, high biomethane subsides can encourage plant managers to increase biomethane production and thus reduce CO2 savings.

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