Avalanches and micrometeorology driving mass and energy balance of the lowest perennial ice field of the Alps: a case study
<p>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...
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| Format: | Article |
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Copernicus Publications
2019-04-01
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| Series: | The Cryosphere |
| Online Access: | https://www.the-cryosphere.net/13/1247/2019/tc-13-1247-2019.pdf |
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| author | R. Mott R. Mott A. Wolf M. Kehl H. Kunstmann H. Kunstmann M. Warscher M. Warscher M. Warscher T. Grünewald |
| author_facet | R. Mott R. Mott A. Wolf M. Kehl H. Kunstmann H. Kunstmann M. Warscher M. Warscher M. Warscher T. Grünewald |
| author_sort | R. Mott |
| collection | DOAJ |
| description | <p>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.</p>
<p>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.</p> |
| first_indexed | 2024-12-11T18:47:29Z |
| format | Article |
| id | doaj.art-1f05802554824768811808e554494730 |
| institution | Directory Open Access Journal |
| issn | 1994-0416 1994-0424 |
| language | English |
| last_indexed | 2024-12-11T18:47:29Z |
| publishDate | 2019-04-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | The Cryosphere |
| spelling | doaj.art-1f05802554824768811808e5544947302022-12-22T00:54:25ZengCopernicus PublicationsThe Cryosphere1994-04161994-04242019-04-01131247126510.5194/tc-13-1247-2019Avalanches and micrometeorology driving mass and energy balance of the lowest perennial ice field of the Alps: a case studyR. Mott0R. Mott1A. Wolf2M. Kehl3H. Kunstmann4H. Kunstmann5M. Warscher6M. Warscher7M. Warscher8T. Grünewald9Institute of Meteorology and Climate Research, Atmospheric Environmental Research (KIT/IMK-IFU), KIT-Campus Alpin, Garmisch-Partenkirchen, GermanyWSL Institute for Snow and Avalanche Research SLF, Davos, SwitzerlandInstitute for Karst and Cave Science, GermanyInstitute of Meteorology and Climate Research, Atmospheric Environmental Research (KIT/IMK-IFU), KIT-Campus Alpin, Garmisch-Partenkirchen, GermanyInstitute of Meteorology and Climate Research, Atmospheric Environmental Research (KIT/IMK-IFU), KIT-Campus Alpin, Garmisch-Partenkirchen, GermanyInstitute of Geography, University of Augsburg, Augsburg, GermanyInstitute of Meteorology and Climate Research, Atmospheric Environmental Research (KIT/IMK-IFU), KIT-Campus Alpin, Garmisch-Partenkirchen, GermanyInstitute of Geography, University of Augsburg, Augsburg, GermanyDepartment of Geography, University of Innsbruck, Innsbruck, AustriaWSL Institute for Snow and Avalanche Research SLF, Davos, Switzerland<p>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.</p> <p>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.</p>https://www.the-cryosphere.net/13/1247/2019/tc-13-1247-2019.pdf |
| spellingShingle | R. Mott R. Mott A. Wolf M. Kehl H. Kunstmann H. Kunstmann M. Warscher M. Warscher M. Warscher T. Grünewald Avalanches and micrometeorology driving mass and energy balance of the lowest perennial ice field of the Alps: a case study The Cryosphere |
| title | Avalanches and micrometeorology driving mass and energy balance of the lowest perennial ice field of the Alps: a case study |
| title_full | Avalanches and micrometeorology driving mass and energy balance of the lowest perennial ice field of the Alps: a case study |
| title_fullStr | Avalanches and micrometeorology driving mass and energy balance of the lowest perennial ice field of the Alps: a case study |
| title_full_unstemmed | Avalanches and micrometeorology driving mass and energy balance of the lowest perennial ice field of the Alps: a case study |
| title_short | Avalanches and micrometeorology driving mass and energy balance of the lowest perennial ice field of the Alps: a case study |
| title_sort | avalanches and micrometeorology driving mass and energy balance of the lowest perennial ice field of the alps a case study |
| url | https://www.the-cryosphere.net/13/1247/2019/tc-13-1247-2019.pdf |
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