Impact of the radiation balance on snowmelt in a sparse deciduous birch forest
The representation of high-latitude surface processes and quantifying surface-climate feedbacks are some of the most serious shortcomings of present day Arctic land surface modelling. The energy balance of seasonally snow-covered sparse deciduous forests at high latitudes is poorly understood and in...
Main Author: | |
---|---|
Other Authors: | , , |
Format: | Doctoral or Postdoctoral Thesis |
Language: | English |
Published: |
The University of Edinburgh
2017
|
Subjects: | |
Online Access: | http://hdl.handle.net/1842/29567 |
id |
ftunivedinburgh:oai:era.ed.ac.uk:1842/29567 |
---|---|
record_format |
openpolar |
spelling |
ftunivedinburgh:oai:era.ed.ac.uk:1842/29567 2023-07-30T03:55:22+02:00 Impact of the radiation balance on snowmelt in a sparse deciduous birch forest Turton, Rachael Heather Essery, Richard Williams, Mathew other 30/11/2017 application/pdf http://hdl.handle.net/1842/29567 en eng The University of Edinburgh http://hdl.handle.net/1842/29567 radiation sparse forest land surface model snow modelling JULES shaded gap shortwave longwave snow melt transmissivity hemispherical photography snow surveys Arctic surface processes high latitude canopy birch Global Change Research Institute Thesis or Dissertation Doctoral PhD Doctor of Philosophy 2017 ftunivedinburgh 2023-07-09T20:32:28Z The representation of high-latitude surface processes and quantifying surface-climate feedbacks are some of the most serious shortcomings of present day Arctic land surface modelling. The energy balance of seasonally snow-covered sparse deciduous forests at high latitudes is poorly understood and inaccurately represented within hydrological and climate models. Snow cover plays an important role in wintertime fluxes of energy, water and carbon, controlling the length of the active growing season and hence the overall carbon balance of Arctic ecosystems. Snow cover is non-uniform and spatially variable, as wind redistributes snow from areas of exposed open tundra to sheltered areas within the forest, where a deeper snowpack develops. Low solar zenith angles, coupled with sparse deciduous leafless trees, cast shadows across the snow surface. The spatial distribution of canopy gaps determines the timing of direct radiation which penetrates down through the canopy to the snow surface. The forest canopy also excludes incoming longwave radiation and yet also emits longwave radiation to the snow surface. Consequently the forest canopy plays a key role in the radiation balance of sparse forests. To improve our knowledge of these complex processes, meteorological and field observations were taken in an area of highly heterogeneous birch Betula pubescens ssp. czerepanovii forest in Abisko, Sweden during the spring of 2008 and 2009. Detailed measurements of short and longwave radiation above and below the canopy, hemispherical photographs, tree temperatures and snow surveys were conducted to quantify the radiation balance of the sparse deciduous forest. An array of below canopy pyranometers found the mean canopy transmissivity to be 74 % in 2008 and 76 % in 2009. Hemispherical photographs taken at the pyranometer locations analysed with Gap Light Analyzer (GLA) showed reasonable agreement with a mean canopy transmissivity of 75 % in 2008 and 74 % in 2009. The canopy transmissivity was found to be independent of the diffuse ... Doctoral or Postdoctoral Thesis Abisko Arctic Tundra Edinburgh Research Archive (ERA - University of Edinburgh) Arctic Abisko ENVELOPE(18.829,18.829,68.349,68.349) Jules ENVELOPE(140.917,140.917,-66.742,-66.742) |
institution |
Open Polar |
collection |
Edinburgh Research Archive (ERA - University of Edinburgh) |
op_collection_id |
ftunivedinburgh |
language |
English |
topic |
radiation sparse forest land surface model snow modelling JULES shaded gap shortwave longwave snow melt transmissivity hemispherical photography snow surveys Arctic surface processes high latitude canopy birch Global Change Research Institute |
spellingShingle |
radiation sparse forest land surface model snow modelling JULES shaded gap shortwave longwave snow melt transmissivity hemispherical photography snow surveys Arctic surface processes high latitude canopy birch Global Change Research Institute Turton, Rachael Heather Impact of the radiation balance on snowmelt in a sparse deciduous birch forest |
topic_facet |
radiation sparse forest land surface model snow modelling JULES shaded gap shortwave longwave snow melt transmissivity hemispherical photography snow surveys Arctic surface processes high latitude canopy birch Global Change Research Institute |
description |
The representation of high-latitude surface processes and quantifying surface-climate feedbacks are some of the most serious shortcomings of present day Arctic land surface modelling. The energy balance of seasonally snow-covered sparse deciduous forests at high latitudes is poorly understood and inaccurately represented within hydrological and climate models. Snow cover plays an important role in wintertime fluxes of energy, water and carbon, controlling the length of the active growing season and hence the overall carbon balance of Arctic ecosystems. Snow cover is non-uniform and spatially variable, as wind redistributes snow from areas of exposed open tundra to sheltered areas within the forest, where a deeper snowpack develops. Low solar zenith angles, coupled with sparse deciduous leafless trees, cast shadows across the snow surface. The spatial distribution of canopy gaps determines the timing of direct radiation which penetrates down through the canopy to the snow surface. The forest canopy also excludes incoming longwave radiation and yet also emits longwave radiation to the snow surface. Consequently the forest canopy plays a key role in the radiation balance of sparse forests. To improve our knowledge of these complex processes, meteorological and field observations were taken in an area of highly heterogeneous birch Betula pubescens ssp. czerepanovii forest in Abisko, Sweden during the spring of 2008 and 2009. Detailed measurements of short and longwave radiation above and below the canopy, hemispherical photographs, tree temperatures and snow surveys were conducted to quantify the radiation balance of the sparse deciduous forest. An array of below canopy pyranometers found the mean canopy transmissivity to be 74 % in 2008 and 76 % in 2009. Hemispherical photographs taken at the pyranometer locations analysed with Gap Light Analyzer (GLA) showed reasonable agreement with a mean canopy transmissivity of 75 % in 2008 and 74 % in 2009. The canopy transmissivity was found to be independent of the diffuse ... |
author2 |
Essery, Richard Williams, Mathew other |
format |
Doctoral or Postdoctoral Thesis |
author |
Turton, Rachael Heather |
author_facet |
Turton, Rachael Heather |
author_sort |
Turton, Rachael Heather |
title |
Impact of the radiation balance on snowmelt in a sparse deciduous birch forest |
title_short |
Impact of the radiation balance on snowmelt in a sparse deciduous birch forest |
title_full |
Impact of the radiation balance on snowmelt in a sparse deciduous birch forest |
title_fullStr |
Impact of the radiation balance on snowmelt in a sparse deciduous birch forest |
title_full_unstemmed |
Impact of the radiation balance on snowmelt in a sparse deciduous birch forest |
title_sort |
impact of the radiation balance on snowmelt in a sparse deciduous birch forest |
publisher |
The University of Edinburgh |
publishDate |
2017 |
url |
http://hdl.handle.net/1842/29567 |
long_lat |
ENVELOPE(18.829,18.829,68.349,68.349) ENVELOPE(140.917,140.917,-66.742,-66.742) |
geographic |
Arctic Abisko Jules |
geographic_facet |
Arctic Abisko Jules |
genre |
Abisko Arctic Tundra |
genre_facet |
Abisko Arctic Tundra |
op_relation |
http://hdl.handle.net/1842/29567 |
_version_ |
1772818318523105280 |