Analysis of the energy balance closure over a FLUXNET boreal forest in Finland
The imbalance in the surface energy budget, when using eddy-covariance techniques to measure turbulent fluxes, is still an unresolved problem. Important progresses have been reported in recent years identifying potential reasons for this lack of energy balance closure. In this paper we focus on the...
Published in: | Hydrology and Earth System Sciences |
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ftcopernicus:oai:publications.copernicus.org:hess7351 2023-05-15T18:20:18+02:00 Analysis of the energy balance closure over a FLUXNET boreal forest in Finland Sánchez, J. M. Caselles, V. Rubio, E. M. 2018-09-27 application/pdf https://doi.org/10.5194/hess-14-1487-2010 https://www.hydrol-earth-syst-sci.net/14/1487/2010/ eng eng doi:10.5194/hess-14-1487-2010 https://www.hydrol-earth-syst-sci.net/14/1487/2010/ eISSN: 1607-7938 Text 2018 ftcopernicus https://doi.org/10.5194/hess-14-1487-2010 2019-12-24T09:57:17Z The imbalance in the surface energy budget, when using eddy-covariance techniques to measure turbulent fluxes, is still an unresolved problem. Important progresses have been reported in recent years identifying potential reasons for this lack of energy balance closure. In this paper we focus on the data collected in a FLUXNET boreal forest site in Sodankylä, Finland. Using one month half-hourly data, an average Energy Balance Ratio (EBR) of 0.72 is obtained. The inclusion of the heat storage terms in the energy budget yields an improvement of about 6% in the total closure. The sensitivity of the energy balance closure to the turbulence intensity is analysed in terms of the friction velocity, and atmospheric stability/instability conditions. Significant better closure is obtained for high values of the friction velocity and unstable conditions. The mismatch in variable footprints for different fluxes is checked by analysing the dependence of the closure on wind direction. The inhomogeneities of the emplacement surrounding the flux tower induce a critical decrease in the EBR of up to 30% for specific wind directions. After filtering all unfavourable conditions, EBR=0.94. This is a reasonable good result for the energy balance closure. However there is still a 6% of the available energy unaccounted. Part of this remaining imbalance could be justified as the impossibility of the 30 min averaging time to capture the low frequency flux contributions, since the closure is improved by a 5% when the averaging time is expanded to 2 h. Text Sodankylä Copernicus Publications: E-Journals Sodankylä ENVELOPE(26.600,26.600,67.417,67.417) Hydrology and Earth System Sciences 14 8 1487 1497 |
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Open Polar |
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Copernicus Publications: E-Journals |
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ftcopernicus |
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English |
description |
The imbalance in the surface energy budget, when using eddy-covariance techniques to measure turbulent fluxes, is still an unresolved problem. Important progresses have been reported in recent years identifying potential reasons for this lack of energy balance closure. In this paper we focus on the data collected in a FLUXNET boreal forest site in Sodankylä, Finland. Using one month half-hourly data, an average Energy Balance Ratio (EBR) of 0.72 is obtained. The inclusion of the heat storage terms in the energy budget yields an improvement of about 6% in the total closure. The sensitivity of the energy balance closure to the turbulence intensity is analysed in terms of the friction velocity, and atmospheric stability/instability conditions. Significant better closure is obtained for high values of the friction velocity and unstable conditions. The mismatch in variable footprints for different fluxes is checked by analysing the dependence of the closure on wind direction. The inhomogeneities of the emplacement surrounding the flux tower induce a critical decrease in the EBR of up to 30% for specific wind directions. After filtering all unfavourable conditions, EBR=0.94. This is a reasonable good result for the energy balance closure. However there is still a 6% of the available energy unaccounted. Part of this remaining imbalance could be justified as the impossibility of the 30 min averaging time to capture the low frequency flux contributions, since the closure is improved by a 5% when the averaging time is expanded to 2 h. |
format |
Text |
author |
Sánchez, J. M. Caselles, V. Rubio, E. M. |
spellingShingle |
Sánchez, J. M. Caselles, V. Rubio, E. M. Analysis of the energy balance closure over a FLUXNET boreal forest in Finland |
author_facet |
Sánchez, J. M. Caselles, V. Rubio, E. M. |
author_sort |
Sánchez, J. M. |
title |
Analysis of the energy balance closure over a FLUXNET boreal forest in Finland |
title_short |
Analysis of the energy balance closure over a FLUXNET boreal forest in Finland |
title_full |
Analysis of the energy balance closure over a FLUXNET boreal forest in Finland |
title_fullStr |
Analysis of the energy balance closure over a FLUXNET boreal forest in Finland |
title_full_unstemmed |
Analysis of the energy balance closure over a FLUXNET boreal forest in Finland |
title_sort |
analysis of the energy balance closure over a fluxnet boreal forest in finland |
publishDate |
2018 |
url |
https://doi.org/10.5194/hess-14-1487-2010 https://www.hydrol-earth-syst-sci.net/14/1487/2010/ |
long_lat |
ENVELOPE(26.600,26.600,67.417,67.417) |
geographic |
Sodankylä |
geographic_facet |
Sodankylä |
genre |
Sodankylä |
genre_facet |
Sodankylä |
op_source |
eISSN: 1607-7938 |
op_relation |
doi:10.5194/hess-14-1487-2010 https://www.hydrol-earth-syst-sci.net/14/1487/2010/ |
op_doi |
https://doi.org/10.5194/hess-14-1487-2010 |
container_title |
Hydrology and Earth System Sciences |
container_volume |
14 |
container_issue |
8 |
container_start_page |
1487 |
op_container_end_page |
1497 |
_version_ |
1766197809140203520 |