Birger Hansen | University of Copenhagen (original) (raw)
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Papers by Birger Hansen
Isprs Journal of Photogrammetry and Remote Sensing, Dec 1, 2018
Arctic and boreal peatlands play a major role in the global carbon (C) cycle. They are particular... more Arctic and boreal peatlands play a major role in the global carbon (C) cycle. They are particularly efficient at sequestering carbon due to their high-water content which makes primary productivity exceed decomposition rates. Though, their future in a climate-change context is quite uncertain in terms of carbon emissions and carbon sequestration.Nuuk-fen site is a well-instrumented greenlandic site of particular interest for testing and validating land-surface models with monitoring of soil physical variables and greenhouse gas fluxes (CH4 and CO2). But knowledge of soil carbon stocks and profiles is missing. This is a crucial shortcoming for a complete evaluation of models, as soil carbon is one of the primary drivers of CH4 and CO2 soil emissions. To tackle this issue, we measured for the first time soil carbon and nitrogen density, profiles and stocks in the Nuuk peatland, at the exact location of fluxes monitoring. Measurements were made along two transects. Measurements horizontal resolution is 5 meter, vertical resolution ranges from 5 to 10 cm. Mean soil carbon density is 50.2 kgC/m³. These new data are in the range of those encountered in other arctic peatlands.
This dataset describes the transect and plots labels for each samples, along with the depth, mass... more This dataset describes the transect and plots labels for each samples, along with the depth, mass, volume, density, dry mass, %weight_loss, and %C and %N issued from elemental analysis. Other quantities described in the paper are easily computed via the following formulas : bulk density (g.cm-3) = dry_mass/volume = density*(1-%weight_loss) soil carbon density (gC.m-3) = bulk density * %C soil nitrogen density (gC.m-3) = bulk density * %N.
Natural Hazards, Jun 1, 2019
Geografisk Tidsskrift-danish Journal of Geography, 1988
Birger Ulf Hansen: Satellite Monitoring of the Biomass Production in Southern Greenland. Geografi... more Birger Ulf Hansen: Satellite Monitoring of the Biomass Production in Southern Greenland. Geografisk Tidsskrift 88:94–99. Copenhagen, 1988. Based on satellite data from Southern Greenland the application of Normalized Difference Vegetation Index (NDVI) for monitoring biomass production has been evaluated. Field measurements of spectral reflectance data are quantitatively correlated with clipped samples of total above-ground biomass production. The relation between NDVI measured on the ground and biomass production is discussed. The seasonal and geographical variation in NDVI is correlated with the climate and water balance. The potential production is estimated as the product of mean NDVI and the length of the growing season. The results suggest that operational satellite monitoring of NDVI provides valuable assistance in agricultural management and forward planning of the potential breeding capacity in an arctic/subarctic environment.
Marine Ecology Progress Series, Feb 27, 2017
Arctic, Antarctic, and Alpine Research, Nov 1, 2016
EGU General Assembly Conference Abstracts, Apr 1, 2018
Cold Regions Science and Technology, 2009
Abstract The release of Acid Mine Drainage, AMD, from mine waste rocks in Arctic areas is commonl... more Abstract The release of Acid Mine Drainage, AMD, from mine waste rocks in Arctic areas is commonly assumed to be limited by low air temperatures and permafrost. Here we show that heat generation within a sulphidic coal mining waste rock pile in Svalbard (78°N) is sufficiently high to keep the pile warm at roughly 5 °C throughout the year despite average winter air temperatures below − 10 °C. A one-dimensional heat and water flow model, CoupModel, is calibrated and validated successfully on the basis of waste rock characteristics and site-specific climate data. Results show that the subsurface temperature regime within the warm waste rock pile can be explained by heat production from microbial-driven pyrite oxidation. Sensitivity analyses indicate that predicted climate changes are likely to increase subsurface temperatures and the associated environmental impact but also that the waste rock pile will freeze if the depth of the pile is reduced or the water content is increased.
Biogeosciences Discussions, 2016
An improvement in our process-based understanding of carbon (C) exchange in the Arctic, and its c... more An improvement in our process-based understanding of carbon (C) exchange in the Arctic, and its climate sensitivity, is critically needed for understanding the response of tundra ecosystems to a changing climate. In this context, we analyzed the net ecosystem exchange (NEE) of CO<sub>2</sub> in West Greenland tundra (64° N) across eight snow-free periods in eight consecutive years, and characterized the key processes of net ecosystem exchange, and its two main modulating components: gross primary production (GPP) and ecosystem respiration (Reco). Overall, the ecosystem acted as a consistent sink of CO<sub>2</sub>, accumulating −30 g C m<sup>−2</sup> on average (range −17 to −41 g C m<sup>−2</sup>) during the years 2008–2015, except 2011 that was associated with a major pest outbreak. The results do not reveal a marked meteorological effect on the net CO<sub>2&...
Isprs Journal of Photogrammetry and Remote Sensing, Dec 1, 2018
Arctic and boreal peatlands play a major role in the global carbon (C) cycle. They are particular... more Arctic and boreal peatlands play a major role in the global carbon (C) cycle. They are particularly efficient at sequestering carbon due to their high-water content which makes primary productivity exceed decomposition rates. Though, their future in a climate-change context is quite uncertain in terms of carbon emissions and carbon sequestration.Nuuk-fen site is a well-instrumented greenlandic site of particular interest for testing and validating land-surface models with monitoring of soil physical variables and greenhouse gas fluxes (CH4 and CO2). But knowledge of soil carbon stocks and profiles is missing. This is a crucial shortcoming for a complete evaluation of models, as soil carbon is one of the primary drivers of CH4 and CO2 soil emissions. To tackle this issue, we measured for the first time soil carbon and nitrogen density, profiles and stocks in the Nuuk peatland, at the exact location of fluxes monitoring. Measurements were made along two transects. Measurements horizontal resolution is 5 meter, vertical resolution ranges from 5 to 10 cm. Mean soil carbon density is 50.2 kgC/m³. These new data are in the range of those encountered in other arctic peatlands.
This dataset describes the transect and plots labels for each samples, along with the depth, mass... more This dataset describes the transect and plots labels for each samples, along with the depth, mass, volume, density, dry mass, %weight_loss, and %C and %N issued from elemental analysis. Other quantities described in the paper are easily computed via the following formulas : bulk density (g.cm-3) = dry_mass/volume = density*(1-%weight_loss) soil carbon density (gC.m-3) = bulk density * %C soil nitrogen density (gC.m-3) = bulk density * %N.
Natural Hazards, Jun 1, 2019
Geografisk Tidsskrift-danish Journal of Geography, 1988
Birger Ulf Hansen: Satellite Monitoring of the Biomass Production in Southern Greenland. Geografi... more Birger Ulf Hansen: Satellite Monitoring of the Biomass Production in Southern Greenland. Geografisk Tidsskrift 88:94–99. Copenhagen, 1988. Based on satellite data from Southern Greenland the application of Normalized Difference Vegetation Index (NDVI) for monitoring biomass production has been evaluated. Field measurements of spectral reflectance data are quantitatively correlated with clipped samples of total above-ground biomass production. The relation between NDVI measured on the ground and biomass production is discussed. The seasonal and geographical variation in NDVI is correlated with the climate and water balance. The potential production is estimated as the product of mean NDVI and the length of the growing season. The results suggest that operational satellite monitoring of NDVI provides valuable assistance in agricultural management and forward planning of the potential breeding capacity in an arctic/subarctic environment.
Marine Ecology Progress Series, Feb 27, 2017
Arctic, Antarctic, and Alpine Research, Nov 1, 2016
EGU General Assembly Conference Abstracts, Apr 1, 2018
Cold Regions Science and Technology, 2009
Abstract The release of Acid Mine Drainage, AMD, from mine waste rocks in Arctic areas is commonl... more Abstract The release of Acid Mine Drainage, AMD, from mine waste rocks in Arctic areas is commonly assumed to be limited by low air temperatures and permafrost. Here we show that heat generation within a sulphidic coal mining waste rock pile in Svalbard (78°N) is sufficiently high to keep the pile warm at roughly 5 °C throughout the year despite average winter air temperatures below − 10 °C. A one-dimensional heat and water flow model, CoupModel, is calibrated and validated successfully on the basis of waste rock characteristics and site-specific climate data. Results show that the subsurface temperature regime within the warm waste rock pile can be explained by heat production from microbial-driven pyrite oxidation. Sensitivity analyses indicate that predicted climate changes are likely to increase subsurface temperatures and the associated environmental impact but also that the waste rock pile will freeze if the depth of the pile is reduced or the water content is increased.
Biogeosciences Discussions, 2016
An improvement in our process-based understanding of carbon (C) exchange in the Arctic, and its c... more An improvement in our process-based understanding of carbon (C) exchange in the Arctic, and its climate sensitivity, is critically needed for understanding the response of tundra ecosystems to a changing climate. In this context, we analyzed the net ecosystem exchange (NEE) of CO<sub>2</sub> in West Greenland tundra (64° N) across eight snow-free periods in eight consecutive years, and characterized the key processes of net ecosystem exchange, and its two main modulating components: gross primary production (GPP) and ecosystem respiration (Reco). Overall, the ecosystem acted as a consistent sink of CO<sub>2</sub>, accumulating −30 g C m<sup>−2</sup> on average (range −17 to −41 g C m<sup>−2</sup>) during the years 2008–2015, except 2011 that was associated with a major pest outbreak. The results do not reveal a marked meteorological effect on the net CO<sub>2&...