scholarly journals Methane and carbon dioxide fluxes and their regional scalability for the European Arctic wetlands during the MAMM project in summer 2012

2014 ◽  
Vol 14 (6) ◽  
pp. 8455-8494 ◽  
Author(s):  
S. J. O'Shea ◽  
G. Allen ◽  
M. W. Gallagher ◽  
K. Bower ◽  
S. M. Illingworth ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Boundary Layer ◽  
Land Surface ◽  
Regional Scale ◽  
Local Area ◽  
The Arctic ◽  
Emission Flux ◽  
Carbon Dioxide Fluxes ◽  
Airborne Measurements ◽  
Simple Boundary

Abstract. Airborne and ground-based measurements of methane (CH4), carbon dioxide (CO2) and boundary layer thermodynamics were recorded over the Fennoscandian wetlands in July 2012 as part of the MAMM (Methane and other greenhouse gases in the Arctic – Measurements, process studies and Modelling) field campaign. Employing these airborne measurements and a~simple boundary layer box model, net regional scale (~100 km) fluxes were calculated to be 1.2 ± 0.5 mg CH4 h−1 m−2 and −350 ± 143 mg CO2 h−1 m−2. These airborne fluxes were found to be relatively consistent with seasonally-averaged surface chamber (1.3 ± 1.0 mg CH4 h−1 m−2) and eddy covariance (1.3 ± 0.3 mg CH4 h−1 m−2 and −309 ± 306 mg CO2 h−1 m−2) flux measurements in the local area. The internal consistency of the aircraft-derived fluxes across a wide swath of Fennoscandia coupled with an excellent statistical comparison with local seasonally-averaged ground-based measurements demonstrates the potential scalability of such localised measurements to regional scale representivity. Comparisons were also made to longer term regional CH4 climatologies from the JULES (Joint UK Land Environment Simulator) and Hybrid8 land surface models within the area of the MAMM campaign. The average hourly emission flux output for the summer period (July–August) across the years 1980 to 2010 was 0.054 mg CH4 h−1 m−2 (minimum 0.0 and maximum 0.38 mg CH4 h−1 m−2) for the JULES model and 0.073 mg CH4 h−1 m−2 (minimum −0.0018 and maximum 4.62 mg CH4 h−1 m−2) for Hybrid8. Based on these observations both models were found to significantly underestimate the CH4 emission flux in this region, which was linked to the under prediction of the wetland extents generated by the models.

scholarly journals Methane and carbon dioxide fluxes and their regional scalability for the European Arctic wetlands during the MAMM project in summer 2012

2014 ◽  
Vol 14 (23) ◽  
pp. 13159-13174 ◽  
Author(s):  
S. J. O'Shea ◽  
G. Allen ◽  
M. W. Gallagher ◽  
K. Bower ◽  
S. M. Illingworth ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Boundary Layer ◽  
Land Surface ◽  
Regional Scale ◽  
Local Area ◽  
The Arctic ◽  
Emission Flux ◽  
Carbon Dioxide Fluxes ◽  
Airborne Measurements ◽  
Simple Boundary

Abstract. Airborne and ground-based measurements of methane (CH4), carbon dioxide (CO2) and boundary layer thermodynamics were recorded over the Fennoscandian landscape (67–69.5° N, 20–28° E) in July 2012 as part of the MAMM (Methane and other greenhouse gases in the Arctic: Measurements, process studies and Modelling) field campaign. Employing these airborne measurements and a simple boundary layer box model, net regional-scale (~ 100 km) fluxes were calculated to be 1.2 ± 0.5 mg CH4 h−1 m−2 and −350 ± 143 mg CO2 h−1 m−2. These airborne fluxes were found to be relatively consistent with seasonally averaged surface chamber (1.3 ± 1.0 mg CH4 h−1 m−2) and eddy covariance (1.3 ± 0.3 mg CH4 h−1 m−2 and −309 ± 306 mg CO2 h−1 m−2) flux measurements in the local area. The internal consistency of the aircraft-derived fluxes across a wide swath of Fennoscandia coupled with an excellent statistical comparison with local seasonally averaged ground-based measurements demonstrates the potential scalability of such localised measurements to regional-scale representativeness. Comparisons were also made to longer-term regional CH4 climatologies from the JULES (Joint UK Land Environment Simulator) and HYBRID8 land surface models within the area of the MAMM campaign. The average hourly emission flux output for the summer period (July–August) for the year 2012 was 0.084 mg CH4 h−1 m−2 (minimum 0.0 and maximum 0.21 mg CH4 h−1 m−2) for the JULES model and 0.088 mg CH4 h−1 m−2 (minimum 0.0008 and maximum 1.53 mg CH4 h−1 m−2) for HYBRID8. Based on these observations both models were found to significantly underestimate the CH4 emission flux in this region, which was linked to the under-prediction of the wetland extents generated by the models.

scholarly journals Environmental controls on ecosystem-scale cold-season methane and carbon dioxide fluxes in an Arctic tundra ecosystem

2020 ◽  
Vol 17 (15) ◽  
pp. 4025-4042
Author(s):  
Dean Howard ◽  
Yannick Agnan ◽  
Detlev Helmig ◽  
Yu Yang ◽  
Daniel Obrist
Keyword(s):  
Carbon Dioxide ◽  
Methane Emission ◽  
Arctic Tundra ◽  
Cold Season ◽  
The Arctic ◽  
Future Climate Change ◽  
Climate Change Scenarios ◽  
Carbon Dioxide Fluxes ◽  
Soil Temperatures ◽  
Annual Total

Abstract. Understanding the processes that influence and control carbon cycling in Arctic tundra ecosystems is essential for making accurate predictions about what role these ecosystems will play in potential future climate change scenarios. Particularly, air–surface fluxes of methane and carbon dioxide are of interest as recent observations suggest that the vast stores of soil carbon found in the Arctic tundra are becoming more available to release to the atmosphere in the form of these greenhouse gases. Further, harsh wintertime conditions and complex logistics have limited the number of year-round and cold-season studies and hence too our understanding of carbon cycle processes during these periods. We present here a two-year micrometeorological data set of methane and carbon dioxide fluxes, along with supporting soil pore gas profiles, that provide near-continuous data throughout the active summer and cold winter seasons. Net emission of methane and carbon dioxide in one of the study years totalled 3.7 and 89 g C m−2 a−1 respectively, with cold-season methane emission representing 54 % of the annual total. In the other year, net emission totals of methane and carbon dioxide were 4.9 and 485 g C m−2 a−1 respectively, with cold-season methane emission here representing 82 % of the annual total – a larger proportion than has been previously reported in the Arctic tundra. Regression tree analysis suggests that, due to relatively warmer air temperatures and deeper snow depths, deeper soil horizons – where most microbial methanogenic activity takes place – remained warm enough to maintain efficient methane production whilst surface soil temperatures were simultaneously cold enough to limit microbial methanotrophic activity. These results provide valuable insight into how a changing Arctic climate may impact methane emission, and highlight a need to focus on soil temperatures throughout the entire active soil profile, rather than rely on air temperature as a proxy for modelling temperature–methane flux dynamics.

scholarly journals Simulating carbon exchange using a regional atmospheric model coupled to an advanced land-surface model

2008 ◽  
Vol 5 (5) ◽  
pp. 4161-4207 ◽  
Author(s):  
H. W. Ter Maat ◽  
R. W. A. Hutjes
Keyword(s):  
Carbon Dioxide ◽  
Land Surface ◽  
Large Scale ◽  
Regional Scale ◽  
Atmospheric Model ◽  
Surface Fluxes ◽  
Heat Fluxes ◽  
Surface Model ◽  
Carbon Exchange ◽  
Regional Atmospheric Modelling System

Abstract. A large scale mismatch exists between our understanding and quantification of ecosystem atmosphere exchange of carbon dioxide at local scale and continental scales. This paper will focus on the carbon exchange on the regional scale to address the following question: What are the main controlling factors determining atmospheric carbon dioxide content at a regional scale? We use the Regional Atmospheric Modelling System (RAMS), coupled with a land surface scheme simulating carbon, heat and momentum fluxes (SWAPS-C), and including also sub models for urban and marine fluxes, which in principle include the main controlling mechanisms and capture the relevant dynamics of the system. To validate the model, observations are used which were taken during an intensive observational campaign in the central Netherlands in summer 2002. These included flux-site observations, vertical profiles at tall towers and spatial fluxes of various variables taken by aircraft. The coupled regional model (RAMS-SWAPS-C) generally does a good job in simulating results close to reality. The validation of the model demonstrates that surface fluxes of heat, water and CO2 are reasonably well simulated. The comparison against aircraft data shows that the regional meteorology is captured by the model. Comparing spatially explicit simulated and observed fluxes we conclude that in general simulated latent heat fluxes are underestimated by the model to the observations which exhibit large standard deviation for all flights. Sensitivity experiments demonstrated the relevance of the urban emissions of carbon dioxide for the carbon balance in this particular region. The same test also show the relation between uncertainties in surface fluxes and those in atmospheric concentrations.

scholarly journals Environmental controls on ecosystem-scale cold season methane and carbon dioxide fluxes in an Arctic tundra ecosystem

2019 ◽  
Author(s):  
Dean Howard ◽  
Yannick Agnan ◽  
Detlev Helmig ◽  
Yu Yang ◽  
Daniel Obrist
Keyword(s):  
Carbon Dioxide ◽  
Methane Emission ◽  
Arctic Tundra ◽  
Cold Season ◽  
The Arctic ◽  
Future Climate Change ◽  
Climate Change Scenarios ◽  
Carbon Dioxide Fluxes ◽  
Soil Temperatures ◽  
Annual Total

Abstract. Understanding the processes that influence and control carbon cycling in Arctic tundra ecosystems is essential for making accurate predictions about what role these ecosystems will play in potential future climate change scenarios. Particularly, air–surface fluxes of methane and carbon dioxide are of interest as recent observations suggest that the vast stores of soil carbon found in the Arctic tundra are becoming more available to release to the atmosphere in the form of these greenhouse gases. Further, harsh wintertime conditions and complex logistics have limited the number of year-round and cold season studies and hence too our understanding of carbon cycle processes during these periods. We present here a two-year micrometeorological data set of methane and carbon dioxide fluxes that provides near-continuous data throughout the active summer and cold winter seasons. Net emission of methane and carbon dioxide in one of the study years totalled 3.7 and 89 g C m−2 a−1 respectively, with cold season methane emission representing 54% of the annual total. In the other year, net emission totals of methane and carbon dioxide were 4.9 and 485 g C m−2 a−1 respectively, with cold season methane emission here representing 82 % of the annual total – a larger proportion than has been previously reported in the Arctic tundra. Regression tree analysis suggests that, due to relatively warmer air temperatures and deeper snow depths, deeper soil horizons – where most microbial methanogenic activity takes place – remained warm enough to maintain efficient methane production whilst surface soil temperatures were simultaneously cold enough to limit microbial methanotrophic activity. These results provide valuable insight into how a changing Arctic climate may impact methane emission, and highlight a need to focus on soil temperatures throughout the entire active soil profile, rather than rely on air temperature as a proxy for modelling temperature–methane flux dynamics.

scholarly journals Importance of the WPL correction for the measurement of small CO<sub>2</sub> fluxes

2021 ◽  
Author(s):  
Katharina Jentzsch ◽  
Julia Boike ◽  
Thomas Foken
Keyword(s):  
Carbon Dioxide ◽  
Data Quality ◽  
Carbon Dioxide Flux ◽  
Density Fluctuations ◽  
The Arctic ◽  
Carbon Dioxide Fluxes ◽  
Gas Fluxes ◽  
Trace Gas Fluxes ◽  
Order Of Magnitude ◽  
Additive Correction

Abstract. The WPL (Webb, Pearman, and Leuning) correction is fully accepted to correct trace gas fluxes like CO2 for density fluctuations due to water vapor and temperature fluctuations for open-path gas analysers. It is known that this additive correction can be in the order of magnitude of the actual flux. However, this is hardly ever included in the analysis of data quality. An example from the Arctic shows the problems, because the size of the correction is a multiple of the actual flux. As a general result, we examined and tabulated the magnitude of the WPL correction for carbon dioxide flux as a function of sensible and latent heat flux. Furthermore, we propose a parameter to better estimate possible deficits in data quality and recommend integrating the quality flag derived with this parameter into the general study of small carbon dioxide fluxes.

scholarly journals Radiative energy budget and cloud radiative forcing in the daytime marginal sea ice zone during Arctic spring and summer

2021 ◽  
Author(s):  
Johannes Stapf ◽  
André Ehrlich ◽  
Christof Lüpkes ◽  
Manfred Wendisch
Keyword(s):  
Boundary Layer ◽  
Sea Ice ◽  
Energy Budget ◽  
Radiative Forcing ◽  
The Arctic ◽  
Radiative Energy ◽  
Cloud Radiative Forcing ◽  
Airborne Measurements ◽  
Marginal Sea ◽  
The Impact

Abstract. Airborne measurements of the surface radiative energy budget (REB) collected in the area of the marginal sea ice zone (MIZ) close to Svalbard (Norway) during two campaigns conducted in early spring and and early summer are presented. From the data, the cloud radiative forcing was derived. The analysis is focussed on the impact of changing atmospheric thermodynamic conditions on the REB and on the linkage of sea ice properties and cloud radiative forcing (CRF). The observed two-mode longwave net irradiance frequency distributions above sea ice are compared with measurements from previous studies. The transition of both states (cloudy and cloud-free) from winter towards summer and the associated broadening of the modes is discussed as a function of the seasonal thermodynamic profiles and the surface type. The influence of cold air outbreaks (CAO) and warm air intrusions on the REB is illustrated for several case studies, whereby the source and sink terms of REB in the evolving CAO boundary layer are quantified. Furthermore, the role of thermodynamic profiles and the vertical location of clouds during on-ice flow is illustrated. The sea ice concentration was identified as the main driver of the shortwave cooling by the clouds. The longwave warming of clouds, estimated to about 75 W m−2, seems to be representative for this region, as compared to other studies. Simplified radiative transfer simulations of the frequently observed low-level boundary layer clouds and average thermodynamic profiles represent the observed radiative quantities fairly well. The simulations illustrate the delicate interplay of surface and cloud properties that modify the REB and CRF, and the challenges in quantifying trends in the Arctic REB induced by potential changes of the cloud optical thickness.

Impact of Clouds on Broadband Radiation Profiles in the Summer Arctic Measured by a Tethered Balloon During MOSAiC: First Results

2021 ◽  
Author(s):  
Michael Lonardi ◽  
Christian Pilz ◽  
Ulrike Egerer ◽  
André Ehrlich ◽  
Matthew D. Shupe ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Radiative Forcing ◽  
Arctic Sea Ice ◽  
Radiative Heating ◽  
The Arctic ◽  
Radiative Energy ◽  
Tethered Balloon ◽  
Local Cooling ◽  
Airborne Measurements ◽  
The Impact

&lt;p&gt;Arctic boundary layer clouds play an important role in the Arctic amplification due to their impact on the radiative energy budget, e. g., local cooling at cloud top which strongly affects boundary-layer dynamics. High resolution in-situ data characterizing the irradiance profile in clouds over the Arctic sea ice are rare due to the accessibility of this region, the challenges posed by icing and the limited resolution of airborne measurements.&lt;/p&gt;&lt;p&gt;The tethered balloon system BELUGA (Balloon-bornE moduLar Utility for profilinG the lower Atmosphere) was deployed from the ice camp of the Multidisciplinary drifting Observatory for the Study of the Arctic Climate (MOSAiC) in July 2020. BELUGA consists of a 90 m&amp;#179; helium-filled tethered balloon with maximum flight altitude of 1500 m and an adaptable scientific payload to characterize radiation, cloud, aerosol and turbulence properties which was specifically developed for Arctic tethered balloon operations.&lt;/p&gt;&lt;p&gt;Here a first analysis of vertical profiles of upwards and downwards solar and terrestrial irradiances in cloudy and cloud-free conditions is presented. Profiles of radiative heating were calculated and compared for different cloud covers. The case studies were evaluated by radiative transfer simulations &amp;#160;to quantify the impact of different cloud and atmospheric properties on the heating rate profiles. In combination with surface-based measurements, the cloud radiative forcing in the summer Arctic was assessed.&lt;/p&gt;

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