Assessing scalar concentration footprint climatology and land surface impacts on tall-tower CO2 concentration measurements in the boreal forest of central Saskatchewan, Canada

2013 ◽  
Vol 118 (1-2) ◽  
pp. 115-132 ◽  
Author(s):  
Baozhang Chen ◽  
Huifang Zhang ◽  
Nicholas C. Coops ◽  
Dongjie Fu ◽  
Douglas E. J. Worthy ◽  
...  
Keyword(s):  
Boreal Forest ◽  
Land Surface ◽  
Co2 Concentration ◽  
Scalar Concentration ◽  
Concentration Measurements ◽  
Concentration Footprint ◽  
Tall Tower

Ecosystem modeling of methane and carbon dioxide fluxes for boreal forest sites

2001 ◽  
Vol 31 (2) ◽  
pp. 208-223 ◽  
Author(s):  
Christopher Potter ◽  
Jill Bubier ◽  
Patrick Crill ◽  
Peter Lafleur
Keyword(s):  
Carbon Dioxide ◽  
Boreal Forest ◽  
Land Surface ◽  
Net Primary Production ◽  
Ground Cover ◽  
Methane Flux ◽  
Growing Season ◽  
Ecosystem Model ◽  
Heat Fluxes ◽  
Water Levels

Predicted daily fluxes from an ecosystem model for water, carbon dioxide, and methane were compared with 1994 and 1996 Boreal Ecosystem–Atmosphere Study (BOREAS) field measurements at sites dominated by old black spruce (Picea mariana (Mill.) BSP) (OBS) and boreal fen vegetation near Thompson, Man. Model settings for simulating daily changes in water table depth (WTD) for both sites were designed to match observed water levels, including predictions for two microtopographic positions (hollow and hummock) within the fen study area. Water run-on to the soil profile from neighboring microtopographic units was calibrated on the basis of daily snowmelt and rainfall inputs to reproduce BOREAS site measurements for timing and magnitude of maximum daily WTD for the growing season. Model predictions for daily evapotranspiration rates closely track measured fluxes for stand water loss in patterns consistent with strong controls over latent heat fluxes by soil temperature during nongrowing season months and by variability in relative humidity and air temperature during the growing season. Predicted annual net primary production (NPP) for the OBS site was 158 g C·m–2 during 1994 and 135 g C·m–2 during 1996, with contributions of 75% from overstory canopy production and 25% from ground cover production. Annual NPP for the wetter fen site was 250 g C·m–2 during 1994 and 270 g C·m–2 during 1996. Predicted seasonal patterns for soil CO2 fluxes and net ecosystem production of carbon both match daily average estimates at the two sites. Model results for methane flux, which also closely match average measured flux levels of –0.5 mg CH4·m–2·day–1 for OBS and 2.8 mg CH4·m–2·day–1 for fen sites, suggest that spruce areas are net annual sinks of about –0.12 g CH4·m–2, whereas fen areas generate net annual emissions on the order of 0.3–0.85 g CH4·m–2, depending mainly on seasonal WTD and microtopographic position. Fen hollow areas are predicted to emit almost three times more methane during a given year than fen hummock areas. The validated model is structured for extrapolation to regional simulations of interannual trace gas fluxes over the entire North America boreal forest, with integration of satellite data to characterize properties of the land surface.

scholarly journals Constraining ecosystem model with Adaptive Metropolis algorithm using boreal forest site eddy covariance measurements

2016 ◽  
Author(s):  
Jarmo Mäkelä ◽  
Jouni Susiluoto ◽  
Tiina Markkanen ◽  
Mika Aurela ◽  
Ivan Mammarella ◽  
...  
Keyword(s):  
Boreal Forest ◽  
Gross Primary Production ◽  
Co2 Concentration ◽  
Moisture Stress ◽  
Ecosystem Model ◽  
Metropolis Algorithm ◽  
Forest Site ◽  
Diurnal Cycles ◽  
Forest Sites ◽  
Eddy Covariance Measurements

Abstract. We examined parameter optimization in JSBACH ecosystem model, applied for two boreal forest sites in Finland. We identified and tested key parameters in soil hydrology and forest water and carbon exchange related formulations and optimized them using the Adaptive Metropolis algorithm for a five year calibration period (2000–2004) followed by a four year validation period (2005–2008). We were able to improve the modelled seasonal, daily and diurnal cycles of gross primary production and evapotranspiration but unable to enhance the models response to dryness. The improvements are mostly accounted for by parameters related to the ratio of leaf internal CO2 concentration to external CO2, relative humidity, transpiration and soil moisture stress.

What is the concentration footprint of a tall tower?

2001 ◽  
Vol 106 (D16) ◽  
pp. 17831-17840 ◽  
Author(s):  
Manuel Gloor ◽  
Peter Bakwin ◽  
Dale Hurst ◽  
Loreen Lock ◽  
Roland Draxler ◽  
...  
Keyword(s):  
Concentration Footprint ◽  
Tall Tower

scholarly journals The Relationship between Land–Ocean Surface Temperature Contrast and Radiative Forcing

2011 ◽  
Vol 24 (13) ◽  
pp. 3239-3256 ◽  
Author(s):  
F. Hugo Lambert ◽  
Mark J. Webb ◽  
Manoj M. Joshi
Keyword(s):  
Surface Temperature ◽  
Heat Transport ◽  
Temperature Change ◽  
Land Surface ◽  
Radiative Forcing ◽  
Co2 Concentration ◽  
Ocean Surface ◽  
Heat Fluxes ◽  
Balance Model ◽  
Surface Temperature Change

Abstract Previous work has demonstrated that observed and modeled climates show a near-time-invariant ratio of mean land to mean ocean surface temperature change under transient and equilibrium global warming. This study confirms this in a range of atmospheric models coupled to perturbed sea surface temperatures (SSTs), slab (thermodynamics only) oceans, and a fully coupled ocean. Away from equilibrium, it is found that the atmospheric processes that maintain the ratio cause a land-to-ocean heat transport anomaly that can be approximated using a two-box energy balance model. When climate is forced by increasing atmospheric CO2 concentration, the heat transport anomaly moves heat from land to ocean, constraining the land to warm in step with the ocean surface, despite the small heat capacity of the land. The heat transport anomaly is strongly related to the top-of-atmosphere radiative flux imbalance, and hence it tends to a small value as equilibrium is approached. In contrast, when climate is forced by prescribing changes in SSTs, the heat transport anomaly replaces “missing” radiative forcing over land by moving heat from ocean to land, warming the land surface. The heat transport anomaly remains substantial in steady state. These results are consistent with earlier studies that found that both land and ocean surface temperature changes may be approximated as local responses to global mean radiative forcing. The modeled heat transport anomaly has large impacts on surface heat fluxes but small impacts on precipitation, circulation, and cloud radiative forcing compared with the impacts of surface temperature change. No substantial nonlinearities are found in these atmospheric variables when the effects of forcing and surface temperature change are added.

scholarly journals Scalar concentration measurements in liquid-phase flows with pulsed lasers

2004 ◽  
Vol 37 (2) ◽  
pp. 310-310
Author(s):  
Jerry W. Shan ◽  
Daniel B. Lang ◽  
Paul E. Dimotakis
Keyword(s):  
Liquid Phase ◽  
Pulsed Lasers ◽  
Scalar Concentration ◽  
Concentration Measurements

scholarly journals Past and future scenarios of the effect of carbon dioxide on plant growth and transpiration for three vegetation types of southwestern France

2008 ◽  
Vol 8 (2) ◽  
pp. 397-406 ◽  
Author(s):  
J.-C. Calvet ◽  
A.-L. Gibelin ◽  
J.-L. Roujean ◽  
E. Martin ◽  
P. Le Moigne ◽  
...  
Keyword(s):  
Land Surface ◽  
Coniferous Forest ◽  
Land Surface Model ◽  
Co2 Concentration ◽  
Sensitivity Study ◽  
Surface Model ◽  
Canopy Conductance ◽  
Vegetation Types ◽  
Precipitation Regime ◽  
Annual Cycles

Abstract. The sensitivity of an operational CO2-responsive land surface model (the ISBA-A-gs model of Météo-France) to the atmospheric CO2 concentration, (CO2), is investigated for 3 vegetation types (winter wheat, irrigated maize, coniferous forest). Past (1960) and future (2050) scenarios of (CO2) corresponding to 320 ppm and 550 ppm, respectively, are explored. The sensitivity study is performed for 4 annual cycles presenting contrasting conditions of precipitation regime and air temperature, based on continuous measurements performed on the SMOSREX site near Toulouse, in southwestern France. A significant CO2-driven reduction of canopy conductance is simulated for the irrigated maize and the coniferous forest. The reduction is particularly large for maize, from 2000 to 2050 (−18%), and triggers a drop in optimum irrigation (−30 mm y−1). In the case of wheat, the response is more complex, with an equal occurrence of enhanced or reduced canopy conductance.

scholarly journals Ion production rate in a boreal forest based on ion, particle and radiation measurements

2004 ◽  
Vol 4 (4) ◽  
pp. 3947-3973 ◽  
Author(s):  
L. Laakso ◽  
T. Petäjä ◽  
K. E. J. Lehtinen ◽  
M. Kulmala ◽  
J. Paatero ◽  
...  
Keyword(s):  
Boreal Forest ◽  
Production Rate ◽  
Radiation Energy ◽  
External Radiation ◽  
Hygroscopic Growth ◽  
Production Rates ◽  
Particle Measurements ◽  
Ion Production ◽  
Aerosol Particle Size ◽  
Concentration Measurements

Abstract. In this study the ion production rates in a boreal forest are studied based on two different methods: 1) cluster ion and particle concentration measurements, 2) external radiation and radon concentration measurements. Both methods produce reasonable estimates for ion production rates. The average ion production rate calculated from aerosol particle size distribution and air ion mobility distribution measurements was 2.6 cm−3s−1 and based on external radiation and radon measurements 4.5 cm−3s−1. The first method based on ion and particle measurements gave lower values for the ion production rates especially during the day. A possible reason for this is that particle measurements started only from 3 nm, so the sink of small ions during the nucleation events was underestimated. Another reason is that the possible fogs, which caused an extra sink of small ions are not taken into account in the calculations. It may also be possible that the hygroscopic growth factors of aerosol particles were underestimated. A fourth possible reason for the discrepancy is the nucleation mechanism itself. If the ions were somehow present in the nucleation process, there could have been an additional ion sink during the nucleation days. On the other hand, not all the radiation energy is converted to ions and the possible effect of alpha recoil is also omitted.

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