Timo Vesala
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View article: Technical note: New insights into stomatal oxygen transport viewed as a multicomponent diffusion process
Technical note: New insights into stomatal oxygen transport viewed as a multicomponent diffusion process Open
We investigate oxygen (O2) transport through stomata, focusing on its interaction with water vapour (H2O) flux. The dominant H2O flux exerts a drag force on other gases, a well-studied effect in the ternary air–water vapor–carbon dioxide (…
View article: Does increased spatial replication above heterogeneous agroforestry improve the representativeness of eddy covariance measurements?
Does increased spatial replication above heterogeneous agroforestry improve the representativeness of eddy covariance measurements? Open
Spatial heterogeneity in terrestrial ecosystems compromises the accuracy of eddy covariance measurements. Examples of heterogeneous ecosystems are temperate agroforestry systems, which have been poorly studied by eddy covariance. Agrofores…
View article: Year‐Round δ <sup>13</sup> C‐CH <sub>4</sub> Reveals Seasonal Transition in Methane‐Related Processes in a Boreal Mire
Year‐Round δ <sup>13</sup> C‐CH <sub>4</sub> Reveals Seasonal Transition in Methane‐Related Processes in a Boreal Mire Open
While boreal mires are known to be a significant natural source of methane (CH 4 ), the seasonality of the related processes and their controls are still poorly understood. Here we aim to characterize CH 4 production, oxidation and transpo…
View article: Ozone dry deposition through plant stomata: multi-model comparison with flux observations and the role of water stress as part of AQMEII4 Activity 2
Ozone dry deposition through plant stomata: multi-model comparison with flux observations and the role of water stress as part of AQMEII4 Activity 2 Open
A substantial portion of tropospheric O3 dry deposition occurs after diffusion of O3 through plant stomata. Simulating stomatal uptake of O3 in 3D atmospheric chemistry models is important in the face of increasing drought-induced declines…
View article: Practical guidelines for reproducible N<sub>2</sub>O flux chamber measurements in nutrient-poor ecosystems
Practical guidelines for reproducible N<sub>2</sub>O flux chamber measurements in nutrient-poor ecosystems Open
The atmospheric concentration of nitrous oxide (N2O) has increased significantly since 1800, mainly due to agricultural activities. However, due to their large area, nutrient-poor natural soils, including those in the (sub-) Arctic, also p…
View article: Technical note: New insights into stomatal oxygen transport viewed as a multicomponent diffusion process
Technical note: New insights into stomatal oxygen transport viewed as a multicomponent diffusion process Open
We investigate oxygen (O2) transport through stomata, focusing on its interaction with water vapour (H2O) flux. The dominant H2O flux exerts a drag force on other gases, a well-studied effect in the ternary air–water vapour–carbon dioxide …
View article: The Contribution of Boreal Wetlands to the Northern Hemisphere Carbonyl Sulfide Sink
The Contribution of Boreal Wetlands to the Northern Hemisphere Carbonyl Sulfide Sink Open
Carbonyl sulfide (COS), a gas used as a tracer in carbon cycle studies, has a potential missing sink in Northern high latitudes. Boreal COS budgets typically account for the contribution by forests, but ignore any uptake that wetland ecosy…
View article: The importance of continuous comprehensive Integrated observations: from feedback loop analysis to CarbonSink+
The importance of continuous comprehensive Integrated observations: from feedback loop analysis to CarbonSink+ Open
The Earth is facing several environmental challenges on a global scale, often called “Grand Challenges” (https://www.wcrp-climate.org/grand-challenges/). The growing population (https://pdp.unfpa.org) needs fresh air, fresh water, food and…
View article: Temporal dynamics and environmental controls of carbon dioxide and methane fluxes measured by the eddy covariance method over a boreal river
Temporal dynamics and environmental controls of carbon dioxide and methane fluxes measured by the eddy covariance method over a boreal river Open
Boreal rivers and streams are significant sources of carbon dioxide (CO2) and methane (CH4) for the atmosphere. Yet the controls and the magnitude of these emissions remain highly uncertain, as current estimates are mostly based on indirec…
View article: Interpretable machine learning guided by physical mechanisms revealsdrivers of runoff under dynamic land use changes
Interpretable machine learning guided by physical mechanisms revealsdrivers of runoff under dynamic land use changes Open
Human activities continuously impact water balances and cycling in watersheds, making it essential to accurately identify the responses of runoff to dynamic changes in land use types. Although machine learning models demonstrate promise in…
View article: Towards improved understanding on flow decoupling at eddy covariance sites with the aid of a universal coupling metric
Towards improved understanding on flow decoupling at eddy covariance sites with the aid of a universal coupling metric Open
Eddy covariance (EC) flux observations deviate from the fluxes at the ecosystem-atmosphere interface when the turbulent flow is decoupled from the surface. This problem severely limits the applicability of the EC technique to monitor ecosy…
View article: Determining the controlling factors for carbon sequestration in two contrasting forests in the Boreal region and the semi-arid Mediterranean
Determining the controlling factors for carbon sequestration in two contrasting forests in the Boreal region and the semi-arid Mediterranean Open
Evergreen-needle forests are among the most adaptive ecosystems, spanning from the cold-wet Boreal to the hot-dry Mediterranean, and can provide insights into differential responses in productivity and carbon storage potential across a geo…
View article: Long term flux measurements of carbon dioxide and methane over a small boreal lake using eddy covariance technique
Long term flux measurements of carbon dioxide and methane over a small boreal lake using eddy covariance technique Open
Advancing our understanding on physical and biogeochemical processes controlling turbulent exchange of energy, carbon dioxide (CO2), methane (CH4) and other trace gases across lacustrine systems is crucial in order to improve climate and w…
View article: First extensive manual N&#8322;O flux measurements reveal a light-dependent N&#8322;O sink in a thawing permafrost peatland
First extensive manual N₂O flux measurements reveal a light-dependent N₂O sink in a thawing permafrost peatland Open
Nitrous oxide (N₂O) is one of the most important greenhouse gases (GHG) with a global warming potential about 298 times stronger than carbon dioxide (CO₂) over a period of 100 years. While most N₂O emissions are released …
View article: Does increased spatial replication above heterogeneous agroforestry improve the representativeness of eddy covariance measurements?
Does increased spatial replication above heterogeneous agroforestry improve the representativeness of eddy covariance measurements? Open
Spatial heterogeneity in terrestrial ecosystems compromises the accuracy of eddy covariance measurements. An example of heterogeneous ecosystems are temperate agroforestry systems, that have been poorly studied by eddy covariance. Agrofore…
View article: Advancing N <sub>2</sub> O flux chamber measurement techniques in nutrient-poor ecosystems
Advancing N <sub>2</sub> O flux chamber measurement techniques in nutrient-poor ecosystems Open
Nitrous oxide (N2O) is the third most important greenhouse gas, with its atmospheric concentration rising from 273 parts per billion (ppb) to 336 ppb since 1800, primarily due to agricultural activities. However, nutrient-poor natural soil…
View article: Characteristics of Energy Fluxes and Cold Frontal Effects on Energy Exchange over a Boreal Lake
Characteristics of Energy Fluxes and Cold Frontal Effects on Energy Exchange over a Boreal Lake Open
Understanding the characteristics and variations of heat exchange and evaporation of lakes is important for regional water resource management and sustainable development. Based on eddy covariance measurements over Lake Vanajavesi in south…
View article: Measuring shoot-level NOx flux in field conditions: the role of blank chambers
Measuring shoot-level NOx flux in field conditions: the role of blank chambers Open
We monitored NOx fluxes in an empty chamber and in chambers containing Scots pine shoots. Our aims were to observe how the chamber blank behaves in non-controlled field conditions and at low ambient NOx concentrations, to find ways of redu…
View article: Ozone flux measurements over a Scots pine forest using eddy covariance method: performance evaluation and comparison with flux-profile method
Ozone flux measurements over a Scots pine forest using eddy covariance method: performance evaluation and comparison with flux-profile method Open
Ozone fluxes were measured over a forest in southern Finland between August 2001 and July 2002 using the eddy covariance method. Systematic errors due to the imperfect frequency response of the instrumentation and random errors due to the …
View article: Eddy covariance measurements of CO2 and sensible and latent heat fluxes during a full year in a boreal pine forest trunk-space
Eddy covariance measurements of CO2 and sensible and latent heat fluxes during a full year in a boreal pine forest trunk-space Open
The eddy covariance method was used to determine turbulent heat fluxes and CO2 flux below a boreal Scots pine canopy 3 m above the forest floor. Data were filtered using standard deviation of the vertical velocity as a measure of the turbu…
View article: Comparison of tree stem diameter variations in beech (Fagus sylvatica L.) in Sorø Denmark and in Scots pine (Pinus sylvestris L.) in Hyytiälä, Finland
Comparison of tree stem diameter variations in beech (Fagus sylvatica L.) in Sorø Denmark and in Scots pine (Pinus sylvestris L.) in Hyytiälä, Finland Open
Tree stem diameter variations were measured simultaneously in beech (Fagus sylvatica L.) in Sorø, Denmark and in Scots pine (Pinus sylvestris L.) in Hyytiälä, Finland. The variations were detected at two heights on the xylem and the whole …
View article: Eddy covariance fluxes over a boreal Scots pine forest
Eddy covariance fluxes over a boreal Scots pine forest Open
We report the results on eddy covariance measurements of net ecosystem exchange (NEE) and accompanying latent and sensible heat fluxes for 44 months in boreal Scots pine forest (southern Finland). We analysed the temperature dependence of …
View article: Xylem diameter changes as an indicator of stand-level evapo-transpiration
Xylem diameter changes as an indicator of stand-level evapo-transpiration Open
Xylem diameters of living trees change diurnally. According to the cohesion-tension theory these changes result from changes in sapwood water content. A model based on the assumptions of that theory was used to predict diameter changes fro…