Footprint Analysis For Measurements Over A Heterogeneous Forest

Rannik, Üllar; Aubinet, Marc; Kurbanmuradov, O.; Sabelfeld, Karl K.; Markkanen, Tiina; Vesala, Timo

doi:10.1023/a:1002702810929

Cited by 170 publications

(116 citation statements)

References 25 publications

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“…The approach is based on a Lagrangian stochastic forward model providing two dimensional contributions of source areas (Rannik et al 2000). The resulting footprint for NamUBT (Fig.…”

Section: Coordinate Rotation and Footprint Analysismentioning

confidence: 99%

Turbulent flux observations and modelling over a shallow lake and a wet grassland in the Nam Co basin, Tibetan Plateau

Biermann

Babel

et al. 2013

Theor Appl Climatol

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The Tibetan Plateau plays an important role in the global water cycle and is strongly influenced by climate change. While energy and matter fluxes have been more intensely studied over land surfaces, a large proportion of lakes have either been neglected or parameterised with simple bulk approaches. Therefore, turbulent fluxes were measured over wet grassland and a shallow lake with a single eddy-covariance complex at the shoreline in the Nam Co basin in summer 2009. Footprint analysis was used to split observations according to the underlying surface, and two sophisticated surface models were utilised to derive gap-free time series. Results were then compared with observations and simulations from a nearby eddy-covariance station over dry grassland, yielding pronounced differences. Observations and footprint integrated simulations compared well, even for situations with flux contributions including grassland and lake. The accessibility problem for EC measurements on lakes can be overcome by combining standard meteorological measurements at the shoreline with model simulations, only requiring representative estimates of lake surface temperature.

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“…The approach is based on a Lagrangian stochastic forward model providing two dimensional contributions of source areas (Rannik et al 2000). The resulting footprint for NamUBT (Fig.…”

Section: Coordinate Rotation and Footprint Analysismentioning

confidence: 99%

Turbulent flux observations and modelling over a shallow lake and a wet grassland in the Nam Co basin, Tibetan Plateau

Biermann

Babel

et al. 2013

Theor Appl Climatol

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“…The five warmseason sites were a Scots pine forest in Hyytiälä, Finland (61°51 ¢ N, 24°17 ¢ E; data from 1997; Rannik et al 2000) , an aspen forest in Prince Albert National Park, Saskatchewan, Canada (53°63 ¢ N, 106°20 ¢ W; data from 1996; Black et al 2000) , a mixed deciduous forest in Walker Branch Watershed in Tennessee, USA (35°58 ¢ N, 84°17 ¢ W; data from 1996; Wilson et al 2000) , a mixed hardwood forest in Massachusetts, USA (Harvard Forest, 42°32 ¢ N, 72°10 ¢ W; data from1992; Goulden et al 1996) , and a native tallgrass prairie in Okalahoma, USA (36°56 ¢ N, 96°41 ¢ W; data from 1997; Suyker and Verma 2001) . These five sites were also used in Gu et al (2003a) .…”

Section: Sites and Data Used In The Present Studymentioning

confidence: 99%

Characterizing the Seasonal Dynamics of Plant Community Photosynthesis Across a Range of Vegetation Types

Post

Baldocchi

et al. 2009

Phenology of Ecosystem Processes

137

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The seasonal cycle of plant community photosynthesis is one of the most important biotic oscillations to mankind. This study built upon previous efforts to develop a comprehensive framework to studying this cycle systematically with eddy covariance flux measurements. We proposed a new function to represent the cycle and generalized a set of phenological indices to quantify its dynamic characteristics. We suggest that the seasonal variation of plant community photosynthesis generally consists of five distinctive phases in sequence each of which results from the interaction between the inherent biological and ecological processes and the progression of climatic conditions and reflects the unique functioning of plant community at different stages of the growing season. We applied the improved methodology to seven vegetation sites ranging from evergreen and deciduous forests to crop to grasslands and covering both cool-season (vegetation active during cool months, This article is a U.S. government work, and is not subject to copyright in the United States. e.g. Mediterranean climate grasslands) and warm-season (vegetation active during warm months, e.g. temperate and boreal forests) vegetation types. Our application revealed interesting phenomena that had not been reported before and pointed to new research directions. We found that for the warm-season vegetation type, the recovery of plant community photosynthesis at the beginning of the growing season was faster than the senescence at the end of the growing season while for the coolseason vegetation type, the opposite was true. Furthermore, for the warm-season vegetation type, the recovery was closely correlated with the senescence such that a faster photosynthetic recovery implied a speedier photosynthetic senescence and vice versa. There was evidence that a similar close correlation could also exist for the cool-season vegetation type, and furthermore, the recovery-senescence relationship may be invariant between the warm-season and cool-season vegetation types up to an offset in the intercept. We also found that while the growing season length affected how much carbon dioxide could be potentially assimilated by a plant community over the course of a growing season, other factors that affect canopy photosynthetic capacity (e.g. nutrients, water) could be more important at this time scale.These results and insights demonstrate that the proposed method of analysis and system of terminology can serve as a foundation for studying the dynamics of plant community photosynthesis and such studies can be fruitful.

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“…At Kalevansuo site footprint functions for passive tracers released from the forest floor were calculated with the forward Lagrangian stochastic model as described by Rannik et al (2000Rannik et al ( , 2003. The model predicted the horizontal distribution of the surface sources of the flux measurements for three selected wind direction (WD) sectors (140 • < WD < 190 • , 190 • < WD < 240 • and 240 • < WD < 320 • ) and for two stability classes (near-neutral and unstable conditions, defined for values of |L| > 200 and −200 < L < 0 respectively, where L is the Obukhov length measured above canopy).…”

Section: Appendix B Footprint Analysismentioning

confidence: 99%

A case study of eddy covariance flux of N<sub>2</sub>O measured within forest ecosystems: quality control and flux error analysis

et al. 2010

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Abstract. Eddy covariance (EC) flux measurements of nitrous oxide (N 2 O) obtained by using a 3-D sonic anemometer and a tunable diode laser gas analyzer for N 2 O were investigated. Two datasets (Sorø, Denmark and Kalevansuo, Finland) from different measurement campaigns including subcanopy flux measurements of energy and carbon dioxide are discussed with a focus on selected quality control aspects and flux error analysis. Although fast response trace gas analyzers based on spectroscopic techniques are increasingly used in ecosystem research, their suitability for reliable estimates of EC fluxes is still limited, and some assumptions have to be made for filtering and processing data. The N 2 O concentration signal was frequently dominated by offset drifts (fringe effect), which can give an artificial extra contribution to the fluxes when the resulting concentration fluctuations are correlated with the fluctuations of the vertical wind velocity. Based on Allan variance analysis of the N 2 O signal, we found that a recursive running mean filter with a time constant equal to 50 s was suitable to damp the influence of the periodic drift. Although the net N 2 O fluxes over the whole campaign periods were quite small at both sites (∼ 5 µg N m −2 h −1 for Kalevansuo and ∼ 10 µg N m −2 h −1 for Sorø), the calculated sub-canopy EC fluxes were in good agreement with those estimated by automatic soil chambers. However, EC N 2 O flux measurements show larger random uncertainty than the sensible heat fluxes, and classification according to statistical significance of single flux values indicates that downward N 2 O fluxes have larger random error.

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Footprint Analysis For Measurements Over A Heterogeneous Forest

Cited by 170 publications

References 25 publications

Turbulent flux observations and modelling over a shallow lake and a wet grassland in the Nam Co basin, Tibetan Plateau

Turbulent flux observations and modelling over a shallow lake and a wet grassland in the Nam Co basin, Tibetan Plateau

Characterizing the Seasonal Dynamics of Plant Community Photosynthesis Across a Range of Vegetation Types

A case study of eddy covariance flux of N<sub>2</sub>O measured within forest ecosystems: quality control and flux error analysis

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Footprint Analysis For Measurements Over A Heterogeneous Forest

Cited by 170 publications

References 25 publications

Turbulent flux observations and modelling over a shallow lake and a wet grassland in the Nam Co basin, Tibetan Plateau

Turbulent flux observations and modelling over a shallow lake and a wet grassland in the Nam Co basin, Tibetan Plateau

Characterizing the Seasonal Dynamics of Plant Community Photosynthesis Across a Range of Vegetation Types

A case study of eddy covariance flux of N&lt;sub&gt;2&lt;/sub&gt;O measured within forest ecosystems: quality control and flux error analysis

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Product

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A case study of eddy covariance flux of N<sub>2</sub>O measured within forest ecosystems: quality control and flux error analysis