Ruppert, J; Thomas, C; Foken, T: Scalar similarity for relaxed Eddy accumulation methods , Boundary-Layer Meteorology, 120, 39-63 (2006)
The relaxed eddy accumulation (REA) method allows the measurement of trace gas fluxes when no fast sensors are available for eddy covariance measurements. The flux parameterisation used in REA is based on the assumption of scalar similarity, i. e. similarity of the turbulent exchange of two scalar quantities. In this study changes in scalar similarity between carbon dioxide, sonic temperature and water vapour were assessed using scalar correlation coefficients and spectral analysis. The infuence on REA measurements was assessed by simulation. The evaluation is based on data recorded during experiments over grassland, irrigated cotton plantation and spruce forest. Scalar similarity between carbon dioxide, sonic temperature and water vapour showed a distinct diurnal pattern and change within the day. Poor scalar similarity was found to be linked to dissimilarities in the energy contained in the low frequency part of the turbulent spectra (< 0.01 Hz). The simulations of REA showed signifcant change in b-factors throughout the diurnal course. The b-factor is part of the REA parameterisation scheme and describes a relation between the concentration diverence and the flux of a trace gas. The diurnal course of b-factors for carbon dioxide, sonic temperature and water vapour matched well. Relative °ux errors induced in REA by varying scalar similarity were generally below +/-10 %. Systematic underestimation of the flux of up to -40% was found for the use of REA applying a hyperbolic deadband (HREA). This underestimation was addressed to poor scalar similarity between the scalar of interest and the scalar used as proxy for the deadband definition.

There are additional file downloads belonging to this publication

Upcoming ...
BayCEER Colloquium:
Th. 2021-01-21
The impact of trees on soil organic carbon dynamics in the Subarctic - Priming effects and microbial N mining
Th. 2021-01-28
BayCEER Member Assembly
Th. 2021-02-04
Investigating communal pathogen defense and its role in social evolution
Th. 2021-04-15
- folgt -
Th. 2021-04-22
- folgt -
BayCEER Blog
Why Science Communication?
Stoichiometric controls of C and N cycling
Flying halfway across the globe to dig in the dirt – a research stay in Bloomington, USA
Picky carnivorous plants?
RSS Blog as RSS Feed
Weather research site
Luftdruck (356m): 975.8 hPa
Lufttemperatur: 0.8 °C
Niederschlag: 0.0 mm/24h
Sonnenschein: <1 h/d
Wind (Höhe 17m): 11.0 km/h
Wind (Max.): 24.1 km/h
Windrichtung: SW

Globalstrahlung: -1 W/m²
Wind (Höhe 32m): 0.0 km/h

This site makes use of cookies More information