Abstract
Abstract. Businger and Delany (1990) presented an approach to estimate the sensor resolution required to limit the contribution of the uncertainty in the chemical concentration measurement to uncertainty in the flux measurement to 10 % for eddy covariance, gradient, and relaxed eddy accumulation flux measurement methods. We describe an improvement to their approach to estimate required sensor resolution for the covariance method, and include disjunct eddy covariance. In addition, we provide data to support selection of a form for the dimensionless scalar standard deviation similarity function based on observations of the variance of water vapor fluctuations from recent field experiments. We also redefine the atmospheric parameter of Businger and Delany in a more convenient, dimensionless form. We introduce a "chemical parameter" based on transfer velocity parameterizations. Finally, we provide examples in which the approach is applied to measurement of carbon dioxide, dimethylsulfide, and hexachlorobenzene fluxes over water. The information provided here will be useful to plan field measurements of atmosphere-surface exchange fluxes of trace gases.
Highlights
Introduction1999), and dimethylsulfide (Blomquist et al, 2010, 2006). Current methods to measure atmospheric trace gas fluxes for which fast response sensors are not available include disjunct eddy covariance (Karl et al, 2002; Rinne et al, 2008; Turnipseed et al, 2009), gradient methods, such as the modified Bowen ratio method (Perlinger et al, 2008, 2005; Walker et al, 2006), and relaxed eddy accumulation REA (Bowling et al, 1999; Businger and Oncley, 1990; Park et al, 2010); for these methods, chemical concentration measurements requiring accumulation times of up to an hour or so may be used, limited by the time of stationarity of the flux
In recent decades, significant developments in technologies and methods for direct measurement of turbulent atmosphere-surface exchange fluxes have been achieved
The statistical sampling error variance of the flux measurement is greater for disjunct eddy covariance (DEC) than for conventional EC because fewer samples are collected over the averaging period (Lenschow et al, 1994)
Summary
1999), and dimethylsulfide (Blomquist et al, 2010, 2006). Current methods to measure atmospheric trace gas fluxes for which fast response sensors are not available include disjunct eddy covariance (Karl et al, 2002; Rinne et al, 2008; Turnipseed et al, 2009), gradient methods, such as the modified Bowen ratio method (Perlinger et al, 2008, 2005; Walker et al, 2006), and relaxed eddy accumulation REA (Bowling et al, 1999; Businger and Oncley, 1990; Park et al, 2010); for these methods, chemical concentration measurements requiring accumulation times of up to an hour or so may be used, limited by the time of stationarity of the flux. Businger and Delany (1990), hereafter referred to as BD90, presented an analysis of sensor resolution, R, required to make chemical flux measurements to an estimated 10 % uncertainty. Rowe et al.: Chemical sensor resolution requirements for near-surface measurements of turbulent fluxes and φσ the similarity function for the dimensionless scalar standard deviation (σc/|c∗|), which is a function of sensor height, z, and the Monin-Obukhov stability length, L. This paper is intended to apply primarily to gaseous scalars In principle, this basic approach can be applied to the case of particle (aerosol) flux measurement. Application to particle flux measurements is deferred to a future paper, and the remainder of this paper applies to gaseous scalars
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