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RECORD NUMBER: 40 OF 42

OLS Field Name OLS Field Data
Main Title Variability of Short Term Eddy-Correlation Estimates of Mass Exchange.
Author Wesely, M. L. ; Hart, R. L. ;
CORP Author Argonne National Lab., IL.;Environmental Protection Agency, Research Triangle Park, NC. Atmospheric Sciences Research Lab.
Year Published 1985
Report Number EPA/600/D-85/039;
Stock Number PB85-172641
Additional Subjects Detectors ; Transport properties ; Mass flow ; Air pollution ; Turbulent diffusion ; Sulfur oxides ; Nitrogen oxides ; Water vapor ; Heat ; Momentum ; Flux(Rate) ; Wind velocity ; Spectroscopic analysis ; Air pollution detection ; Numerical solution
Holdings
Library Call Number Additional Info Location Last
Modified
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Status
NTIS  PB85-172641 Most EPA libraries have a fiche copy filed under the call number shown. Check with individual libraries about paper copy. NTIS 06/21/1988
Collation 26p
Abstract
The signals from sensors used to measure atmospheric scalar fluctuations ordinarily produce characteristic spectra and cospectra with vertical wind velocity that are strongly influenced by vertical transport processes. Unwanted signal noise generated by some of the fast response chemical sensors, however, distort the spectra and cospectra and increase run-to-run variability of eddy-correlation flux estimates. Instead of data collection periods of only 30 min needed to provide a precision of approximately 10-20% in each flux estimate obtained at heights of 5-10 m during ideal daytime conditions, an ensemble derived from several such runs is necessary with certain sensors in order to achieve comparable precision. This has been the practical experiences obtained in numerous experiments above various natural surfaces, and is verified to a limited extent by both empirical and theoretical investigations.