||Argonne National Lab., IL. Biological, Environmental, and Medical Research Div.;Environmental Protection Agency, Research Triangle Park, NC. Atmospheric Sciences Research Lab.;Department of Energy, Washington, DC.
Variances of fluctuations of scalar quantities can be measured and interpreted to yield indirect estimates of their vertical fluxes in the atmospheric surface layer. Strong correlations among scalar fluctuations indicate a similarity of transfer mechanisms. Chemical sensors whose output is contaminated by nonatmospheric noise, covariances with fluctuations of scalar quantities measured with a very good signal-to-noise ratios can be used to extract the needed standard deviation. Field measurements have shown that many of these approaches are successful for gases such as ozone and sulfur dioxide, as well as for temperature and water vapor, and could be extended to other trace substances. In humid areas, it appears that water vapor fluctuations often have a higher degree of correlation to fluctuations of other trace gases than do temperature fluctuations, making water vapor a more reliable reference scalar. These techniques provide some reliable research approaches but for routine or operational measurement they are limited by the need for fast-response sensors. (Copyright (c) 1988 by Kluwer Academic Publishers.)