9 research outputs found
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Measurement of the seasonal and annual variability of total column aerosol in a northeastern U.S. network
A network of multi-filter rotating shadowband radiometers has operated since late 1991 in the northeastern US. The data acquired are simultaneous measurements of total and diffuse horizontal irradiances in six narrowband filtered detectors and one broadband shortwave detector. The direct normal irradiances are calculated from these measurements. These direct data are corrected for cosine response and used to calculate extraterrestrial irradiance (I{sub o}) using the Langley method of regressing the natural logarithm of direct irradiance versus air mass. With frequent determinations of I{sub o}, changes in I{sub o} caused by soiling and filter degradation, for example, can be tracked. Using these I{sub o}`s, total optical depth is calculated for every clear 30-minute period in the record. Consequently, total optical depth may be obtained on a fair number of days throughout the year. Using daily average total optical depth the authors have calculated aerosol optical depths for five wavelengths by subtracting Rayleigh scattering optical depths and Chappuis ozone absorption optical depths at each wavelength. The aerosol pattern at nearly every site is an annual cycle superimposed on a decaying stratospheric loading associated with the Mount Pinatubo volcanic eruption. An attempt is made to remove the volcanic signal using data from another site
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Experimental design for a case study of drift from a mechanical draft cooling tower
A comprehensive experimental study of drift emissions and downwind deposition from a mechanical draft cooling tower is planned for early spring 1978. The objective of the experiment is to develop a data base which can be used for validation of drift deposition models. The key aspects of the study are to measure the characteristics of the drift emitted from the tower, the ambient meteorological conditions responsible for the transport and dispersion of the drift, and the downwind deposition and near surface air concentration patterns of the drift. The source characteristics, including air temperature and velocity profiles at the tower exit, and the transport parameters are to be used as inputs to the models, while the deposition patterns are to serve as comparisons to the outputs of the models