Interpretation of meterorological pollutant roses in areas subject to nocturnal drainage winds
Pollutant roses have long been used as investigative tools to expose significant pollution sources. Certain problems can arise when pollutant roses based on hourly wind data are used with pollutants averaged on longer time scales, such as 24 hour total suspended particulate levels. A report is presented of a nocturnal drainage wind, whose impact on pollutant roses, based on 24 hour integrated samples, could lead to invalid conclusions and misinterpretation as a transport phenomenon if an associated meteorological analysis were not undertaken to define the physical phenomena. The drainage wind can only occur when all other meteorological conditions are the worst in terms of the dilution and dispersal of pollutants. In the generation of the pollutant rose, the occurrence of those wind directions associated with the drainage wind are weighted by the abnormally high pollutant levels on the days of poor dilution. Thus, while the drainage wind direction is consistently associated with poor dilution conditions throughout the year, the daytime directions (synoptic or gradient wind induced directions) associated with the same conditions may vary. In total, this can cause a sharp and sometimes false peak in the pollutant rose for the drainage wind direction. Additional long-range studies are being contemplated to investigate spatial characteristics of the drainage wind because of the possibility of pollutant recirculation and the adverse impact such a phenomenon would have on conventional dispersion modeling techniques.
- OSTI ID:
- 5196352
- Journal Information:
- J. Air Pollut. Control Assoc.; (United States), Vol. 27:3
- Country of Publication:
- United States
- Language:
- English
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