| Contents Notes |
In Medford, Oregon, the major source of pollution is the lumber mill waste burner. Its low combustion efficiency results in the emission of large quantities of particulate into the atmosphere. Due to the influence of the atmospheric radiation inversion and possibly the poor performance of the burners at the time of start-up, concentrations of particulate were found to be highest in the morning. Correlating these morning concentrations with average surface relative humidity, average surface wind speed, and various stability indices, most of which were determined from the U.S. Weather Bureau's 0300 PST radiosonde release, provided a measure of the degree of relationship between these meteorological factors and pollution. In addition, the analysis resulted in a determination of what stability factors could readily be used to predict pollution concentrations with reasonable accuracy (correlation coefficients ≥ 0.65). These included the sounding energy to 850 mb (energy required to lift a parcel of air from surface to 850 mb), the temperature difference index (difference in temperature between 850 mb and surface), the Modified Showalter Stability Index (Showalter Index applied to the layer of air between surface and 850 mb), and the persistence index (the sum of three weighted Modified Showalter Index values for three consecutive mornings). Graphical and regression prediction models involving the persistence index and average surface wind speed were developed. These relationships proved to be more accurate in predicting morning concentrations of particulate (multiple correlation coefficients 0.84) than those involving only one meteorological variable (highest correlation coefficient = 0.74). In order to illustrate the effects of air pollution on visibility, a preliminary relationship between concentrations of suspended particulate and visibility was developed. If visibility were selected as the criterion for judging air quality as it might well be in a tourist-oriented economy, such a relationship could serve as the basis for forecasting conditions of unacceptably low visibility as a result of high concentrations. |
