A study of the effects of the urban mesoclimate on local and regional pollution potential in southeast Texas

Abstract

The extent of influence of the pollution plume of Houston, Texas, was determined for winter and spring 1972, through several techniques based upon routine meterorological data. One method involved the use of 9-hr trajectories of hypothetical air parcels calculated from "adjusted" surface winds at 3-hr intervals. Wind speed, stability, and mixing depths obtained from Environmental Meteorological Support Unit (EMSU) soundings made at Houston were used to determine the dilution factor (DF) along each trajectory. The summary of air trajectories for spring shows different patterns for different times of day. During spring, Bryan/College Station, Texas is directly down-wind from Houston during afternoon, evening, and night-time. During winter, the trajectory patterns show lesser diurnal changes. Average values of DF during spring and winter were used to indicate the areas where highest relative concentrations would occur for each period of the day. During spring, the most important factor affecting the distribution of DF is the radial distance from Houston.