Different land surface types can significantly modify the character and frequency of an air mass. A large urban area can increase the temperature of a warm moist air mass and lengthen its duration over the area. The resulting oppressive air mass may often cause increases in heat-related mortality. In contrast, forested areas may increase the dew point of an air mass while also decreasing the temperature, thus making the air mass less oppressive in character.

During the last 100 years, this country has become increasingly urbanized. As more people move into urban areas, and less people engage in agricultural pursuits, marginal open areas have either been abandoned and are being enveloped by nearby urban areas, or they are returning to the original land cover. Along the East Coast, forest cover has increased by about 7 percent over the last century because of the declining importance of agriculture.

The goal of this presentation is to examine the impact of reforestation on air mass character in urban areas. Climatological records for three North Carolina cities were studied over the last fifty years to determine if reforestation has an effect on the air mass characteristics in these urban regions.

The initial results indicate that increased forest cover near these urban areas has had an impact on the character, frequency, and intensity of air masses. These results suggest that increasing the forest cover in or near urban areas may assist in mitigating the effects of the most oppressive air masses, and could increase the quality of life within the urban areas.