Diffusion under low windspeed, inversion conditions

In recent years there has been much interest in the diffusing ability of the atmosphere under stable conditions with light winds. This paper describes a series of diffusion tests conducted under these conditions over flat, even terrain. The tests were conducted at the Idaho National Engineering Laboratory (INEL) in Southeastern Idaho. The INEL is located in a broad, relatively flat plain at an elevation of about 1500 m above sea level. The climate is dry and the area has semidesert characteristics. The test criteria were a stable lapse rate with winds less than 2 m/sec. These test conditions were most often met in the early morning hours. The tracer was SF6 released at a height of 1.5 m. Because of wind direction variability, it was felt that a full 3600 sampling grid was necessary. Arcs were laid out at radii of 100, 200, and 400m from the grid center. Samplers were placed at intervals of 60 on each arc for a total of 180 ground-level sampling positions. After examining results from the early tests it became apparent that elevated samples would also be desirable. Eight towers, spaced 200 apart on the 200-m arc, were supplied with samplers at the 2, 4.5, 6, and 9m levels. These provided some elevated measurements during the last four tests