This study presents the characteristics of nocturnal inversion layer and their effect on the concentration variations of surface air pollutants using tethersonde and automatic weather station (AWS, 2 layer tower) system in Ulsan during 2003. The method for the distinction of inversion intensity was decided based on the sum of nocturnal temperature gradient. As the results, there was a close correlation (correlation coefficient of 0.76) between the maximum inversion height obtained from tethersonde and the sum of nocturnal temperature gradient. The air pollutant concentration was also directly proportional to the inversion intensity. When the inversion intensity was strong in the nighttime, ozone (O3) concentration was lower, while nitrogen dioxide (NO2) concentration was higher. The carbon monoxide (CO) concentration was gradually higher according to the nocturnal inversion intensity, whereas sulfur dioxide (SO2) concentration was relatively constant. In addition, we found that there was no correlation between the inversion intensity and TSP concentration.

Using measured data at Daegu by tethersonde for the period of 1984～1987, we have investigated the lower atmospheric boundary layer structure including relationships between inversion layer and meteorological factors(wind and temperature), and the inversion strength and inversion height. The inversion layer was defined from the vertical temperature profile and its strength was analyzed with the wind shear as well as the vertical temperature gradient. From October to January, measured inversion layer isn't destroyed, however, in June, after sun rise, it is destroyed by surface heating and mixed layer is developed from surface. According to Pasquill stability classes, the moderately stable cases dominated. It's the larger vertical temperature gradient, the lower SBL height. We have introduced B(bulk turbulence scale) which indicated SBL height. It's larger B, the higher SBL height and vice versa. It was noted that the bulk turbulence scale (B) is appropriate to determine the stable boundary layer height.

Meteorological measurements were carried out in the basin of Cheong-Kwan located Yang-San near Pusan city, from Oct. 30 to Nov. 1, 1988. According to the measured data, we verified the close relationship between the variation of nocturnal inversion layer and the meteorological elements. The nocturnal inversion layer by radiative cooling in this site extends up to 130 meters or so. And the nocturnal jet appears just above or at the top of the inversion layer, and the stronger of the prevailing wind blows, and the lower of the jet level appears. Some meteorological features such as heating, cooling etc., began to change in or in the slightly higher level of the inversion layer, when they are formed, reinforced and disappeared. And the air in the basin preserves its character because it is not affected by local scale air flow.