Application of airport meteorological data for the determination of atmospheric mixing height

Mixing height is a major meteorological factor affecting pollutant dispersion in the vertical direction. It has been commonly used in air quality models. Usually adiabatic method and Nozaki model are used for determining the mixing height. The adiabatic method needs daily sounding data while the Nozaki method requires extensive meteorological information. However, these data are unavailable in meteorological stations. On the other hand, in order to provide meteorological service for air transport, many airports carry out hourly measurements of temperature, wind, humidity, cloudiness, visibility and atmospheric pressure on the ground, and daily sounding measurements of temperature, humidity and wind at different heights. These data can be used in both adiabatic and Nozaki models to determine the mixing heights. In this study, ground and sounding meteorological data at Shijiazhuang Airport (China) during 1988-1993 were collected for estimating the mixing height over Shijiazhuang area. The feasibility of using airport meteorological data to determine the mixing height was the major focus of this research. Also, the Nozaki method was modified for better reflecting local meteorological conditions through introduction of joint frequencies for wind and stability into the modeling framework. The dry adiabatic method is based on daily sounding meteorological data to determine the mixing height at the intersection of a dry adiabatic line and a temperature profile sounded at early morning. The mixing heights obtained by the modified Nozaki method were verified through error analysis. The observed vertical SO₂-concentration profiles provided by the China Institute of Environmental Science indicate that good agreements between observed and estimated values were obtained, thus confirming the feasibility of utilizing airport meteorological data for determining the mixing height.