Average aerosol extinction and water vapor profiles over the southern great plains

An operational Raman lidar deployed at the DOE Atmospheric Radiation Measur ement site in Oklahoma has collected more than 7500 h of aerosol and water vapor data between April 1998 and January 2000. These data, which span a wi de variety of atmospheric conditions, have been analyzed as a function of s eason, integrated amount, and time of day. The scale height of the mean aer osol profiles varies considerably as both a function of season and aerosol optical thickness, with the mean scale height increasing from less than I k m in the winter to over 2 km during turbid summer days. The mean scale heig ht of the water vapor remained very close to 2 km, regardless of season or precipitable water vapor. Furthermore, the distribution of aerosol optical thickness shows a slight shift to smaller values at night compared to day, and the mean aerosol profiles show little diurnal dependence except at the top of the boundary layer.