ASOS ceilometer measurements of aerosols and mixed layer height in the lower troposphere

The Vaisala CT12K ceilometer is evaluated for measurements of atmospheric aerosols and the mixed layer height on the basis of actual field data collected by the National Weather Service between August 2 and 9, 1987. The sequence of height time indicator (HTI) cross sections shows the temporal and height variation of cloud bases, the mixed layer height, the nocturnal inversion, virga, and elevated aerosol layering. Simultaneous and collocated surface and upper air observations are used to compare Vaisala CT12K measurements of the mixed layer height with standard estimation methods. A sample HTI diagram for corrected Vaisala CT12K cross sections is shown. Given the uncertainty underlying the mixed height model procedure and assumptions, the agreement between Vaisala CT12K measurements and model estimates for mixed layer height were good.