Mixing layer height

A Mixing Layer Height measurement option is available. This option retrieves the height of the mixed aerosol layer by applying the gradient method to the ceilometer backscatter signal. This approach, based on the operational algorithm1 Haij, M.J. de, H. Klein Baltink and W.M.F. Wauben: Continuous mixing layer height determination using the LD-40 ceilometer: a feasibility study, Scientific Report WR 2007-01, KNMI, De Bilt, 2007." used by KNMI2 KNMI, officially known as the Royal Netherlands Meteorological Institute, is a national research and information center for meteorology, climate, and seismology., searches for the drop in backscatter associated with the transition from boundary layer aerosols to free troposphere. Since the signals measured depend on the type and amount of aerosol present as well as the background light level, the accuracy of the method varies, and therefore a quality factor is assigned that indicates the confidence in the reported layer height. The module can also detect the top of residual layers and elevated aerosol layers. To activate this option, please contact Campbell Scientific.

This quality factor provides a guide to how well the mixing layer height (MLH) is defined, using a scale from 1 to 3, with 3 indicating the highest confidence. It is determined by the magnitude of the difference between the average backscatter over a distance below the MLH and the average backscatter over a distance above it.