The detection of mixed layer depth and entrainment zone thickness from lidar backscatter profiles

A new method is presented for the extraction of mixed layer depth and entra inment zone thickness from Lidar, backscatter ratio profiles. The method is based on fitting a four parameter, idealized profile to observed profiles. Optimization of the fit yields values for mixed layer depth and entrainmen t zone thickness. Since the fitting procedure is based on the entire measur ed profile, it has a robustness not found in methods based on critical back scatter or backscatter gradient. The method is tested by application to fou r measured profiles and three synthetic profiles. The sets of profiles incl ude some that are very demanding because of small mixed layer to upper laye r backscatter ratio contrasts, or have plumes of high backscatter imbedded in mixed and upper layers. It is shown that the method is robust and simple to implement, even for a sequence of independent profiles.