Ship-based Doppler lidar estimates of mixing layer heights during TexAQS 2006

During the Texas 2006 Air Quality Study, NOAA's Chemical Sciences Division used the High Resolution Doppler Lidar (HRDL) to make continuous measurements of boundary layer winds and relative aerosol backscatter from the aft deck of the RV Brown. Such measurements, and their derived data products, provide information about aerosol transport, aerosol layering and layer heights, dust events, plume detection, and characterization of marine boundary layer dynamics including surface streaks/rolls, turbulence, and boundary layer mixing. Mixing is usually the result of convection and/or shear-induced mechanical turbulence and either of these types can effect the blending of the surface and residual aerosol/pollution layers. We have developed new methods to use Doppler lidar velocity information to estimate and visualize mixed/mixing layer heights as determined by vertical velocity variance (mixing strength) profiles. We then combine this information with wind shear and 2 µm aerosol backscatter profiles to produce mixing and/or mixed layer heights. We present an overview of the methods used in the estimation process and provide examples of marine mixed layer heights, as well as interpretation of such heights, from various conditions encountered during the experiment.