The Effects of Boundary Layer Depth, Stability, Precipitation, and Droplet Concentration on Stratocumulus Evolution Using a New Lagrangian Approach

Clouds are sampled at 62,000 unique locations within the eastern subtropical ocean basins where marine stratocumulus is most abundant. A-Train satellites provide measures of cloud cover, precipitation, boundary layer depth, cloud liquid water path, and cloud microphysical properties for each sample. 24-hour, forward, boundary layer trajectories are then computed for each sample, allowing a comparison of changes in cloud cover for a wide variety of initial conditions without confounding diurnal effects. Biases in this experiment are identified and removed. Most notably a significant viewing zenith angle bias, and a bias associated with stochastic red-noise processes. After the biases are removed, this study shows that stratocumulus amounts and cloud properties are significantly affected by lower tropospheric stability and boundary layer depth more so than by precipitation. The effects of boundary layer depth and stability agree with those predicted by prior models and experiments. Precipitation and droplet concentration effects may depend on the degree of coupling within the boundary layer, warranting a more detailed analysis broken down by boundary layer depth. This method can be expanded and further applied for many other parameters.