Arctic Multi-Layered, Mixed-Phase Cloud Processes Revealed in Millimeter-wave Cloud Radar Doppler Spectra

We use cloud radar Doppler velocity spectra, lidar backscattering coefficients and depolarization ratios, and aircraft in situ measurements to investigate multi-layered, mixed-phase cloud microphysical processes for a case that was observed during the Mixed-Phase Arctic Cloud Experiment over the North Slope of Alaska. Some liquid-cloud layers existed in well-mixed atmospheric layers, but others were found in absolutely stable atmospheric layers. Strong cloud-top cooling was necessary to produce the well-mixed cloud layers; clouds shielded from radiative cooling by overlaying clouds more frequently existed in absolutely stable layers. The in situ measurements revealed that most liquid layers contained drizzle, the production process of which was shown from the radar and lidar measurements to have been interrupted only during heavier ice-precipitation events. Different layers interacted with one another by changing the radiative heating profile, by precipitation which changed the growth paths available to cloud particles and even initiated new hydrometeor classes, or by coherent external forcing from waves that propagated in the very stable environment in which these clouds existed.