Observations of Ice Formation and Growth Processes in the Dendritic Growth Regime using Novel Radar Doppler Spectra Analysis

The US Department of Energy Atmospheric Radiation Measurement (ARM) facility at Utqiagvik, North Slope of Alaska (NSA) collects long-term measurements of high latitude clouds and precipitation using a comprehensive suite of active and passive sensors. Multi-year profiling measurements from the Ka-band ARM Zenith-pointing Radar (KAZR), in synergy with thermodynamic information from thousands of routinely launched radiosondes, provide a unique “laboratory” in which to study ice microphysical properties in the natural environment, with a fine degree of control over ambient thermodynamic conditions. Here we focus on the dendritic growth temperature regime in which we analyze a very large dataset of KAZR Doppler spectra and their moments, in the context of supporting collocated observations, to quantify the depositional growth and sublimation processes, and their associated crystal habit properties, as a function of saturation with respect to ice. We include in our analysis the riming process under supercooled liquid conditions. This work is aimed at unraveling the complexities of the ice crystal life cycle in the natural environment and providing observational benchmarks that can be used to improve the representation of these processes in numerical models.