Characteristics of snow regimes at North Slope Alaska as derived from the NSA snowfall product

Description

The new NSA snowfall product provides information about the characteristics of snowfall occurring at the BRW and OLI facilities. The product includes time-resolved vertical profiles of estimated water contents and size distribution parameters along with snowfall rates at the surface. The data from this product are used to assess modes or regimes of snowfall occurring at NSA and to link those regimes to both the pre- and post-snowfall environmental conditions. The snowfall product allows identifying distinct snow events based on the onset and termination of surface snowfall. For each event, characteristics including duration, total accumulation, mean snowfall rate, precipitation echo top height, and mean profiles of reflectivity and water content are quantified. Using a recently-developed joint analysis of microwave radiometer-derived liquid water path and high spectral resolution lidar depolarization, each event is also characterized based on the apparent significance of liquid water (supercooled liquid or melting precipitation) to the event. These characteristics are aggregated statistically to define distinct snowfall regimes. The properties of the regimes are examined. In particular, the vertical variations in ice water content and Doppler velocity are evaluated as functions of depth below the precipitation echo top for individual events within each regime. These properties, in part, represent the influence of microphysical processing in the snowing column. We examine the degree to which these vertical properties are consistent within individual regimes and differ between regimes in an initial approach to discern differences in microphysical processes across regimes.