Vertical air motions and DSDs retrieved from vertically pointing KAZR, S-band, and 449-MHz radar observations during MC3E

Poster PDF

Description

Using DOE ARM Climate Research Facility vertically pointing radars operating at frequencies sensitive to both Rayleigh and non-Rayleigh scattering provides the opportunity to retrieve the vertical air motion and the raindrop size distribution (DSD). The retrievals need to account for five different parameters: mean vertical air motion and vertical air motion turbulence, and three parameters that describe the intensity, mean size, and spread of the DSD. In order to retrieve the vertical air motion from two vertically pointing radars, the five retrieved parameters must be reduced to four free parameters and a constraining relationship.

The DSD can be described using a gamma function with three parameters. Previous studies have shown that these three parameters are correlated. But there is controversy in the research literature over why the three parameters are correlated. Some studies suggest that the correlation is a statistical artifact due to correlation between the raindrop spectrum moments. Other studies suggest that the correlation is not a statistical artifact and have developed constraining relationships.

Analysis of surface disdrometer observations from the Midlatitude Continental Convective Cloud Experiment (MC3E) and other field campaigns suggests a relationship between the mass-weighted mean diameter and the mass spectrum standard deviation. This relationship is not a statistical artifact due to correlations between spectrum moments and suggests a physical relationship between the two DSD parameters. There are mathematical relationships between the DSD parameters and are used to develop a new constraint to describe the gamma-shaped DSD with two parameters and a constraining relationship.

The poster presented at the ASR Science Team Meeting will have two main components. First, the poster will present how a gamma-shaped DSD can be described with two parameters and a new DSD constraining relationship. And second, the poster will present vertical air motions derived during MC3E using the Ka-band ARM zenith radar (KAZR) (35-GHz) and S-band (3-GHz) vertically pointing radar observations along with comparisons of vertical air motions derived from a 449-MHz radar.