14 November 2024
The Plan Position Indicator (PPI) Hydrometeor Field Statistics (PPIHYD) evaluation data product provides distinct hydrometeor field statistics calculated from ARM scanning radar PPI scans. These statistics include the equivalent reflectivity factor and Doppler spectral width percentiles, min/max values, and first four moments (mean, standard deviation, skewness, and kurtosis) of distinct hydrometeor features (clustered hydrometeor fields). Statistics also include morphological properties, water content and precipitation rate parameterization-based estimates, and thermodynamic properties interpolated using the Interpolated Sonde (INTERPSONDE) value-added product. The data set is organized in tabular (one-dimensional) form and is accompanied by detected hydrometeor field mask arrays with corresponding indices. This straightforward file structure simplifies scanning radar data processing and renders this data set useful for cloud and precipitation process understanding and model evaluation studies, with an emphasis on subgrid-scale parameterizations in large-scale models.
View More
The tabular structure of the PPIHYD product (per-event statistics rather than PPI observations on a multidimensional grid) simplifies the utilization of scanning radar data (mainly by non-radar experts), especially for specific purposes such as model evaluation and analyses that include bulk processing and conditioning on certain parameters (temperature, hydrometeor field total area, etc.).
PPIHYD processing includes second-trip echo mitigation and mean Doppler velocity dealiasing routines. Because these procedures are complex and often require manual tweaking, whereas here they are automated, users should be aware of potential second-trip “residuals” (which are likely to be flagged by PPIHYD) and use the mean Doppler velocity output field cautiously, especially in dealiased sweeps. Once non-meteorological echo mitigation routines are developed as well, users will need to be aware of the possible influence of some “residual” non-meteorological signals, especially in sites where these echoes are common.