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Hydrometeor Field Spatial Statistics Derived From Radar Scans

 
Published: 14 November 2024

A new evaluation data set, Plan Position Indicator (PPI) Hydrometeor Field Statistics (PPIHYD), provides spatial statistics based on distinct (clustered) hydrometeor fields from radar scans.

By leveraging information harvested from Atmospheric Radiation Measurement (ARM) user facility scanning radar measurements, statistics such as spatial moments and percentiles are calculated for radar reflectivity and Doppler spectral width on a per-cluster basis. Other per-cluster statistics include the number of reflectivity peaks; estimated water contents and precipitation rates using parameterizations from the literature; and morphological properties of hydrometeor fields, such as area, solidity, and aspect ratio.

Currently applied to Ka-Band Scanning ARM Cloud Radar (KASACR) observations, PPIHYD comprises two daily data products in netCDF format. These products support the analysis of hydrometeor field spatial variability and microphysical properties, and they can be used to evaluate the subgrid-scale representation of clouds and precipitation in large-scale models. The kasacrppihydmask product provides hydrometeor field feature masks generated on a Cartesian grid for each scan and elevation angle. The kasacrppihydfeat product is a low-volume, one-dimensional data set consisting of the hydrometeor field feature statistics derived for each detected feature (cluster).

Two plots are placed side by side. The left plot shows Ze_skewness, and the right plot shows segmentation_mask.
Selected hydrometeor field feature (cluster) statistics from the kasacrppihydfeat data product are projected onto a corresponding kasacrppihydmask spatial mask for the COMBLE KASACR PPI scan at 0.5 degrees elevation on March 13, 2020, at 17:45 Coordinated Universal Time. The left panel shows skewness of the reflectivity field per feature. The right panel provides morphological feature properties: area in square kilometers (numbers on feature centers), fitted ellipses (transparent pink shapes), and semi-major axes of fitted ellipses (red lines). Black dashed lines designate the KASACR effective field-of-view boundaries. Both panels were generated using the PPIHYD demo Jupyter Notebook and provided by Israel Silber, Pacific Northwest National Laboratory.

An initial set of PPIHYD evaluation data is now available for the full KASACR deployment during the Cold-Air Outbreaks in the Marine Boundary Layer Experiment (COMBLE) near Andenes, Norway, from December 1, 2019, through May 31, 2020. A Jupyter Notebook demonstrating the use of PPIHYD to visualize and evaluate KASACR data from COMBLE is available in the ARM-Notebooks GitHub repository.

More information about PPIHYD is available on the product web page.

Access the new data in the ARM Data Center. (To download the data, first create an ARM account.)

For questions or to report data issues, please contact Israel Silber.

The kasacrppihydmask data can be referenced as doi:10.5439/2203040. The kasacrppihydfeat data can be referenced as doi:10.5439/2203039.

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ARM is a DOE Office of Science user facility operated by nine DOE national laboratories.