Quasi-Vertical Profiles – a New Way to Look at Polarimetric Radar Data

Ryzhkov, A., NOAA - National Severe Storms Laboratory

Cloud Processes

Cloud Life Cycle

Ryzhkov A, P Zhang, H Reeves, M Kumjian, T Tschallener, S Trömel, and C Simmer. 2016. "Quasi-Vertical Profiles—A New Way to Look at Polarimetric Radar Data." Journal of Atmospheric and Oceanic Technology, 33(3), 10.1175/jtech-d-15-0020.1.


An example of composite QVP of radar reflectivity, differential reflectivity, correlation coefficient, and differential phase.


An example of composite QVP of radar reflectivity, differential reflectivity, correlation coefficient, and differential phase.

Science

A novel methodology is introduced for processing and presenting polarimetric radar data collected by scanning weather radars. It involves azimuthal averaging of polarimetric radar variables at high antenna elevation and presenting resulting quasi-vertical profiles (QVPs) in a height-versus-time format.

Impact

The benefits include an ability to examine the temporal evolution of microphysical processes governing precipitation production and to compare polarimetric data obtained from the scanning surveillance weather radars with observations made by vertically looking remote sensors, such as wind profilers, lidars, radiometers, cloud radars, and radars operating on spaceborne and airborne platforms.

Summary

Azimuthal averaging (over a whole 360-deg circle or limited azimuthal sector) helps to dramatically reduce statistical errors in the estimates of polarimetric variables such as differential reflectivity (ZDR), specific differential phase (KDP), and correlation coefficient (ρhv) and to reveal important repetitive signatures in the ice and mixed-phase parts of clouds that have never been observed before with such a clarity.

These polarimetric signatures are particularly pronounced in the dendritic growth layer (DGL) between -10 and -20°C where the bulk of snow is formed and where aggregation and riming do not mask the signatures of very anisotropic and rapidly growing pristine ice crystals. Very informative modulations in the polarimetric properties of the melting layer identified in the QVPs with high vertical and temporal resolution reflect the evolution of ice microphysics aloft and can be used for discrimination between aggregation and riming above the freezing level.