Environmental Science Division (EVS)a Division of Argonne National Laboratory
Predictive environmental understanding

Using polarimetric radar measurements to constrain simulated convective cell evolution

June 11, 2019

Dr. Scott Collis, an EVS atmospheric scientist, has recently collaborated on a paper with scientists from Columbia University and NASA GISS that characterizes how pollution and atmospheric factors may affect the evolution, severity, and spatial distribution of thunderstorms. The study, published in Atmospheric Measurement Techniques, presents a comparison of tracked isolated thunderstorm cells that were observed and simulated around Houston, Texas. An area like Houston, which commonly experiences relatively clean onshore winds, but also has a spatially localized pollution source, provides a potentially strong test for pollution effects on thunderstorms. Applying new open-source tools for analyzing radar data and tracking storms, the research team has shown how these resources might be used to improve models and physical understanding of coupled microphysics and dynamics.

The study demonstrates Lagrangian analysis of isolated deep convective updrafts via tracking of specific differential-phase columns and radar reflectivity structures, signals associated with strong vertical updrafts in storms, in both a simulation and observations. Tracking storms in time provides insights into the evolution of a single updraft cell from birth to death, and how polarimetric radar observables and retrievals and (observed) lightning flash activity correlate over the life cycle of a single convective cell. The study also presents a longer-term analysis of the statistical distribution of isolated convective cells around the Houston area (location, duration, frequency, diurnal timing, propagation direction, and path length).

The Houston area has proven to be a suitable region for more in-depth and statistically robust study of coupled convective dynamics and microphysics. The study motivated the Tracking Aerosol Convection Interactions Experiment (TRACER) experiment which was recently accepted for funding by the Atmospheric Radiation Measurement (ARM) program.

Read the full article in Atmospheric Measurement Techniques.

Radar variable slices through a thunderstorm cell tracked from Houston NEXRAD radar data at four times during tracking. Shown from left to right are reflectivity, differential phase (KDP), differential reflectivity (ZDR), retrievals of double-moment microphysics (Dm), and retrievals of log (Nw). All plots have lightning activity in yellow/orange/red dots.
Radar variable slices through a thunderstorm cell tracked from Houston NEXRAD radar data at four times during tracking. Shown from left to right are reflectivity, differential phase (KDP), differential reflectivity (ZDR), retrievals of double-moment microphysics (Dm), and retrievals of log (Nw). All plots have lightning activity in yellow/orange/red dots. [Source: Fridlind et al., 2019]
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portrait of Scott Collis