More Like this

1. Polarimetric and Electrical Structure of the 19 May 2013 Edmond–Carney, Oklahoma, Tornadic Supercell

   https://doi.org/10.1175/MWR-D-20-0280.1  

   Sharma, Milind; Tanamachi, Robin L.; Bruning, Eric C.; Calhoun, Kristin M. (July 2021, Monthly Weather Review)

   null (Ed.)

   Abstract We demonstrate the utility of transient polarimetric signatures ( Z DR and K DP columns, a proxy for surges in a thunderstorm updraft) to explain variability in lightning flash rates in a tornadic supercell. Observational data from a WSR-88D and the Oklahoma lightning mapping array are used to map the temporal variance of polarimetric signatures and VHF sources from lightning channels. It is shown, via three-dimensional and cross-sectional analyses, that the storm was of inverted polarity resulting from anomalous electrification. Statistical analysis confirms that mean flash area in the Z DR column region was 10 times smaller than elsewhere in the storm. On an average, 5 times more flash initiations occurred within Z DR column regions, thereby supporting existing theory of an inverse relationship between flash initiation rates and lightning channel extent. Segmentation and object identification algorithms are applied to gridded radar data to calculate metrics such as height, width, and volume of Z DR and K DP columns. Variability in lightning flash rates is best explained by the fluctuations in Z DR column volume with a Spearman’s rank correlation coefficient value of 0.72. The highest flash rates occur in conjunction with the deepest Z DR columns (up to 5 km above environmental melting level) and largest volumes of Z DR columns extending up to the −20°C level (3 km above the melting level). Reduced flash rates toward the end of the analysis are indicative of weaker updrafts manifested as low Z DR column volumes at and above the −10°C level. These findings are consistent with recent studies linking lightning to the interplay between storm dynamics, kinematics, thermodynamics, and precipitation microphysics. 

   more » « less
2. Coarse sea spray inhibits lightning

   https://doi.org/10.1038/s41467-022-31714-5  

   Pan, Zengxin; Mao, Feiyue; Rosenfeld, Daniel; Zhu, Yannian; Zang, Lin; Lu, Xin; Thornton, Joel A; Holzworth, Robert H; Yin, Jianhua; Efraim, Avichay; et al (December 2022, Nature Communications)

   Abstract The known effects of thermodynamics and aerosols can well explain the thunderstorm activity over land, but fail over oceans. Here, tracking the full lifecycle of tropical deep convective cloud clusters shows that adding fine aerosols significantly increases the lightning density for a given rainfall amount over both ocean and land. In contrast, adding coarse sea salt (dry radius > 1 μm), known as sea spray, weakens the cloud vigor and lightning by producing fewer but larger cloud drops, which accelerate warm rain at the expense of mixed-phase precipitation. Adding coarse sea spray can reduce the lightning by 90% regardless of fine aerosol loading. These findings reconcile long outstanding questions about the differences between continental and marine thunderstorms, and help to understand lightning and underlying aerosol-cloud-precipitation interaction mechanisms and their climatic effects. 

   more » « less
3. A Polarimetric Radar Operator and Application for Convective Storm Simulation

   https://doi.org/10.3390/atmos13050645  

   Li, Xuanli; Mecikalski, John R.; Otkin, Jason A.; Henderson, David S.; Srikishen, Jayanthi (May 2022, Atmosphere)

   In this study, a polarimetric radar forward model operator was developed for the Weather Research and Forecasting (WRF) model that was based on a scattering algorithm using the T-matrix methodology. Three microphysics schemes—Thompson, Morrison 2-moment, and Milbrandt-Yau 2-moment—were supported in the operator. This radar forward operator used the microphysics, thermodynamic, and wind fields from WRF model forecasts to compute horizontal reflectivity, radial velocity, and polarimetric variables including differential reflectivity (ZDR) and specific differential phase (KDP) for S-band radar. A case study with severe convective storms was used to examine the accuracy of the radar operator. Output from the radar operator was compared to real radar observations from the Weather Surveillance Radar–1988 Doppler (WSR-88D) radar. The results showed that the radar forward operator generated realistic polarimetric signatures. The distribution of polarimetric variables agreed well with the hydrometer properties produced by different microphysics schemes. Similar to the observed polarimetric signatures, radar operator output showed ZDR and KDP columns from low-to-mid troposphere, reflecting the large amount of rain within strong updrafts. The Thompson scheme produced a better simulation for the hail storm with a ZDR hole to indicate the existence of graupel in the low troposphere. 

   more » « less
4. A Polarimetric Radar Operator and Application for Convective Storm Simulation

   Li, Xuanli; Mecikalski, John R.; Otkin, Jason A.; Henderson, David S.; Srikishen, Jayanthi (April 2022, Atmosphere)

   In this study, a polarimetric radar forward model operator was developed for the Weather Research and Forecasting (WRF) model that was based on a scattering algorithm using the T-matrix methodology. Three microphysics schemes—Thompson, Morrison 2-moment, and Milbrandt-Yau 2-moment—were supported in the operator. This radar forward operator used the microphysics, thermodynamic, and wind fields from WRF model forecasts to compute horizontal reflectivity, radial velocity, and polarimetric variables including differential reflectivity (ZDR) and specific differential phase (KDP) for S-band radar. A case study with severe convective storms was used to examine the accuracy of the radar operator. Output from the radar operator was compared to real radar observations from the Weather Surveillance Radar–1988 Doppler (WSR-88D) radar. The results showed that the radar forward operator generated realistic polarimetric signatures. The distribution of polarimetric variables agreed well with the hydrometer properties produced by different microphysics schemes. Similar to the observed polarimetric signatures, radar operator output showed ZDR and KDP columns from low-to-mid troposphere, reflecting the large amount of rain within strong updrafts. The Thompson scheme produced a better simulation for the hail storm with a ZDR hole to indicate the existence of graupel in the low troposphere. 

   more » « less
5. Exploring Impacts of Differing Aerosol Environments on Radar Signatures of Deep Convection near Houston, Texas, using a Bulk Statistical Framework

   https://doi.org/10.1175/JAS-D-24-0008.1  

   Pehl, Jonah; McFarquhar, Greg; Snyder, Jeffrey; Furtado, Jason (April 2025, Journal of the Atmospheric Sciences)

   Abstract Aerosol deep-convective cloud (DCC) interactions remain highly uncertain in the study of water cycles, energy budgets, climate projections, and air quality, partly because it is difficult to disentangle aerosol impacts from the impacts of meteorology in observational studies. Prior studies have shown that increased aerosol ingestion by DCC updrafts can influence their microphysical characteristics through the mixed-phase and condensational aerosol invigoration effects. However, other studies claim that increased aerosol loading produces different microphysical responses that are not consistent with invigoration. This study thus examines the impact of aerosol regimes on DCC microphysics by analyzing ∼1300 DCCs tracked from the Houston–Galveston WSR-88D. Fields from the fifth major global reanalysis produced by ECMWF and Modern-Era Retrospective Analysis for Research and Applications, version 2, are used to estimate meteorological and aerosol conditions near DCCs. DCC tracking was completed using the Multicell Identification and Tracking algorithm applied to radar data. Composite difference contoured frequency by altitude diagrams show statistically significant bulk differences in the vertical structure of dual-polarization radar data that are consistent with previous studies. The probabilistic differences in radar variables were typically 1%–6% above the freezing level and <4% below the freezing level. Microphysical fingerprint distributions showed that DCCs under high aerosol loading exhibit decreased warm rain, increased freezing rates, and increased vapor deposition onto ice. These signatures together are found to be consistent with increased aerosol loading leading to less warm rain, more evaporation under high tropospheric moisture conditions leading to less cold rain, and increased riming/accretion in environments with large instability leading to more cold rain. 

   more » « less