Monday, 28 August 2023
Boundary Waters (Hyatt Regency Minneapolis)
Handout (1.5 MB)
The frequent occurrence of hailstorms due to severe convection in Southeast South America (SESA), impacting nearly 40 million people and its local economy, necessitates additional research into its occurrence using ground-based radar data and long-term observational station records. Broadly, we aim to improve our ability to identify and predict hail threats and understand precipitation mechanisms in convective clouds through the development and use of new algorithms that can help in the interpretation of operational C-Band radar observations of hail in SESA, which will enhance operational warnings and improve hydrologic products from C-Band radar, which are often contaminated by hail and hail-related attenuation. However, to date, few studies have been conducted to enhance our understanding of hailstorm-and hail-related processes and prediction across this region of the continent.
The Remote sensing of Electrification, Lightning, And Mesoscale/microscale Processes with Adaptive Ground Observations (RELAMPAGO) and Clouds, Aerosols, and Complex Terrain Interactions (CACTI) project collected extensive observations of convective storms, including a hail report database, as well as observations from four C-band radars (COW, CSU, CSAPR, and RMA1) and three mobile X-band Doppler on Wheels (DOW 6, 7, and 8) radars near the Sierras de Córdoba, Argentina during 2018-2019 and provided a novel view of hailstorms in this hail-prone region.
This study proposes to examine the hail phenomena in SESA, employing scattering simulations with a novel dual-wavelength radar method. First, the physical characteristics of hydrometeors that lead to differential scattering and emission properties at C- and X-Band will be analyzed from T-matrix scattering calculations. For this, various convective storm conditions, differing by the horizontal shape and the type of precipitation, are considered in these calculations (e.g., rain and hail with hailstones of different diameters, dry, spongy, or coated with liquid water). Then we will apply these analyses to 5 real cases to examine the dual-wavelength radar characteristics observed by the DOW and COW radars during RELAMPAGO, comparing them to single-wavelength dual-polarization radar characteristics and the hail impacts registered by the database. Considerable differences in the polarimetric variables (Z, Zh, ZDR) between both wavelengths for melting hailstones, whereas negligible differences for small raindrops are expected. This work aims to inform and improve single-wavelength polarimetric hail identification and characterization techniques at these radar wavelengths. Also, to report on the relevance of the dual-reflectivity ratio as a potential method for identifying hail impacts on radar measurements in the operational radar network in SESA.
The Remote sensing of Electrification, Lightning, And Mesoscale/microscale Processes with Adaptive Ground Observations (RELAMPAGO) and Clouds, Aerosols, and Complex Terrain Interactions (CACTI) project collected extensive observations of convective storms, including a hail report database, as well as observations from four C-band radars (COW, CSU, CSAPR, and RMA1) and three mobile X-band Doppler on Wheels (DOW 6, 7, and 8) radars near the Sierras de Córdoba, Argentina during 2018-2019 and provided a novel view of hailstorms in this hail-prone region.
This study proposes to examine the hail phenomena in SESA, employing scattering simulations with a novel dual-wavelength radar method. First, the physical characteristics of hydrometeors that lead to differential scattering and emission properties at C- and X-Band will be analyzed from T-matrix scattering calculations. For this, various convective storm conditions, differing by the horizontal shape and the type of precipitation, are considered in these calculations (e.g., rain and hail with hailstones of different diameters, dry, spongy, or coated with liquid water). Then we will apply these analyses to 5 real cases to examine the dual-wavelength radar characteristics observed by the DOW and COW radars during RELAMPAGO, comparing them to single-wavelength dual-polarization radar characteristics and the hail impacts registered by the database. Considerable differences in the polarimetric variables (Z, Zh, ZDR) between both wavelengths for melting hailstones, whereas negligible differences for small raindrops are expected. This work aims to inform and improve single-wavelength polarimetric hail identification and characterization techniques at these radar wavelengths. Also, to report on the relevance of the dual-reflectivity ratio as a potential method for identifying hail impacts on radar measurements in the operational radar network in SESA.
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