Understanding the Ingredients for a Global Convective Hotspot in Subtropical South America: RELAMPAGO-CACTI

Prof. Steve Nesbitt

Professor and Head, Department of Atmospheric Sciences

School of Earth, Society & Environment

University of Illinois Urbana-Champaign

Monday, November 13, 2023, 2 PM ET



Satellite observations and results from field campaigns have elucidated key morphological characteristics and processes in convective storms that produce the majority of global precipitation and hazardous weather.  Errors in models’ representation of the occurrence, timing, and intensity of these systems lead to local and regional biases in temperature and precipitation in weather and climate models where convective systems, often organized by storm-internal and external processes, are part of the precipitation climate, as well as influence regional and global circulation and composition.  In addition, model biases in convection hamper our ability to understand what processes across scales control critical balances in our earth system, including between radiation and convection, coupling of the surface and the atmosphere, and the extent of influence of anthropogenic influences on clouds and precipitation.

The Remote sensing of Electrification, Lightning, And Mesoscale/microscale Processes with Adaptive Ground Observations (RELAMPAGO) and Clouds, Aerosols, and Complex-Terrain Interactions (CACTI) field campaigns were coupled major field campaigns conducted in Córdoba and Mendoza provinces in Argentina, and western Rio Grande do Sul State in Brazil in 2018-2019 to understand convective lifecycle in a unique geo-climatic convective hotspot.  This campaign was motivated by the physical processes and societal impacts of deep convection that frequently initiates in this region, often along the complex terrain of the Sierras de Córdoba and the Andes, and often grows rapidly upscale into dangerous storms that impact society. Observed storms during the experiment produced copious hail, intense flash flooding, and extreme lightning flash rates but few tornadoes. The CACTI campaign and the five distinct scientific foci of RELAMPAGO: convection initiation, severe weather, upscale growth, hydrometeorology, and lightning and electrification are described, as are the initial scientific results revealing the physical processes relevant to these foci. The campaign’s international cooperation, forecasting efforts, and mission planning strategies enabled a successful data collection effort. Leveraging knowledge gained in RELAMPAGO-CACTI, perspectives on improving our understanding and prediction of convective processes and their impacts globally are summarized.



Prof. Nesbitt is the Head of the Department of Atmospheric Sciences at the University of Illinois Urbana-Champaign, where he is also leads a research group comprised of research staff, graduate students, and undergraduate researchers.  He is also a principal investigator of the UIUC Flexible Array of Radars and Mesonets, which includes the Doppler on Wheels radars. His research and teaching interests reside in atmospheric observations, including the remote sensing of precipitation using radar and passive microwave sensors, observations and modeling of mesoscale processes, cloud dynamics and microphysics, and land-atmosphere interaction. He has participated in and led numerous field campaigns spanning four continents using radar, aircraft, and in situ instrumentation. He has taught courses in synoptic and mesoscale meteorology and weather forecasting, remote sensing, radar meteorology, tropical meteorology, mesoscale modeling, and geophysical data analysis.



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Nov 13 2023


John Xun Yang