Utilizing a Storm-Generating Hotspot to Study Convective Cloud Transitions: The CACTI Experiment

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  • 1 Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory, Richland, WA
  • | 2 Department of Atmospheric Sciences, University of Utah, Salt Lake City, UT
  • | 3 Department of Atmospheric Sciences, University of Illinois at Urbana-Champaign, Urbana, IL
  • | 4 Centro de Investigaciones del Mar y la Atmósfera, Instituto Franco-Argentino para el Estudio del Clima y sus Impactos, Universidad de Buenos Aires, Buenos Aires, Argentina
  • | 5 Fortem Technologies, Pleasant Grove, UT
  • | 6 Department of Atmospheric Science, Colorado State University, Fort Collins, CO
  • | 7 Department of Earth and Planetary Science, University of California, Berkeley, CA
  • | 8 Climate and Ecosystem Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA
  • | 9 Universidade dos Açores, Ponta Delgada, Portugal
  • | 10 Cooperative Institute for Mesoscale Meteorological Studies & School of Meteorology, University of Oklahoma, Norman, OK
  • | 11 Department of Atmospheric Sciences, University of Washington, Seattle, WA
  • | 12 Los Alamos National Laboratory, Los Alamos, NM
  • | 13 Servicio Meteorológico Nacional, Buenos Aires, Argentina
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Abstract

The Cloud, Aerosol, and Complex Terrain Interactions (CACTI) field campaign was designed to improve understanding of orographic cloud life cycles in relation to surrounding atmospheric thermodynamic, flow, and aerosol conditions. The deployment to the Sierras de Córdoba range in north-central Argentina was chosen because of very frequent cumulus congestus, deep convection initiation, and mesoscale convective organization uniquely observable from a fixed site. The C-band Scanning Atmospheric Radiation Measurement (ARM) Precipitation Radar was deployed for the first time with over 50 ARM Mobile Facility atmospheric state, surface, aerosol, radiation, cloud, and precipitation instruments between October 2018 and April 2019. An intensive observing period (IOP) coincident with the RELAMPAGO field campaign was held between 1 November and 15 December during which 22 flights were performed by the ARM Gulfstream-1 aircraft.

A multitude of atmospheric processes and cloud conditions were observed over the 7-month campaign, including: numerous orographic cumulus and stratocumulus events; new particle formation and growth producing high aerosol concentrations; drizzle formation in fog and shallow liquid clouds; very low aerosol conditions following wet deposition in heavy rainfall; initiation of ice in congestus clouds across a range of temperatures; extreme deep convection reaching 21-km altitudes; and organization of intense, hail-containing supercells and mesoscale convective systems. These comprehensive datasets include many of the first ever collected in this region and provide new opportunities to study orographic cloud evolution and interactions with meteorological conditions, aerosols, surface conditions, and radiation in mountainous terrain.

Corresponding author: Adam Varble, adam.varble@pnnl.gov

Abstract

The Cloud, Aerosol, and Complex Terrain Interactions (CACTI) field campaign was designed to improve understanding of orographic cloud life cycles in relation to surrounding atmospheric thermodynamic, flow, and aerosol conditions. The deployment to the Sierras de Córdoba range in north-central Argentina was chosen because of very frequent cumulus congestus, deep convection initiation, and mesoscale convective organization uniquely observable from a fixed site. The C-band Scanning Atmospheric Radiation Measurement (ARM) Precipitation Radar was deployed for the first time with over 50 ARM Mobile Facility atmospheric state, surface, aerosol, radiation, cloud, and precipitation instruments between October 2018 and April 2019. An intensive observing period (IOP) coincident with the RELAMPAGO field campaign was held between 1 November and 15 December during which 22 flights were performed by the ARM Gulfstream-1 aircraft.

A multitude of atmospheric processes and cloud conditions were observed over the 7-month campaign, including: numerous orographic cumulus and stratocumulus events; new particle formation and growth producing high aerosol concentrations; drizzle formation in fog and shallow liquid clouds; very low aerosol conditions following wet deposition in heavy rainfall; initiation of ice in congestus clouds across a range of temperatures; extreme deep convection reaching 21-km altitudes; and organization of intense, hail-containing supercells and mesoscale convective systems. These comprehensive datasets include many of the first ever collected in this region and provide new opportunities to study orographic cloud evolution and interactions with meteorological conditions, aerosols, surface conditions, and radiation in mountainous terrain.

Corresponding author: Adam Varble, adam.varble@pnnl.gov
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