RAPID

Rapid SACR Observations of Convection at BNF

25 August 2025 - 30 September 2026

Lead Scientist: Mariko Oue

Observatory: AMF (ARM Mobile Facility 3)

Improving our representation of convective cell processes requires better quantification of convective clouds throughout their entire life cycle. This includes gaining a clearer understanding of the controls on key convective cloud properties, such as updraft intensity, particle size distributions, rainfall rates, and hydrometeor species. Our inability to improve convective cloud process modeling stems, in part, from a limited understanding of convective cell properties, particularly given how rapidly these storms evolve. This lack of detailed observations in the most intense and organized convective storms is especially significant, as large errors remain in representing these clouds, which are critical for severe weather prediction and Earth system model performance.

Cloud and precipitation radars are essential tools for studying cloud microphysics and dynamics, particularly in deeper convective clouds. The recent AMF3-BNF deployment provides a unique opportunity to investigate important land-atmosphere interactions, as well as the environmental controls on deep convective cloud processes, in a location favorable for frequent convection. We operate the X/Ka-band Scanning ARM Cloud Radar (X/Ka SACR) using a scan strategy optimized to capture these rapidly evolving clouds and their properties, thereby improving studies of deep convective cloud processes. This effort is strengthened by a complementary and coordinated partnership with ongoing university and multi-agency radar activities collocated in north Alabama—a unique opportunity to examine clouds and precipitation from a lifetime-centric perspective.

The science objectives of this project are:

1. Rapid measurement of convective cell properties, including updraft and downdraft size and strength, convective cell and core dimensions, cloud-top height, and anvil extent throughout the cell life cycle.
2. Capturing cell initiation and the early stages of the life cycle in order to relate these to the surrounding ambient environment at convective scales (both temporal and spatial) and to the physical processes of interest.

The X-Ka SACR radar uses a scan pattern made up of 10 sweeps, covering directions from about 40º to 135º at a scan speed of 12º/s. It also looks upward at different tilt angles, ranging from about 6.5º to 25º in steps of roughly 2º. This scanning approach will be strengthened through collaboration with the ARM-supported Radar Studies of Convective Dynamics (CONVECT) campaign.