Water samples were manually collected from 11 SGP ARM sites in the early summer of 2022 to measure cosmogenic isotopes of beryllium. The water samples were brought back to the Center for Accelerator Mass Spectrometry (CAMS) at LLNL and analysed for beryllium-10 and beryllium-7 as well as for chlorine-37, chlorine-36, and tritium. A total of six storm events were measured over three weeks. At least five of those storms included overshooting cloud events. Available data include precipitation amount, beryllium-10 concentration, beryllium-7 concentration, and 10/7Be ratio. Spatial and temporal variability in the cosmogenic isotopes was relatively high but could not directly be linked to precipitation amount. Analysis is on-going to explain the measured variability and to see if it can be linked to cloud top height and overshooting depth. 

Beryllium isotopes are commonly used as tracers of Earth surface processes and have enormous potential for elucidating stratospheric/tropospheric exchange processes. Cosmogenic radionuclides 7Be and 10Be are produced in the upper atmosphere through cosmic ray collisions with heavier nuclei, like 16O and 14N. Once produced, they readily bind to aerosol particles and accumulate in the atmosphere until they are delivered to Earth’s surface by precipitation scavenging (wet deposition) or gravitational settling (dry deposition). 7Be has a short half-life of 53 days, while 10Be has a half-life of 1.4 million years and is thus stable over atmospheric timescales. As a result, the ratio of 10Be/7Be measured in rainfall can be used to study the meteorologic controls on atmospheric residence time and subsequent wet deposition of aerosol particles. To study the spatial and temporal dynamics of beryllium isotope deposition during deep convective storms, we conducted a major rain sampling campaign called BIRDIE at the Southern Great Plains ARM site in Oklahoma, covering ~100 km2 and six rain storm events. We measured 7Be and 10Be concentrations in rainwater, along with water stable isotopes and dissolved ion chemistry to understand moisture sources and aerosol transport pathways. The ratio of 10/7Be is then analysed along with precipitation amount, cloud depth and top height, and severity of storm event to see if there is a connection between 10/7Be and overshooting of convective storms into the lower stratosphere. This experiment was done in parallel with a NASA mission (DCOTSS) investigating water intrusion into the lower stratosphere and other chemistry during deep convection storm events.