Phys.org July 9, 2024
Researchers at Pacific Northwest National Laboratory reconfigured the Weather Research Forecasting (WRF) version 4.3 model to quantify the impact of aerosols on evolving cloud fields. Simulations utilizing meteorological boundary conditions were based on 10 case study days offering diverse meteorology during the Aerosol and Cloud Experiments in the Eastern North Atlantic (ACE-ENA). Measurements demonstrated good agreement with the WRF-simulated cloud and aerosol properties. Higher aerosol concentration led to suppressed drizzle and increased cloud water content; that in turn les to larger radiative cooling rates at cloud top, enhanced vertical velocity variance, and increased vertical and horizontal wind speed near the base of the lower-tropospheric inversion. As a result, marine cloud cell area expanded, narrowed the gap between shallow clouds and increased cloud optical thickness, liquid water content, and the top-of-atmosphere outgoing shortwave flux. Similar aerosol effects were observed in lightly to non-raining clouds. The simulations showed a relationship between cloud cell area expansion and the radiative adjustments caused by liquid water path and cloud fraction changes. According to the researchers these results emphasized the importance of addressing mesoscale cloud-state transitions in the quantification of aerosol radiative forcing that cannot be attained from traditional climate models… read more. Open Access TECHNICAL ARTICLEÂ
Flow chart depicting the methodology for studying aerosol-cloud interactions… Credit: Atmospheric Chemistry and Physics, Volume 24, issue 11, ACP, 24, 6455–6476, 2024