Cloud-resolving Simulations of Low Marine Clouds and Their Response to Aerosol Perturbations - Preprint

[Geoengineering News]

https://essopenarchive.org/doi/full/10.22541/essoar.176990453.39470985/v1

Authors: Ehsan Erfani

01 February 2026

Abstract

Marine low clouds exert a strong control on Earth's radiative balance, yet their response to aerosol perturbations remains a major source of uncertainty in climate projections and Solar Radiation Modification strategies such as Marine Cloud Brightening (MCB). This study develops a comprehensive framework to investigate aerosol-cloud interactions using large-eddy simulation (LES). More than 2,200 forward Lagrangian trajectories were constructed across the Northeast Pacific stratocumulus deck region using satellite and reanalysis data. Principal Component Analysis (PCA) was applied to cloud-controlling factors to objectively select 54 representative environmental states that encompass the observed phase space. These cases were used to initialize 48-hour, large-domain LES (UW-SAM coupled to a prognostic aerosol scheme). The resulting LES library reveals robust relationships between aerosol concentration, diurnal cycle of liquid water path (LWP), mesoscale cell size, and stratocumulus-to-cumulus transition. Systematic quantification of model-observation biases further demonstrates strong coupling between cloud droplet number concentration, cloud fraction (CF), and shortwave cloud radiative effect biases, with larger errors occurring in conditions with lower CF. In addition, higher aerosol number concentration leads to stronger diurnal cycle of LWP and larger mesoscale cell size due to precipitation suppression and entrainment enhancement. This framework provides a process-level basis for evaluating aerosol perturbations and MCB efficacy under realistic environmental conditions.

Source: ESS Open Archive