Evaluating Atmospheric Stability and Marine Boundary Layer Cloud Relationships Over the Western North Atlantic on Multiple Temporal Scales

Marine boundary layer clouds play an important role in the global radiation budget and are still a major source of uncertainty within global climate models (GCMs). There are well known stability parameters (i.e. lower tropospheric stability (LTS), and estimated inversion strength (EIS)) that are used to predict seasonal low cloud amount. These parameters have played an important role in predicting low level clouds in GCMs (i.e. within cloud parameterizations in early versions of GCMs and fine tuning the low-level clouds in the model). This study evaluates the performance of LTS and EIS as well as estimated cloud-top entrainment index (ECTEI), and cold-air outbreak index (CAO) on different temporal scales (10-minute, daily, and monthly) using observational field campaign data, reanalysis, and GCM output. The observational data is the dropsonde and lidar data from the Aerosol Cloud meTeorology Interactions oVer the western ATlantic Experiment (ACTIVATE) field campaign that sampled cloud and aerosol properties over the Western North Atlantic Ocean across six campaigns from 2020-2022. The stability parameters relations are evaluated on the daily temporal scales using MERRA-2 and ERA5 reanalysis data while the stability relationships on a monthly scale are evaluated using E3SMv2 output. The dependence of the relationship between low cloud amount and these indices on the temporal scales is quantified. The dramatic differences of these relationships are also found between the observational data and model output. The analysis using MERRA-2 and ERA5 is ongoing, and results should provide interesting insights to bridge the observational and model output differences.