WCD-10. Impact of Sea Surface Temperature Anomalies on Low-Level Cloudiness and Mesoscale Organization of Trade Wind Cumulus in the Northwestern Atlantic

Trade cumulus clouds are a leading source of uncertainty in climate sensitivity estimates. Its cloud feedbacks in the climate models depend on processes controlling the near cloud-base cloudiness. These processes interact with the large-scale environment and are influenced by mesoscale organizations. Hence, a better understanding of the processes controlling the cloud-base cloudiness and the formation mechanisms of mesoscale organizations is crucial for improving climate and weather models. This study utilizes field measurements from the Atlantic Tradewind Ocean-Atmosphere Mesoscale Interaction Campaign (ATOMIC) and satellite observations to find relations among sea surface temperature (SST) anomalies, cloudiness, and surface wind. Analysis on ATOMIC field data shows that SST and 10-m surface wind correlate well at 14km and 26km. On average, significant coherence between SST and surface wind is seen when the lower troposphere is less stable (<15K), and when the surface wind speed exceeds 8 m/s. Satellite data analyses suggest that the relationship between weak (<0.8K), fine-scale (10km~100km) SST anomalies and temporal cloudiness is sensitive to large-scale atmospheric conditions, diurnal cycle, SST gradients, and large-scale background SST. Informed by these observations, idealized cloud-resolving Large Eddy Simulations are being set up to test the cloud response to weak and fine-scale SST anomalies under different large-scale environmental conditions.