Influence of sea stratification and troposphere stability over the coastal squall lines of eastern Amazon

This study investigates the relationship between oceanic and atmospheric parameters and their relation with the occurrence of Coastal Squall Lines (CSL) in the Eastern Amazon. Utilizing a minimalist set of stability and stratification parameters, results indicate a significant coherence in the 8 and 12-month period in bulk parameters, potentially linked to the discharge of the Amazon River and the convective regime of Western Tropical Atlantic. A cross-wavelet analysis shed light on the relation of CSL frequency with the local and remote oceanic stratification and atmosphere stability parameters. Additionally, composite analyses reveal shifts in the distributions of these parameters during CSL occurrences, highlighting the sensitivity of CSL to environmental variables. The environmental variables rely on local and remote drivers, whose interactions still need to be fully addressed. Our results indirectly quantify how these drivers can explain the CSL frequency, with the advantage of bypassing a full assessment of submesoscale processes. These outcomes reveal the need to consider the influence of local shelf sea stratification to enhance the precision of CSL characterization, what can be used to improve the setup of atmospheric models. While this study covers this gap, further research considering the mechanistic approach is needed to improve the understanding of mesoscale convection at the Eastern Amazon.