Examining Mid-Level Stable Layers Over the Tropical Atlantic During ORCESTRA

Abstract

Here we investigate elevated stable layers that frequently appeared at an altitude near 6 km in soundings obtained during the ORCESTRA field campaign. This observation is in conflict with the existing literature, which suggests that tropical stable layers are instead collocated with the 0 C level at around 4-5 km. Our analysis demonstrates a strong relationship between mid-level stability and the change in relative humidity across the stable layer (decreasing upwards). Mechanism-denial tests with an infrared radiative transfer model support the hypothesis that vertical changes in relative humidity layer lead to differential radiative heating rates, thereby generating enhanced mid-level stability. We compare the frequency and strength of these stable layers to those in other ocean basins utilizing data from other field campaigns. These comparisons highlight the correlation between vertically decreasing relative humidity and enhanced stable layers.