Abstract
Mid-tropospheric elevated moist layers (EMLs) near the melting level
have been found in various regional observational studies in the
tropics. Recently, a preponderance of EMLs in the presence of aggregated
convection was found in cloud resolving simulations of radiative
convective equilibrium (RCE), highlighting a significant circulation
coupling. Here, we present global monthly EML occurrence rates based on
reanalysis, yielding a broader view on where and when EMLs occur in the
real world. Over the Atlantic, EML occurrence follows an annual cycle
that maximizes in summer, aligning with maximized ITCZ intensity and
organisation. Resembling the results in RCE, the large-scale circulation
over the Atlantic shifts from a deep overturning in January to a
bottom-heavy circulation in July. While EMLs embedded in the July
cross-equatorial Hadley cell are found to be sourced from the ITCZ, EMLs
north of the ITCZ emerge from the strongly sheared zonal flow over West
Africa.