Bulk stable boundary layer growth
From AMS Glossary
bulk stable boundary layer growth
(Abbreviated bulk SBL growth.) The increase with time of an integral measure of depth of the stable boundary layer.
Often the SBL has a structure with a poorly defined top. Potential temperature gradient and turbulence intensity gradually decrease to zero at the top of the SBL. Because there is no well- defined top, often an integral or e-folding measure of the the SBL depth is used instead. The growth of such a bulk measure of SBL depth can be used to specify the full structure of the SBL evolution.