Stable Boundary Layer Issues

Understanding and prediction of the stable atmospheric boundary layer is a challenging task. Many physical processes are relevant in the stable boundary layer, i.e. turbulence, radiation, land surface coupling, orographic turbulent and gravity wave drag, and land surface heterogeneity. The development of robust stable boundary layer parameterizations for use in NWP and climate models is hampered by the multiplicity of processes and their unknown interactions. As a result, these models suffer from typical biases in key variables, such as 2m temperature, boundary layer depth, boundary layer wind speed. This paper summarizes the physical processes active in the stable boundary layer, their particular role, their interconnections and relevance for different stable boundary layer regimes (if understood). Also, the major model deficiencies are reported