A case study of the near-neutral coastal internal boundary-layer growth: Aircraft measurements compared with different model estimates

A simplified version of a model of the internal boundary layer evolution is compared with aircraft measurements across the southern part of the east coast of Sweden (Blekinge). The two flight occasions used here represent relatively high wind velocities and negligible surface heat flux. Both the vertical potential temperature gradient and the surface temperature difference between land and sea are small. Model predictions of the internal boundary-layer (IBL) height agree well with data, for both short and larger distances from the coastline. The contributions to the IBL growth from the mechanical turbulence and the Zilitinkevich correction are discussed, as are the sensitivities of the growth to a number of physical parameters. In near neutral conditions, the vertical potential temperature gradient is found to be an important parameter for the growth of the IBL. A comparison with several simple model estimates for the height of the IBL is presented. The majority of the models overestimate the IBL height. Some of the models give reasonable results close to the coast, but generally the simple models perform less well at larger distances.