Improving Mellor-Yamada-Janjic boundary layer parameterization, case of marine atmospheric boundary layer

The lower marine atmospheric boundary layer (MABL) structure is relevant among other for climate simulation studies, numerical weather predictions and in particular for offshore wind energy harvesting. In this study, the refinement of the existing Mellor-Yamada-Janjic (MYJ) surface/boundary layer parameterization using a straightforward and an extended approach in the Weather Research and Forecasting (WRF) model is applied to provide improved representation of the lower marine boundary layer characteristics. Wind, temperature and turbulent flux measurement data for one annual cycle in the first 100 meters of marine atmospheric boundary layer in the North Sea (at FINO-1 platform) and half year of the marine surface layer in the Baltic Sea (at Östergarnsholm tower) are analyzed. For the same period as available measurement data, the downscaling of the global NCEP FNL data with WRF model over the North and Baltic Sea has been performed, using MYJ surface/boundary layer parameterization and the stability dependent deviations between measurements and simulations are examined. Based on the comparison of the measurement and simulated data, the existing MYJ boundary/surface parameterization has been adjusted by redefining the dissipative-diffusive length scale. With the adjusted parameterization, the agreement between wind shear measurements and simulation, especially close to the surface has improved.