Sensitivity study of a local numerical fog prediction system

Accurate and reliable information on expected visibility conditions at the airport of Thessaloniki-Greece, is of high importance, concerning safety and operational expenses for the airport and the airway companies. On the other hand, the life cycle of fog involves complex interactions among dynamical, turbulent, microphysical and radiative processes that are still not fully understood. Therefore, the implementation of a numerical fog simulationprediction model could be a very helpful tool, for understanding in depth the physical processes involved in the different stages of fog formation and consequently to accurately forecast fog conditions.
   The main objective of this effort is to investigate and address the sensitivity of the one dimensional COBEL-ISBA (COuche Brouillard Eau Liquide - Interactions Soil Biosphere Atmosphere) local model to different microphysics, planetary boundary layer and surface schemes of the WRF-ARW regional non-hydrostatic atmospheric model at the “Macedonia” airport of Thessaloniki. High-resolution numerical experiments regarding the fog event that was formed on the 6th January 2010 at the airport were performed with the latest version 3.2 of the WRF-ARW regional atmospheric model. The fog was quite thick, with estimated minimum visibility reaching 100 m and it was extended to an area covering the whole airport and the surroundings, that is up to a radius of 5 km. This fog event persisted for about 8 hours. Different combinations of the Mellor-Yamada Nakanishi-Niino (2.5 level) TKE and the Bougeault and Lacarrere TKE boundary layer schemes with microphysics schemes and the Monin-Obukhov (Jannjic Eta) and Mellor-Yamada Nakanishi-Niino surface-layer schemes, have been investigated in order to assess the predictability and the overall performance of the COBEL-ISBA model. The numerical results, regarding meteorological parameters, such as, air temperature, relative humidity and horizontal visibility, have been compared with actual measurements and the findings, have been evaluated and discussed.
   This work describes and evaluates an ensemble approach, which is designed to quantify the sensitivity of COBEL-ISBA model to different physical parameterizations of the WRFARW model at the airport of Thessaloniki.