Advantages of using the Harmonie atmospheric mesoscale model for simulating water dynamics in offshore area

Abstract

The convection-permitting Harmonie model is considered as a modeling component of the atmosphere-sea system. The role of the atmospheric model in the system is to create upper boundary conditions for marine environment model with high spatial (1-2.5 km) and temporal (from one minute to one hour) separating capacity. The research offers description of major modules which govern the configuration, spatial-temporal parameters of the atmospheric model and the way they are implemented in the High Performance Computing Facilities System (the HPCFS) of the European Center for Medium-Range Forecasting (the ECMWF). The use of the HPCFS and direct connection to global output data of the Integrate Forecasting System (the IFS) allows online performance of numerous calculations. The research shows the results of a numerical experiment for the north-western part of the Black Sea and neighbouring continental regions during severe weather conditions with strong wind speeds in January 2018. The high resolution modeling demonstrated high performance parameters of the model when reproducing mesoscale features of the atmospheric circulation. They are as follows: division of two lower-level jets in the north-western atmospheric flow along the coast line; mesoscale offshore patterns associated with thermal contrast and wind shear over different surface types along the coastal area; weaker circulations over regional bays on lee sides. The advantages of the Harmonie model comparing other modeling systems when determining the upper boundary conditions for modeling of the marine environment over offshore regions are listed. In particular, the model has direct access to the ECMWF archive and IFS operational global model output data; assimilation methods use all data available for observation; numerous parameterization schemes can be tuned for different climate zones and specific areas; post-processing provides more than two hundreds of physical, dynamical and chemical output variables at different types of levels, such as isobaric surfaces, model levels, geometric altitudes; output format list includes grib, netcdf and simple text which allows use of results both for their further direct introduction into the marine model and plotting fields, cross-sections and profiles in the metview visualization package.

Keywords

• Harmonie atmospheric model; upper boundary conditions; offshore regions; mesoscale circulation patterns; severe weather conditions