A comparison of WRF model simulations with SAR wind data in two case studies of orographic lee waves over the Eastern Mediterranean Sea

Two case studies of intense lee waves generated by the interaction of the atmospheric flow with the orography over an area in the eastern Mediterranean Sea, located east of Crete and south of Rhodes islands, are analyzed using the Weather Research and Forecasting (WRF) model. The model has been implemented in two different configurations, using distinct boundary layer parametrization schemes, the Yonsei University (YSU) and the Mellor–Yamada–Janjic (MYJ) schemes, and three 2-way nested domains, the inner one covering the area of interest with a horizontal resolution of 1 km. The model-derived wind fields have been compared with the sea surface wind extracted from Envisat Advanced Synthetic Aperture Radar (ASAR) images, from which the wind has been retrieved using a methodology based on the two-dimensional continuous wavelet transform.In the first case, the trains of atmospheric gravity waves, individuated by the signature in the ASAR image, extend downstream for more than 150 km and are realistically simulated in the two model configurations, although some appreciable differences are present. The wavelength spectra of the wind speed from ASAR and the two WRF runs have been calculated along different transects in the area affected by atmospheric gravity waves. The agreement is satisfactory, and the difference in wavelengths among the different wave trains generated by the orographic obstacles is well represented in the model runs. Among the two simulations, the YSU run performs better than MYJ. The latter result is consistent with the fact that the YSU experiment reproduces the observed wind profile and the Scorer parameter profile better than the MYJ run.The second case study is briefly analyzed to test the generality of the results of the first event. In this case, part of the wave energy is distributed at larger scales, due to the interaction of the flow with the Peloponnese. Again, both model configurations are able to reproduce correctly the wave patterns, but in this case the difference between the two model runs is negligible.

► Two case studies of intense lee waves are analyzed in the Aegean Sea
► Wave properties are analyzed with two WRF model runs, differing in PBL parametrization
► Model results are compared with ASAR-retrieved wind fields
► Modeled lee wave properties are consistent with ASAR retrieved-data
► ASAR is not able to catch the lee-vortices downstream of Crete