Quality of the ERA5 and CFSR winds and their contribution to wave modelling performance in a semi-closed sea

ABSTRACT

This study aims to investigate the quality of ERA5, a recent reanalysis wind product, and its contribution to wave modelling performance in a semi-closed sea, the Black Sea. This investigation includes a comparison of ERA5 surface wind fields with the ones from the CFSR to assess if this latest reanalysis improved the representation of the surface winds. Wind speeds from both reanalyses were validated with measurements at Gloria, the only sea wind measurement station on the Black Sea. Validations were also conducted using altimeter and scatterometer satellite data after which results were later compared against each other. The second aim of this study investigates whether a wave hindcast model forced with the ERA5 wind fields has improved prediction of wave parameters. A SWAN model with default settings was used to compare the results under the same conditions. Performance analyzes of the default SWAN wave estimates with both ERA5 and CFSR winds were conducted using three offshore buoy measurements and altimeter data of satellites over the Black Sea. Results show that ERA5 winds are more biased compared to CFSR winds at Gloria location. Both CFSR and ERA5 underestimate wind speeds. ERA5 performs better than the CFSR in lower wind speeds and worse in higher wind speeds. However, ERA5 winds have less bias and are more scattered than the CFSR winds against the satellite data. SWAN driven by CFSR winds performs better than the one driven by ERA5 winds against both buoy and satellite data.

Acknowledgements

We would like to thank the ECMWF and NCEP for providing the ERA5 and CFSR reanalysis data sets, respectively. The authors would like to acknowledge the National Institute for Marine Research and Development - Oceanography Department (NIMRD) for providing wind measurements at Gloria and Razvan Mateescu from NIMRD Oceanography Department for helping in obtaining wind measurements recorded at Gloria drilling platform. We would like to acknowledge Prof. Dr. Erdal Özhan of the Middle East Technical University, Ankara, Turkey, who was the Director of NATO TU-WAVES, for providing the buoy data at Gelendzhik, Sinop, and Hopa, and the NATO Science for Stability Program for supporting the NATO TU-WAVES project. We would like to thank the European Space Agency (ESA) for ERS-1, ERS-2, and ENVISAT satellite missions, NASA for TOPEX satellite missions, U.S. Navy for GFO satellite missions, NASA and National Centre for Space Studies (CNES) for JASON-1 missions, NASA and Jet Propulsion Laboratory (JPL) for QUIKSCAT missions and Australian Ocean Data Network (AODN) Portal, where we obtain calibrated satellite data.

Disclosure statement

No potential conflict of interest was reported by the author(s).