Gradual strengthening of global oceanic surface winds: Correlations with sea surface temperature and implications for wind power extraction.

Understanding the long-term variabilities and trends of global oceanic surface wind speed is critical for extracting wind power. Therefore, 84 years (from 1940 to 2023) of global 10-m wind speed data derived from the fifth-generation ECMWF reanalysis, ERA5 (European Centre for Medium-Range Weather Forecasts Reanalysis v5), were utilised to analyse the long-term trends in the global 10-m wind speed. The results revealed that the wind speeds at the oceanic surface are much greater than those at the terrestrial surface, causing marine areas to be more suitable for extracting wind power. The global average 10-m oceanic wind (OW) speed increased by 0.074 % annually, while 0.065 % and 0.082 % were found for the Northern Hemisphere (NH) and Southern Hemisphere (SH), respectively. The region with the most critical trend of increasing 10-m OW speed is in the SH at S60°, with an average annual increase of approximately 0.02 ms during the winter (December, January, February, DJF). The global 84-year average sum of the wind power density (WPD) at a height of 100 m could reach 110.66 MWm, in which the ocean basin within S40°-S60° accounts for 35.55 %. The SST and 10-m OW speed exhibit a causal relationship and positive correlation; however, this phenomenon can be observed only on a global spatial scale and a yearly temporal scale. The cross-correlations and Granger causality test between the sea surface temperature (SST) and 10-m OW speed indicated that the former can be used to predict the latter on a global scale. Analysing data from 1940 to 2023 showed that a 1 °C increase in the global annual average SST can enhance the global annual average 10-m OW speed by approximately 0.63 ms.