Investigations into mode characteristics of wind fields off the Guangdong coast using Empirical Orthogonal Function

Abstract

As one of the clean and renewable energy sources, wind energy has received increasing attentions from the public in recent years. Large-scale investigations into wind speeds and directions can provide guidance and reference for regional wind energy assessment. In this paper, ECMWF-ERA5 wind field data were used to explore wind field characteristics off the Guangdong coast, where Empirical Orthogonal Function (EOF) analysis was employed to characterize the spatial and temporal patterns of wind fields over a long period. The results show that: (1) According to the characteristics of wind speeds, the research domain can be divided into three major sub-domains, including the landward sub-domain where the wind speed is lower and the wind direction are highly variable, the transitional sub-domain where the wind field has a gradual trend and the wind direction are the most dispersed, and the seaward sub-domain where the wind speed is higher and the wind direction are more concentrated; (2) Variance contributions of the first EOF mode for east–west and north–south components of wind speed vectors are 99.3% and 99.5%, respectively. This indicates that the seasonal oscillation of winter–summer has a one-year cycle. Additionally, variance contributions of the second EOF mode are only 1.4% and 1.5%, respectively, showing a spring–autumn monsoonal oscillation with a six-month to one-year cycle. Variance contributions of the third EOF mode for east–west and north–south components are only 0.5% and 0.7%, respectively. This indicates that a one-year to two-year cycle of oscillations exists, which may be related to the Tropospheric Biennial Oscillation (TBO) of the inter-annual variability of the East Asian summer wind.

Keywords

• Wind field
• Empirical Orthogonal Function
• Guangdong coast
• Mode characteristics