Overestimation of the recent observed near-surface wind speed recovery in China

In this study, the variations in near-surface wind speed (SWS) across China were analysed using 55 years of observational data from 2044 meteorological stations spanning 1970–2024. The results indicate that the SWS in China experienced a persistent decline from 1970 to 2004, then remained constant from 2005 to 2014 and shifted to recovery after 2015. The seasonal and spatial analyses confirmed that the slowdown period occurred nearly nationwide, whereas the apparent recovery displayed a strong spatial heterogeneity. On the basis of long-term station records and metadata from China, station-by-station analysis revealed that SWS records are strongly influenced by widespread relocations; 1237 stations (60.5% of the total stations) with SWS discontinuities were related to relocations, leading to an overestimation of the so-called “recovery phase” at national and regional scales. This emphasized the importance of homogenization to ensure the reliability of the SWS dataset. Afterwards, the SWS breakpoints were detected and adjusted. After homogenization, the SWS displayed slight but significantly negative trends (–‍0.06 m s⁻¹ per decade) after 2005. Representative non-relocated stations were used to validate the homogenized results, and revealed that the homogenized series accurately captured more robust signal from non-relocated stations, which confirmed the consistent declining trends across China and further implied the effect of station relocation. Notably, compared with the original records, the reduction in the homogenized SWS ranged from 3% to 11% among the subregions. This could substantially impact on the assessment of wind energy resources and requires careful attention.