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Evaluating the Effects of Land Use and Cover Change on the Decrease of Surface Wind Speed over China in Recent 30 years Using a Statistical Downscaling Method

  • Wu, J.
  • Zha, J.
  • Zhao, D.

The long-term decrease of surface wind speed (SWS) has been revealed by previous studies in China in recent decades, but the reasons for the SWS decrease remain uncertain. In this paper, we evaluated the effects of land use and cover change (LUCC) on the SWS decrease during 1980–2011 over the Eastern China Plain (ECP) region using a combined method of statistical downscaling and observation minus reanalysis data, which was used to improve the climate prediction of general circulation models and to evaluate the influence of LUCC on climate change. To exclude the potential influence of LUCC on SWS observation, a statistical downscaling model (SDM) was established during 1980–1992 because a lower extent of LUCC occurred during this period than in later periods. The skill of the SDM was checked by comparing the results of different predictor combinations. Then, SDM was used to improve the wind speed data at 10 m above the surface in the ERA-Interim reanalysis data (V10m-ERA) during 1993–2011, which decreased the error in the reanalysis wind speed as far as possible. Then, the difference between the station observed SWS (V10m-OBV) and the downscaled SWS (V10m-SDM) during 1993–2011 (SWSD) was considered the quantitative estimation of the influence of the LUCC on SWS in this period. The V10m-SDM can capture both the large-scale and local characteristics in the observation, and their patterns are very similar. V10m-SDM has better performance in the spatial–temporal changes than does V10m-ERA with respect to V10m-OBV. The impact of LUCC on the SWS was pronounced, the SWSD was −0.24 m s−1 in 1993, and the SWSD reached −0.56 m s−1 in 2011. LUCC could induce a 0.17 m s−1 wind speed decrease per 10 year in the ECP region during 1993–2011. Furthermore, each 10 % rise of the urbanization rate could cause an approximately 0.12 m s−1 decrease in wind speed. Additionally, pressure-gradient force was eliminated as the primary cause of the observed long-term decrease of SWS in ECP by composite analysis and temporal serial analysis, and the rise of the surface drag force caused by LUCC was identified as an important factor inducing the SWS decrease during 1993–2011 in ECP region. Moreover, the results from different time lengths used to construct SDM were compared, and the uncertainties in SWSD were evaluated by different SDMs established by different time periods.

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