Urbanization has stronger impacts than regional climate change on wind stilling: a lesson from South Korea

Abstract

Wind stilling has been observed in many regions across the Northern Hemisphere; however, the related mechanisms are not well understood. Analyses of the wind speed variations in South Korea during 1993-2015 in this study reveal that the annual-mean surface wind speeds at rural stations have increased by up to 0.41 m s −1 decade −1 , while those at urban stations have decreased by up to −0.63 m s −1 decade −1 . The local wind speed variations are found to be negatively correlated with the population density at the corresponding observation sites. Gustiness analyses show the increase in local surface roughness due to urbanization can explain the observed negative wind speed trends at urban stations as the urbanization effect overwhelms the positive wind speed trend due to climate change. The observed negative wind speed trend in urban areas are not found in the regional climate model simulations in the Coordinated Regional Climate Downscaling Experiment-East Asia (CORDEX-EA) as these models do not take into account the impact of urbanization on wind variations during the period. This study suggests that urbanization can play an important role in the recent wind stilling in rapidly developing regions such as South Korea. Our results suggest that future climate projections in CORDEX-EA may overestimate wind speeds in urban areas, and that future regional climate projections need to consider the effects of urbanization for a more accurate projection of wind speeds.

Rapid urbanization induced daily maximum wind speed decline in metropolitan areas: A case study in the Yangtze River Delta (China)

“…As urban expansion and development increased both the number and the height of buildings, the resulting increase in surface roughness could have weakened the near-surface wind speed, e.g., DMWS, according to the theoretical wind speed profile (Han et al, 2016). Existing studies have documented a similar relationship between mean wind speed trend and urbanization-induced surface roughness changes (Li et al, 2018;Chen et al, 2020), while our study is one of the few to provide empirical evidence for the effect of urbanization on extreme winds (Li et al, 2011).…”

Wind stilling‐reversal across Sweden: The impact of land‐use and large‐scale atmospheric circulation changes

“…Increase of surface roughness can be associated with factors such as urbanization, growth of forests, changes in trees and forest distribution or changes in agricultural practices (Yupeng et al, 2019). Previous studies have mainly focused on land-use changes induced by urbanization, with comparison between urban and rural stations (Chen et al, 2020). In this study, we evaluate how wind speed long-term trends can be impacted by surface roughness changes associated with forest cover modifications.…”

A high-resolution monitoring approach of canopy urban heat island using a random forest model and multi-platform observations

“…3. There is a significant correlation between LULC and wind speed (Chen et al, 2020). Areas with tall buildings in built-up areas have high surface roughness and low wind speed, whereas water bodies have low surface roughness and high wind speed.…”