LAUSR

Trends in urban fraction around meteorological station were used to quantify the relationship between urban growth and local urban warming rate in temperature records in China. Urban warming rates were estimated by comparing observed temperature trends with those derived from ERA-Interim reanalysis data. With urban expansion surrounding observing stations, daily minimum temperatures were enhanced, and daily maximum temperatures were slightly reduced. On average, a change in urban fraction from 0% to 100% induces additional warming in daily minimum temperature of +1.7 ± 0.3 °C; daily maximum temperature changes due to urbanization are -0.4 ± 0.2 °C. Based on this, the regional area-weighted average trend of urban-related warming in daily minimum (mean) temperature in eastern China was estimated to be +0.042 ± 0.007 (+0.017 ± 0.003) °C decade-1, representing about 9% (4%) of overall warming trend and reducing the diurnal temperature range by -0.05 °C decade-1. No significant relationship was found between background temperature anomalies and the strength of urban warming.