Quantifying the contribution of land use change to surface temperature in the lower reaches of the Yangtze River

Abstract. Anthropogenic land use has a significant impact on climate change. Located in the typical East Asian monsoon region, the land–atmosphere interaction in the lower reaches of the Yangtze River is even more complicated due to intensive human activities and different types of land use in this region. To better understand these effects on microclimate change, we compare differences in land surface temperature ( T s ) for three land types around Nanjing from March to August, 2013, and then quantify the contribution of land surface factors to these differences (Δ T s ) by considering the effects of surface albedo, roughness length, and evaporation. The atmospheric background contribution to Δ T s is also considered based on differences in air temperature (Δ T a ). It is found that the cropland cooling effect decreases T s by 1.76° and the urban heat island effect increases T s by 1.25°. They have opposite impacts but are both significant in this region. Various changes in surface factors affect radiation and energy distribution and eventually modify T s . It is the evaporative cooling effect that plays the most important role in this region and accounts for 1.40° of the crop cooling and 2.29° of the urban warming. Moreover, the background atmospheric circulation is also an indispensable part in land–atmosphere feedback induced by land use change and reinforces both these effects.