Attribution of Local Temperature Response to Deforestation

Land use and land cover change (LULCC) such as deforestation can directly induce changes in land surface temperature (LST). Accurately attributing changes in LST to different biophysical changes induced by LULCC is important for developing warming mitigation strategies. Using observational data from four paired eddy covariance sites, we attribute changes in LST induced by deforestation to changes in radiation, aerodynamic resistance, the Bowen ratio or surface resistance, and heat storage using two different methods: the intrinsic biophysical mechanism (IBM) method and the two-resistance mechanism (TRM) method. Both methods indicate that the warming effect of deforestation during the daytime is mostly induced by changes in aerodynamic resistance (i.e., the surface becomes smoother after deforestation), and the cooling effect of deforestation during the nighttime is controlled by changes in aerodynamic resistance, radiation, and heat storage. Both methods also indicate that changes in the atmospheric temperature should be considered in the LST attribution. However, there are significant differences in the attribution results from the two methods. The IBM method tends to overestimate the contribution of aerodynamic resistance due to the assumption that the aerodynamic resistance and the Bowen ratio are independent of each other. Additionally, the IBM method underestimates the contributions of albedo and heat storage during the daytime but overestimates them during the nighttime. By highlighting the similarity and dissimilarity between two attribution methods, this study suggests that acceptable agreement between observed and modeled LST change is the prerequisite for attribution but does not guarantee correct attribution.