Land use and land cover change impact on surface temperature: the scale issue

While land use and land cover change (LULCC) is often a temporal phenomenon (i.e., a patch transitions from one land cover type to another), many studies use a space-for-time approximation that quantifies the LULCC impact (say on surface temperature or fluxes) by comparing two adjacent patches of different land covers. An important consideration embedded in this space-for-time approximation is the scale, which determines what assumptions we can make when constructing models for studying land-atmosphere interactions over heterogeneous terrain. Most previous studies employ one-dimensional models without considering the appropriate scale associated with these models. In this presentation, the scale issue in studying LULCC-induced surface temperature anomalies will be discussed using a hierarchy of models. Typical one-dimensional models based on the surface energy balance and/or convective boundary layer dynamics will be compared to two-dimensional models where horizontal advection is explicitly considered. The results highlight the importance of scale in determining the sensitivity of land surface temperature to changes in albedo and moisture/vegetation characteristics.