Surface [Urban] Energy and Water Balance Scheme (v2020a) in non-urban areas: developments, parameters and performance

Abstract. This paper extends the applicability of the SUEWS (Surface [Urban] Energy and Water Balance Scheme) to extensive pervious areas (deciduous trees, evergreen trees, grass, croplands, soil and water) outside cities. It can be used either offline or online (i.e., coupled to weather/climate models). The required parameters to simulate the turbulent latent heat (or evaporative) flux are derived using observations. Both the parameters (leaf area index (LAI), albedo, roughness parameters and surface conductance) and the surface energy balance fluxes are evaluated at independent sites and/or different periods at the same site. Methods to obtain parameters and guidance to apply SUEWS are provided. Results demonstrate the impacts from differences in LAI dynamics and albedo for various types of vegetation. The relation between LAI and albedo is explored. Deciduous, evergreen, and grass land covers all have long periods of LAI maxima, but croplands normally have a short sharp peak due to harvesting. For most of the vegetation types studied the maximum albedo coincides with the maximum LAI period, but for some evergreen trees the maxima are associated with leaves changing colour (needles/leaves get darker as they age during autumn and winter). Ensuring these dynamics are captured is important for assessing urban-rural differences (e.g. canopy layer air temperature).