Articles | Volume 10, issue 2
Development and technical paper
01 Mar 2017
Development and technical paper |  | 01 Mar 2017

Efficiently modelling urban heat storage: an interface conduction scheme in an urban land surface model (aTEB v2.0)

Mathew J. Lipson, Melissa A. Hart, and Marcus Thatcher

Abstract. Intercomparison studies of models simulating the partitioning of energy over urban land surfaces have shown that the heat storage term is often poorly represented. In this study, two implicit discrete schemes representing heat conduction through urban materials are compared. We show that a well-established method of representing conduction systematically underestimates the magnitude of heat storage compared with exact solutions of one-dimensional heat transfer. We propose an alternative method of similar complexity that is better able to match exact solutions at typically employed resolutions. The proposed interface conduction scheme is implemented in an urban land surface model and its impact assessed over a 15-month observation period for a site in Melbourne, Australia, resulting in improved overall model performance for a variety of common material parameter choices and aerodynamic heat transfer parameterisations. The proposed scheme has the potential to benefit land surface models where computational constraints require a high level of discretisation in time and space, for example at neighbourhood/city scales, and where realistic material properties are preferred, for example in studies investigating impacts of urban planning changes.

Short summary
City-scale models describing the surface energy balance have difficulties representing heat storage in urban materials. This paper proposes an alternative method to discretise heat conduction through urban materials. We compare the new method with an approach commonly used in urban models and find the new method better matches exact solutions to heat transfer for a wide variety of urban material compositions. We also find the new method improves the bulk energy flux response of an urban model.