Urban Surface Energy Balance Models: Model Characteristics and Methodology for a Comparison Study - Meteorological and Air Quality Models for Urban Areas - page 85

Chapter 11
Urban Surface Energy Balance Models:
Model Characteristics and Methodology
for a Comparison Study

CSB Grimmond, Martin Best, Janet Barlow, A. J. Arnfield, J.-J. Baik,
A. Baklanov, S. Belcher, M. Bruse, I. Calmet, F. Chen, P. Clark, A. Dandou,
E. Erell, K. Fortuniak, R. Hamdi, M. Kanda, T. Kawai, H. Kondo,
S. Krayenhoff, S. H. Lee, S.-B. Limor, A. Martilli, V. Masson, S. Miao,
G. Mills, R. Moriwaki, K. Oleson, A. Porson, U. Sievers, M. Tombrou,
J. Voogt, and T. Williamson

Abstract Many urban surface energy balance models now exist. These vary in
complexity from simple schemes that represent the city as a concrete slab, to those
which incorporate detailed representations of momentum and energy fluxes dis-
tributed within the atmospheric boundary layer. While many of these schemes have
been evaluated against observations, with some models even compared with the
same data sets, such evaluations have not been undertaken in a controlled man-
ner to enable direct comparison. For other types of climate model, for instance the
Project for Intercomparison of Land-Surface Parameterization Schemes (PILPS)
experiments (Henderson-Sellers et al., 1993), such controlled comparisons have
been shown to provide important insights into both the mechanics of the models
and the physics of the real world. This paper describes the progress that has been
made to date on a systematic and controlled comparison of urban surface schemes.
The models to be considered, and their key attributes, are described, along with the
methodology to be used for the evaluation.

11.1 Introduction

The world's population is becoming increasingly urbanised. The fraction of the
global population living in cities now exceeds 50% and urban dwellers are expected
to reach 6 billion people, or two-thirds of the global population, by the year
2050 (UN, 2004). On the same timescale, climate change predictions estimate an
increase in global mean temperature of 0.5-1.5 ◦ C (IPCC, 2001). Whilst predicting
human induced climate change on a regional scale is still uncertain, one climate