Exploring scale-adaptive representations and distinctive signatures of cities using multi-resolution analysis

Exploring scale-adaptive representations and distinctive signatures of cities using multi-resolution analysis

Petros Mouzourides1, Andreas Kyprianou2, Michael J. Brown3, Marina K.-A. Neophytou1*

1 Environmental Fluid Mechanics Laboratory, Department of Civil and Environmental Engineering, School of Engineering, University of Cyprus 2 Department of Mechanical and Manufacturing Engineering, School of Engineering, University of Cyprus 3 Los Alamos National Laboratory, Los Alamos NM 87545, U.S.A.

The 3-D variation of urban geometries often poses questions in the multi-scale modelling of air pollution dispersion and other climate or weather-related modelling applications, particularly such as: (a) how we represent urban attributes (e.g. morphological parameters) appropriately for the multi-scale nature and multi-resolution basis of weather numerical models, and (b) how we quantify the uniqueness of an urban database in the context of modelling urban effects in large-scale weather numerical models. In this paper, we illustrate how multi-resolution analysis (MRA) addresses and answers the afore-mentioned questions by taking as examples the urban building datasets for a number of European and North-American cities in order to unveil the multi-scale nature of an urban morphology and therefore propose a scale-adaptive representation. The selection of MRA is motivated by its capacity for multi-scale sampling; in the MRA the “urban” signal depicting a city is decomposed into an approximation, a representation at a higher scale, and a detail, the part removed at lower scales to yield the approximation. Different levels of approximations were deduced for the building height and planar packing density ëp. A spatially-varying characterization with a scale-adaptive capacity is obtained for the boundary-layer parameters (aerodynamic roughness length z0 and zero-plane displacement d) using the MRA-deduced results for the building height and the planar packing density with a morphometric model; an attribute that is shown to be of great advantage to multi-scale and multi-resolution numerical weather prediction models. It is shown that the MRA provides for models, gridded and scaled attributes as well as subgrid information for a hierarchy of grid sizes. The paper illustrates as well how the MRA can provide an innovative means to perform forensic analyses and descriptions of any urban area: in essence, the DNA-like description of a city (Mouzourides et al., 2013).

References:

Mouzourides P., Kyprianou A., Neophytou M.K.-A. (2013). A Scale-Adaptive Approach for Spatially-Varying Urban Morphology Characterization in Boundary Layer Parametrization Using Multi-Resolution Analysis. Boundary-Layer Meteorol, DOI 10.1007/s10546-013-9848-4