A coupled energy transport and hydrological model for urban canopies evaluated using a wireless sensor network

Abstract

We propose a new surface exchange scheme coupling the transport of energy and water in urban canopies. The new model resolves the subfacet heterogeneity of urban surfaces, which is particularly useful for capturing surface exchange processes from vegetated urban surfaces, such as lawns or green roofs. We develop detailed urban hydrological models for surfaces consisting of either natural (soil and vegetation) or engineered materials with water-holding capacity. The coupling of energy and water transport enables us to parametrize surface evaporation from different urban facets including soils, vegetation and water-holding engineered surfaces. The new coupled model is evaluated using field measurement data obtained through a wireless sensor network deployed over the Princeton University campus. Comparison of model prediction and measured results shows that the proposed surface exchange scheme is able to predict widely varying surface temperatures for each subfacet with good accuracy. Different weather conditions and seasonal variability are found to have insignificant effect on the model performance. The new model is also able to capture the subsurface hydrological processes with reasonable accuracy, particularly for urban lawns. The proposed model is then applied to assess different mitigation strategies of the urban heat island effect.Key Words: urban canopy model; urban hydrology; urban heat island; land-atmosphere interaction; water-holding pavements

Spatio-Temporal Modeling of the Urban Heat Island in the Phoenix Metropolitan Area: Land Use Change Implications

“…The effect of the built-up environment manifests itself by impacting turbulent transport radiative heat exchange and hydrological processes, especially in urban canopies [36]. Schatz and Kucharik also demonstrated in their paper that the built-up environment was the primary driver of the spatial change in temperature patterns in the urban area [37].…”

Environmental impacts of reflective materials: Is high albedo a ‘silver bullet’ for mitigating urban heat island?

“…To do this, one group of models having particularly promising potential is the urban land surface modeling schemes, the so-called urban canopy models (UCMs) developed in the widely-used Weather Research and Forecasting (WRF) platform [101,102] by the National Center for Atmospheric Research (NCAR). The most common urban land surface models in WRF are the single layer [103][104][105][106][107] and the multi-layer UCMs [108][109][110][111]. WRF-UCM system integrates the physics of energy and mass transport in the urban canopy layers and the mesoscale atmospheric dynamics, thus provides a versatile modeling framework for multi-scale numerical simulations ranging from building to regional scales.…”

Evaluating the impact of built environment characteristics on urban boundary layer dynamics using an advanced stochastic approach

“…In addition, a posteriori analysis of surface energy budgets found that only 1 % of the residual variance can be attributed to advection and is not statistically significant (Higgins, 2012). The turbulent sensible and latent heat fluxes arising from the urban area (H u and LE u ) are the areal average of those from roofs (H R and LE R ) and the street canyon (H can and LE can ) (Wang et al, 2013):…”

“…In this paper, urban land-atmosphere interactions are modeled using a 1-D stand-alone and scalable numerical framework (Song and Wang, 2015a), by coupling an advanced single layer urban canopy model (SLUCM) for urban land surface processes (Wang et al, 2011b;Wang et al, 2013) and a single column model (SCM) for boundary layer dynamics (Noh et al, 2003;Troen and Mahrt, 1986). To single out the direct impact of urban landscape modification, we test the sensitivity of the boundary layer only in the vertical direction without taking advection effect into consideration.…”

“…Specifically, aerodynamic resistance is a function of roughness length based on MOST (Mascart et al, 1995;Wang et al, 2013). In this study, we set the roughness lengths of momentum at the roof level as uncertain parameters for both conventional and green roofs.…”