Evaluating the impact of urban morphology configurations on the accuracy of urban canopy model temperature simulations with MODIS

Abstract

Simulations of the urban environment contribute to assessments of current and future urban vulnerabilities to extreme heat events. The accuracy of simulations of the urban canopy can be degraded by inaccurate or oversimplified representations of the urban-built environment within models. Using a 10 year (2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012) series of offline 1 km simulations over Greater Houston with the High-Resolution Land Data Assimilation System (HRLDAS), this study explores the model accuracy gained by progressively increasing the complexity of the urban morphology representation in an urban canopy model. The fidelity of the simulations is primarily assessed by a spatiotemporally consistent comparison of a newly developed HRLDAS radiative temperature variable with remotely sensed estimates of land surface temperature from the Moderate Resolution Imaging Spectroradiometer. The most accurate urban simulations of radiative temperature are yielded from experiments that (1) explicitly specify the urban fraction in each pixel and (2) include irrigation. The former modification yields a gain in accuracy that is larger than for other changes, such as increasing the number of urban land use types. The latter modification (irrigation) substantially reduces simulated temperature biases and increases model precision compared to model configurations that lack irrigation, presumably because watering of lawns, parks, etc. is a common activity that should be represented in urban canopy models (although it is generally not). Ongoing and future efforts to improve urban canopy model simulations may achieve important gains through better representations of urban morphology, as well as processes that affect near-surface energy partitioning within cities, such as irrigation.

Urban–rural differences in near‐surface air temperature as resolved by the Central Europe Refined analysis (CER): sensitivity to planetary boundary layer schemes and urban canopy models

“…Furthermore, we complement other studies that have applied land surface temperature (e.g. Li and Bou-Zeid, 2014;Monaghan et al, 2014;Ramamurthy et al, 2015) or vertical temperature profiles (e.g. Hu et al, 2010;Garcia-Diez et al, 2013;Trusilova et al, 2016) for evaluating PBL schemes and UCMs.…”

Evapotranspiration of urban landscapes in Los Angeles, California at the municipal scale

“…NLDAS models used in this study (Noah, Mosaic, and VIC) compute ET as a fraction of potential ET derived with Penman‐Monteith equation [ Mahrt and Ek , ], using parameters that represent (1) soil moisture, (2) fractional vegetation cover, and (3) surface resistance [Noah —Chen et al ., ; Mosaic —Koster and Suarez , ; VIC— Liang et al ., ]. The associated errors are (1) underestimation of soil moisture caused by the absence of irrigation module, (2) misrepresentation of urban canopy because model grids (∼14 km) are larger than the scale of urban heterogeneity [ Monaghan et al ., ], and (3) inaccurate representation of urban canopy resistance that deviates from Penman‐Monteith scheme [ Litvak et al ., ].…”

“…Despite the simplicity of the irrigation scheme used by Monaghan et al . []—it simulated permanent uninterrupted irrigation of all greater Houston—it led to more realistic representation of latent heat flux compared to the original models. Unfortunately, direct comparison of our estimates with ET produced by such high resolution models was impractical because in their current state these models may not be applied to large heterogeneous areas such as Los Angeles municipal districts.…”

Improved meteorology and ozone air quality simulations using MODIS land surface parameters in the Yangtze River Delta urban cluster, China

“…It is found that both urban representations (bulk urban parameterization in Noah LSM and SLUCM) could adequately capture the main weather features over urban regions. However, in the following sections, detailed discussions are based on model results from WRF‐default and WRF‐modified, because of the large uncertainty in the specification of urban canopy parameters within SLUCM [ Liao et al , ; Monaghan et al , ; Adachi et al , ; Li et al , ].…”