A Double-Canyon Radiation Scheme for Multi-Layer Urban Canopy Models

Schubert, Sebastian; Grossman‐Clarke, Susanne; Martilli, Alberto

doi:10.1007/s10546-012-9728-3

Cited by 65 publications

(74 citation statements)

References 27 publications

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“…This effort helped to identify the dominant physical processes, the level of complexity needed in an application specific context, and parameter requirements. Other ULSM evaluations in online mode (coupled to an atmospheric/climate model) include: a single‐ and a multi‐layer urban parametrization within the Coupled Ocean–Atmosphere Mesoscale Prediction System for the New York City metropolitan area (Holt and Pullen, 2007); various urban canopy schemes (slab, single‐layer and multi‐layer with and without a building energy model) in the Weather Research and Forecasting/Chemistry model to evaluate the regional climate and air quality of the Yangtze River Delta (China) (Liao et al , 2014), and high‐resolution regional climate simulations over Berlin (Germany) with the COSMO‐CLM regional climate model coupled to the Town Energy Budget (TEB) model (Trusilova et al , 2013, 2015), the Double Canyon Effect Parametrization (DCEP) scheme (Schubert and Grossman‐Clarke, 2012) and TERRA_URB (Wouters et al , 2015, 2016).…”

Section: Introductionmentioning

confidence: 99%

Impact of urban canopy models and external parameters on the modelled urban energy balance in a tropical city

Demuzere

Harshan

Järvi

et al. 2017

Quart J Royal Meteoro Soc

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To date, existing urban land surface models (ULSMs) have been mostly evaluated and optimized for mid‐ and high‐latitude cities. For the first time, we provide a comparative evaluation of four ULSMs for a tropical residential neighbourhood in Singapore using directly measured energy balance components. The simulations are performed offline, for an 11 month period, using the bulk scheme TERRA_URB and three models of intermediate complexity (CLM, SURFEX and SUEWS). In addition, information from three different parameter lists are used to quantify the impact (interaction) of (between) external parameter settings and model formulations on the modelled urban energy balance components. Encouragingly, overall results indicate good model performance for most energy balance components and align well with previous findings for midlatitude regions, suggesting the transferability of these models to (sub)tropical regions. Similar to results from midlatitude regions, the outgoing long‐wave radiation and latent heat flux remain the most problematic fluxes. In addition, the various combinations of models and different parameter values suggest that error statistics tend to be dominated more by the choice of the latter than the choice of model. Finally, our intercomparison framework enabled the attribution of common deficiencies in the different model approaches found previously in midlatitude regions: the simple representation of water intercepted by impervious surfaces leading to a positive bias in the latent heat flux directly after a precipitation event; and the positive bias in modelled outgoing long‐wave radiation that is partly due to neglecting the radiative interactions of water vapour between the surface and the tower sensor. These findings suggest that future developments in urban climate research should continue the integration of more physically based processes in urban canopy models, ensure the consistency between the observed and modelled atmospheric properties and focus on the correct representation of urban morphology, water storage and thermal and radiative characteristics.

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Section: Introductionmentioning

confidence: 99%

Impact of urban canopy models and external parameters on the modelled urban energy balance in a tropical city

Demuzere

Harshan

Järvi

et al. 2017

Quart J Royal Meteoro Soc

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“…Therefore, the investigation and evaluation of modelling the water balance for cities is limited as well (eg., Grimmond and Oke, 1991;Kanda et al, 2005;Nakayoshi et al, 2009;Demuzere et al, 2013). As a result, the representation of the urban water balance in existing urban land-surface parametrizations is very rudimentary: For instance, various urban models do not consider evaporation from the impervious surfaces as a first approximation to the reduction of ET in cities (Hénon et al, 2012;Martilli et al, 2002;Schubert et al, 2012). Up to now, the accuracy, validity and applicability of water-storage parametrizations employed in existing land-surface models (Masson, 2000;Kanda et al, 2005;Oleson et al, 2008;Demuzere et al, 2013Demuzere et al, , 2014a have not been investigated in detail.…”

Section: Introductionmentioning

confidence: 99%

The impact of impervious water-storage parametrization on urban climate modelling

et al. 2015

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a b s t r a c tIn order to improve the representation of the water balance in urban land-surface models, we present a new impervious waterstorage parametrization that assumes a distribution of water reservoirs. It has been implemented in TERRA-URB, a new urban parametrization for COSMO-CLM's standard land-surface module TERRA-ML. The water-storage capacity and the maximal wet surface fraction of the urban impervious land cover consisting of streets and buildings are estimated for Toulouse centre by matching the modelled and observed evapotranspiration (ET) rates. They amount to 1.31 ± 0.20 kg m À2 and 12 AE 4%, respectively. The model successfully reproduces the timespan and magnitude of increased ET for both urban observations campaigns CAPITOUL and BUBBLE. Our sensitivity study reveals that water-storage parametrization largely affects the performance of modelled ET rates. Hereby, the simulation employing the new water-storage parametrization is improved compared to arbitrary or existing water-storage parametrizations. The ET, surface sensible heat exchange and upwelling infra-red radiation are all affected until 12 day-time hours after rainfall on average. The modelled annual-mean ET during the CAP-ITOUL campaign from the urban land in Toulouse is an order of magnitude lower than that observed for the natural surroundings.

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“…To this end, we employ the non‐hydrostatic limited area model system COSMO (Consortium for Small‐scale Modelling) in Climate Mode (CCLM, Steppeler et al , ) coupled with a multilayer urban canopy model, the Double‐Canyon Effect parametrization scheme (DCEP, Schubert et al , ). Previous studies with CCLM and DCEP for Berlin (Germany) and Basel (Switzerland), showed that diurnal variation and magnitude of the UHI is represented well in the model during summer months (Schubert and Grossman‐Clarke, ; Schubert and Grossman‐Clarke, ; Trusilova et al , ).…”

Section: Introductionmentioning

confidence: 99%

Urban effects on summertime air temperature in Germany under climate change

Grossman‐Clarke

Schubert

Fenner

2016

Intl Journal of Climatology

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The impact of global climate change on urban relative to rural summertime air temperatures is investigated for nine major cities in Germany, under the Representative Concentration Pathway trajectory 8.5. The analysis is based on simulations of representative summers with a regional climate model (RCM) in conjunction with a multilayer urban parametrization when driven by three global circulation models (GCMs). The GCMs are selected because they project different warming rates for Germany. Specifically, each GCM provides boundary conditions for the RCM for two past and two future summers that resemble average conditions for Germany with respect to 2‐m air temperature statistics during a historical (1976–2005) and a future (2031–2060) period. Thus, one emphasis of our study is on the effects of the different driving GCMs on urban–rural air temperature differences (ΔTu−r). The simulations show climate change signals (CCSs) in summer‐mean ΔTu−r of the city ensemble of up to 0.15 K. Across all driving GCMs, the largest changes are projected for the city of Berlin. Characteristics of the diurnal courses of ΔTu−r, the magnitude of the CCS and its physical reasons are GCM specific. Specifically, CCSs are caused either by positive or negative changes in the Bowen ratio of the rural boundary with little change in the urban surface fluxes, or vice versa. The study emphasizes the importance of the driving GCM in RCM simulations when investigating urban effects on air temperature under global climate change.

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A Double-Canyon Radiation Scheme for Multi-Layer Urban Canopy Models

Cited by 65 publications

References 27 publications

Impact of urban canopy models and external parameters on the modelled urban energy balance in a tropical city

Impact of urban canopy models and external parameters on the modelled urban energy balance in a tropical city

The impact of impervious water-storage parametrization on urban climate modelling

Urban effects on summertime air temperature in Germany under climate change

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