Enhanced modeling of latent heat flux from urban surfaces in the Noah/single-layer urban canopy coupled model

Miao, Shiguang; Chen, Fei

doi:10.1007/s11430-014-4829-0

Cited by 57 publications

(53 citation statements)

References 32 publications

(35 reference statements)

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“…For the downward shortwave radiation modeled by MP‐BEP‐BEM (Figure a), significant errors also occur on the third day, corresponding to the highest warm bias period, which is related to the inability of WRF model to capture boundary layer clouds and shallow convection leading to a too‐high downward shortwave radiation reaching the surface. Sensible (latent) heat flux is significantly overestimated (underestimated) by MP‐BEP‐BEM (red lines in Figures b and c), an outstanding issue in urban areas (Grimmond et al, ; Miao & Chen, ). It should be noted that observed daytime latent heat flux here is comparable to or even higher than sensible heat flux and an average Bowen ratio of around 1.0 in summer was observed when conducting a year‐round analysis of clear‐day flux measurements for this tower (Miao et al, ).…”

Section: Resultsmentioning

confidence: 97%

Using WRF‐Urban to Assess Summertime Air Conditioning Electric Loads and Their Impacts on Urban Weather in Beijing

Chen

Shen

et al. 2018

JGR Atmospheres

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The air conditioning (AC) electric loads and their impacts on local weather over Beijing during a 5 day heat wave event in 2010 are investigated by using the Weather Research and Forecasting (WRF) model, in which the Noah land surface model with multiparameterization options (Noah‐MP) is coupled to the multilayer Building Effect Parameterization and Building Energy Model (BEP+BEM). Compared to the legacy Noah scheme coupled to BEP+BEM, this modeling system shows a better performance, decreasing the root‐mean‐square error of 2 m air temperature to 1.9°C for urban stations. The simulated AC electric loads in suburban and rural districts are significantly improved by introducing the urban class‐dependent building cooled fraction. Analysis reveals that the observed AC electric loads in each district are characterized by a common double peak at 3 p.m. and at 9 p.m. local standard time, and the incorporation of more realistic AC working schedules helps reproduce the evening peak. Waste heat from AC systems has a smaller effect (~1°C) on the afternoon 2 m air temperature than the evening one (1.5~2.4°C) if AC systems work for 24 h and vent sensible waste heat into air. Influences of AC systems can only reach up to ~400 m above the ground for the evening air temperature and humidity due to a shallower urban boundary layer than daytime. Spatially varying maps of AC working schedules and the ratio of sensible to latent waste heat release are critical for correctly simulating the cooling electric loads and capturing the thermal stratification of urban boundary layer.

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Section: Resultsmentioning

confidence: 97%

Using WRF‐Urban to Assess Summertime Air Conditioning Electric Loads and Their Impacts on Urban Weather in Beijing

Chen

Shen

et al. 2018

JGR Atmospheres

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“…The urban hydrological parameterization include the processes of the following: (1) anthropogenic latent heat from cooling systems and vehicles, (2) multilayer green roof systems, (3) evaporation from impervious surfaces, (4) urban irrigation, and (5) the urban oasis effect. More details of the urban hydrological parameterization can be found in Miao and Chen (2014) and . The other major physics packages used in the simulations include the WRF single-moment 3-class scheme for microphysics (Hong et al, 2004), the Eta similarity scheme for surface layer parameterization (Janjić, 2001), the Mellor-Yamada-Janjić (MYJ) turbulent kinetic energy (TKE) scheme for planetary boundary layer (Janjić, 2001), the rapid radiative transfer model for longwave radiation (Mlawer et al, 1997), and the Dudhia scheme for shortwave radiation (Dudhia, 1989), as well as the Noah land surface model (LSM), which is coupled with the SLUCM (Chen et al, 2011).…”

Section: Model Configurationmentioning

confidence: 99%

Assessing the Impact of Urban Hydrological Processes on the Summertime Urban Climate in Nanjing Using the WRF Model

et al. 2019

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The impacts of urban hydrological processes, such as anthropogenic latent heat (ALH), multilayer green roof systems (GRO), evaporation from impervious surfaces (EIMP), urban irrigation (IRR), and the urban “oasis effect” (OASIS) on regional hydrometeorology in Nanjing, are assessed by the Weather Research and Forecasting Single‐Layer Urban Canopy Models (WRF‐SLUCM). The results show that including all five urban hydrological processes, ALL best improves the prediction of near‐surface meteorology and has the largest correlation coefficients, the smallest root mean square errors, and the most accurate diurnal variations compared with observations. The improvements of ALH, GRO, and OASIS are larger than those of IRR and EIMP. The influence of ALH, GRO, and OASIS is comparable in commercial areas, whereas the influence of OASIS is significantly greater and plays essential roles in low‐intensity residential areas. Therefore, the overall effect of urban hydrological processes is especially large over low‐intensity residential areas, where the ALL case‐simulated monthly mean 2‐m air temperature (surface temperature) is reduced by approximately 1.3 (5.0) °C, the 2‐m specific humidity increases by 0.8 g kg–1, and the sensible heat (latent heat) flux is reduced (increased) at most by 90 W m–2. The changes in the vertical profiles indicate that urban hydrological processes reduce the potential temperature and wind speed, whereas they increase specific humidity over the entire urban boundary layer, leading to a more stable atmospheric conditions, reduced vertical mixing, and weaker convective rolls. These effects could mitigate the intensity of urban heat/dry islands while simultaneously exacerbating low‐level air pollution.

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“…SLUCM coupled with WRF has been extensively validated (e.g. Chen et al, 2011;Miao and Chen, 2014). AH is added as sensible heat into the atmosphere directly in the WRF-SLUCM model.…”

Section: Wrf and Its Urban Modelmentioning

confidence: 99%

The impact of an urban canopy and anthropogenic heat fluxes on Sydney's climate

Pitman

Hart

et al. 2017

Intl Journal of Climatology

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We use the Weather Research and Forecast model and estimate anthropogenic heat (AH) fluxes based on fine‐scale energy consumption data for Sydney, Australia, to investigate the effects of urbanization on temperature. We examine both the impact of urban canopy effects (UCE) and AH which in combination causes the urban heat island effect. Sydney's urban heat island (UHI) varies from −1 to >3.4 °C between day and night and between seasons. UHI intensity is highest at night and an urban cool island is often experienced during the day. UCE contributes 80% of the UHI during summer nights because of the release of stored heat from urban infrastructure that has been absorbed during the day. During the day for UCE, the reduced net radiation and greater heat storage by urban infrastructure combine to slightly cool. In contrast, AH contributes 90% of the UHI during winter nights because it does not dissipate into the higher levels of the boundary layer efficiently. The opposite applies during summer nights and during daytime in both summer and winter where heat mixes effectively into the atmosphere. Our results show contrasting impacts of UCE and AH by time of day and time of year and point to major simulation biases if only one of these phenomena is represented, or if their seasonal contributions are not accounted for separately.

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Enhanced modeling of latent heat flux from urban surfaces in the Noah/single-layer urban canopy coupled model

Cited by 57 publications

References 32 publications

Using WRF‐Urban to Assess Summertime Air Conditioning Electric Loads and Their Impacts on Urban Weather in Beijing

Using WRF‐Urban to Assess Summertime Air Conditioning Electric Loads and Their Impacts on Urban Weather in Beijing

Assessing the Impact of Urban Hydrological Processes on the Summertime Urban Climate in Nanjing Using the WRF Model

The impact of an urban canopy and anthropogenic heat fluxes on Sydney's climate

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