scholarly journals Coupling the Town Energy Balance (TEB) Scheme to an Operational Limited-Area NWP Model: Evaluation for a Highly Urbanized Area in Belgium

2012 ◽  
Vol 27 (2) ◽  
pp. 323-344 ◽  
Author(s):  
R. Hamdi ◽  
Daan Degrauwe ◽  
P. Termonia
Keyword(s):  
Energy Balance ◽  
Urban Areas ◽  
Weather Prediction ◽  
Single Layer ◽  
Urban Canopy ◽  
Sea Breeze ◽  
High Heat ◽  
Limited Area ◽  
Coarse Resolution ◽  
The Town

Abstract The Town Energy Balance (TEB) single-layer scheme is implemented in a numerical weather prediction model running operationally at ~4-km resolution. The primary question addressed is the ability of TEB to function at this relatively coarse resolution and, thus, assessing its potential use in an operational configuration to improve sensible weather performance over Belgium. For this effort, simulations with and without TEB are first evaluated against 2-m observations and wind above the urban canopy for two months (January and July 2010). The results show that promising improvements are achieved by introducing TEB. The 2-m temperature and 2-m relative humidity improve compared to measurements in urban areas. The comparison of wind speed and wind direction above the urban canopy indicates that the structure of the flow in urban areas is better reproduced with TEB. It was found that the implementation of TEB results in an increase in winter precipitation over urban areas and downwind from urban areas, but during the summer TEB tended to cause rainfall to be locally concentrated and the total accumulated precipitation decreased obviously. Results from a 36-h case study during a high heat day with inland sea-breeze penetration (8 July 2010) indicate that the model satisfactorily captured the penetration of the sea breeze. In particular during the day, the TEB run shows a delay in the sea-breeze evolution compared to the operational run. During the night the results indicate that even at this coarse resolution, TEB is able to correctly reproduce the intensity of the observed urban heat island (UHI) of Brussels.

ANALYZE THE URBAN ENERGY BALANCE OF DENSELY AREA JAKARTA USING SINGLE-LAYER URBAN CANOPY MODEL

2016 ◽  
Vol 78 (5) ◽  
Author(s):  
M. Muslim ◽  
Y. Koesmaryono
Keyword(s):  
Energy Balance ◽  
Urban Areas ◽  
Morphological Changes ◽  
Single Layer ◽  
Urban Canopy ◽  
Urban Canopy Model ◽  
Dense Area ◽  
Dominant Component ◽  
Urban Energy Balance ◽  
Canopy Model

Modification of surface and urban morphological changes, resulting in disruption of thermodynamic and dynamics properties in sub lowest layer of atmosphere, lead air temperature in downtown area higher than suburban. Study aims to analyze components of energy balance dense area of Jakarta using single-layer urban canopy model. H flux in solid area was dominant at noon. LE flux from dense area was very low Maximum intensity nocturnal heat island in dense areas was 2.5 °C. Higher value of h/w, S↓ received by wall and road decreases, causing H flux emitted by surface weakened. Instead L↑ emission trapped increases. The most dominant component that controls the balance of radiation and energy dense area are S↓ radiation, and H emission. Roof and road most active to respond heat during the day, and wall at night. Energy received or emitted by roof and road are greater than wall, due to shadowing effect. Surface temperature of urban areas is strongly influenced by local buildings configuration. Walls surfaces are less active emiting H at night for the h/w increasingly large. H emission from road surface decreases with increasing h/w. Increasing breadth of walls surfaces causing L↓ trapped in the canyon becomes higher, thus canyon temperatures remain high. 

scholarly journals Evaluation and Parameter-Sensitivity Study of a Single-Layer Urban Canopy Model (SLUCM) with Measurements in Nanjing, China

2014 ◽  
Vol 15 (3) ◽  
pp. 1078-1090 ◽  
Author(s):  
Wenjing Zhao ◽  
Ning Zhang ◽  
Jianning Sun ◽  
Jun Zou
Keyword(s):  
Heat Flux ◽  
Energy Balance ◽  
Surface Energy ◽  
Surface Energy Balance ◽  
Sensible Heat Flux ◽  
Single Layer ◽  
Urban Canopy ◽  
Sensible Heat ◽  
Urban Canopy Model ◽  
Canopy Model

Abstract An offline single-layer urban canopy model (SLUCM) was driven by the surface energy balance observations in winter in Nanjing, China, to evaluate the capability of the model to simulate the urban surface energy balance. The results of the evaluation suggest that the simulated daytime net radiation is approximately 20% lower than the observed and display relatively high systematic error, which is due to the relatively poor capacity of the model to simulate the daytime longwave radiation (which is underestimated by approximately 35%). By contrast, the simulated sensible heat flux shows mainly unsystematic error. Moreover, the one-at-a-time method is used to conduct a sensitivity analysis of the model parameters. The sensitivity analysis demonstrates that the major factors affecting the surface energy balance are the albedo, the thermal conductivity, and the roof and wall volumetric heat capacity. The influences of the shape of the street canyon and the average height of buildings are relatively weaker. The effects of the albedo on the fluxes are nearly linear. The effects of the thermal parameters are approximately logarithmic. Furthermore, the simulated sensible heat flux in the SLUCM is insensitive to the morphological parameters of the buildings.

scholarly journals A New Single-Layer Urban Canopy Model for Use in Mesoscale Atmospheric Models

2011 ◽  
Vol 50 (9) ◽  
pp. 1773-1794 ◽  
Author(s):  
Young-Hee Ryu ◽  
Jong-Jin Baik ◽  
Sang-Hyun Lee
Keyword(s):  
Energy Balance ◽  
Surface Energy ◽  
Surface Energy Balance ◽  
Single Layer ◽  
Urban Canopy ◽  
Heat Fluxes ◽  
Urban Surface ◽  
Urban Canopy Model ◽  
Canopy Model ◽  
Urban Surface Energy Balance

AbstractA new single-layer urban canopy model for use in mesoscale atmospheric models is developed and validated. The urban canopy model represents a built-up area as a street canyon, two facing buildings, and a road. In this model, the two facing walls are divided into sunlit and shaded walls on the basis of solar azimuth angle and canyon orientation, and individual surface temperature and energy budget are calculated for each wall. In addition, for better estimation of turbulent energy exchange within the canyon, a computational fluid dynamics model is employed to incorporate the effects of canyon aspect ratio (height-to-width ratio) and reference wind direction on canyon wind speed. The model contains the essential physical processes occurring in an urban canopy: absorption and reflection of shortwave and longwave radiation, exchanges of turbulent energy and water between surfaces (roof, two facing walls, and road) and adjacent air, and heat transfer by conduction through substrates. The developed urban canopy model is validated using datasets obtained at two urban sites: Marseille, France, and Basel, Switzerland. The model satisfactorily reproduces canyon air temperatures, surface temperatures, net radiation, sensible heat fluxes, latent heat fluxes, and storage heat fluxes for both sites. Extensive experiments are conducted to examine the sensitivities of the urban surface energy balance to meteorological factors and urban surface parameters. The reference wind speed is found to be a more crucial meteorological factor than the reference air temperature in altering urban surface energy balance, especially for weak winds. The urban surface energy balance is most sensitive to the roof albedo among urban surface parameters. The roof fraction, canyon aspect ratio, and ratio of roughness length for momentum to that for heat for the roof play important roles in altering urban surface energy balance.

scholarly journals Turbulence-permitting air pollution simulation for the Stuttgart metropolitan area

2020 ◽  
Author(s):  
Thomas Schwitalla ◽  
Hans-Stefan Bauer ◽  
Kirsten Warrach-Sagi ◽  
Thomas Bönisch ◽  
Volker Wulfmeyer
Keyword(s):  
Air Pollution ◽  
Air Quality ◽  
Metropolitan Area ◽  
Urban Areas ◽  
Single Layer ◽  
Urban Canopy ◽  
Surface Fluxes ◽  
Residential Areas ◽  
Near Surface ◽  
Air Quality Forecast

Abstract. Air pollution is one of the major challenges in urban areas. It can have a major impact on human health and society and is currently a subject of several litigations at European courts. Information on the level of air pollution is based on near surface measurements, which are often irregularly distributed along the main traffic roads and provide almost no information about the residential areas and office districts in the cities. To further enhance the process understanding and give scientific support to decision makers, we developed a prototype for an air quality forecasting system (AQFS) within the EU demonstration project Open Forecast. For AQFS, the Weather Research and Forecasting model together with its coupled chemistry component (WRF-Chem) is applied for the Stuttgart metropolitan area in Germany. Three model domains from 1.25 km down to a turbulence permitting resolution of 50 m were used and a single layer urban canopy model was active in all domains. As demonstration case study the 21 January 2019 was selected which was a heavy polluted day with observed PM10 concentrations exceeding 50 µg m−3. Our results show that the model is capable to reasonably simulate the diurnal cycle of surface fluxes and 2-m temperatures as well as evolution of the stable and shallow boundary layer typically occurring in wintertime in Stuttgart. The simulated fields of particulates with a diameter of less than 10 µm (PM10) and Nitrogen dioxide (NO2) allow a clear statement about the most heavily polluted areas apart from the irregularly distributed measurement sites. Together with information about the vertical distribution of PM10 and NO2 from the model, AQFS will serve as a valuable tool for air quality forecast and has the potential of being applied to other cities around the world.

scholarly journals Impact of Urban Canopy Parameters on a Megacity’s Modelled Thermal Environment

Atmosphere ◽  
2020 ◽  
Vol 11 (12) ◽  
pp. 1349
Author(s):  
Mikhail Varentsov ◽  
Timofey Samsonov ◽  
Matthias Demuzere
Keyword(s):  
Urban Areas ◽  
Climate Model ◽  
Thermal Environment ◽  
Weather Prediction ◽  
Urban Canopy ◽  
Anthropogenic Heat ◽  
Climate Modelling ◽  
Local Climate ◽  
Anthropogenic Heat Flux ◽  
Local Climate Zones

Urban canopy parameters (UCPs) are essential in order to accurately model the complex interplay between urban areas and their environment. This study compares three different approaches to define the UCPs for Moscow (Russia), using the COSMO numerical weather prediction and climate model coupled to TERRA_URB urban parameterization. In addition to the default urban description based on the global datasets and hard-coded constants (1), we present a protocol to define the required UCPs based on Local Climate Zones (LCZs) (2) and further compare it with a reference UCP dataset, assembled from OpenStreetMap data, recent global land cover data and other satellite imagery (3). The test simulations are conducted for contrasting summer and winter conditions and are evaluated against a dense network of in-situ observations. For the summer period, advanced approaches (2) and (3) show almost similar performance and provide noticeable improvements with respect to default urban description (1). Additional improvements are obtained when using spatially varying urban thermal parameters instead of the hard-coded constants. The LCZ-based approach worsens model performance for winter however, due to the underestimation of the anthropogenic heat flux (AHF). These results confirm the potential of LCZs in providing internationally consistent urban data for weather and climate modelling applications, as well as supplementing more comprehensive approaches. Yet our results also underline the continued need to improve the description of built-up and impervious areas and the AHF in urban parameterizations.

scholarly journals The Enviro-HIRLAM online integrated meteorology–chemistry modelling system: strategy, methodology, developments, and applications

2017 ◽  
Author(s):  
Alexander Baklanov ◽  
Ulrik Smith Korsholm ◽  
Roman Nuterman ◽  
Alexander Mahura ◽  
Kristian Pagh Nielsen ◽  
...  
Keyword(s):  
Indirect Effects ◽  
Urban Areas ◽  
Weather Forecasting ◽  
Weather Prediction ◽  
Cloud Microphysics ◽  
Research Strategy ◽  
Integrated Modelling ◽  
Limited Area ◽  
Main Research ◽  
Modelling System

Abstract. The Environment – HIgh Resolution Limited Area Model (Enviro-HIRLAM) is developed as a fully online integrated numerical weather prediction (NWP) and atmospheric chemical transport (ACT) model for research and forecasting of joint meteorological, chemical and biological weather. The integrated modelling system is developed by DMI in collaboration with several European universities. It is the baseline system in the HIRLAM Chemical Branch and used in several countries and different applications. The development was initiated at DMI more than 15 years ago. The first version was based on the DMI-HIRLAM NWP model with online integrated passive pollutant transport and dispersion, chemistry, aerosol dynamics, deposition and indirect effects. To make the model suitable for chemical weather forecasting (CWF) in urban areas the meteorological part was improved by implementation of urban parameterizations. The dynamical core was improved by implementing a locally mass conserving semi-Lagrangian numerical advection scheme, which improves forecast accuracy and model performance. The latest developing version is based on HIRLAM reference v7.2 with a more advanced and effective chemistry, aerosol multi-compound approach, aerosol feedbacks (direct and semi-direct) on radiation and (first and second indirect effects) on cloud microphysics. Since 2004 the Enviro-HIRLAM is used for different studies, including operational pollen forecasting for Denmark since 2009. Following main research and development strategy the further model developments will be extended towards the new NWP platform – HARMONIE. Different aspects of online coupling methodology, research strategy and possible applications of the modelling system, and fit-for-purpose model configurations for the meteorological and air quality communities are discussed.

scholarly journals The urban fingerprint in the sea-breeze hodograph reveled by high resolution WRF simulations.

2021 ◽  
Author(s):  
David Avisar ◽  
Ran Pelta ◽  
Alexandra Chudnovsky ◽  
Dorita Rostkier-Edelstein
Keyword(s):  
Wrf Model ◽  
Single Layer ◽  
Urban Canopy ◽  
Sea Breeze ◽  
Building Energy ◽  
Weather Research And Forecasting ◽  
Diurnal Cycles ◽  
Convergence Line ◽  
Urban Heat ◽  
First Time

<p>We implement and verify for the first time four Weather Research and Forecasting (WRF) model urban configurations, focused on the coastal metropolitan area of Tel-Aviv (MTA) using updated land use and urban morphological maps. We analyze the mesoscale summertime flow and the urban canopy (UC) role in the occurrence of different hodograph dynamics observed within MTA at night. These events may be significant in the context of air quality research. The four configurations – bulk (MM), single-layer (SLUCM), multi-layer (BEP), and BEP coupled with the building energy model (BEPBEM) – reproduce the observed diurnal temperature and wind diurnal cycles, with similar 10m wind direction bias and RMSE (15° and ~30°, respectively), with preference for MM and SLUCM at night. However, the SLUCM shows the lowest skill for the 10m wind speed (WS) (bias and RMSE equal or larger than 1ms-1), and the BEP shows the largest underestimation of the 2m temperature, ~-2.5°C. In the SLUCM, the WS increases over an UC region and with increasing building heights. The simulations show that at night, a convergence line (CL) builds up with the urban heat island, downstream of the NW flow. West of the CL, the wind continues flowing from the sea, and rotates anti-clockwise to form a non-elliptical sea-breeze hodograph. Removing MTA UC restores an elliptical hodograph. East of the CL, the UC supports an elliptical hodograph with a clockwise rotation through the NE sector, previously reported as dynamically unstable. We expect such wind hodograph dynamics within similar coastal metropolitan areas.</p>

scholarly journals Turbulence-permitting air pollution simulation for the Stuttgart metropolitan area

2021 ◽  
Vol 21 (6) ◽  
pp. 4575-4597
Author(s):  
Thomas Schwitalla ◽  
Hans-Stefan Bauer ◽  
Kirsten Warrach-Sagi ◽  
Thomas Bönisch ◽  
Volker Wulfmeyer
Keyword(s):  
Air Pollution ◽  
Air Quality ◽  
Metropolitan Area ◽  
Urban Areas ◽  
Single Layer ◽  
Urban Canopy ◽  
Surface Fluxes ◽  
Residential Areas ◽  
Near Surface ◽  
Air Quality Forecasting

Abstract. Air pollution is one of the major challenges in urban areas. It can have a major impact on human health and society and is currently a subject of several litigations in European courts. Information on the level of air pollution is based on near-surface measurements, which are often irregularly distributed along the main traffic roads and provide almost no information about the residential areas and office districts in the cities. To further enhance the process understanding and give scientific support to decision makers, we developed a prototype for an air quality forecasting system (AQFS) within the EU demonstration project “Open Forecast”. For AQFS, the Weather Research and Forecasting model together with its coupled chemistry component (WRF-Chem) is applied for the Stuttgart metropolitan area in Germany. Three model domains from 1.25 km down to a turbulence-permitting resolution of 50 m were used, and a single-layer urban canopy model was active in all domains. As a demonstration case study, 21 January 2019 was selected, which was a heavily polluted day with observed PM10 concentrations exceeding 50 µg m−3. Our results show that the model is able to reasonably simulate the diurnal cycle of surface fluxes and 2 m temperatures as well as evolution of the stable and shallow boundary layer typically occurring in wintertime in Stuttgart. The simulated fields of particulates with a diameter of less than 10 µm (PM10) and nitrogen dioxide (NO2) allow a clear statement about the most heavily polluted areas apart from the irregularly distributed measurement sites. Together with information about the vertical distribution of PM10 and NO2 from the model, AQFS will serve as a valuable tool for air quality forecasting and has the potential of being applied to other cities around the world.

scholarly journals Interactions Between the Nocturnal Low-Level Jets and the Urban Boundary Layer: A Case Study over London

2022 ◽  
Author(s):  
Aristofanis Tsiringakis ◽  
Natalie E. Theeuwes ◽  
Janet F. Barlow ◽  
Gert-Jan Steeneveld
Keyword(s):  
Boundary Layer ◽  
Wind Speed ◽  
Urban Areas ◽  
Prediction Models ◽  
Weather Prediction ◽  
Urban Boundary Layer ◽  
Limited Area ◽  
Low Level ◽  
Low Level Jets

AbstractUnderstanding the physical processes that affect the turbulent structure of the nocturnal urban boundary layer (UBL) is essential for improving forecasts of air quality and the air temperature in urban areas. Low-level jets (LLJs) have been shown to affect turbulence in the nocturnal UBL. We investigate the interaction of a mesoscale LLJ with the UBL during a 60-h case study. We use observations from two Doppler lidars and results from two high-resolution numerical-weather-prediction models (Weather Research and Forecasting model, and the Met Office Unified Model for limited-area forecasts for the U.K.) to study differences in the occurrence frequency, height, wind speed, and fall-off of LLJs between an urban (London, U.K.) and a rural (Chilbolton, U.K.) site. The LLJs are elevated ($$\approx $$ ≈ 70 m) over London, due to the deeper UBL, while the wind speed and fall-off are slightly reduced with respect to the rural LLJ. Utilizing two idealized experiments in the WRF model, we find that topography strongly affects LLJ characteristics, but there is still a substantial urban influence. Finally, we find that the increase in wind shear under the LLJ enhances the shear production of turbulent kinetic energy and helps to maintain the vertical mixing in the nocturnal UBL.

scholarly journals Dealing with uncertainty: an analysis of the severe weather events over Italy in 2006

2009 ◽  
Vol 9 (6) ◽  
pp. 1775-1786 ◽  
Author(s):  
L. Molini ◽  
A. Parodi ◽  
F. Siccardi
Keyword(s):  
Urban Areas ◽  
Weather Prediction ◽  
Objective Evaluation ◽  
Horizontal Resolution ◽  
Limited Area ◽  
Civil Protection ◽  
Forecast Verification ◽  
Common Definition ◽  
Mediterranean Countries ◽  
Definition Of

Abstract. Forecast verification is a long-standing issue of the whole meteorologists' community. A common definition of a truly satisfying prediction skill has not been achieved so far. Even the definition of "event", due to its spatio-temporal discontinuity, is highly affected by uncertainty. Moreover, decision-making demands numerical weather prediction modellers to provide information about the "inner" uncertainty, i.e. the degree of uncertainty related to the choice of a specific setting of the model (microphysics, turbulence scheme, convective closure, etc.). Most European Mediterranean countries, due to dense development, steep coastal orography and short hydrological response time of the drainage basins, have to deal very frequently with flash floods and sudden shallow land sliding impacting on urban areas. Civil protection organizations are in place to issue early warnings in order to allow local authorities and population to take precautionary measures. To do so in Mediterranean catchments, hydrologists are required to use numerical rainfall predictions in place of rainfall observations on large European catchments. Estimating the measure of uncertainty is for this reason crucial. The goal of this work is to propose an objective evaluation of the performance of the currently operational weather prediction model COSMO-I7 over quite a long time period and to check forecast verification at different space-time scales by the comparison of predictions with observations. Due to large investments in the last years, in fact, Italy has built up one of the most dense hourly-reporting network of rain gauges. The network has a mean space density of about 1/100 km2, very similar to the horizontal resolution of currently operating limited area models. An objective procedure to identify and compare the extreme events of precipitation has been applied to the full set of rainfall observations and over the severe events forecast by COSMO-I7 and announced in official warnings by Italian Civil Protection Department. The procedure allows to classify rainfall events as long-lived and spatially distributed or as having a shorter duration and a minor spatial extent. We show that long-lived events are less affected by overall uncertainty than short-lived ones, yet the inner uncertainty of the event affects both.

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