James A Voogt

Western University | UWO · Department of Geography and Environment

Remote sensing of urban environments has unveiled a significant shift from single-city investigations to the inclusion of multiple cities. Originated from the ideas of the Remote Sensing of Environment special issue entitled "Remote Sensing of the Urban Environment: Beyond the Single City," this paper offers a comprehensive examination of the state...

Urban vegetation has a large impact on urban microclimates and is an important element in urban environmental design. Its representation within state of the art urban climate models provides new capabilities for urban planners and designers to consider the impact of trees on urban climates. However, assessing the climate impact of urban vegetation...

While projected urban air temperatures under climate change and urbanization have received attention, projections of pedestrian thermal stress are scarce and usually produced by statistical downscaling. In this study, we present and evaluate a dynamical downscaling methodology to assess urban outdoor thermal exposure. We dynamically downscale Earth...

A comprehensive comparison of the trends and drivers of global surface and canopy urban heat islands (termed Is and Ic trends, respectively) is critical for better designing urban heat mitigation strategies. However, such a global comparison remains largely absent. Using spatially continuous land surface temperatures and surface air temperatures (2...

Remotely sensed land surface temperature (LST) has become one of primary observational sources for urban climate research. However, LST is subject to considerable angular variation, particularly in urban areas caused by a large variation of sensor viewing angles and non-isothermal façades of 3D urban structures. Anisotropy varies seasonally and diu...

Warming trends in cities are influenced both by large-scale climate processes and by local-scale urbanization. However, little is known about how surface warming trends of global cities differ from those characterized by weather observations in the rural background. Here, through statistical analyses of satellite land surface temperatures (2002 to...

InterventionOntario’s Harmonized Heat Warning and Information System (HWIS) brings harmonized, regional heat warnings and standard heat-health messaging to provincial public health units prior to periods of extreme heat.Research questionWas implementation of the harmonized HWIS in May 2016 associated with a reduction in emergency department (ED) vi...

The land surface temperature (LST)—based surface urban heat island (SUHI) is suitable for exploring thermal environments at large scales. Despite a few studies focused on the intra-urban SUHI intensity (SUHII) of a single city or cities with similar climates by adopting the local climate zone (LCZ) scheme, exploration of the spatial-temporal charac...

The significant reduction in human activities during COVID‐19 lockdown is anticipated to substantially influence urban climates, especially urban heat islands (UHIs). However, the UHI variations during lockdown periods remain to be quantified. Based on the MODIS daily land surface temperature and the in‐situ surface air temperature observations, we...

The directional variation in upwelling thermal radiance (referred to as “thermal anisotropy”) is one of the important issues in retrieving representative urban land surface temperature (LST) from remote sensing data. Yet, there is a gap between urban thermal anisotropy assessed from different observational and modeling approaches at different time...

Atmospheric and surface urban heat islands (UHI) originate from common energetic processes, but the status of scientific knowledge on their time evolution is highly disparate. The diurnal cycles of atmospheric UHI are well known based on years of continuous measurements in cities; the cycles of surface UHI, however, cannot be measured continuously...

Infrastructure-based heat reduction strategies can help cities adapt to high temperatures, but simulations of their cooling potential yield widely varying predictions. We systematically review 146 studies from 1987 to 2017 that conduct physically based numerical modelling of urban air temperature reduction resulting from green-blue infrastructure a...

Urban areas have complex thermal distribution. We examined the association between extreme temperature and mortality in urban Ontario, using two temperature data sources: high-resolution and weather station data. We used distributed lag non-linear Poisson models to examine census division-specific temperature–mortality associations between May and...

For this volume, a survey was conducted among WMO Members in 2018 to judge the level of service provision in each area, the extent to which users and providers collaborate and the status of urban services currently provided. The common hazards that require Integrated Urban Services are identified as heavy rainfall, flooding, windstorms, tropical st...

A R T I C L E I N F O Editor name: Jing M. Chen Keywords: Thermal remote sensing Urban thermal anisotropy Angular effect MODIS land surface temperature (LST) Model simulation A B S T R A C T Satellite observation of land surface temperature (LST) is an important tool for monitoring urban thermal environments but is prone to significant angular effe...

This chapter describes a new World Meteorological Organisation (WMO) approach to the provision of science-based services to assist the planning of safe, healthy, resilient and climate-friendly cities. The approach is outlined in full in the WMO Guidance on Integrated Urban Hydrometeorological, Climate and Environmental Services. Volume I, Concepts...

The urban heat island (UHI) is a major topic in the study of urban climates. However, comprehensive research on the atmospheric UHI (UHIAtm), surface UHI (UHISurf), and subsurface UHI (UHISub) simultaneously has yet not been reported. Using the MODIS land surface temperature and atmospheric profile data during the 2010–2016 period, we investigated...

Most previous studies of surface urban heat islands (SUHIs) have focused solely on their controlling factors on a seasonal/annual timescale, while the controls on daily variations are largely unknown. By extracting the daily variations of nighttime SUHI features using the Gaussian model and investigating their correlations with various explanatory...

Cities are particularly vulnerable to extreme weather episodes, which are expected to increase with climate change. Cities also influence their own local climate, for example, through the relative warming known as the urban heat island (UHI) effect. This review discusses urban climate features (even in complex terrain) and processes. We then presen...

This is a comment to the paper "Magnitude of urban heat islands largely explained by climate and population" by Manoli et al. (2019, Nature 573 p. 55-60; https://doi.org/10.1038/s41586-019-1512-9)

Rapid urbanization combined with climate change necessitates new types of urban services that make best use of science and technology. The Integrated Urban Hydro-Meteorological, Climate and Environmental Services and systems are a new initiative from the World Meteorological Organization (WMO) that seeks to provide science-based integrated urban se...

Wall surface temperatures are important components of urban climates but are under-sampled by satellite and airborne remote sensing and at the microscale are under-sampled in observational studies. In urban canopy models, they are represented with simplistic geometries. This study examines the effect of microscale (sub-facet) surface structure geom...

Integrated Urban hydrometeorological, climate and environmental Services (IUS) is a WMO initiative to aid development of science-based services to support safe, healthy, resilient and climate friendly cities. Guidance for Integrated Urban Hydrometeorological, Climate and Environmental Services (Volume I) has been developed with the intent to provid...

Vegetation alters urban climates via transpirational cooling; however, unlike shorter vegetation, trees additionally provide shade and shelter. Urban canopy models (UCMs) are coupled with mesoscale models for assessment of neighbourhood-scale climate, but their representation of urban trees is limited. We present BEP-Tree, a multi-layer UCM that in...

The anisotropy of directional radiative surface temperature measurements over urban building surfaces is expected to have strong temporal variation. However, a model with the capability to simulate the temporal variation of urban thermal anisotropy (UTA) and with inversion abilities has not yet been developed. In this paper, the relationship betwee...

Assessment of surface urban heat islands (SUHI) has been hampered by the lack of a consistent framework to permit consistent interpretation between cities. Local Climate Zones (LCZ) are a universal description of local scale landscape types based on expected variation at neighbourhood scale (≥1km 2) in and around cities. In this study, we investiga...

Understanding the diurnal dynamics of surface urban heat islands (SUHIs) is an indispensable step towards their full interpretation at multiple time scales. However, because of the tradeoff between the spatial and temporal resolutions of satellite-derived land surface temperature (LST) data, the climatology, variety, and taxonomy of diurnal SUHI (D...

Green rooftops are installed in many climates worldwide to support urban ecosystem services. Across North America, green roofs often make use of the same limited set of plant species, but the effects of regional climates on the survival and growth of a core set of plant species has seldom been investigated. To identify the impact of climate on gree...

The Pan and ParaPan American Games (PA15) are the third largest sporting event in the world and were held in Toronto in the summer of 2015 (10-26 July, 7-15 August). This was used as an opportunity to coordinate and showcase existing innovative research and development activities related to weather, air quality (AQ) and health at Environment and Cl...

With the expected increase in warmer conditions caused by climate change, heat-related illnesses are becoming a more pressing issue. One way that humans can protect themselves from this is to seek shade. The design of urban spaces can provide individuals with a variety of ways to obtain this shade. The objective of this study was to perform a detai...

Complete urban surface temperature (TC) is a key variable for quantifying the urban surface - atmosphere interactions. The estimation of TC usually requires detailed knowledge of surface geometry and facet temperatures, which are difficult to obtain by remote sensing. Therefore, simple but efficient strategies for the remote estimation of TC are cu...

Traditional methods for remote sensing of urban surface temperatures (Tsurf) are subject to a suite of temporal and geometric biases. The effect of these biases on our ability to characterize the true geometric and temporal nature of urban Tsurf is currently unknown, but is certainly nontrivial. To quantify and overcome these biases, we present a m...

Urban Climates is the first full synthesis of modern scientific and applied research on urban climates. The book begins with an outline of what constitutes an urban ecosystem. It develops a comprehensive terminology for the subject using scale and surface classification as key constructs. It explains the physical principles governing the creation o...

The study of urban climates now represents a full scientific field on its own. The 9th International Conference on Urban Climate (ICUC-9), held in July 2015 in Toulouse, France, provided a recent forum for urban climate scientists to share the results of their research. This introduction paper presents the 20 articles of this special issue. They ar...

doi: 10.1175/BAMS-D-17-0106.1

Human settlement, through the development of towns and cities, affects both the properties of the surface and that of the atmosphere above them. Urban regions therefore develop distinct urban climates in which the mean characteristics of the atmosphere within, above, and downwind of cities are modified by the city and constitute an unintentional mo...

The three-dimensional structure of cities under clear sky solar radiation loading leads to strong temperature differentiation between the main urban facets (roofs, roads, walls) and their sunlit and shaded fractions. When viewed by a narrow field-of-view thermal remote sensor a strong effective anisotropic distribution of the sensor brightness temp...

This paper presents a method of analysis for deriving temporally continuous urban surface temperature and heat island assessments from hemispherical measurements of upwelling thermal radiation. This method was developed to overcome geometric and temporal biases inherent in traditional thermal remote sensing of urban surface climates. Hemispherical...

This study aims to evaluate the effects of urban geometry on retrieval of emissivity and surface temperature in urban areas. An improved urban emissivity model based on sky view factor (IUEM-SVF) was further enhanced to consider all radiance contributions leaving the urban canopy, including (i) emission by all facets within an instantaneous field o...

Green roofs are becoming increasingly popular for moderating stormwater runoff in urban areas. This study investigated the impact different climates have on the retention performance of identical green roofs installed in London Ontario (humid continental), Calgary Alberta (semi-arid, continental), and Halifax Nova Scotia (humid, maritime). Drier cl...

Surface temperature is a key variable in boundary-layer meteorology and is typically acquired by remote observation of emitted thermal radiation. However, the three-dimensional structure of cities complicates matters: uneven solar heating of urban facets produces an "effective anisotropy" of surface thermal emission at the neighbourhood scale. Remo...

This study examined hourly temperature data of two locations of Mumbai metropolitan city. One data point (Coloba, Mumbai) is in centre of the city and the other one (Santacruz, Mumbai) is at the airport. The study finds that there were many occasions when night-time hourly temperatures over the city centre were considerably higher than that of the...

A sensor view model is modified to include trees using a gap probability approach to estimate foliage view factors and an energy budget model for leaf surface temperatures (SUMVEG). The model is found to compare well with airborne thermal infrared (TIR) surface temperature measurements. SUMVEG is used to investigate the influence of trees on therma...

Any radiometer at a fixed location has a biased view when observing a convoluted, three-dimensional surface such as an urban canopy. The goal of this contribution is to determine the bias of various sensors views observing a simple urban residential neighbourhood (nadir, oblique, hemispherical) over a 24 hour cycle under clear weather conditions. T...

Urbanization modifies surface energy and water budgets, and has significant impacts on local and regional hydroclimate. In recent decades, a number of urban canopy models have been developed and implemented into the Weather Research and Forecasting (WRF) model to capture urban land-surface processes. Most of these models are inadequate due to the l...

Any radiometer at a fixed location has a biased view when observing a convoluted, three dimensional surface such as an urban canopy. The goal of this contribution is to determine the bias of various sensors views observing a simple urban residential neighbourhood (nadir, oblique, hemispherical) over a 24 h cycle under clear weather conditions. The...

Modeling diurnal temperature cycle (DTC) is of great significance to various fields concerning land surface temperature (LST) applications. However, previous DTC model-based methods require four or more LST observations in one diurnal cycle and neglect the angular effect of remotely sensed LSTs. This research proposes a hybrid method combining a DT...

Subsurface soil temperature is a key variable of land surface processes and not only responds to but also modulates the interactions of energy fluxes at the Earth's surface. Thermal remote sensing has traditionally been regarded as incapable of detecting the soil temperature beneath the skin-surface. This study shows that thermal remote sensing can...

The interpolation of urban surface temperatures (USTs) is crucial to the utilization of temporally sporadic observations from satellites and to understanding urban climate. This study directly connects diurnal USTs with thermal inertia and presents a physically based approach to interpolate the diurnal USTs of an urban facet with sporadic thermal o...

A large number of researchers from many disciplines and nations attended the Urban Weather and Climate Workshop to address the future risks and define mitigation strategies in an effort to understand the weather and regional climate affected by cities. The presentations by the workshop's participants covered a wide range of topics ranging from the...

Surface brightness temperatures modeled using the SOLENE model with effective model parameters derived from Part 1 Hénon et al. (2012) are compared to temperatures obtained from an airborne thermal camera at the facet and pixel scales. The measurements were made during both summer and winter intense observation periods over the center of Toulouse,...

A methodology is proposed to analyze the radiative and thermal exchanges between a small urban neighborhood and the atmosphere based on the use of the thermoradiative model SOLENE and radiometric measurements to optimize the effective values of its constant parameters. Applied to the center of Toulouse, France, the optimization data are building su...

Thermal inertia over vast earth surfaces is a crucial parameter in many related disciplines. However, remote estimates of urban thermal inertia show anisotropy effects due to thermal anisotropy. This study investigates the impacts of thermal anisotropy on the estimation of urban thermal inertia. We present the concepts of DTI (directional thermal i...

The complete surface temperature T0,C of a complex urban surface is an important parameter in the urban energy balance. As direct measurements of T0,C in an urban setting are difficult, remote sensing techniques are often used to retrieve integrated temperatures, however, these sensors inherently define a preferential view direction and field of vi...

Thermal inertia over vast earth surfaces is a crucial parameter in many related disciplines. However, remote estimates of urban thermal inertia show anisotropy effects due to thermal anisotropy. This study investigates the impacts of thermal anisotropy on the estimation of urban thermal inertia. We present the concepts of DTI (directional thermal i...

The paper addresses the question of whether the modeling practice of summing separate land-cover tiles to give urban fluxes at the neighborhood scale has merit. A central-city site in Basel, Switzerland, was instru-mented to measure turbulent sensible heat fluxes Q H from the two main land-cover types (roofs and canyons) separately and from the who...

Modeled carbon-dioxide (CO 2) emissions from an urban area are validated against direct eddy-covariance flux measurements. Detailed maps of modeled local carbon-dioxide emissions for a 4 km 2 residential neighborhood in Vancouver, BC, Canada are produced. Inputs to the emission model include urban object classifications (buildings, trees, land-cove...

As part of the ‘Environmental Prediction in Canadian Cities’ (EPiCC) network (2007-2010), pyranometer and pyrgeometer were simultaneously recording all four components of the surface radiation balance continuously over more than a year above a residential urban site and a rural site in Vancouver, BC. In the yearly total, short-wave irradiance was s...

Urban land surface schemes have been developed to model the distinct features of the urban surface and the associated energy exchange processes. These models have been developed for a range of purposes and make different assumptions related to the inclusion and representation of the relevant processes. Here, the first results of Phase 2 from an int...

Urban land surface schemes have been developed to model the distinct features of the urban surface and the associated energy exchange processes. These models have been developed for a range of purposes and make different assumptions related to the inclusion and representation of the relevant processes. Here, the first results of Phase 2 from an int...

It can be expected that integrative greenhouse-gas emission modeling at block or neighborhood-scales becomes an increasingly relevant part of urban planning processes in the future. A particular challenge forms the geographical distribution of emissions and a proper validation of modeled emissions at this fine scale where consumption statistics are...