scholarly journals Impact of COVID-19-Related Traffic Slowdown on Urban Heat Characteristics

Atmosphere ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 243
Author(s):  
Bernardo Teufel ◽  
Laxmi Sushama ◽  
Vincent Poitras ◽  
Tarek Dukhan ◽  
Stéphane Bélair ◽  
...  
Keyword(s):  
Heat Stress ◽  
Surface Temperature ◽  
Urban Areas ◽  
Heavy Traffic ◽  
Urban Climate ◽  
Surface Wind ◽  
Warm Season ◽  
Well Being ◽  
Urban Centre ◽  
Near Surface

Governments around the world have implemented measures to slow down the spread of COVID-19, resulting in a substantial decrease in the usage of motorized transportation. The ensuing decrease in the emission of traffic-related heat and pollutants is expected to impact the environment through various pathways, especially near urban areas, where there is a higher concentration of traffic. In this study, we perform high-resolution urban climate simulations to assess the direct impact of the decrease in traffic-related heat emissions due to COVID-19 on urban temperature characteristics. One simulation spans the January–May 2020 period; two additional simulations spanning the April 2019–May 2020 period, with normal and reduced traffic, are used to assess the impacts throughout the year. These simulations are performed for the city of Montreal, the second largest urban centre in Canada. The mechanisms and main findings of this study are likely to be applicable to most large urban centres around the globe. The results show that an 80% reduction in traffic results in a decrease of up to 1 °C in the near-surface temperature for regions with heavy traffic. The magnitude of the temperature decrease varies substantially with the diurnal traffic cycle and also from day to day, being greatest when the near-surface wind speeds are low and there is a temperature inversion in the surface layer. This reduction in near-surface temperature is reflected by an up to 20% reduction in hot hours (when temperature exceeds 30 °C) during the warm season, thus reducing heat stress for vulnerable populations. No substantial changes occur outside of traffic corridors, indicating that potential reductions in traffic would need to be supplemented by additional measures to reduce urban temperatures and associated heat stress, especially in a warming climate, to ensure human health and well-being.

scholarly journals Features of Urban Heat Island in Mountainous Chongqing from a Dense Surface Monitoring Network

Atmosphere ◽  
2019 ◽  
Vol 10 (2) ◽  
pp. 67 ◽  
Author(s):  
Ping Jiang ◽  
Xiaoran Liu ◽  
Haonan Zhu ◽  
Yonghua Li
Keyword(s):  
Urban Heat Island ◽  
Urban Areas ◽  
Surface Wind ◽  
Warm Season ◽  
Monitoring Network ◽  
Anthropogenic Heat ◽  
Heat Island ◽  
Near Surface ◽  
Urban Heat ◽  
Surface Monitoring

The spatial and temporal features of urban heat island (UHI) intensity in complex urban terrain are barely investigated. This study examines the UHI intensity variations in mountainous Chongqing using a dense surface monitoring network. The results show that the UHI intensity is closely related to underlying surfaces, and the strongest UHI intensity is confined around the central urban areas. The UHI intensity is most prominent at night and in warm season, and the magnitude could reach ~4.5 °C on summer night. Our quantitative analysis shows a profound contribution of urbanization level to UHI intensity both at night and in summer, with regression coefficient b = 4.31 and 6.65, respectively. At night, the urban extra heat such as reflections of longwave radiation by buildings and release of daytime-stored heat from artificial materials, is added into the boundary layer, which compensates part of urban heat loss and thus leads to stronger UHI intensity. In summer, the urban areas are frequently controlled by oppressively hot weather. Due to increased usage of air conditioning, more anthropogenic heat is released. As a result, the urban temperatures are higher at night. The near-surface wind speed can serve as an indicator predicting UHI intensity variations only in the diurnal cycle. The rural cooling rate during early evening transition, however, is an appropriate factor to estimate the magnitude of UHI intensity both at night and in summer.

scholarly journals Global long-term mapping of surface temperature shows intensified intra-city urban heat island extremes

2021 ◽  
Author(s):  
Lorenzo Mentaschi ◽  
Gregory Duveiller ◽  
Grazia Zulian ◽  
Christina Corbane ◽  
Martino Pesaresi ◽  
...  
Keyword(s):  
Heat Stress ◽  
Surface Temperature ◽  
Urban Heat Island ◽  
Urban Areas ◽  
Human Impacts ◽  
Warm Season ◽  
Mitigation Strategies ◽  
Heat Island ◽  
Urban Heat

Abstract Surface temperatures are generally higher in cities than in rural surroundings. This phenomenon, known as surface urban heat island (SUHI), increases the risk of heat-related human illnesses and mortality. Past global studies analysed this phenomenon aggregated at city scale or over seasonal and annual time periods, while human impacts strongly depend on shorter term heat stress experienced locally. Here we develop a global long-term high-resolution dataset of daytime SUHI as urban-rural surface temperature differences. Our results show that across urban areas worldwide over the period 2003-2020, 3-day SUHI extremes are on average more than twice as high as the warm-season median SUHI, with local exceedances up to 10 K. Over this period, SUHI extremes have increased more rapidly than warm-season medians, and averaged worldwide are now 1.04 K or 31% higher compared to 2003. This can be linked with increasing urbanisation, more frequent heatwaves, and greening of the earth, processes that are all expected to continue in the coming decades. Within many cities there are hotspots where extreme SUHI intensity is 10 to 15 K higher compared to relatively cooler city parts. Given the limited human adaptability to heat stress, our results advocate for mitigation strategies targeted at reducing SUHI extremes in the most vulnerable and exposed city neighbourhoods.

scholarly journals On the changes in the sea surface temperature in the Benguela upwelling region. Part 1: season cycle

2019 ◽  
pp. 33-44
Author(s):  
A. B. Polonsky ◽  
A. N. Serebrennikov
Keyword(s):  
Surface Temperature ◽  
Seasonal Variability ◽  
Surface Wind ◽  
Water Layer ◽  
Hydrodynamic Characteristics ◽  
Entire Area ◽  
Near Surface ◽  
Sea Level Anomalies ◽  
Benguela Upwelling ◽  
Upwelling Index

Based on daily ocean surface temperature values for 1982–2017, near-surface wind for 1988–2017. and sea level anomalies for 1993–2017, obtained from satellite data, the seasonal variability of the hydrodynamic characteristics of the upper water layer in the vicinity of the Benguela upwelling is investigated. It is shown that the thermal upwelling index averaged over the entire area with lower temperature values does not give a correct idea on the seasonal course of the water lifting rate in the upwelling zone due to the significant horizontal advection of waters of upwelling origin. The seasonal variations of the vertical velocity of wind origin in the Benguela upwelling zone are characterized by the presence of two extremes from October to March, which is manifested in the predominance of the semiannual harmonic. At the same time, the thermal upwelling index in the zone of distribution of upwelling waters is subject to seasonal variability with an annual period.

scholarly journals Heat Stress in Indoor Environments of Scandinavian Urban Areas: A Literature Review

2019 ◽  
Vol 16 (4) ◽  
pp. 560 ◽  
Author(s):  
Karin Lundgren Kownacki ◽  
Chuansi Gao ◽  
Kalev Kuklane ◽  
Aneta Wierzbicka
Keyword(s):  
Heat Stress ◽  
Literature Review ◽  
Urban Areas ◽  
Heat Waves ◽  
Well Being ◽  
Heat Index ◽  
Vulnerable Groups ◽  
Heat Radiation ◽  
Indoor Environments ◽  
Promising Alternative

Climate change increases the risks of heat stress, especially in urban areas where urban heat islands can develop. This literature review aims to describe how severe heat can occur and be identified in urban indoor environments, and what actions can be taken on the local scale. There is a connection between the outdoor and the indoor climate in buildings without air conditioning, but the pathways leading to the development of severe heat levels indoors are complex. These depend, for example, on the type of building, window placement, the residential area’s thermal outdoor conditions, and the residents’ influence and behavior. This review shows that only few studies have focused on the thermal environment indoors during heat waves, despite the fact that people commonly spend most of their time indoors and are likely to experience increased heat stress indoors in the future. Among reviewed studies, it was found that the indoor temperature can reach levels 50% higher in °C than the outdoor temperature, which highlights the importance of assessment and remediation of heat indoors. Further, most Heat-Health Warning Systems (HHWS) are based on the outdoor climate only, which can lead to a misleading interpretation of the health effects and associated solutions. In order to identify severe heat, six factors need to be taken into account, including air temperature, heat radiation, humidity, and air movement as well as the physical activity and the clothes worn by the individual. Heat stress can be identified using a heat index that includes these six factors. This paper presents some examples of practical and easy to use heat indices that are relevant for indoor environments as well as models that can be applied in indoor environments at the city level. However, existing indexes are developed for healthy workers and do not account for vulnerable groups, different uses, and daily variations. As a result, this paper highlights the need for the development of a heat index or the adjustment of current thresholds to apply specifically to indoor environments, its different uses, and vulnerable groups. There are several actions that can be taken to reduce heat indoors and thus improve the health and well-being of the population in urban areas. Examples of effective measures to reduce heat stress indoors include the use of shading devices such as blinds and vegetation as well as personal cooling techniques such as the use of fans and cooling vests. Additionally, the integration of innovative Phase Change Materials (PCM) into facades, roofs, floors, and windows can be a promising alternative once no negative health and environmental effects of PCM can be ensured.

scholarly journals Response of Near-Surface Meteorological Conditions to Advection under Impact of the Green Roof

Atmosphere ◽  
2019 ◽  
Vol 10 (12) ◽  
pp. 759
Author(s):  
Haochen Tan ◽  
Pallav Ray ◽  
Mukul Tewari ◽  
James Brownlee ◽  
Ajaya Ravindran
Keyword(s):  
Surface Temperature ◽  
Urban Areas ◽  
Green Roof ◽  
Wrf Model ◽  
Single Layer ◽  
Meteorological Conditions ◽  
Rapid Urbanization ◽  
Near Surface ◽  
Budget Analysis ◽  
The Impact

Due to rapid urbanization, the near-surface meteorological conditions over urban areas are greatly modulated. To capture such modulations, sophisticated urban parameterizations with enhanced hydrological processes have been developed. In this study, we use the single-layer urban canopy model (SLUCM) available within the Weather Research and Forecasting (WRF) model to assess the response of near-surface temperature, wind, and moisture to advection under the impact of the green roof. An ensemble of simulations with different planetary boundary layer (PBL) schemes is conducted in the presence (green roof (GR)) and absence (control (CTL)) of green roof systems. Our results indicate that the near-surface temperature is found to be driven primarily by the surface heat flux with a minor influence from the zonal advection of temperature. The momentum budget analysis shows that both zonal and meridional momentum advection during the evening and early nighttime plays an important role in modulating winds over urban areas. The near-surface humidity remains nearly unchanged in GR compared to CTL, although the physical processes that determine the changes in humidity were different, in particular during the evening when the GR tends to have less moisture advection due to the reduced temperature gradient between the urban areas and the surroundings. Implications of our results are discussed.

Horizontal distribution of temperature in a building-block using a Mobile Cart for Meteorological Observation (MCMO)

2020 ◽  
Author(s):  
Minsoo Kang ◽  
Moon-Soo Park ◽  
Jung-Hoon Chae ◽  
Jae-Sik Min
Keyword(s):  
High Resolution ◽  
Surface Temperature ◽  
Building Block ◽  
Urban Areas ◽  
Heavy Traffic ◽  
Video Camera ◽  
Horizontal Distribution ◽  
Meteorological Observation ◽  
Weather Information ◽  
Experimental Campaign

<p>Horizontal distribution of building block scale meteorological information is important to understand the disastrous weather phenomena occurred at urban areas. Most meteorological models assume the same surface temperature, or an ideal surface temperature to simulate the high-resolution wind field in or above urban boundary-layer. This study aims to establish the basic foundation for producing the high-resolution and high-quality user-specific horizontal meteorological information at an urban building block in the Seoul Metropolitan Area. Therefore, the Mobile Cart for Meteorological Observation (MCMO) was developed and used in a meteorological experimental campaign during heat wave event days.<br>The MCMO includes 3 air temperature sensors, 1 weather transmitter, 1 infrared surface temperature sensor, 1 GPS (global positioning system), and video camera on the mobile cart. The MCMO measures the temperature at 4 altitudes (surface, 0.5m, 1.5m, and 2.5m), latitude, longitude, and surrounding environment condition of measurement site. The observation cycle is 1 second to produce pedestrian-friendly weather information. The meteorological experimental campaign was conducted in Gwanghwamun square in the Seoul, Korea. Gwanghwamun square is complex area which has high-rise building block, wide roads of heavy traffic, and green lung. Observation period was from 1200 LST 5 August 2019 to 2200 LST 6 August 2019 including the hottest day of the year. Through the meteorological experimental campaign, the MCMO shows the detail temperature change over time, location, and altitudes. The temperature was changed as the altitude of the sun changed. When the MCMO was move through the green lung or building block, also the temperature was changed. Temperature changes were the largest at surface temperature and tended to decrease as altitude increased. The MCMO can be used to understand high-resolution weather information and horizontal distribution of temperature in urban area. Additionally, another meteorological experimental campaign will be held in the summer of 2020.</p>

Role of Advection on the Evolution of Near-Surface Temperature and Wind in Urban-Aware Simulations

2020 ◽  
Author(s):  
Pallav Ray ◽  
Haochen Tan ◽  
Mukul Tewari ◽  
James Brownlee ◽  
R. S. Ajayamohan ◽  
...  
Keyword(s):  
Surface Temperature ◽  
Urban Areas ◽  
Single Layer ◽  
Windward Side ◽  
Leeward Side ◽  
Land Use Patterns ◽  
Near Surface ◽  
Horizontal Advection ◽  
The City

AbstractThe role of advection of heat and momentum on the evolution of near-surface temperature and wind is evaluated in urban-aware simulations over Houston under dry conditions on a light-wind day. Two sets of experiments, each consisting of four simulations using different planetary boundary layer (PBL) schemes, were conducted over 48 hours using the default urban scheme (BULK) and the single-layer urban canopy model (SLUCM) available within the Weather Research and Forecasting (WRF) model. We focus on understanding and quantifying the role played by temperature and momentum advection, particularly on the windward and leeward sides of the city. Previous studies have largely ignored any quantitative analysis of impacts from the advection of momentum over an urban area.The horizontal advection of temperature was found to be more important in the BULK because of the larger surface temperature gradient caused by warmer surface temperatures over urban areas than in the SLUCM. An analysis of the momentum budget shows that horizontal advection of zonal and meridional momentum plays a prominent role during the period of peak near-surface winds, and this effect is more pronounced in the windward side of the city. The local tendency in peak winds in the leeward side lags that in the windward side by about 1-2 hours, similar to the lag found in horizontal momentum advection. The sensitivity of the results to different urban and PBL schemes was explored. The results imply that representation and influence of land-use patterns via sophisticated urban parameterizations generates locally driven winds that best resemble observations.

scholarly journals One-Way Coupling of the WRF–QUIC Urban Dispersion Modeling System

2015 ◽  
Vol 54 (10) ◽  
pp. 2119-2139 ◽  
Author(s):  
A. K. Kochanski ◽  
E. R. Pardyjak ◽  
R. Stoll ◽  
A. Gowardhan ◽  
M. J. Brown ◽  
...  
Keyword(s):  
Urban Areas ◽  
Surface Wind ◽  
Wrf Model ◽  
Conclusive Evidence ◽  
Dispersion Modeling ◽  
Industrial Complex ◽  
Urban Dispersion ◽  
Canopy Layer ◽  
Near Surface ◽  
Wind Profiles

AbstractSimulations of local weather and air quality in urban areas must account for processes spanning from meso- to microscales, including turbulence and transport within the urban canopy layer. Here, the authors investigate the performance of the building-resolving Quick Urban Industrial Complex (QUIC) Dispersion Modeling System driven with mean wind profiles from the mesoscale Weather Research and Forecasting (WRF) Model. Dispersion simulations are performed for intensive observation periods 2 and 8 of the Joint Urban 2003 field experiment conducted in Oklahoma City, Oklahoma, using an ensemble of expert-derived wind profiles from observational data as well as profiles derived from WRF runs. The results suggest that WRF can be used successfully as a source of inflow boundary conditions for urban simulations, without the collection and processing of intensive field observations needed to produce expert-derived wind profiles. Detailed statistical analysis of tracer concentration fields suggests that, for the purpose of the urban dispersion, WRF simulations provide wind forcing as good as individual or ensemble expert-derived profiles. Despite problems capturing the strength and the elevation of the Great Plains low-level jet, the WRF-simulated near-surface wind speed and direction were close to observations, thus assuring realistic forcing for urban dispersion estimates. Tests performed with multilayer and bulk urban parameterizations embedded in WRF did not provide any conclusive evidence of the superiority of one scheme over the other, although the dispersion simulations driven by the latter showed slightly better results.

scholarly journals O USO DE SISTEMAS EMBARCADOS PARA IDENTIFICAR O ESTRESSE AO CALOR EM VACAS LEITEIRAS

2017 ◽  
Vol 13 (Especial 2) ◽  
pp. 364-371
Author(s):  
Larissa Christyna de Paula ◽  
João Paulo Barros ◽  
João Victor Firmino Garcia ◽  
Aline Sousa Camargos ◽  
Paulo Eduardo Nogueira ◽  
...  
Keyword(s):  
Heat Stress ◽  
Embedded Systems ◽  
Surface Temperature ◽  
Respiratory Rate ◽  
Animal Feed ◽  
Daily Life ◽  
Well Being ◽  
Tropical Environments ◽  
Feed Control ◽  
Irrigation Control

The embedded systems are present in the daily life of humans, from a simple microwave to a car of the years 2000. In recent years these systems have spread in Brazilian agriculture, such as irrigation control and animal feed control. Heat tolerance and adaptability to tropical environments are important factors to be considered in dairy cattle. The increase in the ambient temperature and, consequently, the heat stress causes a series of effects on the animal's metabolism that alter its behavior and well-being, directly affecting milk production. Surface temperature and respiratory rate are variables that can be used to identify heat stress by animals. Thus, a device, using the Arduino platform, it will be developed to measure the surface temperature and the respiratory rate of the animal, allowing a greater reliability in the information generated.

scholarly journals EVALUATION OF MODIS-DERIVED LST PRODUCTS WITH AIR TEMPERATURE MEASUREMENTS IN CYPRUS

2019 ◽  
Vol 6 (1) ◽  
pp. 1 ◽  
Author(s):  
Andreas Marios Georgiou ◽  
Stefani Theofanis Varnava
Keyword(s):  
Surface Temperature ◽  
Air Temperature ◽  
Land Surface ◽  
Urban Areas ◽  
Remote Sensing Data ◽  
High Standard ◽  
Temperature Reconstruction ◽  
Seasonal Temperature ◽  
Limited Information ◽  
Near Surface

Air temperature data is usually obtained from measurements made in meteorological stations, providing only limited information about spatial patterns over wide areas. The use of remote sensing data can help overcome this problem, particularly in areas with low station density, having the potential to improve the estimation of air surface temperature at both regional and global scales. Land Surface (skin) Temperatures (LST) derived from Moderate Resolution Imaging Spectroradiometer (MODIS) sensor aboard the Terra and Aqua satellite platforms provide spatial estimates of near-surface temperature values. In this study, LST values from MODIS are compared to ground-based near surface air (Tair) measurements obtained from 4 observational stations during 2011 to 2015, covering coastal, mountainous and urban areas over Cyprus. Combining Terra and Aqua LST-8 Day and Night acquisitions into a mean 8-day value, provide a large number of LST observations and a better overall agreement with Tair. Comparison between mean monthly LSTs and mean monthly Tair for all sites and all seasons pooled together yields a very high correlations (r > 0.96) and biases ranging from 1.9oC to 4.1oC. MODIS capture overall variability with a slightly systematic overestimation of seasonal fluctuations of surface temperature. For the evaluation of intra-seasonal temperature variability, MODIS showed biases up to 6.7oC in summer with a tendency to overestimate the variability while in cold seasons, limited biases were presented (0.10oC ± 0.50oC) with a tendency to underestimate the variability. Finally, there was no indication of tendency for MODIS to systematically under- or overestimate the amplitude of the inter-annual variability analysis. The presented high standard deviation can be explained by the influence of surface heterogeneity within MODIS 1km2 grid cells, the presence of undetected clouds and the inherent difference between LST and Tair. Overall, MODIS LST data proved to be a reliable proxy for surface temperature and mostly for studies requiring temperature reconstruction in areas with lack of observational stations.

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