scholarly journals A spatially explicit approach to simulate urban heat mitigation with InVEST (v3.8.0)

2021 ◽  
Vol 14 (6) ◽  
pp. 3521-3537
Author(s):  
Martí Bosch ◽  
Maxence Locatelli ◽  
Perrine Hamel ◽  
Roy P. Remme ◽  
Jérôme Chenal ◽  
...  

Abstract. Mitigating urban heat islands has become an important objective for many cities experiencing heat waves. Despite notable progress, the spatial relationship between land use and/or land cover patterns and the distribution of air temperature remains poorly understood. This article presents a reusable computational workflow to simulate the spatial distribution of air temperature in urban areas from their land use and/or land cover data. The approach employs the InVEST urban cooling model, which estimates the cooling capacity of the urban fabric based on three biophysical mechanisms: tree shade, evapotranspiration and albedo. An automated procedure is proposed to calibrate the parameters of the model to best fit air temperature observations from monitoring stations. In a case study in Lausanne, Switzerland, spatial estimates of air temperature obtained with the calibrated model show that the urban cooling model outperforms spatial regressions based on satellite data. This represents two major advances in urban heat island modeling. First, unlike in black-box approaches, the calibrated parameters of the urban cooling model can be interpreted in terms of the physical mechanisms that they represent; therefore, they can help promote an understanding of how urban heat islands emerge in a particular context. Second, the urban cooling model requires only land use and/or land cover and reference temperature data and can, therefore, be used to evaluate synthetic scenarios such as master plans, urbanization prospects and climate scenarios. The proposed approach provides valuable insights into the emergence of urban heat islands which can serve to inform urban planning and assist the design of heat mitigation policies.

2020 ◽  
Author(s):  
Martí Bosch ◽  
Maxence Locatelli ◽  
Perrine Hamel ◽  
Roy P. Remme ◽  
Jérôme Chenal ◽  
...  

Abstract. Mitigating urban heat islands has become an important objective for many cities experiencing heat waves. Despite notable progress, the spatial relationship between land use/land cover patterns and the distribution of air temperature remains poorly understood. This article presents a reusable computational workflow to simulate the spatial distribution of air temperature in urban areas from their land use/land cover data. The approach employs the InVEST urban cooling model, which estimates the cooling capacity of the urban fabric based on three biophysical mechanisms, i.e., tree shade, evapotranspiration and albedo. An automated procedure is proposed to calibrate the parameters of the model to best fit air temperature observations from monitoring stations. In a case study in Lausanne, Switzerland, spatial estimates of air temperature obtained with the calibrated model show that the urban cooling model outperforms spatial regressions based on satellite data. This represents two major advances in urban heat island modeling. First, unlike in black-box approaches, the calibrated parameters of the urban cooling model can be interpreted in terms of the physical mechanisms that they represent and can therefore help understanding how urban heat islands emerge in a particular context. Second, the urban cooling model requires only land use/land cover and reference temperature data and can therefore be used to evaluate synthetic scenarios such as master plans, urbanization prospects, and climate scenarios. The proposed approach provides valuable insights into the emergence of urban heat islands which can serve to inform urban planning and assist the design of heat mitigation policies.


Author(s):  
Chaobin Yang ◽  
Ranghu Wang ◽  
Shuwen Zhang ◽  
Caoxiang Ji ◽  
Xie Fu

Temporal variation of urban heat island (UHI) intensity is one of the most important themes in UHI studies. However, fine-scale temporal variability of UHI with explicit spatial information is sparse in the literature. Based on the hourly air temperature from 195 meteorological stations during August 2015 in Changchun, China, hourly spatiotemporal patterns of UHI were mapped to explore the temporal variability and the effects of land use on the thermal environment using time series analysis, air temperature profiling, and spatial analysis. The results showed that: (1) high air temperature does not indicate strong UHI intensity. The nighttime UHI intensity (1.51 °C) was much stronger than that in the daytime (0.49 °C). (2) The urban area was the hottest during most of the day except the period from late morning to around 13:00 when there was about a 40% possibility for an “inverse UHI intensity” to appear. Paddy land was the coolest in the daytime, while woodland had the lowest temperature during the nighttime. (3) The rural area had higher warming and cooling rates than the urban area after sunrise and sunset. It appeared that 23 °C was the threshold at which the thermal characteristics of different land use types changed significantly.


Author(s):  
Ehsan Kamali Maskooni ◽  
Hossein Hashemi ◽  
Ronny Berndtsson ◽  
Peyman Daneshkar Arasteh ◽  
Mohammad Kazemi

2019 ◽  
Vol 33 (2) ◽  
pp. 162-172
Author(s):  
Iswari Nur Hidayati ◽  
R Suharyadi

Impervious surface is one of the major land cover types of urban and suburban environment. Conversion of rural landscapes and vegetation area to urban and suburban land use is directly related to the increase of the impervious surface area. The impervious surface expansion is straight-lined with decreasing green spaces in urban areas. Impervious surface is one of indicator for detecting urban heat islands. This study compares various indices for mapping impervious surfaces using Landsat 8 OLI imagery by optimizing the different spectral characteristics of Landsat 8 OLI imagery. The research objectives are (1) to apply various indices for impervious surface mapping and (2) identifies impervious surfaces in urban areas based on multiple indices and provide recommendations and find the best index for mapping impervious surface in urban areas. In addition to utilizing the index, land use supervised classification method, maximum likelihood classification used for extracting built-up, and non-built-up areas. Accuracy assessment of this research used field data collection as primary data for calculating kappa coefficient, producer accuracy, and user accuracy. The study can also be extended to find the land surface temperature and correlate the impervious surface extraction data with urban heat islands.


Geografie ◽  
2019 ◽  
Vol 124 (1) ◽  
pp. 83-101 ◽  
Author(s):  
Ján Feranec ◽  
Monika Kopecká ◽  
Daniel Szatmári ◽  
Juraj Holec ◽  
Pavel Šťastný ◽  
...  

The urban heat island phenomenon occurs in urban areas. It is characterized by increased temperature of both the air and ground surface, compared to the surrounding rural landscape, and is a typical feature of the urban climate. As this phenomenon may affect quality of life in the cities, a variety of scientific studies have been carried out. The article provides a review and evaluation of selected published studies devoted to the issue of the urban heat island, from the point of view of the application of land cover and land use data in the 3-dimensional microscale urban model. Part of the review brings into focus the MUKLIMO model, which computes the atmospheric conditions in urban landscapes and predicts thermal and other climatic characteristics. Evaluated studies confirmed the correlation between the land cover/land use classes and occurrence of the urban heat islands, i.e. a higher percentage of impermeable surfaces within the urban heat island causes more intensive thermal manifestation. The urban heat island effect diminishes when there are less impermeable surfaces and a greater representation of urban greenery in land cover/land use classes.


2021 ◽  
Author(s):  
Sebastian Schlögl ◽  
Nico Bader ◽  
Julien Gérard Anet ◽  
Martin Frey ◽  
Curdin Spirig ◽  
...  

<p>Today, more than half of the world’s population lives in urban areas and the proportion is projected to increase further in the near future. The increased number of heatwaves worldwide caused by the anthropogenic climate change may lead to heat stress and significant economic and ecological damages. Therefore, the growth of urban areas in combination with climate change can increase future mortality rates in cities, given that cities are more vulnerable to heatwaves due to the greater heat storage capacity of artificial surfaces towards higher longwave radiation fluxes.</p><p>To detect urban heat islands and resolve the micro-scale air temperature field in an urban environment, a low-cost air temperature network, including 450 sensors, was installed in the Swiss cities of Zurich and Basel in 2019 and 2020. These air temperature data, complemented with further official measurement stations, force a statistical air temperature downscaling model for urban environments, which is used operationally to calculate hourly micro-scale air temperatures in 10 m horizontal resolution. In addition to air temperature measurements from the low-cost sensor network, the model is further forced by albedo, NDVI, and NDBI values generated from the polar-orbiting satellite Sentinel-2, land surface temperatures estimated from Landsat-8, and high-resolution digital surface and elevation models.</p><p>Urban heat islands (UHI) are processed averaging hourly air temperatures over an entire year for each grid point, and comparing this average to the overall average in rural areas. UHI effects can then be correlated to high-resolution local climate zone maps and other local factors.</p><p>Between 60-80 % of the urban area is modeled with an accuracy below 1 K for an hourly time step indicating that the approach may work well in different cities. However, the outcome may depend on the complexity of the cities. The model error decreases rapidly by increasing the number of spatially distributed sensor data used to train the model, from 0 to 70 sensors, and then plateaus with further increases. An accuracy below 1 K can be expected for more than 50 air temperature measurements within the investigated cities and the surrounding rural areas. </p><p>A strong statistical air temperature model coupled with atmospheric boundary layer models (e.g. PALM-4U, MUKLIMO, FITNAH) will aid to generate highly resolved urban heat island prediction maps that help decision-makers to identify local heat islands easier. This will ensure that financial resources will be invested as efficiently as possible in mitigation actions.</p>


2021 ◽  
Author(s):  
Julien G. Anet ◽  
Sebastian Schlögl ◽  
Curdin Spirig ◽  
Martin P. Frey ◽  
Manuel Renold ◽  
...  

<p>With progressive climate change, weather extremes are very likely to become more frequent. While rural regions may suffer from more intense and longer drought periods, urban spaces are going to be particularly affected by severe heat waves. This urban temperature anomaly, also known as “urban heat island” (UHI), can be traced back to different factors, the most prominent being soil sealing, lower albedo and lack of effective ventilation.</p><p>City planners have started developing mitigation strategies to reduce future forecasted heat stress in urban regions. While some heat reduction strategies are currently intensely scrutinized and applied within pilot projects, the efficiency of latter mitigation actions can be overseen due to the low density of reference in situ air temperature measurements in urban environments. The same problem applies when trying to benchmark modeling studies of UHI as the amount of benchmarking data may be insufficient.</p><p>To overcome this lack of data, over the last two years, a dense air temperature measurement network has been installed in the Swiss cities of Basel and Zurich, counting more than 450 sensors. The low-cost air temperature sensors are installed on street lamps and traffic signs in different local climate zones of the city with an emphasis on street canyons, where air temperatures are expected to be the largest and most of the city’s population lives and works. These low-cost sensors add valuable meteorological information in cities and complement the WMO reference stations.</p><p>Air temperature measurements from the low-cost sensor network were controlled for accuracy, reliability and robustness and homogenized in order to minimize radiation errors, although 40% of the stations were equipped with self-built radiation shields, allowing an efficient passive ventilation of the installed sensors.</p><p>We demonstrate the strength of our network by presenting first results of two exemplary heat waves that occurred in July 2019 and August 2020 and show that a) the radiation-error corrected datasets correlate well with different high-quality reference WMO stations, and b) the existence of urban heat islands in Zurich and Basel can be well confirmed, showing significant air temperature differences of several degrees between rural and urban areas.</p><p>The results demonstrate the advantages of a high-density low-cost air temperature network as a benchmark for future urban heat islands modelling studies.</p>


2018 ◽  
Vol 136 ◽  
pp. 279-292 ◽  
Author(s):  
Janilci Serra Silva ◽  
Richarde Marques da Silva ◽  
Celso Augusto Guimarães Santos

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