Heatwaves and Summer Urban Heat Islands: A Daily Cycle Approach to Unveil the Urban Thermal Signal Changes in Lisbon, Portugal

Lisbon is a European Mediterranean city, greatly exposed to heatwaves (HW), according to recent trends and climate change prospects. Considering the Atlantic influence, air temperature observations from Lisbon’s mesoscale network are used to investigate the interactions between background weather and the urban thermal signal (UTS) in summer. Days are classified according to the prevailing regional wind direction, and hourly UTS is compared between HW and non-HW conditions. Northern-wind days predominate, revealing greater maximum air temperatures (up to 40 °C) and greater thermal amplitudes (approximately 10 °C), and account for 37 out of 49 HW days; southern-wind days have milder temperatures, and no HWs occur. Results show that the wind direction groups are significantly different. While southern-wind days have minor UTS variations, northern-wind days have a consistent UTS daily cycle: a diurnal urban cooling island (UCI) (often lower than –1.0 °C), a late afternoon peak urban heat island (UHI) (occasionally surpassing 4.0 °C), and a stable nocturnal UHI (1.5 °C median intensity). UHI/UCI intensities are not significantly different between HW and non-HW conditions, although the synoptic influence is noted. Results indicate that, in Lisbon, the UHI intensity does not increase during HW events, although it is significantly affected by wind. As such, local climate change adaptation strategies must be based on scenarios that account for the synergies between potential changes in regional air temperature and wind.

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Automated detection of urban heat islands based on satellite imagery, digital surface models, and a low-cost sensor network

10.5194/egusphere-egu21-14143 ◽

2021 ◽

Author(s):

Sebastian Schlögl ◽

Nico Bader ◽

Julien Gérard Anet ◽

Martin Frey ◽

Curdin Spirig ◽

...

Keyword(s):

Climate Change ◽

Air Temperature ◽

Rural Areas ◽

Urban Areas ◽

Low Cost ◽

Urban Heat Islands ◽

Heat Islands ◽

Micro Scale ◽

Air Temperatures ◽

Urban Heat

Today, more than half of the world&#8217;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.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.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.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.&#160;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.

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Changes in Temperature and Rainfall as a Result of Local Climate Change in Pasadena, California

10.20944/preprints201803.0192.v1 ◽

2018 ◽

Author(s):

David Eugene Kimbrough

Keyword(s):

Climate Change ◽

Air Temperature ◽

Mediterranean Climate ◽

Local Climate ◽

Air Temperatures ◽

Median Volume ◽

Local Climate Change ◽

Local Water ◽

The City ◽

Regional Rainfall

The City of Pasadena is located in southern California; a region which has a Mediterranean climate and where the vast majority of rainfall occurs between October and April with the period between January and March being the most intense. A significant amount of the local water supply comes from regional rainfall, therefore any changes in precipitation patterns in the area has considerable significance. HYPOTHESIS: Local climate change has been occurring in the Pasadena area over the last 100 years resulting in changes in air temperature and rainfall. AIR TEMPERATURES: Between 1886 and 2016 the air temperature in Pasadena, California has increased significantly, from a minimum of 23.8°C in the daytime and 8.1°C at night between 1911 and 1920 to 27.2°C and 13.3°C between 2011 and 2016. The increase in nighttime temperature was uniform throughout the year, however daytime temperatures showed more seasonal variation. There was little change in the daytime temperatures May through July but more change the rest of the year. For example, the median daytime temperature for June between 1911 and 1920 was 27.9°C but was 28.7°C between 2011 and 2016, a difference of 0.8°C. In contrast, for October for the same periods the median daytime temperatures were 25.6°C and 28.9°C, a difference of 3.3°C. RAINFALL: There has been a change in local rainfall pattern over the same period. In comparing rainfall between 1883 – 1949 and 1950 – 2016, there appeared to be less rainfall in the months of October, December, and April while other months seemed to show no change in rainfall. For example, between the two periods mentioned above, the median rainfall in October was 12.4 mm and 8.9 mm respectively while for December they were 68.6 mm and 40.4 mm. There was comparatively a smaller change in the median volume of rainfall in April (18.8 mm vs. 17.5 mm). However, between 1883 and 2016 there were 13 with less than 1 mm of rain, 12 of which occurred after 1961. In the same line of logic, no measureable amount of rain occurred for 23 Octobers, 15 of those occurred after 1961. CONCLUSION: As air temperatures increased over the last 100 years in the Pasadena area, rainfall may have decreased in October, December, and April.

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LOCAL CLIMATE CHANGE AND URBAN HEAT ISLAND MITIGATION TECHNIQUES – THE STATE OF THE ART

Journal of Civil Engineering and Management ◽

10.3846/13923730.2015.1111934 ◽

2015 ◽

Vol 22 (1) ◽

pp. 1-16 ◽

Cited By ~ 148

Author(s):

Hashem Akbari ◽

Constantinos Cartalis ◽

Denia Kolokotsa ◽

Alberto Muscio ◽

Anna Laura Pisello ◽

...

Keyword(s):

Climate Change ◽

Urban Heat Island ◽

State Of The Art ◽

Ambient Air ◽

The State ◽

Heat Island ◽

Local Climate ◽

Local Climate Change ◽

Urban Heat ◽

Mitigation Techniques

Increase of the ambient air temperature in cities caused by the urban heat island phenomenon has a seri- ous impact on the economic and social system of cities. to counterbalance the consequences of the increased urban temperatures important research has been carried out resulting in the development of efficient mitigation technologies. the present paper aims to present the state of the art in terms of local climate change and urban heat island mitigation techniques. In particular, developments in the field on highly reflective materials, cool and green roofs, cool pavements, urban green and of other mitigation technologies are presented in detail, while examples of implemented projects are given.

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Impact of local climate change on drinking water quality in a distribution system

Water Quality Research Journal ◽

10.2166/wqrj.2019.054 ◽

2019 ◽

Vol 54 (3) ◽

pp. 179-192

Author(s):

David Eugene Kimbrough

Keyword(s):

Public Health ◽

Climate Change ◽

Distribution System ◽

Ammonia Oxidizing Bacteria ◽

Local Climate ◽

Air Temperatures ◽

Increased Risk ◽

Local Climate Change ◽

Local Water ◽

Water District

Abstract In this study, air temperatures were collected between 1985 and 2016 and compared with water temperatures in four locations in the distribution system of Pasadena Water and Power (PWP), which received surface water imported into Pasadena between 2001 and 2016 from the Metropolitan Water District. The concentrations of chloramine residual and nitrite concentrations were collected between 2001 and 2016 from these five locations. The results indicate that the median nighttime temperature of the period 2009–2016 was 1.6 °C warmer than the period 1985–2000 and 0.5 °C warmer than the period 2001–2008. The median water temperature in the four distribution system samples increased by 0.8–1.4 °C depending on the location over the study period (p < 0.001). The median chloramine concentration fell significantly (p < 0.001) at three distribution system locations, and the nitrite concentrations increased significantly at all four distribution system locations (p < 0.001). As air temperature in the study area increased, water temperatures also increased resulting in the loss of disinfectant residual and the increase in the activity of ammonia-oxidizing bacteria. As this represented an increased risk to public health, PWP took additional steps to increase disinfectant residuals by adding chlorine and flushing stale water. In localities where climate change is most measurable, local water purveyors must adapt to warmer water to ensure stable concentrations of disinfectants. This article has been made Open Access thanks to the kind support of CAWQ/ACQE (https://www.cawq.ca).

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Urban Heat Island and Local Climate Change

Minimizing Energy Consumption, Energy Poverty and Global and Local Climate Change in the Built Environment: Innovating to Zero ◽

10.1016/b978-0-12-811417-9.00003-9 ◽

2019 ◽

pp. 65-102

Author(s):

Matthaios Santamouris

Keyword(s):

Climate Change ◽

Urban Heat Island ◽

Heat Island ◽

Local Climate ◽

Local Climate Change ◽

Urban Heat

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The Impact of Local Climate Change on Drinking Water Quality in a Distribution System

10.20944/preprints201809.0180.v1 ◽

2018 ◽

Cited By ~ 1

Author(s):

David Eugene Kimbrough

Keyword(s):

Climate Change ◽

Water Quality ◽

Drinking Water ◽

Surface Water ◽

Water Temperature ◽

Distribution System ◽

Local Climate ◽

Air Temperatures ◽

Local Climate Change ◽

The Impact

In this study, air temperatures were collected between 1985 and 2016 and compared to water temperatures in four locations in the distribution system of Pasadena Water & Power (PWP) that received imported surface water between 2001 and 2016 and from the purveyor of imported water.  The concentration of chloramine residual and nitrite concentrations were collected between 2001 and 2016 these five locations.  The results indicate that the median nighttime temperature of the period 2009 - 2016 was 1.6 oC warmer than the period of 1985 - 2000 and 0.5 oC warmer than the period 2001 - 2008.  The median water temperature in the four distribution system samples increased by 0.8 oC to 1.4 oC depending on the location over the study period (p<0.001).  The median chloramine concentration fell significantly (p<0.001) at three distribution system locations and the nitrite concentrations increased significantly at all four distribution system locations.

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Impact of Build-Up Areas and Housing Estate Vegetation on Diversity of the Local Climate in Warsaw

Miscellanea Geographica ◽

10.2478/mgrsd-2010-0012 ◽

2010 ◽

Vol 14 (1) ◽

pp. 121-134

Author(s):

Maria Stopa-Boryczka ◽

Jerzy Boryczka ◽

Jolanta Wawer

Keyword(s):

Air Temperature ◽

Central City ◽

Spatial Diversity ◽

Urban Heat Islands ◽

Local Climate ◽

Heat Islands ◽

Urban Heat ◽

The Impact ◽

The City ◽

Housing Estates

Abstract The more important research results on the impact of building development and vegetation on the local climate, conducted in Warsaw in the years 1959–2009 by the Department of Climatology, are presented. Majority of the issues associated with determining the deformation of air temperature limits (urban heat islands), humidity and wind vector areas, because of buildings in housing estates, located in various parts of the city, were resolved in master’s thesis. Areas with high building density are characterized by slow cooling and warming pace, especially during the summer months. Spatial changes in the urban heat islands in the east-west direction well describe the latitudinal profiles (W-E) of air temperature differences (∆T ≥ 0) between the city and its urban fringe. The urban heat island ∆T does not appears till 5PM, initially in the Central City District. Spatial diversity of effective temperature and catathermal cooling allowed to mark off in housing estates („Stawki”, „Służew nad Dolinką”, „Sady Żoliborskie”) places with perceptible conditions, e.g. heat, warmth, comfort, cold.

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Urban Heat Island in Mediterranean Coastal Cities: The Case of Bari (Italy)

Climate ◽

10.3390/cli8060079 ◽

2020 ◽

Vol 8 (6) ◽

pp. 79 ◽

Cited By ~ 2

Author(s):

Alessandra Martinelli ◽

Dionysia-Denia Kolokotsa ◽

Francesco Fiorito

Keyword(s):

Urban Heat Island ◽

Air Temperature ◽

National Standard ◽

Heat Island ◽

Night Time ◽

Local Climate ◽

Sea Breezes ◽

Pollution Levels ◽

Air Temperatures ◽

Urban Heat

In being aware that some factors (i.e. increasing pollution levels, Urban Heat Island (UHI), extreme climate events) threaten the quality of life in cities, this paper intends to study the Atmospheric UHI phenomenon in Bari, a Mediterranean coastal city in Southern Italy. An experimental investigation at the micro-scale was conducted to study and quantify the UHI effect by considering several spots in the city to understand how the urban and physical characteristics of these areas modify air temperatures and lead to different UHI configurations. Air temperature data provided by fixed weather stations were first compared to assess the UHI distribution and its daily, monthly, seasonal and annual intensity in five years (from 2014 to 2018) to draw local climate information, and then compared with the relevant national standard. The study has shown that urban characteristics are crucial to the way the UHI phenomenon manifests itself. UHI reaches its maximum intensity in summer and during night-time. The areas with higher density (station 2—Local Climate Zone (LCZ) 2) record high values of UHI intensity both during daytime (4.0 °C) and night-time (4.2 °C). Areas with lower density (station 3—LCZ 5) show high values of UHI during daytime (up to 4.8 °C) and lower values of UHI intensity during night-time (up to 2.8 °C). It has also been confirmed that sea breezes—particularly noticeable in the coastal area—can mitigate temperatures and change the configuration of the UHI. Finally, by analysing the frequency distribution of current and future weather scenarios, up to additional 4 °C of increase of urban air temperature is expected, further increasing the current treats to urban liveability.

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