Local Weather Types by Thermal Periods: Deepening the Knowledge about Lisbon’s Urban Climate

Urbanized hot spots incorporate a great diversity of microclimates dependent, among other factors, on local meteorological conditions. Until today, detailed analysis of the combination of climatic variables at local scale are very scarce in urban areas. Thus, there is an urgent need to produce a Local Weather Type (LWT) classification that allows to exhaustively distinguish different urban thermal patterns. In this study, hourly data from air temperature, wind speed and direction, accumulated precipitation, cloud cover and specific humidity (2009–2018) were integrated in a cluster analysis (K-means) in order to produce a LWT classification for Lisbon’s urban area. This dataset was divided by daytime and nighttime and thermal periods, which were generated considering the annual cycle of air temperatures. Therefore, eight LWT sets were generated. Results show that N and NW LWT are quite frequent throughout the year, with a moderate speed (daily average of 4–6 m/s). In contrast, the frequency of rainy LWT is considerably lower, especially in summer (below 10%). Moreover, during this season the moisture content of the air masses is higher, particularly at night. This methodology will allow deepening the knowledge about the multiple Urban Heat Island (UHI) patterns in Lisbon.

Download Full-text

Smart tools of urban climate evaluation for smart spatial planning

Moravian Geographical Reports ◽

10.1515/mgr-2015-0017 ◽

2015 ◽

Vol 23 (3) ◽

pp. 47-57 ◽

Cited By ~ 7

Author(s):

Hana Středová ◽

Tomáš Středa ◽

Tomáš Litschmann

Keyword(s):

Urban Heat Island ◽

Spatial Planning ◽

Urban Climate ◽

Quality Data ◽

Heat Island ◽

Corine Land Cover ◽

Air Temperatures ◽

Urban Heat ◽

Gis Methods ◽

The Impact

Abstract Air temperature and humidity conditions were monitored in Hradec Králové, Czech Republic, by a network of meteorological stations. Meteorological sensors were placed across a representative variety of urban and suburban environments. The data collected over the 2011–2014 period are analysed in this paper. The data from reference standard meteorological stations were used for comparison and modelling purposes. Air temperatures at the points of interest were successfully modelled using regression relationships. The spatial expression of point measurements of air temperatures was provided by GIS methods in combination with CORINE land cover layer, and satellite thermal images were used to evaluate the significance of these methods. The use of standard climate information has low priority for urban planners. The impact of the urban heat island on city residents and visitors was evaluated using the HUMIDEX index, as it is more understandable for urban planners than temperature conditions as such. The aim of this paper is the modification, description and presentation of urban climate evaluation methods that are easily useable for spatial planning purposes. These methods are based on comprehensible, easily available but quality data and results. This unified methodology forms a theoretical basis for better urban planning policies to mitigate the urban heat island effects.

Download Full-text

Features of the formation of urban heat islands effects in tropical climates and their impact on the ecology of the city

E3S Web of Conferences ◽

10.1051/e3sconf/20199105005 ◽

2019 ◽

Vol 91 ◽

pp. 05005 ◽

Cited By ~ 2

Author(s):

Minh Tuan Le ◽

Nguyen Anh Quan Tran

Keyword(s):

Urban Areas ◽

Building Materials ◽

Urban Landscape ◽

Urban Climate ◽

Ecological Systems ◽

Urban Heat Islands ◽

Heat Islands ◽

Urban Heat ◽

Tropical Climates ◽

The City

The cumulative heating in some urban areas due to the urban growth and its types of industry, energy and transport, is the effect of urban heat island (UHI). It is recognized as one of the characteristics of the urban climate. The temperature increase caused by the effect (UHI) affects the energy flow in urban ecological systems, creates an unusual urban climate. By studying the effects of climate factors, local building materials to optimize energy efficiency, urban landscape, UHI phenomenon could be significantly moderated.

Download Full-text

Cool Pavement Strategies for Urban Heat Island Mitigation in Suburban Phoenix, Arizona

Sustainability ◽

10.3390/su11164452 ◽

2019 ◽

Vol 11 (16) ◽

pp. 4452 ◽

Cited By ~ 7

Author(s):

Sushobhan Sen ◽

Jeffery Roesler ◽

Benjamin Ruddell ◽

Ariane Middel

Keyword(s):

Urban Heat Island ◽

Air Temperature ◽

Urban Areas ◽

Meteorological Data ◽

Heat Island ◽

Land Use Patterns ◽

Reflective Coating ◽

Air Temperatures ◽

Artificial Surfaces ◽

Urban Heat

Urban areas are characterized by a large proportion of artificial surfaces, such as concrete and asphalt, which absorb and store more heat than natural vegetation, leading to the Urban Heat Island (UHI) effect. Cool pavements, walls, and roofs have been suggested as a solution to mitigate UHI, but their effectiveness depends on local land-use patterns and surrounding urban forms. Meteorological data was collected using a mobile platform in the Power Ranch community of Gilbert, Arizona in the Phoenix Metropolitan Area, a region that experiences harsh summer temperatures. The warmest hour recorded during data collection was 13 August 2015 at 5:00 p.m., with a far-field air temperature of about 42 ∘ C and a low wind speed of 0.45 m/s from East-Southeast (ESE). An uncoupled pavement-urban canyon Computational Fluid Dynamics (CFD) model was developed and validated to study the microclimate of the area. Five scenarios were studied to investigate the effects of different pavements on UHI, replacing all pavements with surfaces of progressively higher albedo: New asphalt concrete, typical concrete, reflective concrete, making only roofs and walls reflective, and finally replacing all artificial surfaces with a reflective coating. While new asphalt surfaces increased the surrounding 2 m air temperatures by up to 0.5 ∘ C, replacing aged asphalt with typical concrete with higher albedo did not significantly decrease it. Reflective concrete pavements decreased air temperature by 0.2–0.4 ∘ C and reflective roofs and walls by 0.4–0.7 ∘ C, while replacing all roofs, walls, and pavements with a reflective coating led to a more significant decrease, of up to 0.8–1.0 ∘ C. Residences downstream of major collector roads experienced a decreased air temperature at the higher end of these ranges. However, large areas of natural surfaces for this community had a significant effect on downstream air temperatures, which limits the UHI mitigation potential of these strategies.

Download Full-text

Observed Spatial Characteristics of Beijing Urban Climate Impacts on Summer Thunderstorms

Journal of Applied Meteorology and Climatology ◽

10.1175/jamc-d-13-0355.1 ◽

2015 ◽

Vol 54 (1) ◽

pp. 94-105 ◽

Cited By ~ 80

Author(s):

Jingjing Dou ◽

Yingchun Wang ◽

Robert Bornstein ◽

Shiguang Miao

Keyword(s):

Urban Area ◽

Urban Climate ◽

Climate Impacts ◽

Interactive Effects ◽

Specific Humidity ◽

Heat Island ◽

Urban Center ◽

Breeze Circulation ◽

Mountain Valley ◽

Urban Heat

AbstractThis study investigates interactive effects from the Beijing urban area on temperature, humidity, wind speed and direction, and precipitation by use of hourly automatic weather station data from June to August 2008–12. Results show the Beijing summer urban heat island (UHI) as a multicenter distribution (corresponding to underlying land-use features), with stronger nighttime than daytime values (averages of 1.7° vs 0.8°C, respectively). Specific humidity was lower in urban Beijing than in surrounding nonurban areas, and this urban dry island is stronger during day than night (maximum of −2.4 vs −1.9 g kg−1). Wind direction is affected by both a mountain–valley-breeze circulation and by urbanization. Morning low-level flows converged into the strong UHI, but afternoon and evening southerly winds were bifurcated by an urban building-barrier-induced divergence. Summer thunderstorms also thus bifurcated and bypassed the urban center because of the building-barrier effect during both daytime and nighttime weak-UHI (<1.25°C) periods. This produced a regional-normalized rainfall (NR) minimum in the urban center and directly downwind of the urban area (of up to −35%), with maximum values along its downwind lateral edges (of >15%). Strong UHIs (>1.25°C), however, induced or enhanced thunderstorm formation (again day and night), which produced an NR maximum in the most urbanized area of up to 75%.

Download Full-text

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.

Download Full-text

Lisbon Urban Heat Island Updated: New Highlights about the Relationships between Thermal Patterns and Wind Regimes

Advances in Meteorology ◽

10.1155/2013/487695 ◽

2013 ◽

Vol 2013 ◽

pp. 1-11 ◽

Cited By ~ 22

Author(s):

António Lopes ◽

Elis Alves ◽

Maria João Alcoforado ◽

Raquel Machete

Keyword(s):

Urban Heat Island ◽

Urban Climate ◽

City Centre ◽

Heat Island ◽

Local Wind ◽

Urban Heat ◽

Thermal Patterns ◽

Wind Regimes ◽

The Relationship ◽

The City

Urban growth implies significant modifications in the urban climate. To understand the influence of the city of Lisbon on the urban boundary layer, a mesoscale meteorological network was installed in 2004. The main goals of the present study are to update the results of the research published in 2007 and to bring more precise information about the relationship between the Urban Heat Island (UHI) and the regional and local wind systems. The highest frequencies of the UHI were found in the city centre (Restauradores). In the green park of Monsanto, the highest frequency occurred between −2 and 0°C. During the summer, the effect of the breezes was observed in Belém, lowering the temperature. The “strong” UHI (intensity >4°C) occurred more often during the summer, with median values of 2°C by night and 1.8°C by day. The highest frequencies of UHI occurred for winds between 2 and 6 m/s and were not associated with atmospheric calm, as pointed out in the literature. Winds above 8 m/s inhibit the occurrence of strong UHI in Lisbon. Summer nighttime strong UHI should be further investigated, due to the heat stress consequences on the population and probable increase of energy consumption.

Download Full-text

Heat and dry islands observed over Jakarta, Indonesia, in 2012

Proceedings of the International Association of Hydrological Sciences ◽

10.5194/piahs-364-140-2014 ◽

2014 ◽

Vol 364 ◽

pp. 140-144

Author(s):

H. Widyasamratri ◽

K. Souma ◽

T. Suetsugi ◽

H. Ishidaira ◽

Y. Ichikawa ◽

...

Keyword(s):

Urban Areas ◽

Thermal Environment ◽

Monsoon Season ◽

Sea Breeze ◽

Early Morning ◽

Specific Humidity ◽

Air Temperatures ◽

Temperature And Humidity ◽

Urbanized Areas ◽

The Difference

Abstract. Recent population increases in urban areas of Asian countries have extended artificial land cover, increased energy consumption, and caused various problems. Higher air temperatures over urban areas (heat islands) degrade residential environments and affect human health. In Jakarta, the largest city in Indonesia and the second largest city in Asia, previous studies have relied on only a few observation points and physically-based models. To study the thermal environment in Jakarta in more detail, we performed seven fixed-point temperature and humidity observations from the dry to the pre-monsoon season (from 16 September to 18 October) in 2012. Over densely urbanized areas, higher temperatures and lower humidity were observed around noon compared with the sparsely urbanized areas. The maximum differences in temperature and specific humidity were found to be around 3 °C and 0.005 kg/kg, respectively. The differences in temperature and humidity became smaller in the afternoon because of the penetration of sea breezes. At night, the differences became larger again because the sea breeze weakened. Then, a difference of around 3°C was observed, except in the early morning. Although the difference in daytime temperature was smaller between densely urbanized areas and suburban areas, similar tendency was also confirmed in the daily time series averaged for sunny days in dry season.

Download Full-text

Modelling spatiotemporal variations of the canopy layer urban heat island in Beijing at the neighbourhood scale

Atmospheric Chemistry and Physics ◽

10.5194/acp-21-13687-2021 ◽

2021 ◽

Vol 21 (17) ◽

pp. 13687-13711

Author(s):

Michael Biggart ◽

Jenny Stocker ◽

Ruth M. Doherty ◽

Oliver Wild ◽

David Carruthers ◽

...

Keyword(s):

Urban Heat Island ◽

Land Surface ◽

Urban Climate ◽

Anthropogenic Heat ◽

Heat Island ◽

Canopy Layer ◽

Near Surface ◽

Air Temperatures ◽

Urban Heat ◽

Neighbourhood Scale

Abstract. Information on the spatiotemporal characteristics of Beijing's urban–rural near-surface air temperature difference, known as the canopy layer urban heat island (UHI), is important for future urban climate management strategies. This paper investigates the variation of near-surface air temperatures within Beijing at a neighbourhood-scale resolution (∼ 100 m) during winter 2016 and summer 2017. We perform simulations using the urban climate component of the ADMS-Urban model with land surface parameters derived from both local climate zone classifications and OpenStreetMap land use information. Through sensitivity simulations, the relative impacts of surface properties and anthropogenic heat emissions on the temporal variation of Beijing's UHI are quantified. Measured UHI intensities between central Beijing (Institute of Atmospheric Physics) and a rural site (Pinggu) during the Atmospheric Pollution and Human Health in a Chinese Megacity (APHH-China) campaigns, peak during the evening at ∼ 4.5 ∘C in both seasons. In winter, the nocturnal UHI is dominated by anthropogenic heat emissions but is underestimated by the model. Higher-resolution anthropogenic heat emissions may capture the effects of local sources (e.g. residential buildings and adjacent major roads). In summer, evening UHI intensities are underestimated, especially during heatwaves. The inability to fully replicate the prolonged release of heat stored in the urban fabric may explain this. Observed negative daytime UHI intensities in summer are more successfully captured when surface moisture levels in central Beijing are increased. However, the spatial correlation between simulated air temperatures and satellite-derived land surface temperatures is stronger with a lower urban moisture scenario. This result suggests that near-surface air temperatures at the urban meteorological site are likely influenced by fine-scale green spaces that are unresolved by the available land cover data and demonstrates the expected differences between surface and air temperatures related to canopy layer advection. This study lays the foundations for future studies of heat-related health risks and UHI mitigation strategies across Beijing and other megacities.

Download Full-text

Climate Integration in Sustainable Urban Planning

10.4018/978-1-7998-8331-9.ch008 ◽

2022 ◽

pp. 152-173

Author(s):

Asia Lachir

Keyword(s):

Urban Planning ◽

Global Climate Change ◽

Urban Areas ◽

Global Climate ◽

Urban Climate ◽

Climate Impacts ◽

Local Climate ◽

Urban Heat ◽

Negative Impacts ◽

Tools And Methods

Currently, cities are home to more than half of the world's population. The increasing urbanization rates create an unprecedented urban sprawl that worsens the urban climate situation. Urban areas modify their local climate and face the consequent urban climate impacts, which are particularly exacerbated by global climate change. This chapter shares scientific knowledge on how cities affect their climate and how urban spatial planning can mitigate the negative impacts of urban climate. Focus is given on the urban heat island, the most documented aspect of urban climate, directly linked to city spatial characteristics and functions. This phenomenon is explained, and tools and methods to assess it and mitigate its intensity are introduced in an attempt to help urban planners and designers to use climatic knowledge in urban planning to build more sustainable and climate-resilient cities.

Download Full-text

Modelling of the Annual Mean Urban Heat Island Pattern for Planning of Representative Urban Climate Station Network

Advances in Meteorology ◽

10.1155/2011/398613 ◽

2011 ◽

Vol 2011 ◽

pp. 1-9 ◽

Cited By ~ 21

Author(s):

János Unger ◽

Stevan Savić ◽

Tamás Gál

Keyword(s):

Urban Heat Island ◽

Urban Areas ◽

Vegetation Index ◽

Urban Climate ◽

Satellite Image ◽

Classification Systems ◽

Heat Island ◽

Intensity Pattern ◽

Urban Heat ◽

Novi Sad

The spatial distribution of the annual mean urban heat island (UHI) intensity pattern was analysed for the medium-sized city Novi Sad, Serbia, located on the low and flat Great Hungarian Plain. The UHI pattern was determined by an empirical modelling method developed by (Balázs et al. 2009). This method was based on datasets from urban areas of Szeged and Debrecen (Hungary). The urban study area in Novi Sad (60 km2) was established as a grid network of 240 cells (0.5 km ×0.5 km). A Landsat satellite image (from June 2006) was used in order to evaluate normalized difference vegetation index and built-up ratio by cells. The pattern of the obtained UHI intensity values show concentric-like shapes when drawn as isotherms, mostly increase from the suburbs towards the inner urban areas. Results of this thermal pattern and determination of one of the local climate classification systems were used for recommending 10 locations for representative stations of an urban climate network in Novi Sad.

Download Full-text