Nitrogen-oxide layer over the urban heat island in Okayama City

Sahashi, Ken; Hieda, Takashi; Yamashita, Eiji

doi:10.1016/1352-2310(95)00141-7

Cited by 13 publications

(7 citation statements)

References 3 publications

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“…What we did observe, and frequently photograph at dawn, were elevated polluted layers over the Kathmandu Valley. Nighttime elevated layers of pollutants have been measured at the top of skyscrapers in Phoenix [ Berkowitz et al , 2006] and Milan [ Rubino et al , 1998], and by sampling air with a customized tethersonde in Japan [ Sahashi et al , 1996]. Elevated layers of aerosols have also been observed over the Rhine Valley [ Frioud et al , 2003].…”

Section: Discussionmentioning

confidence: 99%

Diurnal cycle of air pollution in the Kathmandu Valley, Nepal: Observations

Panday¹,

Prinn²

2009

J. Geophys. Res.

103

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[1] During the dry season of [2004][2005] we carried out field measurements of air pollution and meteorology in the Kathmandu Valley, Nepal, a bowl-shaped urban basin in the Himalayan foothills of Nepal. We measured the trace gases carbon monoxide (CO) and ozone (O 3 ) and particulates (PM 10 ), as well as meteorological variables. In our field observations we noted a very regular pattern of morning and evening peaks in CO and PM 10 occurring daily in the valley bottom, interspersed with low values in the afternoons and at night. This pattern occurred even on days with unusual timing of emissions and was influenced by the timing of ventilation from the valley. Meteorological variables showed great day-to-day similarity, with a strong westerly wind blowing through the valley from late morning until dusk. We found that the air mass on nearby mountaintops was disconnected from pollution within the valley during the night, but received significant pollution during the morning, when up-slope flows began. At a pass on the western edge of the valley we found a diurnal switch in wind direction, with an inflow from late morning until late evening, and an outflow during the rest of the time. We found that part of the morning peak in pollution was caused by recirculation of pollutants emitted the night before, which spend the night in elevated layers over the valley.

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Section: Discussionmentioning

confidence: 99%

Diurnal cycle of air pollution in the Kathmandu Valley, Nepal: Observations

Panday¹,

Prinn²

2009

J. Geophys. Res.

103

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“…The pollution created by emissions from power generation increases absorption of radiation in the boundary layer (Oke, 1982) and contributes to the creation of inversion layers. Inversion layers prevent rising air from cooling at the normal rate and slow the dispersion of pollutants produced in urban areas (Sahashi et al, 2004).…”

Section: Urban Heat Island As a Hazardmentioning

confidence: 99%

Characterizing the urban heat island in current and future climates in New Jersey

Rosenzweig

Solecki

Parshall

et al. 2005

Environmental Hazards

113

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Climate change caused by increased anthropogenic emissions of carbon dioxide (CO 2 ) and other greenhouse gases is a long-term climate hazard with the potential to alter the intensity, temporal pattern, and spatial extent of the urban heat island (UHI) in metropolitan regions. Particular meteorological conditions-including high temperature, low cloud cover, and low average wind speed-tend to intensify the heat island effect. Analyses of existing archived climate data for the vicinities of Newark and Camden, New Jersey indicate urban to suburban/rural temperature differences over the previous half-century. Surface temperatures derived from a Landsat thermal image for each site were also analyzed for spatial patterns of heat islands. Potential interactions between the UHI effect and projected changes in temperature, wind speed, and cloud cover are then examined under a range of climate change scenarios, encompassing different greenhouse gas emissions trajectories. The scenarios include those utilized in the Metropolitan East Coast Regional Assessment of Climate Variability and Change and the A2 and B2 scenarios of the Intergovernmental Panel on Climate Change (IPCC) Special Report on Emissions Scenarios (SRES).The UHI effect was detected in Newark and Camden in both satellite surface-temperature and meteorological station airtemperature records. The average difference in urban-nonurban minimum temperatures was 3.0 1C for the Newark area and 1.5 1C for Camden. Extrapolation of current trends and the selected global climate models (GCMs) project that temperatures in the case study areas will continue to warm in the current century, as they have over the past half-century. An initial analysis of global climate scenarios shows that wind speed may decline, and that cloud cover may increase in the coming decades. These generally small countervailing tendencies suggest that urban-nonurban temperature differences may be maintained under climate change.Overall warmer conditions throughout the year may extend the spatial and temporal dimensions of the urban-suburban heat complex. The incidence of heat-related morbidity and mortality are likely to increase with interactions between the increased frequency and duration of heat waves and the UHI effect. Camden and Newark will likely be subjected to higher temperatures, and areas experiencing UHI-like conditions and temperature extremes will expand. Thus, urban heat island-related hazard potential is likely to increase in a warmer climate. Published by Elsevier Ltd.

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“…The method used involved a comparison of the temperature data series obtained from weather stations located at urban and rural points, as has been used in a number of other studies (García 1996, Sahashi & Hieda 1996, Figuerola & Mazzeo 1998, Unger et al 2001, Kim & Baik 2002, Alonso et al 2003. The first step in a study of this type is to select reliable weather stations in zones with representative characteristics; e.g.…”

Section: Methodsmentioning

confidence: 99%

The urban heat island in Salamanca (Spain) and its relationship to meteorological parameters

Alonso¹,

Fidalgo²,

Labajo³

2007

Clim. Res.

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An urban heat island (UHI) was found to exist in Salamanca, Spain -a medium-sized European city that has a continental climate and relatively little industrial pollution. We demonstrate that urban heating can occur in cities with these characteristics, giving rise to a microclimate that may alter the biological rhythm of the zone e.g. under these conditions, spring arrives earlier in the urban zone then in the rural zone. The study was carried out using data from 2 recording stations (one in and the other outside the city) for the years 1996-1998. The existence of a nocturnal UHI was observed, with a highest annual mean value of 3.6°C and a lowest annual mean value (cool island) of -0.9°C. The most intense nocturnal UHI was seen in autumn, while the strongest sinks occurred in spring and summer. As in other types of city with different characteristics, the UHI was seen to vary according to the atmospheric situation. The meteorological variables that most affected the UHI were found to be: (1) wind, which at speeds of >~6 m s -1 prevented the development of UHIs; (2) cloudiness, which altered the flux of incident solar radiation (the intensity of the nocturnal UHI was greater with high clouds); and (3) atmospheric pressure, which characterised the days of atmospheric stability or instability, leading to variations in the intensity of the UHI. KEY WORDS: Urban heat island · Local climate · UHI sink · Wind · Cloudiness · Synoptic conditions · SalamancaResale or republication not permitted without written consent of the publisher Clim Res 34: 39-46, 2007 mainly derives from the absorption of the solar radiation that reaches the ground and buildings from dawn until the sun reaches its maximum height. When the sun's radiation reaches buildings, the ensuing successive reflections lead to more energy being confined within their sphere of influence than in rural settings (Wilby 2003). Materials forming the surface of cities usually have a greater heat absorption capacity than natural soils, so that in urban zones the energy is stored for longer than in rural zones (Hoyano et al. 1999). In turn, long-wave radiation coming from the ground is less able to cross the pollution layer, thus further contributing to heating the urban zone.Meteorological factors also alter the energy balance existing between the ground and the top of the atmosphere. For example, wind causes turbulence that homogenises the air temperature (Jáuregui 1988, Morris & Simmonds 2000, and clouds absorb or reflect solar radiation, thereby varying the amount of radiation that reaches the ground (Labajo et al. 1988).Following the results of a pioneer study by Sundborg (1950) into the temperature conditions of an urban zone; and those of Morris & Simmons (2000) and Morris et al. (2001) who related the intensity of an UHI to meteorological factors, we were prompted to determine the existence of a UHI in a mediumsized European city and to analyse the temporal evolution of its intensity and its relationship to meteorological variables. To conduct ...

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Nitrogen-oxide layer over the urban heat island in Okayama City

Cited by 13 publications

References 3 publications

Diurnal cycle of air pollution in the Kathmandu Valley, Nepal: Observations

Diurnal cycle of air pollution in the Kathmandu Valley, Nepal: Observations

Characterizing the urban heat island in current and future climates in New Jersey

The urban heat island in Salamanca (Spain) and its relationship to meteorological parameters

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