Global Megacities Research Articles

Urban Heat Islands as Viewed by Microwave Radiometers and Thermal Time Indices

Urban heat islands (UHIs) have been long studied using both ground-based observations of air temperature and remotely sensed thermal infrared (TIR) data. While ground-based observations lack spatial detail even in the occasional “dense” urban network, skin temperature retrievals using TIR data have lower temporal coverage due to revisit frequency, limited swath width, and cloud cover. Algorithms have recently been developed to retrieve near-surface air temperatures using microwave radiometer data, which enables characterization of UHIs in metropolitan areas, major conurbations, and global megacities at regional to continental scales using temporally denser time series than those that have been available from TIR sensors. Here we examine how UHIs appear across the entire Western Hemisphere using surface air temperatures derived from the Advanced Microwave Scanning Radiometers (AMSRs), AMSR-E onboard the National Aeronautics and Space Administration’s (NASA’s) Aqua and AMSR2 onboard the Japan Aerospace eXploration Agency’s Global Change Observation Mission-Water1 (JAXA’s GCOM-W1) satellites. We compare these data with station observations from the Global Historical Climate Network (GHCN) for 27 major cities across North America (in 83 urban-rural groupings) to demonstrate the capability of microwave data in a UHI study. Two measures of thermal time, accumulated diurnal and nocturnal degree-days, are calculated from the remotely sensed surface air temperature time series to characterize the urban-rural thermal differences over multiple growing seasons. Daytime urban thermal accumulations from the microwave data were sometimes lower than in adjacent rural areas. In contrast, station observations showed consistently higher day and night thermal accumulations in cities. UHIs are more pronounced at night, with 55% (AMSRs) and 93% (GHCN) of urban-rural groupings showing higher accumulated nocturnal degree-days in cities. While urban-rural thermal gradients may vary according to different datasets or locations, day-night differences in thermal time metrics were consistently lower (>90% of urban-rural groupings) in urban areas than in rural areas for both datasets. We propose that the normalized difference accumulated thermal time index (NDATTI) is a more robust metric for comparative UHI studies than simple temperature differences because it can be calculated from either station or remotely sensed data and it attenuates latitudinal effects.

Design Research Direction for Smart Mobility in Mega Cities

Background This article is about the various smart mobility strategies that are initiated by major global mega-cities so that they may develop into future metropolises. Despite the high quality of infrastructure and transportation policies that Seoul has already put into place, the citizens of Seoul still have encounter some problems when using public transportation. One of the most practical solutions that can be suggested is applying the smart mobility system in appropriate ways. The main purpose of this article is to define the role of design research in developing a smart mobility system for rapidly changing future cities. Methods A literature review and a case study were conducted for this study. By using these methods, a variety of specific instances were categorized and analyzed in order to define the current state of smart mobility and its prospects. Through these processes, this article arguedfor the role and aim of design research in developing smart mobility. Results The crucial components of smart mobility were identified as “intelligent” “ecofriendly” and “personalized.” Based on this analysis, this article presented the prospects of design research. Conclusions In this research, the possible role and expected contribution of design research in developing a smart mobility system for people in near future cities with improved quality of life were argued and identified.

Viewing Global Megacities Through MODIS $4\hbox{-}\upmu \text{m}$ Radiance: Effects of Time of Year, Latitude, Land Cover, and View Zenith Angle

Cities are often obscured by haze and smoke when viewed in the visible and near infrared, but the longer wavelengths of the middle infrared can penetrate fine aerosol layers. We characterized variation in $4\hbox{-}\upmu \text{m}$ radiance in and nearby eight global megacities using MODIS band 23 calibrated radiance. The seasonality of middle infrared (MIR) radiance was more pronounced at higher latitudes. Precipitation attenuated MIR radiance. The seasonality of MIR radiance from exposed soils was very similar to urban surfaces, complicating discrimination. The variety of urban surfaces across the megacities also affected the seasonality of MIR radiance. Additional data and MIR radiance with higher spatial resolution could improve and refine/detail information about MIR radiance behavior for further investigation.

Adaptation responses to climate change differ between global megacities

Research now shows that there is a large discrepancy between how much megacities spend on adaptation. Those in developing countries spend considerably less per person than their developed counterparts, despite being the most vulnerable. Urban areas are increasingly at risk from climate change, with negative impacts predicted for human health, the economy and ecosystems1,2. These risks require responses from cities to improve their resilience. Policymakers need to understand current adaptation spend to plan comprehensively and effectively. Through the measurement of spend in the newly defined ‘adaptation economy’, we analyse current climate change adaptation efforts in ten megacities. In all cases, the adaptation economy remains a small part of the overall economy, representing a maximum of 0.33% of a city’s gross domestic product (here referred to as GDPc). Differences in total spend are significant between cities in developed, emerging and developing countries, ranging from £15 million to £1,600 million. Comparing key subsectors, we demonstrate the differences in adaptation profiles. Developing cities have higher proportional spend on health and agriculture, whereas developed cities have higher spend on energy and water. Spend per capita and percentage of GDPc comparisons more clearly show disparities between cities. Developing country cities spend half the proportion of GDPc and significantly less per capita, suggesting that adaptation spend is driven by wealth rather than the number of vulnerable people. This indicates that current adaptation activities are insufficient in major population centres in developing and emerging economies.

Status and characteristics of ambient PM2.5 pollution in global megacities

Ambient PM2.5 pollution is a substantial threat to public health in global megacities. This paper reviews the PM2.5 pollution of 45 global megacities in 2013, based on mass concentration from official monitoring networks and composition data reported in the literature. The results showed that the five most polluted megacities were Delhi, Cairo, Xi'an, Tianjin and Chengdu, all of which had an annual average concentration of PM2.5 greater than 89μg/m3. The five cleanest megacities were Miami, Toronto, New York, Madrid and Philadelphia, the annual averages of which were less than 10μg/m3. Spatial distribution indicated that the highly polluted megacities are concentrated in east-central China and the Indo-Gangetic Plain. Organic matter and SNA (sum of sulfate, nitrate and ammonium) contributed 30% and 36%, respectively, of the average PM2.5 mass for all megacities. Notable seasonal variation of PM2.5 polluted days was observed, especially for the polluted megacities of China and India, resulting in frequent heavy pollution episodes occurring during more polluted seasons such as winter. Marked differences in PM2.5 pollution between developing and developed megacities require more effort on local emissions reduction as well as global cooperation to address the PM2.5 pollution of those megacities mainly in Asia.

A ‘sustainability window’ of urban form

With global environmental change and the rise of global megacities, environmental and social externalities of urban systems, and especially of urban form, become increasingly prevalent. The question of optimal urban form has been debated and investigated by different disciplines in numerous contexts, including those of transport costs, land consumption and congestion. Here we elucidate theoretically how urban form and the urban transport system systematically modifies sustainability concerns, such as greenhouse gas emissions, local air pollution and congestion. We illustrate our analytical considerations with empirical analysis. Denser urban form would almost unambiguously mitigate climate change, but it would also lead to undesired effects, such as a higher proportion of urban dwellers affected by air pollution. Our study presents a ‘sustainability window’ by highlighting trade-offs between these sustainability concerns as a function of urban form. Only a combination of transportation policies, infrastructure investments and progressive public finance enables the development of cities that perform well in several sustainability dimensions. We estimate that a residential population density between 50 and 150 persons/ha and a modal share of environmental modes above at least 50% corresponds to the sustainability window of urban form. The parameters of the sustainability window of urban form is subject to policy changes and technological progress.

It's Not Where You're From, It's Where You're At

Climate change and sustainability expert Mark Watts imagines what it might be like to look back from the year 2050. What might the view be from his position as Executive Director of the C40 Cities Climate Leadership Group? What crucial political moves and actions might be required from global megacities if they are to address climate change and make the ultimate shift to a low‐carbon world?

Urban density mapping of global megacities from polarimetric SAR images

We propose an algorithm for estimating urban density from polarimetric synthetic aperture radar (SAR) images, and compare the urban density patterns of global megacities. SAR images are uniquely able to detect structural information of objects, but they are very sensitive to orientation angle. This issue has been an obstacle to applying SAR images to urban areas. Kajimoto and Susaki (2013b) proposed an algorithm to handle this issue. The effects of polarization orientation angle (POA) are removed by rotating the coherency matrix and then calculating the mean and standard deviation of scattering power by POA domain. The algorithm can estimate urban density from a single fully polarimetric SAR image but has the drawback that the generated urban density maps of multiple images are not comparable with each other because the algorithm generates a relative urban density valid only within the analyzed image. We therefore extend the method by calculating POA-domain statistics from all images of interest so that the generated maps can be compared. Estimated urban densities are assessed on two types of urban density generated from GIS data, building-to-land ratio and floor-area ratio. We demonstrate that the extended method can estimate urban density with reasonable accuracy. Finally, we generate two scattergrams of indices derived from urban density maps of global megacities. An analysis using the scattergrams indicates insightful information about the patterns of urban development. We conclude that the proposed algorithm and the analysis using the obtained results are beneficial to understanding the conditions in megacities.

Review: Drawing the Future: Chicago Architecture on the International Stage, 1900–1925

Drawing the Future: Chicago Architecture on the International Stage, 1900–1925 Mary & Leigh Block Museum of Art, Northwestern University, Evanston, Illinois 19 April 2013–6 August 2013 At a moment when architecture, urban design, and urban planning are focused on the phenomenon of global megacities, which are made possible by global finance and networks and made necessary by rapid urbanization, Drawing the Future: Chicago Architecture on the International Stage, 1900–1925 offered an important historical perspective (Figure 1). An illustrated exegesis on the ways in which urban design and planning principles, formal architectural devices, and building technologies traveled between Chicago and Europe via Canberra, Australia, the exhibition positioned the winning entry to that city’s Federal Capital Design Competition, by Chicago architects Marion Mahony and Walter Burley Griffin in 1912, as the hinge on which these exchanges turned immediately before and after World War I. Figure 1 Installation of Drawing the Future: Chicago Architecture on the International Stage, 1900–1925 (Mary & Leigh Block Museum of Art, Northwestern University). Curated by David Van Zanten, with Ashley Elizabeth Dunn and Leslie Coburn, Drawing the Future was a sequel to the Block Museum’s Marion Mahony Griffin: Drawing the Form of Nature exhibition in 2005. Both exhibitions drew heavily upon the rich legacy of drawings gifted to Northwestern University by Marion Mahony Griffin. In addition to material from the Art Institute of Chicago and other collections, Drawing the Future also borrowed extensive materials from the Charles Deering McCormick Library of Special Collections at Northwestern. The exhibitions and their accompanying catalogues demonstrated the depth of materials and scholarship at Northwestern relating to Chicago’s progressive architectural movement …

Analytical approach to estimating aerosol extinction and visibility from satellite observations

This study investigates the application of satellite data to the evaluation of aerosol extinction and visibility, for a better understanding of the spatio-temporal variation of local air quality in urban areas. A new analytical model based on aerosol microphysics and non-linear exponential fitting was applied to the analysis of aerosol extinction using aerosol optical thickness (AOT, τa) data retrieved from the MODerate-resolution Imaging Spectroradiometer (MODIS), over one of the largest global megacities: Seoul, Korea. The relationship between the MODIS τa and ground-based aerosol measurements of particulate matter mass concentration, extinction, and surface visibility was assessed over Seoul, Korea, during eight intensive observation periods in 2007–2009. The results clearly demonstrate that satellite-derived τa is a good surrogate for monitoring aerosol extinction and visibility over this study area. In particular, it is found that MODIS-estimated visibility values have a closer relation to the observed values than traditionally assumed Koschemeider's relation. The analytical results shown in this study can provide a better understanding of aerosol extinction and visibility in megacity, as well as for routine visibility monitoring.

Correlation of ambient pollution levels and heavily-trafficked roadway proximity on the prevalence of smear-positive tuberculosis

Varying levels of evidence exist for the contribution of indoor air pollution and environmental tobacco smoke as a risk factor for tuberculosis (TB). Despite a similar mechanism of action, the influence of outdoor air pollution exposure as an independent contributor to TB disease has yet to be explored. This area of inquiry is of increasing importance given the level of pollution in the rising economies of many TB-endemic nations. Los Angeles' unique physical environs and traffic patterns mirror other global megacities with a greater burden of TB therefore allowing for preliminary correlative studies. This preliminary study hypothesizes that individuals who reside proximal to elevated pollutant exposures are likely to have a greater burden of disease--as evidenced by sputum smear-positive TB. Retrospective medical records review. Medical records of non-homeless individuals (n = 196) diagnosed with culture positive TB at Los Angeles County and University of Southern California Medical Center Hospital were analyzed from January 2007 to December 2008. The study population was grouped according to acid-fast bacilli (AFB) smear-positive (n = 111) and smear-negative (n = 85) status. Air pollutant exposure was captured using measurements of ozone (O3) and particulate matter with an aerodynamic diameter of less than 2.5 (PM2.5). Individual assignment to O3 and PM2.5 exposures were based on residential proximity to the nearest US Environmental Protection Agency's monitoring station. Proximity of home residences to traffic-related pollutants occurred by measurement of distance to the nearest freeway and major non-freeway road. Single factorial models yielded a significant correlation of smear-positive status and residential exposure to PM2.5. Residential distance to freeways and major arterial roads did not yield an association. This is the first report linking ambient pollution exposure as a risk factor for TB. PM2.5 may have the potential to impact TB lung pathology as evidenced by the linkage of fine particulate matter levels and smear-positive TB.

Water Wars in Mumbai

This essay excavates the complex politics of water in contemporary Mumbai. In the context of a burgeoning water crisis in the city, it explores in detail how the city’s social and political elites demonize the efforts of inhabitants of Mumbai’s slums to hydrate their communities. Such demonization is paralleled by legal crackdowns and the deliberate destruction of improvised water infrastructure. The essay uses the Mumbai case study to reveal the costs of marginalizing the majority urban poor in global megacities: in public health, death rates, and communicable and waterborne diseases; in the burden of waiting for and carrying water (especially for women and children); in the burden of incurring high water expenses; in water extortion against the poor by predatory rackets; and in the problems of systematic dehydration.

Manila’s urbanism and Philippine visual cultures

Cities are sites and crucibles of creativity and destruction. How we order and imagine ourselves is revealed by the visible forms of our built environments. Cities are the ultimate material expression of human desire and design. They are also forces of energy and fields of tension that structure our everyday imaginings and activities. How we move, think, act, interact, create and maintain our lives is bounded by what cities provide us. How we make common-wealth and differentiate ourselves from others also determines what cities are and might be for us. This issue explores the urbanism that is Manila in all its vital contradictions. A mega-urban region of over 20 million souls, it is both dynamic and discordant, creative and destructive. Like most global mega-cities, Manila is dangerous to its own citizens – polluted, dense, violent, and poor, with inadequate and badly maintained infrastructure and public utilities, but it is also a fecund incubator of cultural ideas, projects and networks. This issue explore both sides of this Janus-faced city – its urbanism and its visual cultures. Two common threads run through the articles in this issue: first is the dialectic of private and public, and second is the cultural traffic that informs place-making across time through the constant movement of peoples around the world-system and in the ever-pragmatic syncretic and local appropriations of cultural ideas, traditions and artefacts into new configurations, stories and views. As these contributions take issue with visual culture, we have given pride of place to photos, images and artworks themselves. For, as our colleague, Eduardo de la Fuente, has observed in this journal’s pages (2010), the sociology of art is more than a socio-aesthetics. It is also a chronicle of the experience, performance and movement of aesthetic objects lodged in and across institutions, traditions and collective consciousness.

The Urban Precariat, Neoliberalization, and the Soft Power of Humanitarian Design

This essay examines the humanitarian design movement's efforts to address the crushing need, social precarity, and ecological frailty that define global megacities. The aims and character of the humanitarian design movement have been shaped by both the ethical demands of antiglobalization struggles and the rise of nongovernmental organizations as a principal means of social service-delivery in the Global South. The emergent humanitarian design movement offers a compelling critique of the failure of mainstream architectural and industrial design practices to address profound human suffering. Champions of humanitarian design, however, offer a technological fix (e.g., life straws, paper log houses, and hippo rollers) for problems rooted in imperial histories and neoliberal restructuring. In failing to address the dynamics of structural underdevelopment, do-good design performs the grassroots ideological work of neoliberalism by promoting market values and autoregulation. Within the humanitarian-corporate complexes, the global poor are construed as objects of elite benevolence and non-profit largesse, rather than as historical subjects possessing their own unique worldviews, interests, and notions of progress. This essay concludes by briefl y sketching an alternative approach to self-determination for the poor where technological development is grounded in egalitarian cultures of anticapitalist social movements.

Cities and sustainable urban development: challenges, conflicts, and cohesion

Considering the rapid growth of world population, especially the global urban population, it comes as no surprise that many conventional means of delivering the planning, development, and management of cities are unlikely to remain viable over the long term. Although this realization has only recently been acknowledged, the shift towards the adoption of what can best be described as a sustainable development perspective on urban form and function has profound implications for both what is done in urban areas and how actions are delivered. With regard to the future of urban areas—which range in size from small remote rural settlements that are home to a few families, to global megacities whose populations run in millions—there are many implications, and consequently, there is an urgent need to rethink both the approaches used to construct and implement urban policy and the methods utilized to ensure the full and active engagement of all members of the urban community in securing the long-term future of cities. An important guiding concept, which can be used to provide a high level of coherence with regard to both the general approach and the particular mechanisms adopted to ensure effective implementation and engagement, is encapsulated by the term ‘human urban environment’ (Roberts, Ravetz, and George 2009). This overarching concept is, in turn, derived from Artur Glikson’s notion of the ‘urban environment’, which he memorably described as ‘the space which surrounds human movement, work, habitation, rest, and interaction’ (Glikson 1971). What Glikson was offering was a model that transcends the normal definition of the environment with its primary concern for natural resources and ecosystems. This expresses the desirability of a wider perspective, which views the transformation of biological and physical factors in space, and considers the urban outcomes and consequences of these various transformational Introduction The context for sustainable urban development The elaboration and implementation of policy Future development pathways References

Global comparison of VOC and CO observations in urban areas

Speciated volatile organic compound (VOC) and carbon monoxide (CO) measurements from the Marylebone Road site in central London from 1998 through 2008 are presented. Long-term trends show statistically significant decreases for all the VOCs considered, ranging from −3% to −26% per year. Carbon monoxide decreased by −12% per year over the measurement period. The VOC trends observed at the kerbside site in London showed greater rates of decline relative to trends from monitoring sites in rural England (Harwell) and a remote high-altitude site (Hohenpeissenberg), which showed decreases for individual VOCs from −2% to −13% per year. Over the same 1998 through 2008 period VOC to CO ratios for London remained steady, an indication that emissions reduction measures affected the measured compounds equally. Relative trends comparing VOC to CO ratios between Marylebone Road and Hohenpeissenberg showed greater similarities than absolute trends, indicating that emissions reductions measures in urban areas are reflected by regional background locations. A comparison of VOC mixing ratios and VOC to CO ratios was undertaken for London and other global cities. Carbon monoxide and VOCs (alkanes greater than C 5 , alkenes, and aromatics) were found to be strongly correlated (>0.8) in the Annex I countries, whereas only ethene and ethyne were strongly correlated with CO in the non-Annex I countries. The correlation results indicate significant emissions from traffic-related sources in Annex I countries, and a much larger influence of other sources, such as industry and LPG-related sources in non-Annex I countries. Yearly benzene to ethyne ratios for London from 2000 to 2008 ranged from 0.17 to 0.29 and compared well with previous results from US cities and three global megacities.

Women of Fes

The city of Fes, the once “bourgeois citadel” (J. Berque’s words) of Moroccoand once the world’s most populous city (1170-80), has in modernity beenunhappily bypassed for coastal trading hubs and global mega-cities. Materialand symbolic elements of Fassi power persist, however, and anthropologistRachel Newcomb’s finely researched and written ethnography identifies them in upper-middle-class women’s gender identity. In so doing, Women ofFes helps the fields of anthropology, sociology, gender studies, and Islamicstudies to illuminate the often-neglected power of class to shape gender in theMuslim Middle East and North Africa, demonstrating, not pointedly, thatclass divides women within as much as across cultures.Newcomb’s book concerns women of, not merely in, Fes, namely, a classof women of “original” Fassi families navigating the social ruins and newopportunities of daily urban life. Its disparate topics – urban rumors, women’sNGOs, reforms of the Moroccan Muslim family code (mudawanah), flexiblekinship, public space, a dépassé lounge singer – shift the book’s centerfrom class to gender and public life. Her skillful identification of class issueswithin the latter, however, gives the book a necessary coherence ...

Planning for sustainable urbanisation in fast growing cities: Mitigation and adaptation issues addressed in Dhaka, Bangladesh

Issues related to sustainable urbanisation are best addressed when coordinated within a strategic framework and facilitated by a system of policy formulation that combines local opinions with scientific insights. This implies that planning for sustainable urbanisation has the potential to minimise climate change threats. While there is a pressing need for this potential to be realised globally, the current level of success in fast growing cities of the developing world is very limited. An approach to overcome this limitation has recently been successful in Dhaka, one of the fastest growing global megacities. It involved the identification of a strategic framework for the city. This framework was then combined with a locally-informed model of sustainable urbanisation to produce the Dhaka Metropolitan Development Planning Support System (DMDPSS). This paper discusses the climate change adaptation and mitigation issues that can be addressed through such a method in Dhaka, using a scenario-based approach. Two alternative development options (constrained and unconstrained) are constructed and analysed. A common set of indicators are used: first to evaluate which alternative is more sustainable; and then the mitigation and adaptation issues addressed. Results show that the ‘constrained’ scenario, which includes a series of development limitations, is both more sustainable and can address more mitigation and adaptation issues than the other alternative. The scenario analysis, however, is only a part of the strategic framework needed for Dhaka. Indeed other factors, such as dissemination of facts and issues, and the ease and equity of communication in the community, are critical both for progress towards sustainability and to enhance community resilience to climate change. The paper concludes that the optimum combination of adaptation and mitigation measures can be identified in fast growing cities by using systems, such as the DMDPSS, based on the core principles of sustainable development.

Relationships between submicrometer particulate air pollution and air mass history in Beijing, China, 2004–2006

Abstract. The Chinese capital Beijing is one of the global megacities where the effects of rapid economic growth have led to complex air pollution problems that are not well understood. In this study, ambient particle number size distributions in Beijing between 2004 and 2006 are analysed as a function of regional meteorological transport. An essential result is that the particle size distribution in Beijing depends to large extent on the history of the synoptic scale air masses. A first approach based on manual back trajectory classification yielded differences in particulate matter mass concentration by a factor of two between four different air mass categories, including three main wind directions plus the case of stagnant air masses. A back trajectory cluster analysis refined these results, yielding a total of six trajectory clusters. Besides the large scale wind direction, the transportation speed of an air mass was found to play an essential role on the PM concentrations in Beijing. Slow-moving air masses were shown to be associated with an effective accumulation of surface-based anthropogenic emissions due to both, an increased residence time over densely populated land, and their higher degree of vertical stability. For the six back trajectory clusters, differences in PM1 mass concentrations by a factor of 3.5, in the mean air mass speed by a factor of 6, and in atmospheric visibility by a factor of 4 were found. The main conclusion is that the air quality in Beijing is not only degraded by anthropogenic aerosol sources from within the megacity, but also by sources across the entire Northwest China plain depending on the meteorological situation.