Towards the Understanding and Development of an Urban-influenced Climate Framework

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Thursday, 8 January 2015
Bradford Johnson, University of Georgia, Athens, GA; and J. M. Shepherd

Urbanization is apparent in all regions of world and is especially aggressive in developing regions. For the first time in history, more people now live in urban areas than rural regions. Urban population has outnumbered rural population in developed nations since 1950. However, the highest rates of urban migration and growth occur in Asia and Africa where urban population will surpass rural population by 2020 and 2035, respectively. Only 1 in 8 residents of developing regions live in cities with populations greater than 10 million. With the anticipated growth of small- to mid-sized cities, increased dispersion of land cover/land use change and overlapping of adjacent cities are also likely. Most urban climate studies have focused on an individual or a regional collection of cities and have collectively constructed a substantial knowledge of the urban heat island's role in local climate modification. The abundance of urban heat island (UHI) studies increases the knowledge base regarding these particular phenomena, yet perspective is underdeveloped. While understanding of the nuances of particular urban environments has grown, considerations of urbanization's role in the larger scale view of regional climate have not kept pace. Yet, recent findings continue to show the effects of urban areas are not limited to the boundaries of the impervious surfaces that define them but may have regional implications on temperature, the water cycle, aerosols, and biogeochemical cycles. Therefore, confining the focus of urban climate studies to the limited scope of the well-known UHI also inhibits our ability to understand larger scale ramifications of urban growth dynamics. A new framework called the Urban Climate Archipelago (UCA) effect is proposed by this study to investigate aggregate effects that urban environments increasingly have on the climate system. The traditional archipelago is defined roughly as a loosely connected chain of islands. Each island may have its own cultural makeup and even source of origin. This paper will provide a definition of the UCA and describe a process whereby one may identify its various forms. Investigation of each UCA's complex identities and interactions will adopt techniques from various disciplines including, but not limited to, traditional UHI studies, climatological analysis, Geographical Information Science (GIS), remote sensing, and spatial ecology. Better understanding of cities' abilities to modify precipitation patterns is of crucial importance to urban planning and resource management and is one manifestation of potential UCA effects. In particular, winter weather events like Washington D.C's Snowmaggedon or Atlanta's Ice Jam 2014 require the mobilization of resources throughout urban areas. The heterogeneity of land cover and land use along with differing spatial characteristics of UCAs may result in greater (and lesser) impacts within, between, and outside of traditional city boundaries. In addition to the classification of the UCA, we will explore preliminary results surrounding the climatological modification of winter season precipitation through a composite climatological approach.