UVB RADIATION DISTRIBUTION IN CANADA DURING 1992 AND 1993

One of the steps leading to an assessment of the biological significance of ozone destruction is to determine the biologically effective ultraviolet radiation (UVB) distribution. The objective of this study is to describe and analyze broadband UVB radiation at 24 locations across Canada, during the period from July 1992 through December 1993. This is the first study of broadband UVB measurements involving such a large number of UVB measuring instruments. Quantitative characteristics and statistical analysis of the surface UVB radiation in Canada with respect to ozone amount, as well as cloudiness, are presented. The results indicate higher UVB irradiance in the second half of 1992, compared with the same period in 1993. Among all the locations, Toronto received the greatest dose of UVB radiation in 1993. Excluding Yellowknife, due to its northernmost location (larger zenith angles), Ste-Agathe, Quebec received the smallest dose. Unusually high UVB fluxes were found to occur in March 1993 over eastern Canada. A study of the correlation of UVB radiation with total ozone and cloud opacity was carried out for most of the locations. The results suggest that other meteorological parameters have a significant impact on the ultraviolet levels.     

Exploring the land development process and its impact on urban form in Hamilton, Ontario

The form of many Canadian cities has dramatically evolved over the past six decades due to urban sprawl. Several patterns can characterize this evolution including unlimited horizontal expansion of the city, leapfrog, and low‐density residential development at the outskirts, and widespread strip commercial and power centre retail development. Hamilton, Ontario is an example of a Canadian city that has experienced suburbanization and sprawled development for several decades. However, the nature of this sprawled development is unclear and its impact on urban form is not entirely understood. In this article, several hypotheses pertaining to sprawled land development and urban form are postulated and tested. The tests rely on point source data of the developed land parcels in Hamilton during the period 1950–2003. A number of spatial statistics techniques, including kernel estimation and complete spatial randomness (CSR) K‐function tests, are employed to examine the emerging nature of urban form. We hypothesize that while the city has been sprawling, the ongoing land development process is leading urban form into multinucleation. To support this assumption, we further hypothesize the existence of an interdependent spatial relationship between residential and commercial land uses at the emerging nuclei. Accordingly, we examine the strength of co‐clustering among these land use activities over time. The findings indicate that while the city has been sprawling, several consequent urban nuclei with mixed land use activities have been emerging and become more visible in recent years. This is an indication that the city's form is progressively becoming multinuclear. Furthermore, the estimates for the 1990s indicate interdependence between the locational patterns of residential and commercial land development. Co‐clustering between these two types of land uses is bi‐directional and occurs at a time lag of three to seven years. These findings affirm the existence of interdependence between land use activities at the observed nuclei, which support the emergence of a multinucleation.     

Smart growth strategies,transportation and urban sprawl: simulated futures for Hamilton,Ontario

North American cities have undergone dramatic changes over the last century. Locations that were once inconvenient have become accessible through extensive road networks leading to population decentralization from the traditional urban centre to suburbia, creating polycentric sprawls from once monocentric communities. Hamilton, Ontario is one such city. The decentralization and urban decline of the city is widely attributed to sprawling development. This change in the sociospatial structure creates challenges for transportation planners as we see greater automobile dependency, greater commuting distances and increased congestion. Smart growth policies such as urban residential intensification (URI) aim to increase population densities in the urban core. This exploratory study estimates the benefits of such policies from a transportation aspect. It is predicted that the City of Hamilton will experience household growth of approximately 80,000 households over the period 2005–2031. Using IMULATE, an integrated urban transportation and land‐use model, a variety of development scenarios model this anticipated growth. Changes in vehicular emissions, traffic congestion and energy consumption as a result of URI are examined. Models of the land‐use/transportation relationship demonstrate how increasing population densities within a city's urban centre drastically reduce congestion, emissions and gasoline consumption.