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Locations of four NatChem monitoring sites in southern Ontario, Canada.
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Programs such as MARYP have produced good quality environmentaldata during a summer collection period. Such programs can producecost effective regional acid rain data. The question arises whether summer collection (July, August) of acid rain depositionand concentration data can be used to reliably estimate annualacid deposition? Precipitation, sulf...
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Context 1
... sites roughly running in a transect from southwest to northeast were selected (Figure 1) in southern Ontario. Only complete data years were used in the analysis. ...
Context 2
... higher concentration of sulfate at Warsaw Caves compared to Egbert (Table I) suggested that Warsaw Caves was influenced by a source of sulfate that Egbert was not. The likely source is the Greater Toronto Area which is upstream of Warsaw Caves but not of Egbert (see Figure 1). Summers and Barrie (1986) provide a plausible mechanism that rationalizes these results. ...
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Citations
... When air temperatures over 31 • C can occur for three consecutive days, this is defined as a regional extreme heat event [88]. Coupled with high humidity, the Humidex values can reach 40 • C during a summer heat event [9,10,37,89,90]. To contextualize the study within general climate conditions, the climate normal for Toronto, Ontario, Canada (1981-2010), for the months of July and August for the mean daily air temperature are 22.3 • C and 21.5 • C, respectively [6]. ...
Nature-based solutions (NbS) present an opportunity to reduce rising temperatures and the urban heat island effect. A multi-scale study in Toronto, Ontario, Canada, evaluates the effect of NbS on air and land surface temperature through two field campaigns at the micro and mesoscales, using in situ measurements and LANDSAT imagery. This research demonstrates that the application of NbS in the form of green infrastructure has a beneficial impact on urban climate regimes with measurable reductions in air and land surface temperatures. Broad implementation of green infrastructure is a sustainable solution to improve the urban climate, enhance heat and greenspace equity, and increase resilience.
... Air temperatures over 31°C can occur during the summer where three consecutive days of such air temperatures are defined as an extreme heat event in southern Ontario (Anderson 2016). Coupled with high humidity, the humidex values can climb into the 40°C range during a summer heat event (Gough and Rosanov 2001;Gough et al. 2002 ...
The application of green infrastructure presents an opportunity to mitigate rising temperatures using a multi-faceted ecosystems-based approach. A controlled field study in Toronto, Ontario, Canada, evaluates the impact of nature-based solutions on near surface air temperature regulation focusing on different applications of green infrastructure. A field campaign was undertaken over the course of two summers to measure the impact of green roofs, green walls, urban vegetation and forestry systems, and urban agriculture systems on near surface air temperature. This study demonstrates that multiple types of green infrastructure applications are beneficial in regulating near surface air temperature and are not limited to specific treatments. Widespread usage of green infrastructure could be a viable strategy to cool cities and improve urban climate.
... The City of Toronto is Canada's largest urban area, which is situated on the northwest shore of Lake Ontario (43.7 • N, 79.4 • W). Southern Ontario is a transition zone between polar and tropical air masses, resulting in midlatitude cyclones and considerable weather variation [1][2][3]. These cyclones are common in the midlatitudes and have a significant impact on day-to-day climate variability [3,4]. ...
One hundred and sixty–nine years of weather station data were analyzed to quantify the changing nature of the winter season precipitation phase in the downtown area of Toronto (Canada). The precipitation variables examined were rainfall, snowfall water equivalent, total precipitation, rain days, snow days, and precipitation days. From these precipitation variables, three precipitation phase metrics were constructed for further analysis: the fraction of total precipitation that fell as snow, the fraction of precipitation days that recorded snow, and finally, the precipitation phase index (PPI) derived from comparing the rainfall to the snowfall water equivalent. Snowfall and snow days were decreasing at the most significant rate over this time period, and although rain days were increasing, total precipitation and precipitation days were also decreasing at a statistically significant rate. All three precipitation phase metrics suggest that winters are becoming less snowy in Toronto’s urban center. We also looked at trends and changes in average winter season temperatures to explore correlations between warming temperatures and changes in the winter season precipitation phase. Of the three precipitation phase metrics considered, the ratio of snow days to precipitation days recorded the strongest time series trend and the strongest correlation with warming temperatures.
... All four locations (the Toronto Zoo, Buttonville station, Oshawa station and Toronto station) are embedded in the general climate of Southern Ontario and influenced by the regional climate of the GTA. This climate is described in detail elsewhere (Gough et al. 2002;Gough 2010, 2012;Tam and Gough 2012;. In summary, Toronto experiences a mid-latitude climate with four distinct seasons (Koppen Dfb). ...
Based on a case study of the Toronto Zoo (Canada), multivariate regression analysis, involving both climatic and social variables, was employed to assess the relationship between daily weather and visitation. Zoo visitation was most sensitive to weather variability during the shoulder season, followed by the off-season and, then, the peak season. Temperature was the most influential weather variable in relation to zoo visitation, followed by precipitation and, then, wind speed. The intensity and direction of the social and climatic variables varied between seasons. Temperatures exceeding 26 °C during the shoulder season and 28 °C during the peak season suggested a behavioural threshold associated with zoo visitation, with conditions becoming too warm for certain segments of the zoo visitor market, causing visitor numbers to decline. Even light amounts of precipitation caused average visitor numbers to decline by nearly 50 %. Increasing wind speeds also demonstrated a negative influence on zoo visitation.
... Toronto, Ontario, Canada, is located at 43.7°N, 79.4°W on the northwest shore of Lake Ontario, part of the Laurentian Great Lakes (Fig. 1). Toronto has a humid continental climate influenced by the interplay of polar and subtropical air masses (Gough et al. 2002;Ho and Gough 2006;Mohsin and Gough 2010;Tam and Gough 2012;Tam et al. 2015). The humid continental climate is defined by warm to hot summers and cold winters with snow, with no dry season and having a wide range in annual temperature coupled with modifications caused by the lake effect due to the proximity of Toronto to Lake Ontario. ...
... This resulted into a global cooling, with a 0.5-0.6 K decrease in temperature in the Northern Hemisphere (McCormick et al. 1995;Parker et al. 1996;Gough et al. 2002). ...
Toronto, Ontario, Canada, experienced a cooler summer in 2014, in spite of worldwide record temperatures. In this work, we assess the relative coldness of summer 2014 from a climatological perspective. Using historical temperature data and several thermal metrics, summer 2014 was ranked using three time periods, 1840–2014 (175 years), the full extent of the local instrumental data; 1965–2014, the most recent 50 years; and 1985–2014, the most recent 30 years. For each of the periods, rank within the time period, recurrence interval and average temperature were calculated. Summer of 2014 in Toronto was ranked 118th since 1840 (175 years of data) using the mean daily temperature. The summer of 2014 with an average mean temperature of 20.8 °C was not extreme in nature and is in fact warmer than the average temperature of the time period (19.9 °C). For the more recent time periods, however, the summer was cooler than average but not an extremely cold summer. A monthly analysis showed in particular a cooler July compared to June and August, ranking July 2014 as the 4th coldest July since 1985 whereas June and August were 21st and 10th coldest during the 30-year period, respectively. Recurrence rates did not exceeded 5 years for the seasonal data and 8.3 years for the monthly data. Although the summer of 2014 was cooler than some recent summers, it was not an extreme event such as the Mount Pinatubo-induced cool summer of 1992 which it was explicitly compared to. Finally, an air mass analysis showed that the cooler July of 2014 was the result of a reduced frequency of warm air masses compared to 1992 when there was both a reduction of warm air masses and an increase in colder ones.
... The two Ontario parks selected as case studies were Pinery Provincial Park and Grundy Lake Provincial Park (Fig. 1b), located in southern Ontario. Southern Ontario is located in the Mixedwood Plains ecozone of Ontario and in a humid, continental climate (Dfb) (Gough et al. 2002;Tam and Gough 2012). This climate is characterised by warm to hot summers, snowy cold winters, no well-identified dry seasons and a wide range in annual temperatures. ...
... The average daily rainfall total between each park was the same (2.7 mm); however, out of the 2,760 summer days from 1971 to 2000, there was a 34.0 % chance of experiencing a total daily rainfall of 0.5 mm or greater at Grundy Lake, compared to a 30.7 % chance at Pinery. Southern Ontario is often located within the polar front zone where polar and tropical air masses meet, thus generating midlatitude cyclones and causing considerable weather variability (Gough et al. 2002;Gough 2008;Tam and Gough 2012). The passage of fronts has been found to cause noticeable rapid changes in wind direction and speed, temperature, humidity and cloud cover (Tam and Gough 2012) which will have a direct impact on park tourism. ...
Climate and weather act as central motivators for the travel decisions of tourists. Due to their seasonality, these factors determine the availability and quality of certain outdoor recreational activities. Park visitation in Ontario, Canada, has been identified as a weather sensitive tourism and recreation activity. This study used a survey-based approach to identify and compare stated weather preferences and thresholds, as well as weather-related decision-making for campers at two provincial parks in Ontario, Canada. The two parks were selected for differing physical and environmental characteristics (forested lake versus coastal beach). Statistically significant differences were detected between the two parks in relation to the importance of weather and weather-based decision-making. Specific temperatures that were considered ideal and thresholds that were too cool and too warm were identified for both parks, both during the day and the night. Heavy rain and strong winds were the most influential factors in weather-related decision-making and on-site behavioural adaptations. Beach campers placed greater importance on the absence of rain and the presence of comfortable temperatures compared to forest campers. In addition, beach campers were more likely to leave the park early due to incremental weather changes. The results of this study suggest that beach campers are more sensitive to weather than forest campers
... Toronto, located in the midlatitudes and situated on the northwest shore of Lake Ontario, is a large urban city in southern Ontario, Canada (43.7°N, 79.4°W) (Tam and Gough, 2012). Southern Ontario is a transition zone between polar and tropical air masses, resulting in midlatitude cyclones and considerable weather variation (Gough et al., 2002;Gough, 2008). These cyclones are common in the midlatitudes and have a significant impact on day-to-day climate variability (Gough, 2008;Tam and Gough, 2012). ...
The extreme cold weather alerts (ECWAs) were examined for Toronto, Canada for the winters of 2004–05 to 2011–12. ECWAs are triggered by extreme cold temperature, wind chill and intense winter precipitation. Just over 40% of the ECWAs occurred when the temperature fell below a −15 °C threshold. All but two of the alerts had a wind chill below −15 °C. The use of a −10 °C threshold captured well the frequency of wind chill events with half the −10 °C or lower events meeting the wind chill threshold. The modified −10 °C threshold and the −15 °C threshold were subsequently used to first assess how well climate models reproduced contemporary climate conditions, as well as three projection periods (2020s, 2050s, 2080s) to assess the impacts of a changing climate. The climate models reproduced current conditions well. In all projection cases the frequency of occurrence of events below the two thresholds decreases throughout the projection period but do not completely disappear. Interannual variability of projected events indicates a range of frequencies with some years similar to the contemporary climate. This suggests that thermal and wind driven ECWAs will continue for Toronto under climate change scenarios, although with gradual decreasing frequency.
... In this work, we examine extreme temperature records for the Greater Toronto Area (GTA). Toronto (43.7 N,79.4 W) is located in the midlatitudes, on the northwest shore of Lake Ontario of Southern Ontario (Gough et al. 2002;Gough 2008;Mohsin and Gough 2010;Tam and Gough 2012). Southern Ontario is a transition zone between polar and sub-tropical air masses, resulting in mid-latitude cyclones and considerable weather fluctuations. ...
Temperature extremes in Toronto, Ontario, Canada are examined using an under-utilized approach. The frequency of temperature extreme records per year is examined for the period of 1971 to 2000. Consistent with other published metrics, record extreme cold temperatures is decreasing at five weather observing stations in the Greater Toronto Area. This was confirmed using three different statistical tests indicating the change signal was stronger for weather stations on the fringe of the urban area suggesting that expanding urbanization was a major factor in this net change. However, this was not found to be the case for record extreme warm temperatures where increasing trends were not statistically significant. The effects of the Mt. Pinatubo eruption in 1991 were detected in both the minimum and maximum temperatures records.
... Toronto is one of the fastest growing urban areas in North America with a population of 2.5 million and an area of 641 square km (Statistics Canada, 2001). Being situated in the midlatitudes, Toronto's climate is influenced by the moving boundary between continental polar air that originates in northern Canada and maritime tropical air which forms over the Gulf of Mexico and subtropical North Atlantic (Gough et al., 2002). At the local scale, the climate of Toronto is affected by topography with a change in elevation of 275 m within 35 km of the shore of Lake Ontario, which on occasion produces slope winds at night or subsidence heating when there is a strong northeast gradient (Munn et al., 1969). ...
... Toronto is one of the fastest growing urban areas in North America with a population of 2.5 million and an area of 641 km 2 (Statistics Canada 2001). Being situated in the midlatitudes, Toronto's climate is influenced by the moving boundary between continental polar air that originates in northern Canada and maritime tropical air which forms over the Gulf of Mexico and subtropical North Atlantic (Gough et al. 2002). At the local scale, the climate of Toronto is affected by topography with a change in elevation of 275 m within 35 km of the shore of Lake Ontario, which on occasion produces slope winds at night or subsidence heating when there is a strong northeast gradient (Munn et al. 1969). ...
As the majority of the world’s population is living in urban environments, there is growing interest in studying local urban
climates. In this paper, for the first time, the long-term trends (31–162years) of temperature change have been analyzed
for the Greater Toronto Area (GTA). Annual and seasonal time series for a number of urban, suburban, and rural weather stations
are considered. Non-parametric statistical techniques such as Mann–Kendall test and Theil-Sen slope estimation are used primarily
for the assessing of the significance and detection of trends, and the sequential Mann test is used to detect any abrupt climate
change. Statistically significant trends for annual mean and minimum temperatures are detected for almost all stations in
the GTA. Winter is found to be the most coherent season contributing substantially to the increase in annual minimum temperature.
The analyses of the abrupt changes in temperature suggest that the beginning of the increasing trend in Toronto started after
the 1920s and then continued to increase to the 1960s. For all stations, there is a significant increase of annual and seasonal
(particularly winter) temperatures after the 1980s. In terms of the linkage between urbanization and spatiotemporal thermal
patterns, significant linear trends in annual mean and minimum temperature are detected for the period of 1878–1978 for the
urban station, Toronto, while for the rural counterparts, the trends are not significant. Also, for all stations in the GTA
that are situated in all directions except south of Toronto, substantial temperature change is detected for the periods of
1970–2000 and 1989–2000. It is concluded that the urbanization in the GTA has significantly contributed to the increase of
the annual mean temperatures during the past three decades. In addition to urbanization, the influence of local climate, topography,
and larger scale warming are incorporated in the analysis of the trends.
