Figure 1 - uploaded by David Sills
Content may be subject to copyright.
Map of southern Ontario giving the names of lakes and nearby urban centres. The study area is located within the circle depicting the effective Doppler range of the Exeter operational weather radar.
Context in source publication
Context 1
... Meteorological Service of Canada (MSC), York University, University of Western Ontario (UWO), and University of Guelph -Ridgetown College conducted a field experiment during the summer of 2001 as part of the ELBOW 2001 -Effects of Lake Breezes On Weather project. The study area is located in southwestern On- tario, a generally flat and mainly agricultural district within the Great Lakes region of North America ( Figure 1). The project objectives are to: ...
Similar publications
Na hun vermissing haalden de foto’s van de blonde jongetjes verschillende keren het journaal. Het was het voorjaar van 2013 en ze waren voor het laatst gezien met hun vader. Zijn eigen lichaam was eerder in een bos in Limburg aangetroffen. Na verschillende publieke zoekacties werden de kinderen van 7 en 9 jaar dood gevonden bij een afwateringsbuis...
![Figure 1: LAGO sites, modified from [2].](profile/Eli-Santos-Rodriguez/publication/326811270/figure/fig1/AS:655551558062080@1533307079687/LAGO-sites-modified-from-2_Q320.jpg)
![Figure 3: Schema of the inside of the tank, modified from [5].](profile/Eli-Santos-Rodriguez/publication/326811270/figure/fig3/AS:655551558074370@1533307079784/Schema-of-the-inside-of-the-tank-modified-from-5_Q320.jpg)
Citations
... This influence is especially true in the Great Lakes Region in Canada and the USA, where numerous populated cities exist along the shorelines of the Great Lakes. This region has been the subject of many investigations of the effect of the lakes on complex meteorological phenomena (Comer and Mckendry, 1993;Estoque, 1981;Keen and Lyons, 1978;Laird et al., 2001;Lyons, 1972;Lyons andCole, 1976, 1973;Mariani et al., 2018;Sills et al., 2011;Sills and King, 1998;Wang et al., 2019), including their role in the initiation of thunderstorms and the associated development of severe weather (Alexander et al., 2018;King et al., 2003;Moroz, 1967;Sills, 1998;Sills et al., 2002), and their modification of air quality in southern Ontario (Blanchard and Aherne, 2019;Brook et al., 2013;Hastie et al., 1999;Hayden et al., 2011;Lyons and Olsson, 1973;Reid et al., 1996;Sills et al., 2011;Wentworth et al., 2015). Air quality is modified by the presence of the lakes primarily via lake-breeze circulations (LBC), the extended lifetime of ozone (O 3 ) and other pollutants over the lakes as opposed to land surface, and the potential for reduced mixing due to the relatively shallow and stable thermal internal boundary layer (TIBL) (Fig. 1) within the LBC Lyons et al., 1995;Lyons andCole, 1976, 1973;Sillman et al., 1993;& others). ...
The lake breezes that frequently occur in Southern Ontario impact the levels of pollutants experienced by the populations in urban areas. The effects of lake breeze circulations on pollution transport and processing are not well understood. Few studies have measured the circulations’ impact on pollutants both at the surface and within the tropospheric column. In this study, pollutants in the tropospheric column (NO2 VCDs and AODs) were measured using MAX-DOAS concurrent with near-surface measurements of NOx, O3, and PM2.5 on lake breeze days in Toronto in September and October. The arrival of lake-breeze fronts (LBF) was identified using co-located meteorological data. The presence of lake breezes was confirmed using mesoscale analyses of radar, satellite and a network of meteorological stations. NO2 VCDs exhibited short-term increases of 0.8-3.4×1016 molecules cm-2 above the pre-LBF levels following the arrival of a LBF. These measurements are the first confirmation of the theorized presence of enhanced total burden of pollution within the total column behind the front within a lake-breeze circulation on multiple lake breeze days. Rapid decreases of O3 of up to 13 ppb at the arrival of the LBF were unexpected based on observed increases in O3 in other studies, but can be attributed to reduced photochemical O3 production during late summer and fall compared to mid-summer. AODs exhibited delayed enhancements compared to NO2 VCDs, appearing to be driven by enhanced humidity following the front, in addition to enhanced particle concentration. Our measurements highlight the complex 3-D structure of lake-breeze circulations. Keywords: Lake breeze, MAX-DOAS, Nitrogen oxides, Aerosol extinction, Ozone, Toronto
... A number of observational studies have also been conducted in Ontario and Manitoba to characterize lake breezes and examine their role in the initiation and development of thunderstorms and related severe weather. These include ELBOW in 2001 (Sills et al., 2002), BAQS-Met in 2007 , ELBOW-MB in 2013 (Curry et al., 2017), and the ECPASS in 2015 (Joe et al., 2018). Observational platforms have included radar, aircraft, surface mesonets, ground-based mobile observations and profiling, as well as a lightning mapping array. ...
The science of understanding severe thunderstorms and developing techniques for their prediction is relatively young, with most fundamental research having been carried out only during the last 75 years. Though it is not widely known, Canada has played an important role in such research and development, and some of Canada’s atmospheric scientists have been pioneers globally in a number of areas. This brief review attempts to describe the full breadth of the Canadian contribution, with sections dedicated to radar meteorology, field studies, laboratory work, and forecasting. Key areas requiring further investment in order to improve our understanding and predictive skill are also identified.
... In the more recent studies of lake breezes in the GTA, it was found that GTA lake breezes occurred on more than 70% of warm season days (Wentworth et al. 2015;Mariani et al. 2018). Other studies of lake breezes in southern Ontario have shown that lake breezes can penetrate as far inland as 215 km (Sills et al. 2011), initiate thunderstorms (Sills et al. 2002;King et al. 2003), and affect air quality (Hastie et al. 1999;Hayden et al. 2011;Wentworth et al. 2015). Lake breezes have a large influence on the meteorology and climate of coastal cities, particularly in spring and summer, and it is therefore important to forecast lake breezes accurately. ...
Canadian Global Environmental Multiscale (GEM) numerical model output was compared with the meteorological data from an enhanced observational network to investigate the model's ability to predict Lake Ontario lake breezes and their characteristics for two cases in the Greater Toronto Area-one in which the large-scale wind opposed the lake breeze and one in which it was in the same direction as the lake breeze. An enhanced observational network of surface meteorological stations, a C-band radar, and two Doppler wind lidars were deployed among other sensors during the 2015 Pan and Parapan American Games in Toronto. The GEM model was run for three nested domains with grid spacings of 2.5, 1, and 0.25 km. Comparisons between the model predictions and ground-based observations showed that the model successfully predicted lake breezes for the two events. The results indicated that using GEM 1 and 0.25 km increased the forecast accuracy of the lake-breeze location, updraft intensity, and depth. The accuracy of the modeled lake breeze timing was approximately ±135 min. The model underpredicted the surface cooling caused by the lake breeze. The GEM 0.25-km model significantly improved the temperature forecast accuracy during the lake-breeze circulations, reducing the bias by up to 72%, but it mainly underpredicted the moisture and overpredicted the surface wind speed. Root-mean-square errors of wind direction forecasts were generally high because of large biases and high variability of errors.
... Several studies have analyzed lake-breeze events in the Great Lakes region using radar and mesonet observations. For instance, during the Effects of Lake-breezes on Weather (ELBOW) 1997 (King et al. 1998) and ELBOW 2001(Sills et al. 2002 campaigns, several case studies of the LBF affecting thunderstorm development in southern Ontario were analyzed (Sills 1998). During the 2007 Border Air Quality and Meteorological Study (BAQS-Met) cam-paign, Great Lakes lake-breeze events in south-western Ontario were found to occur more frequently than previously reported, penetrating up to 200 km inland (Sills et al. 2011). ...
Enhanced meteorological observations were made during the 2015 Pan and Parapan American Games in Toronto in order to measure the vertical and horizontal structure of lake-breeze events. Two scanning Doppler lidars (one fixed and one mobile), a C-band radar, and a network including 53 surface meteorological stations (mesonet) provided pressure, temperature, humidity, and wind speed and direction measurements over Lake Ontario and urban areas. These observations captured the full evolution (prior, during, and after) of 27 lake-breeze events (73% of observation days) in order to characterize the convective and dynamic processes driving lake breezes at the local scale and mesoscale. The dominant signal of a passing lake-breeze front (LBF) was an increase in dew-point temperature of \(2.3 \pm 0.3 \,^{\circ }\hbox {C}\), coinciding with a \(180^{\circ }\) shift in wind direction and a decrease in air temperature of \(2.1 \pm 0.2 \,^{\circ }\hbox {C}\). Doppler lidar observations over the lake detected lake breezes 1 hour (on average) before detection by radar and mesonet. On days with the synoptic flow in the offshore direction, the lidars observed wedge-shaped LBFs with shallow depths, which inhibited the radar’s ability to detect the lake breeze. The LBF’s ground speed and inland penetration distance were found to be well-correlated (\(r = 0.78\)), with larger inland penetration distances occurring on days with non-opposing (non-offshore) synoptic flow. The observed enhanced vertical motion \(({>} 1\hbox { m s}^{-1})\) at the LBF, observed by the lidar on 54% of lake-breeze days, was greater (at times \({>} 2.5\hbox { m s}^{-1}\)) than that observed in previous studies and longer-lasting over the lake than over land. The weaker and less pronounced lake-breeze structure over land is illustrated in two case studies highlighting the lifetime of the lake-breeze circulation and the impact of propagation distance on lake-breeze intensity.
... Canada contains many of the world's largest lakes, not least of which include the venerable Great Lakes. Lake breezes have been researched extensively around the Great Lakes of southern Ontario by Sills et al. (1998Sills et al. ( , 2002Sills et al. ( , and 2011, however similar research on other Canadian lakes has been much more limited. The province of Manitoba also contains many large inland bodies of water, including Lakes Winnipeg and Manitoba, which rank among the largest lakes in Canada and among the largest in the world. ...
Honours thesis in partial fulfillment of the requirements for the B.Sc. Honours Degree
... The primary goal of ELBOW-MB was to fill gaps in the knowledge of Manitoba lake breezes through a field campaign. Similar field studies, under the same name (ELBOW), have been conducted in southern Ontario, specifically ELBOW-97 (Sills, 1998) and ELBOW 2001 (Sills, Taylor, King, Hocking, & Nichols, 2002). In addition, the 2007 Border Air Quality and Meteorology Study investigated lake breezes in southern Ontario (Sills et al., 2011). ...
The Effects of Lake Breezes On Weather-Manitoba (ELBOW-MB) field project, conducted around Lakes Manitoba and Winnipeg in July 2013, was the first in-depth field study of lake breezes in Manitoba, Canada. Using observational data collected during ELBOW-MB and output from the 2.5km Canadian High Resolution Deterministic Prediction System (HRDPS), comparisons were made between HRDPS output and observational data to determine whether the HRDPS can simulate Manitoba lake breezes. The model comparisons considered various lake-breeze characteristics, such as depth, inland penetration distance, and initiation and dissipation time. In addition, cross-sections of lake-breeze circulations were analyzed. The results show that the HRDPS was able to correctly simulate lake breezes, or lack thereof, in 78% of cases on Lake Winnipeg and 68% of cases on Lake Manitoba. Modelled lake-breeze initiation and dissipation times were found to be too early in some cases and too late in others when compared with observations. Overall, it was found that the HRDPS was able to simulate most aspects of lake breezes, although inland penetration distance was one characteristic that the HRDPS was not able to simulate realistically.
... The area northeast of Lake St. Clair, a region where multiple lake breeze fronts frequently interact, experiences the highest lightning flash density (flashes km −2 yr −1 ) in Canada (Burrows and Kochtubajda, 2010). The influence of lake-breeze circulations on severe thunderstorm formation in this region has therefore been the subject of several past studies (King et al., 2003;Sills et al., 2002;King and Sills, 1998;Sills, 1998). This enhanced deep convection "overturns" the atmosphere, potentially having a significant impact on air quality (Dickerson et al., 1987). ...
... The instrumented aircraft, National Research Council of Canada's Twin Otter, obtained measurements during 16 separate flights . Past experience with and knowledge of lake-breeze circulations in southwestern Ontario (Sills, 1998;King and Sills, 1998;Sills et al., 2002;King et al., 2003), as well as payload limitations, informed decisions related to flight plans originating in London, Ontario. To maximize measurement time within the study region, the Chatham airport was used for refuelling and staging when multiple flights per day were undertaken. ...
This paper serves as an overview and discusses the main findings from the Border Air Quality and Meteorology Study (BAQS-Met) in southwestern Ontario in 2007. This region is dominated by the Great Lakes, shares borders with the United States and consistently experiences the highest ozone (O3) and fine particulate matter concentrations in Canada. The purpose of BAQS-Met was to improve our understanding of how lake-driven meteorology impacts air quality in the region, and to improve models used for forecasting and policy scenarios. Results show that lake breeze occurrence frequencies and inland penetration distances were significantly greater than realized in the past. Due to their effect on local meteorology, the lakes were found to enhance secondary O3 and aerosol formation such that local anthropogenic emissions have their impact closer to the populated source areas than would otherwise occur in the absence of the lakes. Substantial spatial heterogeneity in O3 was observed with local peaks typically 30 ppb above the regional values. Sulfate and secondary organic aerosol (SOA) enhancements were also linked to local emissions being transported in the lake breeze circulations. This study included the first detailed evaluation of regional applications of a high-resolution (2.5 km grid) air quality model in the Great Lakes region. The model showed that maxima in secondary pollutants occur in areas of convergence, in localized updrafts and in distinct pockets over the lake surfaces. These effects are caused by lake circulations interacting with the synoptic flow, with each other or with circulations induced by urban heat islands. Biogenic and anthropogenic emissions were both shown to play a role in the formation of SOA in the region. Detailed particle measurements and multivariate receptor models reveal that while individual particles are internally mixed, they often exist within more complex external mixtures. This makes it difficult to predict aerosol optical properties and further highlights the challenges facing aerosol modelling. The BAQS-Met study has led to a better understanding of the value of high-resolution (2.5 km) modelling for air quality and meteorological predictions and has led to several model improvements.
... The area northeast of Lake St. Clair, a region where multiple lake breeze fronts frequently interact, experiences the highest lightning flash density (flashes km −2 yr −1 ) in Canada (Burrows and Kochtubajda, 2010). The influence of lake-breeze circulations on severe thunderstorm formation in this region has therefore been the subject of several past studies (King et al., 2003;Sills et al., 2002;King and Sills, 1998;Sills, 1998). This enhanced deep convection "overturns" the atmosphere, potentially having a significant impact on air quality (Dickerson et al., 1987). ...
... The instrumented aircraft, National Research Council of Canada's Twin Otter, obtained measurements during 16 separate flights . Past experience with and knowledge of lake-breeze circulations in southwestern Ontario (Sills, 1998;King and Sills, 1998;Sills et al., 2002;King et al., 2003), as well as payload limitations, informed decisions related to flight plans originating in London, Ontario. To maximize measurement time within the study region, the Chatham airport was used for refuelling and staging when multiple flights per day were undertaken. ...
This paper serves as an overview and discusses the main findings from
the Border Air Quality and Meteorology Study (BAQS-Met) in southwestern
Ontario in 2007. This region is dominated by the Great Lakes, shares
borders with the United States and consistently experiences the highest
ozone (O3) and fine particulate matter in Canada. The purpose
of BAQS-Met was to improve our understanding of how lake-driven
meteorology impacts air quality in the region, and to improve models
used for forecasting and policy scenarios. Results show that lake breeze
occurrence frequencies and inland penetration distances were
significantly greater than realized in the past. Due to their effect on
local meteorology, the lakes were found to enhance secondary
O3 and aerosol formation such that local anthropogenic
emissions have their impact closer to the populated source areas than
would otherwise occur in the absence of the lakes. Substantial spatial
heterogeneity in O3 was observed with local peaks typically
30 ppb above the regional values. Sulphate and secondary organic aerosol
(SOA) enhancements were also linked to local emissions being transported
in the lake breeze circulations. This study included the first detailed
evaluation of regional applications of a high resolution (2.5 km grid)
air quality model in the Great Lakes region. The model showed that
maxima in secondary pollutants occur in areas of convergence, in
localized updrafts and in distinct pockets over the lake surfaces. These
effects are caused by lake circulations interacting with the synoptic
flow, with each other or with circulations induced by urban heat
islands. Biogenic and anthropogenic emissions were both shown to play a
role in the formation of SOA in the region. Detailed particle
measurements and multivariate receptor models reveal that while
individual particles are internally mixed, they often exist within more
complex external mixtures. This makes it difficult to predict aerosol
optical properties and further highlights the challenges facing aerosol
modelling. The BAQS-Met study has led to a better understanding of the
value of high resolution (2.5 km) modeling for air quality and
meteorological predictions and has led to several model improvements.
... Environment Canada and several universities located in southwestern Ontario coordinated a scientific experiment in the summer of 2001 with the objective of improving the understanding of lake breeze circulations and their interactions with severe weather, particularly convective events.The experiment was undertaken in the study area during a hot and unusually dry summer (2001), which resulted in more frequent lake breezes and less severe weather than normal. However, most of the severe thunderstorms that did occur during this summer were initiated or enhanced by lake breeze fronts (Sills et al. 2002). King et al. (2003utilized Geostationary Operational Environmental Satellite (GOES) images to illustrate the cloud patterns associated with lake breezes during summer-time convection in Southern Ontario and suggested that these lake influences can also alter severe thunderstorm intensities and frequencies during the spring and summer. ...
Southern Ontario, Canada, has been impacted in recent years by many heavy rainfall and flooding events that have exceeded existing historical estimates of infrastructure design rainfall intensity–duration–frequency (IDF) values. These recent events and the limited number of short-duration recording raingauges have prompted the need to research the climatology of heavy rainfall events within the study area, review the existing design IDF methodologies, and evaluate alternative approaches to traditional point-based heavy rainfall IDF curves, such as regional IDF design values. The use of additional data and the regional frequency analysis methodology were explored for the study area, with the objective of validating identified clusters or homogeneous regions of extreme rainfall amounts through Ward's method. As the results illustrate, nine homogeneous regions were identified in Southern Ontario using the annual maximum series (AMS) for daily and 24-h rainfall data from climate and rate-of-rainfall or tipping bucket raingauge (TBRG) stations, respectively. In most cases, the generalized extreme value and logistic distributions were identified as the statistical distributions that provide the best fit for the 24-h and sub-daily rainfall data in the study area. A connection was observed between extreme rainfall variability, temporal scale of heavy rainfall events and location of each homogeneous region. Moreover, the analysis indicated that scaling factors cannot be used reliably to estimate sub-daily and sub-hourly values from 24- and 1-h data in Southern Ontario.
Citation Paixao, E., Auld, H., Mirza, M.M.Q., Klaassen, J. & Shephard, M.W. (2011) Regionalization of heavy rainfall to improve climatic design values for infrastructure: case study in Southern Ontario, Canada. Hydrol. Sci. J. 56(7), 1067–1089.
... BAQS-Met builds upon previous work in southern Ontario and southeast Michigan related to lake breezes and air quality. Field studies were conducted in 1992-1993 (SON-TOS/SEMOS - Reid et al., 1996;Wolff and Korsog, 1996;Sills, 1998;Hastie et al., 1999(ELBOW 97 -King and Sills, 1998Sills, 1998(ELBOW 2001-Sills et al., 2002. These observational studies furthered knowledge of lake breezes and/or air quality problems (particularly with respect to ozone) in the region. ...
Meteorological observations from the BAQS-Met field experiment during the summer months of 2007 were integrated and manually analyzed in order to identify and characterize lake breezes in the southern Great Lakes region of North America, and assess their potential impact on air quality. Lake breezes occurred frequently, with one or more lake breezes identified on 90 % of study days. They affected all parts of the study region, including southwestern Ontario and nearby portions of southeast Lower Michigan and northern Ohio, with lake-breeze fronts occasionally penetrating from 100 km to over 200 km inland. Occurrence rates and penetration distances were found to be higher than previously reported in the literature. This comprehensive depiction of observed lake breezes allows an improved understanding of their influence on the transport, dispersion, and production of pollutants in this region.
The observational analyses were compared with output from subsequent runs of a high-resolution numerical weather prediction model. The model accurately predicted lake breeze occurrence and type in a variety of synoptic wind regimes, but selected cases showed substantial differences in the detailed timing and location of lake-breeze fronts, and with the initiation of deep moist convection. Knowledge of such strengths and weaknesses aids in the interpretation of results from air quality models driven by this meteorological model.
