Lake Breezes in SW Ontario and Their Influence During BAQS-Met 2007
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Lake Breezes in SW Ontario and Their Influence During BAQS-Met 2007 David Sills 1 , Jeff Brook 2 , Katherine Hayden 2 , Paul Makar 2 , Peter Taylor 3 and Lesley Hill 1 1 Cloud Physics and Severe Weather Research Section, Environment Canada, Toronto, Canada 2 Air Quality Research Division, Environment Canada, Toronto, Canada 3 Department of Earth and Space Science and Engineering, York University, Toronto, Canada 2009 CMOS Congress 31 May – 4 June, Halifax, NS
description
Lake Breezes in SW Ontario and Their Influence During BAQS-Met 2007. David Sills 1 , Jeff Brook 2 , Katherine Hayden 2 , Paul Makar 2 , Peter Taylor 3 and Lesley Hill 1 1 Cloud Physics and Severe Weather Research Section, Environment Canada, Toronto, Canada - PowerPoint PPT Presentation
Transcript of Lake Breezes in SW Ontario and Their Influence During BAQS-Met 2007
Lake Breezes in SW Ontario and Their Influence During BAQS-Met 2007
David Sills1, Jeff Brook2, Katherine Hayden2, Paul Makar2, Peter Taylor3 and Lesley Hill1
1Cloud Physics and Severe Weather Research Section, Environment Canada, Toronto, Canada2Air Quality Research Division, Environment Canada, Toronto, Canada
3Department of Earth and Space Science and Engineering, York University, Toronto, Canada
2009 CMOS Congress31 May – 4 June, Halifax, NS
Why are lake breezes important?
• Affect the climate of the region around the lake• Affect air quality:
– 3-D transport of pollutants / precursors in lake breeze circulations
– Increased insolation for photochemistry– Decreased mixing heights reduce pollutant dispersion
• Affect summer severe weather:– Lake air suppresses thunderstorms– The lake breeze front provides a lifting mechanism for the
initiation of thunderstorms
• In SW Ontario, surrounded by large and small lakes
Past Lake Breeze Research
• Lots of work done on sea breezes and their effects on air quality in coastal regions: Canada, US, UK, Greece, Japan
• A number of studies of Great Lakes lake breezes have been conducted: Biggs and Graves 1962, Moroz 1967, Lyons 1972, Estoque et al. 1976, Comer and McKendry 1993, Sills et al. 2002
• Lake breezes and air quality in the Great Lakes region studied by: Lyons and Olsson 1973 (Lake Michigan), Mukammal et al. 1982 (Lake Erie), Sills 1998 (SW Ontario), Hastie et al. 1999 (Lake Ontario)
What we know…
1000
2000
Hei
gh
t (m
)
0
0 40Distance (km)
Lake Breeze InflowLake Breeze Inflow
UpdraftsWeak
SubsidenceWeak
Subsidence
Return Flow Return Flow
Assume midday heating over land between two lakes
Building Lake Breezes
1000
2000
Hei
gh
t (m
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0
0 40Distance (km)
Lake Breeze InflowLake Breeze Inflow
ConvectiveMixedLayer
ResidualLayer
ResidualLayer
F r e e A t m o s p h e r e
CAPPING INVERSION
CAPPING INVERSION CAPPING INVERSION
CAPPING INVERSION
ENTRAINMENT ZONE
SURFACE LAYER
TIBL TIBLL
ake Breeze F
ron
t Lak
e B
reez
e F
ron
t
Eight different air regimes crossing from lake to lake
ConvectiveMixedLayer
ResidualLayer
ResidualLayer
F r e e A t m o s p h e r e
CAPPING INVERSION
CAPPING INVERSION CAPPING INVERSION
CAPPING INVERSION
ENTRAINMENT ZONE
SURFACE LAYER
TIBL TIBL
Building Lake Breezes
1000
2000
Hei
gh
t (m
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0
0 40Distance (km)
Lake Breeze InflowLake Breeze Inflow
LCL LCL
LCL
Classic vs. High Deformation‘Classic’ lake breeze circulations
Weak synoptic wind regime
‘High deformation’ lake breeze circulations
Moderate synoptic wind regime (SW)
Outstanding Questions
• Are most ozone exceedances that occur in the absence of long-range transport associated with lake breeze circulations and their effects?
• Why do pollutant concentrations often peak with the passage of the lake breeze front then fall off?
• How important are vertical motions (upward and downward) associated with lake breeze circulations in transporting pollutants/precursors?
• How well do current NWP models handle:– changes in boundary-layer depth due to lake breeze circulations?– the intensity of upward and downward vertical motions?– the initiation of thunderstorms at lake breeze fronts?
BAQS-Met 2007
A multi-agency field program combining both high resolution AQ
and met measurements
N
Lake Huron
Detroit
Windsor
London
Toledo
Sarnia
Lake Erie
Lake Huron
Detroit
Windsor
London
Toledo
Sarnia
Lake Erie
Lake Huron
Detroit
Windsor
London
Toledo
Lake St. Clair
Lake St. Clair
Lake ErieLake Erie
Harrow
Ridgetown
Bear Creek
0 30 km
U of Toronto
York UEC
BAQS-Met 2007 Mesonet
IADN
PTK
VLL
DET
DTWYIPARB
MTC
PHNYZR
YQG
XHA
WNB
WAJ
YXU
DUH
THLO1
45005
FTGM4
THR01
TTF
XRG
XPT
45147
LSCM4
N
FNT
12016
12059
13001
16015
KONZ
85135
SOM
ALV
LAR
PAL
CRO
PAI
MER
LIG
STA
WOO
COT
PAQ
LEA
WHE
BEALSC
Lake Huron
Detroit
Windsor
London
Toledo
LEGEND 0 30 km
Existing operational met stn
Existing OME AQ + met stn
EC AQ supersite + met stn
Univ AQ supersite + met stn + profiles
EC ATMOS met stn + AQ
YorkU ATMOS met stn
EC buoy met
EC buoy AQ + met
EC AMMOS mobile met
Sarnia
Lake Erie
Lake Huron
Detroit
Windsor
London
Toledo
Sarnia
Lake Erie
Lake Huron
Detroit
Windsor
London
Toledo
45132
AMM
Mobile:• Twin Otter aircraft• CRUISER AQ lab• AMMOS met vehicle
Lake Breeze Detection
Each of these can also be ambiguous at times...
Lake Breeze Detection
Wind Speed
Temperature
Dew Point
1 min dataMerlin Station
Wind DirectionOzonePM2.5
Lake Breeze Detection
Lake Breeze Stats (Preliminary)
• 30% were Classic, 70% were HD lake breezes
• 100% of high ozone* days had active lake breezes
• 86% of days with thunderstorms had active lake breezes
• 100% of severe thunderstorm days had active lake breezes
For entire June – August 2007 period:
June July August Total
Lake Huron 27 days 26 days 19 days 78%
Lake St. Clair 26 days 26 days 22 days 80%
Lake Erie 26 days 27 days 23 days 83%
* 1-hr avg O3 >= 80 ppb at more than one station
Lake Breeze Stats (Preliminary)
• Lake breezes somewhere within study region every day of intensive!
• 3 Classic lake breeze days (Jun 23rd, 25th, Jul 2nd), the rest HD
• 9 high ozone days, 3 thunderstorm days, 2 severe thunderstorm days – all with lake breezes
• Wide variety of synoptic regimes – wind speed light to moderate, direction S through NNE
During the 20-day intensive period:
Jun 20 – Jul 9
Lake Huron 19 days
Lake St. Clair 18 days
Lake Erie 19 days
25 Jun 2007
Max ozone 70-90 ppb in study area
ConvectiveMixedLayer
ResidualLayer
ResidualLayer
F r e e A t m o s p h e r e
CAPPING INVERSION
CAPPING INVERSION CAPPING INVERSION
CAPPING INVERSION
ENTRAINMENT ZONE
SURFACE LAYER
TIBL TIBL
25 June 07 Cross-section
1000
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Hei
gh
t (m
)
Lake Erie Lake St. ClairSouthwestern Ontario0
0 40Distance (km)
Lake Breeze InflowLake Breeze Inflow
Convective Mixed Layer Depth ~ 1500 m Lake St. Clair lake breeze depth ~ 300 m
ConvectiveMixedLayer
ResidualLayer
ResidualLayer
F r e e A t m o s p h e r e
CAPPING INVERSION
CAPPING INVERSION CAPPING INVERSION
CAPPING INVERSION
ENTRAINMENT ZONE
SURFACE LAYER
TIBL TIBL
25 June 07 Cross-section
1000
2000
Hei
gh
t (m
)
Lake Erie Lake St. ClairSouthwestern Ontario0
0 40Distance (km)
Lake Breeze InflowLake Breeze Inflow
Updrafts at fronts up to 5 m s-1 but not quite how we thought…
ConvectiveMixedLayer
ResidualLayer
ResidualLayer
F r e e A t m o s p h e r e
CAPPING INVERSION
CAPPING INVERSION CAPPING INVERSION
CAPPING INVERSION
ENTRAINMENT ZONE
SURFACE LAYER
TIBL TIBL
25 June 07 Cross-section
1000
2000
Hei
gh
t (m
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Lake Erie Lake St. ClairSouthwestern Ontario0
0 40Distance (km)
Lake Breeze InflowLake Breeze Inflow
Updrafts at fronts up to 5 m s-1 but not quite how we thought…
8 July 07 @ 17 UTC (13 EDT) Ozone at surface and cross-sections
Courtesy of Paul Makar/AQRD
8 July 07 @ 17 UTC (13 EDT) Ozone at surface and cross-sections
0.4 ug/kg/2min ozone Production isosurface encloses higher ozone production regions
Surface-level productionover Lake Erie.
Ozone production inlake breeze convergencesouth of Lake Erie.
Production region just north of Lake St. Clair
Courtesy of Paul Makar/AQRD
8 July 07 @ 17 UTC (13 EDT) Ozone at surface and cross-sections
0.4 ug/kg/2min ozone transport isosurface, encloses regions where ozone is increasing due to higher transport rates
Pollution pipeline apparent from source region near Lake St. Clair through to Toronto!
Courtesy of Paul Makar/AQRD
8 July 07 @ 17 UTC (13 EDT) Ozone at surface and cross-sections
Summary and Future Work
• Lake breezes very frequently affected SW Ontario in the summer months of 2007
• The circulations can strongly influence air quality over all of SW Ontario due to 3-D motions, reduced mixing heights, and increased insolation
• They also frequently help to initiate thunderstorms, including severe weather
• Mesonet, aircraft and other BAQS-Met data will be used to further address the ‘outstanding questions’ related to lake breezes
Acknowledgements
• Norbert Driedger, Emma Bradbury for their hard work on the mesoanalysis database and products
Thank you / merci!
ReferencesBiggs, W. G. and M. E. Graves, 1962: A Lake Breeze Index. J. Appl. Meteorol., 1, 474- 480.
Comer, N. T. and I. G. McKendry, 1993: Observations and Numerical Modelling of Lake Ontario Breezes. Atmos-Ocean, 31, 481-499.
Estoque, M. A.; J. Gross and H. W. Lai, 1976: A Lake Breeze over Southern Lake Ontario. Mon. Wea. Rev., 104, 386-396.
Hastie, D. R., J. Narayan, C. Schiller, H. Niki, P. B. Shepson, D. M. L. Sills, P. A. Taylor, Wm. J. Moroz, J. W. Drummond, N. Reid, R. Taylor, P. B. Roussel and O. T. Melo, 1999: Observational evidence for the impact of lake breeze circulation on ozone concentrations in southern Ontario. Atmospheric Environment, 33, 323-335.
Lyons, W. A., 1972: The Climatology and Prediction of the Chicago Lake-breeze. J. Appl. Meteorol., 11, 1259-1270.
Lyons, W. A. and L. E. Olsson, 1973: Detailed Mesometeorological Studies of Air Pollution Dispersion in the Chicago Lake Breeze. Mon. Wea. Rev., 101, 387-403.
Moroz, W. J., 1967: A Lake Breeze on the Eastern Shore of Lake Michigan: Observation and Model. J. Atmos. Sci., 24, 337-355.
Mukammal, E. I., H. H. Neumann, and T. J. Gillespie, 1982: Meteorological conditions associated with ozone in southwestern Ontario, Canada. Atmospheric Environment, 16, 2095–2106.
Sills, D. M. L., 1998: Lake and land breezes in southwestern Ontario: observations, analyses and numerical modelling. PhD dissertation, CRESS, York University, 338 pp.
Sills, D., P. Taylor, P. King, W. Hocking and I. Nichols, 2002: ELBOW 2001 - studying the relationship between lake breezes and severe weather: project overview and preliminary results. Preprints, 21st Severe Local Storms Conference, San Antonio, TX, Amer. Meteorol. Soc., 611-614.
