Martin O’Malley, Governor | Anthony G. Brown, Lt. Governor | Robert M. Summers, Ph.D, Acting Secretary MARAMA Data Analysis Workshop Laura Landry January 20, 2011 The Influence of the Chesapeake Bay Breeze on Maryland Air Quality
Martin O’Malley, Governor | Anthony G. Brown, Lt. Governor | Robert M. Summers, Ph.D, Acting Secretary
MARAMA Data Analysis WorkshopLaura Landry
January 20, 2011
The Influence of theChesapeake Bay Breeze on
Maryland Air Quality
2
Outline
Introduction
Investigation of the interaction between Maryland’s air quality and the bay breeze
Methodology
Overall results
Case Study: August 18, 2009
Future workSource: AIRNow
3
Introduction
4
A Bay Breeze’s Influence
Forms due to a large temperature difference between land and bay waters
Creates a boundary, much like a small scale cold front
Ozone pollution easily accumulates along this boundary
Warm airrises
Cold airsinks
5
2009 Ozone SeasonAir Monitoring Sites D
aily peak 8-hour ozone concentration
(ppb)
Daily num
ber of sites w
ith an exceedance
Aldino
Davidsonville
Edgewood
Essex
Furley ES, Baltim
ore
Padonia
So. Carroll
Calvert Cnty
PG County
Equest. Ctr
Frederick County
HU
-Beltsville
Rockville
So. Maryland
Fair Hill
Millington
Hagerstow
n
Piney Run
4/25/2009 76 76 1
4/26/2009 78 78 1
6/8/2009 76 76 76 2
6/25/2009 79 109 86 76 109 4
6/26/2009 81 91 83 91 3
7/13/2009 77 77 1
7/15/2009 82 82 1
7/16/2009 81 77 81 2
8/16/2009 85 85 1
8/18/2009 83 83 1
8/27/2009 76 76 1
Number of exceedance days
2009: 11 2 0 9 1 0 1 0 1 0 0 1 0 0 3 0 0 0
Bay Breeze Effect
Bay Breeze EffectBay Breeze Effect
Bay Breeze Effect
Bay Breeze Effect
56% of 2009 Edgewood exceedance days also observed a bay breeze
6
Bay Breeze Climatology Days of analysis were selected based on...
75 ppb ozone NAAQS
Baltimore NAA exceedance days in June-August from 2004-2009*
High ozone days were analyzed for event types Criteria were developed using Miller and Keim (2003)
Event types: bay breeze, marginal, and non-bay breeze
Identified the “Maximum Ozone Gradient” for each day Difference between ozone at a monitoring site along the bay’s coast and
ozone at a site further inland
Used AIRNow-Tech Navigator GIS-based tool that plots current and archived pollution and meteorological
data on to customizable map
* No 2006 exceedance days were included in this study due to irregular wind data at the Edgewood site in June-August 2006.
* The Fort Meade monitor was discontinued in December 2004.
*
8
Bay Breeze Climatology Based on 83 events
24 bay breeze (29%)
15 marginal (18%)
44 non-bay breeze (53%)
Bay breeze events
Showed much higher Max. Ozone Gradients
Hour of onset: 12 PM EDT(16 UTC)
Hour of dissipation: 7 PM (23 UTC)
Baltimore NAA Ozone Exceedance Day ClimatologyDistribution by Event Type
29%
53%
18%
Bay BreezeMarginalNon-Bay Breeze
Maximum Ozone Gradient by Event Type
-25
-15
-5
5
15
25
35
45
55
65
Bay Breeze Marginal Non-Bay Breeze
Ozo
ne g
radi
ent (
ppb)
Q3MaxMedianMinQ1
Martin O’Malley, Governor | Anthony G. Brown, Lt. Governor | Robert M. Summers, Ph.D, Acting Secretary
Case Study: August 18, 2009
10
Weather Conditions
August 18th
High pressure system over Mid-Atlantic and Southeast
Clear skies
Light and variable surface winds
High temperatures in upper 80’s to lower 90’s ( F)
8 AM (EDT)
H
11
Vertical Wind Profile atBeltsville, MD
8 PM 11 PM 2 AM 5 AM 8 AM
Radar Wind Profiler
A nocturnal low level jet (NLLJ) formed
Fast moving stream of air
Shown in vertical profile measurements of wind speed and direction
Known to transport ozone into Maryland
12
Ozonesonde
Balloon carrying instruments that measure:
Ozone
Temperature
Wind speed and direction
GPS coordinates and height
Measured 100 ppb at approximately 1 km in the afternoon, 2:40 PM EDT
Source: Howard University
13
Surface Ozone Measurements
Daily maximum 8-hour ozone average
Highest at Edgewood with 83 ppb
All other sites were 31-71 ppb
Maximum ozone gradient was 60 ppb
Ozone gradient = Coastal site’s ozone – Inland site’s ozone
14
Hourly Ozone Concentrations
0
10
20
30
40
50
60
70
80
90
100
110
120
130
0 2 4 6 8 10 12 14 16 18 20 22 24
Hour (EDT)
1-hr
ozo
ne c
once
ntra
tions
(ppb
)
AldinoBeltsvilleEdgewoodEssexFair HillPadoniaPiney RunShenandoah
August 18, 2009
Edgewood peaked at 119 ppb
Short-lived, increase at Padonia at 4 PM
Decrease at Edgewood at 3 PM from the bay breeze’s shift inland
Essex began decline around the same time
Major drop in ozone by nearly all sites at
5 PM due to thunderstorms
15
Ozone and Wind Analysis10 AM (EDT)
Estimated bay breeze
Onshore flow
Source: AIRNow-Tech
Edgewood
Direction wind is coming from
16
Ozone and Wind Analysis12 PM (EDT)
Estimated bay breeze
High values started at Edgewood
Source: AIRNow-Tech
17
Ozone and Wind Analysis1 PM (EDT)
Estimated bay breeze
Edgewood jumped ~20 ppb from 12 – 1 PM
Source: AIRNow-Tech
18
Ozone and Wind Analysis2 PM (EDT)
Estimated bay breeze
…then ~20 ppb again by 2 PM
Source: AIRNow-Tech
Ozone gradient:
119 (Edgewood) – 59 (Aldino) = 60 ppb 90 (Essex) – 53 (Padonia) = 37 ppb
19
Ozone and Wind Analysis3 PM (EDT)
Estimated bay breeze
Edgewood began its decline while surrounding
sites started to rise
Source: AIRNow-Tech
20
Ozone and Wind Analysis4 PM (EDT)
Estimated bay breeze
Bay breeze moved inland
Source: AIRNow-Tech
21
Ozone and Wind Analysis5 PM (EDT)
Estimated bay breeze
Source: AIRNow-Tech
22
Ozone and Wind Analysis6 PM (EDT)
Estimated bay breeze
Back to Green (Good) air quality -thunderstorms moved eastward
through MD
Source: AIRNow-Tech
23
Bay Breeze in the Radar
Next you will see the bay breeze in an animation of radar imagery
Pay close attention to the white dashed lines
It will indicate where the boundary will briefly appear
24
Bay Breeze in the Radar
Bay breeze close to Edgewood
Boundary moved inland by 3 PM
25
End to the Episode
Strong thunderstorms swept through the state from the west
The following day brought cloudier skies
Afternoon thunderstorms moved in earlier than they had on August 18th
August 18th
August 19th
26
Future Work
Formulate a bay breeze climatology for Edgewood only
Seems most prone to its ozone being negatively affected by the bay breeze
Tentative methodology
Edgewood ozone exceedance days
Use the NOAA MADIS mesonet of weather observations to aid in wind analysis This dataset will aid in determining how far inland the bay breeze
can move More precise hour of onset/dissipation
27
Maryland Department of the Environment1800 Washington Boulevard | Baltimore, MD 21230
410-537-3000 | TTY Users: 1-800-735-2258www.mde.state.md.us
Contact and ReferencesContact Information:
Laura LandryMeteorologist
Air Monitoring Program / MDEPhone: 410-537-3122
Email: [email protected]
Acknowledgements:
Duc Nguyen and Michael Woodman
References:
AIRNow, cited 2009: AIRNow-Tech. [www.airnowtech.org]
Miller, S. T. and B. T. Keim, 2003: Synoptically-driven controls on the sea breeze of the central New England coast. Wea. Forecasting, 18, 236-248.
NOAA NCDC, cited 2009: NCDC NEXRAD Data Inventory Search. [www.ncdc.noaa.gov/nexradinv/]
Plymouth State University, cited 2009: Plymouth State Weather Center. [http://vortex.plymouth.edu]
28
Appendix
The appendix includes the following items:
1. Event Type Criteria
2. Additional measurements from the August 18th
ozonesonde
3. Poster presented at the 2010 AMS Annual Meeting and the 2010 National Air Quality Conference
29
Event Type CriteriaCriteria were developed to identify bay breeze, marginal, and non-bay breeze events. These were an adaptation of Miller and Keim (2003) sea breeze event criteria.
BAY BREEZE:
1. An onshore wind shift must occur at 1+ coastal sites. Coastal sites: Edgewood, Essex
Average of morning to midday cloud cover must be < BKN to ensure a wind shift was not synoptically driven
2. 1+ inland sites must display parallel, antiparallel, or perpendicular wind flow to the shoreline. Inland sites: Aldino, Padonia
3. Wind speeds associated with the bay breeze must be ≥ 3 kts. 1 hour of lighter wind speed was allowable due to the bay breeze’s light wind nature.
4. Criteria #1-3 must be sustained for ≥ 3 hrs.
MARGINAL:
1. All bay breeze event criteria were met except the bay breeze duration, lasting < 3 hrs.
NON-BAY BREEZE:
1. Bay breeze and marginal event criteria were not met.
30
Ozonesonde on August 18th
Ozonesonde at Beltsville, MDLaunched: August 18, 2009, 2:40 PM (EDT)
0
0.5
1
1.5
2
2.5
3
3.5
4
70 120 170 220 270
Hei
ght (
km)
Wind Direction (deg)
Ozonesonde at Beltsville, MDLaunched: August 18, 2009, 2:40 PM (EDT)
0
0.5
1
1.5
2
2.5
3
3.5
4
0 2 4 6 8 10 12 14
Hei
ght (
km)
Wind Speed (m/s)
Ozonesonde at Beltsville, MDLaunched: August 18, 2009, 2:40 PM (EDT)
0
0.5
1
1.5
2
2.5
3
3.5
4
-5 5 15 25 35 45 55 65 75 85 95 105
Heig
ht (k
m)
0
0.5
1
1.5
2
2.5
3
3.5
4
T (degC)RH (%)
WE S
The Influence of the Chesapeake Bay Breeze on Maryland Air QualityLaura Landry, Michael Woodman, and Duc Nguyen | Maryland Department of the Environment, Baltimore, MD
OVERVIEWMaryland has greatly improved its air quality over the past several years. However, one region within the
Baltimore Nonattainment Area (BNAA) presents many challenges in meeting the 2008 8-hour average ground-level ozone National Ambient Air Quality Standard (NAAQS) of 75 ppb. The northern Chesapeake Bay regionobserves the highest ozone concentrations throughout the state, largely due to its location downwind of twomajor metropolitan areas as well as the development of the bay breeze. The formation of this micro-scalecirculation has been known to create a sharp gradient of monitored ozone concentrations across its boundary.
A climatological study of the Chesapeake Bay breeze is presented, specifically focusing on the northern bayregion of the BNAA. The results of this study describe bay breeze frequency during the months of June-August,2004-2009 with respect to days when ozone exceeded the standard. In addition, a comparison of ozoneconcentrations between inland and coastal air monitoring sites will help quantify the ozone load that can beattributed to the bay breeze.
METHODOLOGYCriteria were developed to identify bay breeze, marginal,
and non-bay breeze events. These were an adaptation ofMiller and Keim (2003) sea breeze event criteria.
BAY BREEZE:1) An onshore wind shift must occur at 1+ coastal sites.
Coastal sites: Edgewood, EssexInland sites: Aldino, Padonia
2) 1+ inland sites must display parallel, antiparallel, orperpendicular wind flow to the shoreline.
3) Wind speeds associated with the bay breeze must be≥ 3 kts. 1 hour of lighter wind speed was allowable dueto the bay breeze’s light wind nature.
4) Criteria #1-3 must be sustained for ≥ 3 hrs.
MARGINAL:All bay breeze criteria were met except the bay breeze duration lasts < 3 hrs.
NON-BAY BREEZE:Bay breeze and marginal criteria were not met.
NOTE: Fort Meade was closed in 2004
NON-BAY BREEZEOnset: - Dissipation: -• Maximum ozone gradient of 17 ppb at 2100 UTC• High pressure over the Midwest and western Mid-Atlantic
regions• Synoptic wind flow from N• Mostly sunny skies• Maximum temperatures in the low 90’s ( F)
July 31 2007
1600 UTC
July 31 2007
2100 UTC
Aug. 1, 2007
0000 UTC
Hourly Ozone Trends: July 31, 2007
0
20
40
60
80
100
120
140
500 800 1100 1400 1700 2000 2300 200
Hour (UTC)
Ozo
ne (p
pb)
AldinoDavidsonvilleEdgewoodEssexFurleyPadoniaSouth Carroll
MARGINALOnset: 1900 UTC Dissipation: 2100 UTC• Maximum ozone gradient of 21 ppb at 2000 UTC• High pressure over the southern Mid-Atlantic• Stationary front W-E across the Midwest and PA• Mostly sunny skies• Maximum temperatures in the low 90’s ( F)
Aug. 4, 2004
1900 UTC
Aug. 4, 2004
2000 UTC
Aug. 4, 2004
2100 UTC
Hourly Ozone Trends: August 4, 2004
020406080
100120140
500 800 1100 1400 1700 2000 2300 200
Hour (UTC)
Ozo
ne (
ppb)
AldinoDavidsonvilleEdgewoodEssexFort MeadePadoniaSouth Carroll
BAY BREEZEOnset: 1600 UTC Dissipation: 0100 UTC• Maximum ozone gradient of 55 ppb at 2100 UTC• Weak high pressure over Mid-Atlantic region• Synoptic wind flow from WNW• Mostly sunny skies• Maximum temperatures in the upper 80’s ( F)
June 25, 2009
1600 UTC
KDOX, 1653 UTC
June 25, 2009
2100 UTC
June 26, 2009
0100 UTC
Hourly Ozone Trends: June 25, 2009
020
406080
100
120140
500 800 1100 1400 1700 2000 2300 200Hour (UTC)
Ozo
ne (p
pb)
AldinoDavidsonvilleEdgewoodEssexFurleyPadoniaSouth Carroll
RESULTS
Of the 83 cases selected from 130 BNAA exceedance days, there were 24 bay breeze events, 15 marginalevents, and 44 non-bay breeze events. For bay breeze events, the average hour of onset was 1600 UTC, whilethe typical hour of dissipation was 2300 UTC. For marginal events, most had an hour of onset and dissipation of1800 and 2000 UTC, respectively. The maximum ozone gradient was calculated by taking the difference in ozoneconcentrations from coastal sites to inland sites. These gradients showed a large spread of values, especially formarginal events. However, they do show that the bay breeze’s median gradient of 37 ppb was the largest whilenon-bay breeze events had the lowest of 13 ppb. This means that the median gradient of bay breeze events wasnearly 3X greater than the non-bay breeze.
Maximum Ozone Gradient by Event Type
-25
-15
-5
5
15
25
35
45
55
65
Bay Breeze Marginal Non-Bay BreezeOzo
ne g
radi
ent (
ppb)
Q3
Max
Median
Min
Q1
Hour of Onset
0123456789
101112
1400 1500 1600 1700 1800 1900 2000 2100Hour (UTC)
Freq
uenc
y
Bay BreezeMarginal
Hour of Dissipation
0123456789
101112
1600 1700 1800 1900 2000 2100 2200 2300Hour (UTC)
Freq
uenc
y
Bay BreezeMarginal
Distribution by Event Type
29%
53%
18%
Non-Bay Breeze
Bay Breeze
Marginal
REFERENCES:
AIRNow, cited 2009: AIRNow-Tech. [www.airnowtech.org]
Miller, S. T. and B. T. Keim, 2003: Synoptically-driven controls on the sea breeze of the central New England coast. Wea. Forecasting, 18, 236-248.
NASA, cited 2009: The LANDSAT Program. [landsat.gsfc.nasa.gov]DDEPARTMENT OF THE EPARTMENT OF THE EENVIRONMENTNVIRONMENT
CONTACT:ARMA / Ambient Air Monitoring Program
1800 Washington Blvd., Suite 730Baltimore, MD 21230Phone: (410) 537-3616 V
ersi
on: 1
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09