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An evaluation of the spatio-temporal characteristics of meteorologically-adjusted ozone trends in North Texas A preliminary analysis by Mahdi Ahmadi and Kuruvilla John Department of Mechanical and Energy Engineering University of North Texas Air Quality Technical Meeting, NCTCOG Arlington, TX. April 17, 2014
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Transcript of unt-nctcog-presentation-041714
An evaluation of the spatio-temporal characteristics of meteorologically-adjusted ozone trends in North Texas
A preliminary analysis
by
Mahdi Ahmadi and Kuruvilla John
Department of Mechanical and Energy Engineering University of North Texas
Air Quality Technical Meeting, NCTCOG Arlington, TX. April 17, 2014
2
The Research Study objective: Evaluate the meteorologically adjusted trends in
the measured ozone concentrations in north Texas
Study area: North Texas region including DFW metroplex
Study period: 1997-2014 (12-17 years worth of data)
Air quality data: Ozone and meteorological parameters
Number of air quality monitoring sites: 16 CAMS operated by TCEQ
Method: Statistical analysis of raw ozone data (part I) and
meteorologically adjusted ozone trend using KZ- filtering method (part II)
3
TCEQ CAMS : North Texas Sites Current ozone level
Source: https://www.tceq.texas.gov
4
Data
Time series of 8-hr average ozone concentrations were extracted from TCEQ’s Texas Air Monitoring Information System (TAMISWeb) for the 1997-2014 period (some of the monitoring stations were activated later than 1997) at sixteen state operated Continuous Ambient Monitoring Stations (CAMS).
In addition to the 8-hr ozone data, hourly and 8-hr averaged values of meteorological parameters for the same period were also acquired. Meteorological data include ambient temperature (T), solar radiation (SR), relative humidity (RH), and wind speed and direction (W).
Time series of the daily maxima of all parameters were compiled and used in
this study to evaluate the meteorologically adjusted trends in the ozone concentrations over the north Texas region.
5
Study Area Total number of gas wells:
• At the end of 2007: 5720 wells • At the end of 2013: 17,494 wells
Rate: 713 wells/year (between 2000-2006), and 1682 wells/year (2007-2013)
Source: RRC and TCEQ
6
Monitoring Sites
CAMS # Name County Parameters No. of wells - 10
mi C76 Parker County Parker O3, SR, T, W 158 C73 Granbury Hood O3, SR, T, W 428 C75 Eagle Mountain Tarrant O3, SR, T, W 2723 C77 Cleburne Airport Johnson O3, SR, T, W 1474 C13 Ft. Worth Northwest Tarrant O3, SR, T, RH, W 1092 C17 Keller Tarrant O3, SR, T, W 1364 C56 Denton Municipal Airport Denton O3, SR, T, RH, W 1362 C61 Arlington Muni. Airport Tarrant O3, SR, T, W 862 C70 Grapevine Fairway Grapevine O3, SR, T, RH, W 299 C402 Dallas Executive Airport Dallas O3, T, W 1 C60 Dallas Hinton St. Dallas O3, SR, T, RH, W 2 C63 Dallas North No. 2 Dallas O3, SR, T, W 2 C31 Frisco Collin O3, SR, T, W 0 C69 Rockwall Heat Rockwall O3, SR, T, W 0 C71 Kaufman Kaufman O3, SR, T, RH, W 0 C1006 Greenville Hunt O3, SR, T, W 0
“Fracking
region” (FR)
“Non-fracking
region” (NFR)
7
Methods
Part I: Statistical evaluation of trends in the raw ozone data • Ozone design value: “the 3-year average annual fourth-
highest daily maximum 8-hour average ozone concentration”
• Ozone exceedances: Number of days with maximum 8-hour ozone concentration exceeding NAAQS threshold (75 ppb)
Evaluations performed for the FR and NFR regions over two
contiguous periods: 2000-2006 (B07) and 2007-2013 (A07)
8
Results – Part I Trend in the ozone design values within FR
Average percent change from B07 (2000-2006) to A07 (2007-2013): -10%
65
70
75
80
85
90
95
100
105
2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013
Ozo
ne
des
ign
val
ue
(pp
b)
Year
C73 C17 C56 C70 C13 C75 C76 C77 C61
NAAQS :75 ppb
B07 A07
9
Results – Part I Trend in the ozone design values within NFR
Average percent change from B07 (2000-2006) to A07 (2007-2013): -10%
65
70
75
80
85
90
95
100
105
2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013
Ozo
ne
des
ign
val
ue
(pp
b)
Year
C60 C63 C69 C71 C402 C1006 C31 C77 C61
NAAQS :75 ppb
B07 A07
10
Results – Part I Annual trend in the average number of exceedance days (> 75 ppb)
Average percent change from B07 (2000-2006) to A07 (2007-2013): • Fracking region: -61.6% • Non-fracking region: -65.7%
0
5
10
15
20
25
30
352
00
0
20
01
20
02
20
03
20
04
20
05
20
06
20
07
20
08
20
09
20
10
20
11
20
12
20
13
Nu
mb
er o
f ex
ceed
ance
s d
ays
Year
FR NFRB07 A07
11
Results – Part I Number of average ozone exceedance days by month (> 75 ppb)
0
1
2
3
4
5
6
7
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Nu
mb
er o
f o
zon
e ex
ceed
ance
day
s
FR (B07) NFR (B07)
FR (A07) NFR (A07)
12
Results – Part I Average percent change of ozone exceedances between 2000-2006
(B07) and 2007-2013 (A07)
Ozone exceedances
Time period (75 ppb threshold)
FR NFR
May -47% -78%
Jun -74% -76%
Jul -66% -72%
Aug -49% -54%
Sep -64% -64%
Whole year -61.6% -65.7%
13
Results – Part I Trend of the average of maximum daily ozone values by month
20
25
30
35
40
45
50
55
60
65
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Ave
rage
of
max
imu
m d
aily
ozo
ne
(pp
b)
FR (B07) NFR (B07)
FR (A07) NFR (A07)
14
Results – Part I Number of days with temperatures exceeding 100 F
0
10
20
30
40
50
60
20
00
20
01
20
02
20
03
20
04
20
05
20
06
20
07
20
08
20
09
20
10
20
11
20
12
20
13
Nu
mb
er o
f D
ays
Year
FR NFRB07 A07
15
Results – Part I Wind rose for CAMS 13 (Ft. Worth Northwest) (May, Jun, Jul, Aug, Sep)
0
5
10
15
20
25
30
35N
NE
E
SE
S
SW
W
NW
0
5
10
15
20
25
30
35
Fre
qu
ency
(p
erce
nt)
Wind speed (mph)
>= 10
8 - 10
6 - 8
4 - 6
2 - 4
0 - 2
0
5
10
15
20
25
30
35N
NE
E
SE
S
SW
W
NW
0
5
10
15
20
25
30
35
Fre
qu
ency
(p
erce
nt)
Wind speed (mph)
>= 10
8 - 10
6 - 8
4 - 6
2 - 4
0 - 2
B07 (2000-2006) A07 (2007-2013)
16
Results – Part I Wind rose at CAMS 60 (Dallas, Hinton St.) (May, Jun, Jul, Aug, Sep)
B07 (2000-2006) A07 (2007-2013)
0
5
10
15
20
25
30
35N
NE
E
SE
S
SW
W
NW
0
5
10
15
20
25
30
35
Fre
qu
ency
(p
erce
nt)
Wind speed (mph)
>= 10
8 - 10
6 - 8
4 - 6
2 - 4
0 - 2
0
5
10
15
20
25
30
35N
NE
E
SE
S
SW
W
NW
0
5
10
15
20
25
30
35
Fre
qu
ency
(p
erce
nt)
Wind speed (mph)
>= 10
8 - 10
6 - 8
4 - 6
2 - 4
0 - 2
17
Meteorologically Adjusted Ozone
Part II: Statistical evaluation of trends of meteorologically adjusted (M.A.) ozone • Construction of M.A. ozone: application of Kolmogorov-
Zurbenko (KZ) filter
• M.A. ozone trends: statistical evaluation of total, long-term, and baseline M.A. ozone
Evaluations performed for the FR and NFR regions over two contiguous periods: 2000-2006 (B07) and 2007-2013 (A07)
18
Method – KZ-filter KZ-filter is a robust low-pass filter used for spectral (frequency-based)
decomposition of time-series*
Computationally KZ-filter is a simple iterative moving average technique
Log-transformed raw ozone time series
Spectral decomposition (KZ-
filter)
* Rao ST, Zurbenko IG. Detecting and tracking changes in ozone air quality. Air & waste 1994; 44: 1089-1092. Rao ST, Zalewsky E, Zurbenko IG. Determining temporal and spatial variations in ozone air quality. Journal of the Air & Waste Management Association 1995; 45: 57-61.
𝑌𝑖 =1
𝑚 𝑋𝑖+𝑗
k
𝑗=−𝑘
Long-term
Seasonal
Short-term
19
Meteorologically Adjusted Ozone • Step 1: Spectral decomposition of the ozone and meteorological time
series by applying KZ-filter
• Step 2: Baseline and short-term components of ozone time-series are calculated using a three variable linear regression model (with temperature and solar radiation)
• Step 3: Meteorologically adjusted ozone time-series is calculated as the residuals of linear regressions
• Step 4: KZ-filter is applied again to M.A. ozone time-series to calculate long-term and baseline components of M.A. ozone
𝑂 𝑡 = 𝐹 𝑇, 𝑆𝑅 + 𝑂MA(𝑡)
𝑂MA(𝑡) = 𝜖BL(𝑡) + 𝜖𝑊(𝑡)
𝑋(𝑡) = 𝑒(𝑡) + 𝑆(𝑡) +𝑊(𝑡)
&𝑒 𝑡 = 𝑋365,3(𝑡
&𝑆 𝑡 = 𝑋15,5(𝑡) − 𝑋365,3(𝑡
&𝑊 𝑡 = 𝑋 𝑡 − 𝑋15,5(𝑡
&𝐵𝐿 𝑡 = 𝑒 𝑡 + 𝑆 𝑡
20
Results – Part II
Because all expressions are given for the natural logarithm of raw ozone data, M.A. ozone values have multiplicative effects in original ozone time series
Also since OM.A. values are sufficiently small therefore:
Therefore 𝑂MA 𝑡 × 100 values represent change in mean value of the
original ozone time series
Statistical evaluation of all components of M.A. ozone (mean value, long-term, short-term, and baseline) is performed to evaluate the contribution of non-meteorological variables including anthropogenic influences affecting ozone formation and destruction.
exp 𝑂𝑀.𝐴.& ≈ 1 + 𝑂𝑀.𝐴.&
21
Results – Part II Examples of calculated and measure ozone time series and residuals (M.A. ozone)
1
1.5
2
2.5
3
3.5
4
4.5
5
2001 2003 2004 2006 2007 2008 2010 2011
Log
of
ozo
ne
(pp
b)
Measured Calculated
-2
-1.5
-1
-0.5
0
0.5
1
2001 2003 2004 2006 2007 2008 2010 2011
M.A
. ozo
ne
Year
M.A. ozone Baseline of M.A. ozone
Constructing M.A. ozone for C56 (Denton)
1
1.5
2
2.5
3
3.5
4
4.5
5
2003 2004 2006 2007 2008 2009 2010 2011
Lo
g o
f o
zon
e (p
pb
)
Measured Calculated
-2
-1.5
-1
-0.5
0
0.5
1
2003 2004 2006 2007 2008 2009 2010 2011
Lo
g o
f M
.A. o
zon
e (p
pb
)
Year
M.A. ozone Baseline of M.A. ozone
Constructing M.A. ozone for C31 (Frisco)
-3
-2.5
-2
-1.5
-1
-0.5
0
0.5
1
2002 2003 2004 2005 2006 2007 2008 2009 2010 2011
M.A
. ozo
ne
con
cen
trat
ion
Year
22
Results – Part II Box plot presentation of 𝑂MA(𝑡) (the maximum, 75th percentile, median,
mean, 25th percentile, and minimum) for FR and NFR
𝑂MA 𝑡 × 100 values represent change in mean value of the original ozone time series
23
Results – Part II Mean values of 𝑂MA(𝑡)
𝑂MA 𝑡 × 100 values represent change in mean value of the original ozone time series
-0.06
-0.04
-0.02
0.00
0.02
0.04
0.06
0.08
0.10
2002 2003 2004 2005 2006 2007 2008 2009 2010 2011
Ave
rage
M.A
. ozo
ne
Year
FR NFR
24
Results – Part II Mean value of of 𝑂MA 𝑡 during ozone season (May, Jun, Jul, Aug, Sep)
𝑂MA 𝑡 × 100 values represent change in mean value of the original ozone time series
-0.10
-0.05
0.00
0.05
0.10
0.15
0.20
2002 2003 2004 2005 2006 2007 2008 2009 2010 2011
Ave
rage
of
M.A
. ozo
ne
(war
m m
on
ths)
Year
FR NFR
25
Results – Part II Mean values of 𝑂MA(𝑡) in FR and NFR during winter time (Nov, Dec, Jan, Feb)
𝑂MA 𝑡 × 100 values represent change in mean value of the original ozone time series
-0.10
-0.05
0.00
0.05
0.10
0.15
0.20
2002 2003 2004 2005 2006 2007 2008 2009 2010 2011
Ave
rage
of
M.A
. ozo
ne
(co
ld m
on
ths)
Year
FR NFR
26
Results – Part II Mean values of long-term component of 𝑂MA(𝑡) (that is devoid of
meteorological influence)
-0.06
-0.04
-0.02
0
0.02
0.04
0.06
2003 2004 2005 2006 2007 2008 2009 2010
Lo
ng-
term
co
mp
on
ent
of
M.A
. Ozo
ne
Year
Fracking Counties Non-fracking counties
𝑂MA 𝑡 × 100 values represent change in mean value of the original ozone time series
27
Remarks Daily vehicle miles traveled (VMT) is relatively flat during 2007-2010.
Source: TxDOT (Total VMT for Dallas, Denton, Wise, Tarrant, Hood, Parker, Hunt, Ellis, Collin, Rockwall & Kaufman counties)
28
Remarks Based on raw ozone data (B07 vs. A07):
Sites located in NFR show about 4% more reduction in the number of average ozone exceedances than in FR
Average of winter time daily maximum ozone values in FR is 3% more than in NFR
Based on the mean value of meteorologically-adjusted ozone 𝑂MA 𝑡 (post-2008): 12% increase within FR and a 4% increase in NFR was
noted During the winter time, 21% increase within FR and a
5% increase in NFR was noted
29
Future Research Needs Conduct similar adjusted trend analyses using long-term
measurements of NOx, VOC and PM2.5 in the region.
Additional rural monitoring of NOx, VOC and PM2.5 may be needed.
Perform source-receptor and source apportionment analyses using measured concentrations.
Develop a comprehensive regional emissions inventory for a more recent base year.
Conduct photochemical modeling for a recent episode as well as a year-round modeling using revised estimates of emissions and perform source apportionment analysis for various regions.
