Updated CART Analysis for Ozone through 2008 (PRELIMINARY DRAFT)
Summary
CART analysis was performed for 11 geographic areas in the LADCO region. Each of the major
metropolitan areas is represented, as well as several regions where ozone formation is dominated by
transport. Only monitors with continuous records for the 1995 - 2008 period were included. For each
geographic area, regression trees were developed that classify each summer day (May-September) by
its meteorological conditions. An example regression tree (for Cleveland) is presented in Figure 1.
(Regression trees for other cities are provided in Attachment 1.) The splitting criteria for each node are
given in the blue boxes. If the condition is true, then follow the left branch; if not, then follow the right
branch. Terminal nodes (red boxes) give an average concentration and standard deviation of all the
ozone concentrations that fall into that node.
Node 1
TAVGPM <= 76.019
STD = 0.017
Avg = 0.046
N = 17455
<= 76.019
> 76.019
Node 2
TMAX <= 70.601
STD = 0.012
Avg = 0.038
N = 11322
Node 8
TAVGPM <= 84.308
STD = 0.016
Avg = 0.060
N = 6133
<= 70.601
> 70.601
<= 84.308
> 84.308
Node 3
RHAVG <= 75.990
STD = 0.011
Avg = 0.034
N = 7084
Node 5
RHAVG <= 59.735
STD = 0.011
Avg = 0.043
N = 4238
Node 9
WNDRUN <= 311.450
STD = 0.013
Avg = 0.056
N = 4537
Node 14
TD850 <= 55.769
STD = 0.016
Avg = 0.072
N = 1596
<= 75.990
Node 4
RHAVG <= 56.440
STD = 0.010
Avg = 0.037
N = 4385
Terminal
Node 3
Avg = 0.030
N = 2699
<= 59.735
> 59.735
<= 311.450
> 311.450
Node 6
AVG_S_AM <= -1.820
STD = 0.012
Avg = 0.050
N = 696
Node 7
TMAX <= 73.751
STD = 0.011
Avg = 0.042
N = 3542
Node 10
TDELTA <= 18.090
STD = 0.014
Avg = 0.061
N = 1379
Node 12
TMAX <= 80.861
STD = 0.013
Avg = 0.054
N = 3158
> 18.090
Terminal
Node 1
Avg = 0.043
N = 871
Terminal
Node 2
Avg = 0.036
N = 3514
Terminal
Node 4
Avg = 0.038
N = 142
Terminal
Node 5
Avg = 0.053
N = 554
Terminal
Node 6
Avg = 0.039
N = 1442
Terminal
Node 7
Avg = 0.044
N = 2100
Terminal
Node 8
Avg = 0.055
N = 647
Node 11
T925 <= 64.220
STD = 0.014
Avg = 0.065
N = 732
Terminal
Node 9
Avg = 0.060
N = 383
Terminal
Node 10
Avg = 0.071
N = 349
Terminal
Node 14
Avg = 0.075
N = 1081
Terminal
Node 15
Avg = 0.065
N = 515
> 80.861
Terminal
Node 11
Avg = 0.051
N = 1359
Node 13
TD850 <= 46.130
STD = 0.013
Avg = 0.057
N = 1799
Terminal
Node 12
Avg = 0.063
N = 470
Terminal
Node 13
Avg = 0.055
N = 1329
Figure 1. Regression tree for Cleveland
No a priori selection of important meteorological variables is used to develop the trees; instead, the
CART model searches exhaustively through the 60 meteorological variables supplied to determine which
are most efficient in predicting ozone. Although the exact selection of predictive variables changes from
site to site, the universally common predictors are temperature, wind direction, and relative humidity.
These are included in the dataset as daily averages and maximums as well as averages at specific times
throughout the day (morning 7-10 am, afternoon 1-4 pm, etc.). Only occasionally did upper air
variables, transport time or distance, lake breeze, or other variables become significant. Notably, the
Door County site in Wisconsin is one where transport variables are more important than temperature.
Meteorological data are from National Weather Service stations, usually airports. Upper air data are
included as well. Because the upper air sites are far fewer in number than surface observation sites,
data from the nearest upper air site is matched to each surface site. USEPA provided the
meteorological dataset, which was compared to a similar dataset compiled at LADCO and found to be
largely identical. The USEPA dataset offered the advantage of some additional variables based on
trajectory calculations for each surface station.
Individual nodes represent days with similar meteorological conditions. Ozone trends in these nodes
were plotted (see example trend plot for Cleveland in Figure 2 – trend plots for other cities are provided
in Attachment 2). By grouping days with similar meteorology, the influence of meteorological variability
on the underlying trend in ozone concentrations is partially removed; the remaining trend is presumed
to be due to trends in precursor emissions or other non-meteorological influences. Trends in almost all
cases were declining or flat.
Figure 2. Trend in higher concentration CART nodes for Cleveland
The CART results were further examined by developing an index of ozone-conduciveness as a means to
compare the propensity of particular years to form ozone. Years with many days characterized by
meteorological conditions like high temperatures and low humidity are expected to produce higher
ozone concentrations than years with less conducive conditions. An index based on the number of days
assigned to high-concentration nodes in each year compared to the average days in those nodes over
the 14-year study period should reflect this varying ozone conduciveness. For each geographic region,
the index is shown (see example plot for Cleveland in Figure 3 – plots for other cities are provided in
Attachment 2). For most sites examined, ozone concentrations in the most recent years are lower than
previous years, even when the ozone index indicates the meteorological conditions were similar to
those in previous years. This is a possible indication that regional NOx controls implemented under the
NOx SIP call, which were largely completed by 2004, have been effective in reducing ozone.
Figure 3. Trend in ozone conduciveness index for Cleveland
Attachment 1
Regression Trees
Chicago
Node 1
TAVGPM <= 78.800
STD = 0.016
Avg = 0.041
N = 25732
<= 78.800
> 78.800
Node 2
TAVGPM <= 70.295
STD = 0.012
Avg = 0.034
N = 17570
Node 10
TAVGPM <= 85.280
STD = 0.015
Avg = 0.055
N = 8162
<= 70.295
> 70.295
<= 85.280
> 85.280
Node 3
RHAVG <= 58.485
STD = 0.011
Avg = 0.031
N = 10957
Node 7
RHAVGMID <= 81.025
STD = 0.011
Avg = 0.041
N = 6613
Node 11
MHMAX <= 1119.525
STD = 0.012
Avg = 0.050
N = 5253
Node 14
RHAVGMID <= 53.130
STD = 0.015
Avg = 0.063
N = 2909
<= 58.485
> 58.485
<= 81.025
<= 1119.525
> 1119.525
<= 53.130
Node 4
AVG_W_WIN <= -0.080
STD = 0.010
Avg = 0.037
N = 2302
Node 5
AVG_W_PM <= -2.470
STD = 0.011
Avg = 0.029
N = 8655
Node 8
TRANSOUTH <= -326.230
STD = 0.011
Avg = 0.041
N = 6154
Node 12
RHAVGMID <= 68.465
STD = 0.012
Avg = 0.048
N = 3745
Node 13
WDAVGPM <= 218.750
STD = 0.013
Avg = 0.056
N = 1508
Node 15
WSAVG <= 3.425
STD = 0.014
Avg = 0.066
N = 2036
> -2.470
Terminal
Node 1
Avg = 0.041
N = 1162
Terminal
Node 2
Avg = 0.033
N = 1140
> -326.230
Node 6
TMAX <= 66.641
STD = 0.011
Avg = 0.026
N = 4594
Terminal
Node 3
Avg = 0.032
N = 4061
Terminal
Node 4
Avg = 0.024
N = 3138
Terminal
Node 9
Avg = 0.030
N = 459
Terminal
Node 6
Avg = 0.036
N = 1369
Terminal
Node 5
Avg = 0.030
N = 1456
Node 9
MHMAX <= 1328.360
STD = 0.011
Avg = 0.043
N = 4785
Terminal
Node 7
Avg = 0.042
N = 4178
Terminal
Node 10
Avg = 0.049
N = 3200
Terminal
Node 11
Avg = 0.040
N = 545
Terminal
Node 12
Avg = 0.059
N = 1051
Terminal
Node 13
Avg = 0.050
N = 457
Terminal
Node 14
Avg = 0.071
N = 1048
Terminal
Node 15
Avg = 0.061
N = 988
Terminal
Node 8
Avg = 0.049
N = 607
Cincinnati
Node 1
TAVGPM <= 79.331
STD = 0.018
Avg = 0.049
N = 5859
<= 79.331
> 79.331
Node 2
RHAVGMID <= 70.520
STD = 0.014
Avg = 0.039
N = 3251
Node 8
TAVGPM <= 86.081
STD = 0.015
Avg = 0.061
N = 2608
<= 70.520
> 70.520
<= 86.081
> 86.081
Node 3
TMAX <= 69.881
STD = 0.013
Avg = 0.043
N = 2363
Node 7
RHAVGMID <= 83.955
STD = 0.012
Avg = 0.030
N = 888
Node 9
RHAVGMID <= 58.270
STD = 0.013
Avg = 0.056
N = 1577
Node 12
TRANDIS <= 284.375
STD = 0.014
Avg = 0.069
N = 1031
<= 69.881
> 69.881
Node 4
RHAVG <= 68.105
STD = 0.012
Avg = 0.036
N = 960
Node 5
RHAVG <= 72.120
STD = 0.012
Avg = 0.047
N = 1403
Terminal
Node 6
Avg = 0.033
N = 559
Terminal
Node 7
Avg = 0.025
N = 329
<= 58.270
> 58.270
<= 284.375
> 284.375
Node 10
TRANDIS <= 391.515
STD = 0.012
Avg = 0.061
N = 971
Node 11
RHAVGMID <= 69.990
STD = 0.011
Avg = 0.049
N = 606
Node 13
H850 <= 1531.500
STD = 0.013
Avg = 0.075
N = 447
Node 14
TDELTA <= 23.670
STD = 0.013
Avg = 0.064
N = 584
> 72.120
Terminal
Node 1
Avg = 0.041
N = 502
Terminal
Node 2
Avg = 0.031
N = 458
Terminal
Node 3
Avg = 0.051
N = 718
Node 6
TMAX <= 78.062
STD = 0.011
Avg = 0.043
N = 685
Terminal
Node 4
Avg = 0.040
N = 432
Terminal
Node 5
Avg = 0.048
N = 253
Terminal
Node 8
Avg = 0.064
N = 579
Terminal
Node 9
Avg = 0.055
N = 392
Terminal
Node 10
Avg = 0.052
N = 408
Terminal
Node 11
Avg = 0.043
N = 198
Terminal
Node 12
Avg = 0.066
N = 69
Terminal
Node 13
Avg = 0.077
N = 378
Terminal
Node 14
Avg = 0.061
N = 447
Terminal
Node 15
Avg = 0.072
N = 137
Terminal
Node 16
Avg = 0.055
N = 873
Detroit
Node 1
TAVGPM <= 79.349
STD = 0.017
Avg = 0.045
N = 12382
<= 79.349
> 79.349
Node 2
TAVGPM <= 72.239
STD = 0.012
Avg = 0.038
N = 8383
Node 9
TAVGPM <= 85.784
STD = 0.016
Avg = 0.060
N = 3999
<= 72.239
> 72.239
<= 85.784
> 85.784
Node 3
RHAVG <= 58.920
STD = 0.011
Avg = 0.035
N = 5263
Node 7
AVG_S_WIN <= -0.355
STD = 0.012
Avg = 0.044
N = 3120
Node 10
WNDRUN <= 408.580
STD = 0.014
Avg = 0.056
N = 2844
Node 16
AVG_W_WIN <= 1.990
STD = 0.016
Avg = 0.069
N = 1155
<= 58.920
> 58.920
Node 4
TAVGPM <= 61.331
STD = 0.010
Avg = 0.042
N = 1557
Node 5
AVG_S_PM <= -0.665
STD = 0.010
Avg = 0.032
N = 3706
Terminal
Node 6
Avg = 0.038
N = 1252
> -0.355
<= 408.580
> 408.580
<= 1.990
Node 8
RHAVGMID <= 73.225
STD = 0.012
Avg = 0.048
N = 1868
Node 11
TRANSOUTH <= -104.410
STD = 0.014
Avg = 0.062
N = 1360
Node 14
AVG_S_WIN <= -1.480
STD = 0.011
Avg = 0.051
N = 1484
Node 17
AVG_S_WIN <= 0.005
STD = 0.015
Avg = 0.075
N = 579
> -0.665
Terminal
Node 1
Avg = 0.038
N = 764
Terminal
Node 2
Avg = 0.045
N = 793
Terminal
Node 3
Avg = 0.030
N = 1833
> -104.410
Node 6
TAVGPM <= 67.577
STD = 0.010
Avg = 0.035
N = 1873
Terminal
Node 7
Avg = 0.050
N = 1525
Terminal
Node 8
Avg = 0.039
N = 343
> -1.480
Node 12
RHAVGMID <= 60.730
STD = 0.014
Avg = 0.065
N = 1013
Terminal
Node 9
Avg = 0.052
N = 347
> 0.005
Node 15
RHAVG <= 76.265
STD = 0.011
Avg = 0.052
N = 1306
Terminal
Node 13
Avg = 0.042
N = 178
Terminal
Node 19
Avg = 0.063
N = 576
Terminal
Node 16
Avg = 0.058
N = 86
Node 18
RHAVG <= 66.640
STD = 0.014
Avg = 0.078
N = 493
<= 60.730
Terminal
Node 4
Avg = 0.032
N = 1190
Node 13
TAVGPM <= 82.814
STD = 0.013
Avg = 0.068
N = 748
Terminal
Node 5
Avg = 0.038
N = 683
Terminal
Node 10
Avg = 0.064
N = 450
Terminal
Node 12
Avg = 0.057
N = 265
Terminal
Node 14
Avg = 0.054
N = 964
Terminal
Node 15
Avg = 0.046
N = 342
Terminal
Node 17
Avg = 0.083
N = 268
Terminal
Node 11
Avg = 0.073
N = 298
Indiana - Lakeshore
Node 1
TAVGPM <= 79.349
STD = 0.017
Avg = 0.048
N = 7312
<= 79.349
> 79.349
Node 2
TAVGPM <= 70.952
STD = 0.012
Avg = 0.041
N = 4910
Node 7
TAVGPM <= 84.524
STD = 0.016
Avg = 0.063
N = 2402
<= 70.952
> 70.952
<= 84.524
> 84.524
Node 3
RHAVG <= 67.255
STD = 0.010
Avg = 0.037
N = 2691
Node 4
RHAVG <= 59.360
STD = 0.012
Avg = 0.046
N = 2219
Node 8
TDELTA <= 18.810
STD = 0.013
Avg = 0.058
N = 1472
Node 10
TDELTA <= 19.890
STD = 0.016
Avg = 0.070
N = 930
> 59.360
Terminal
Node 1
Avg = 0.042
N = 1015
Terminal
Node 2
Avg = 0.034
N = 1676
Terminal
Node 3
Avg = 0.054
N = 355
Node 5
TDELTA <= 12.510
STD = 0.011
Avg = 0.044
N = 1864
Terminal
Node 7
Avg = 0.053
N = 801
> 18.810
<= 19.890
> 19.890
Node 9
TRANSOUTH <= -117.910
STD = 0.013
Avg = 0.063
N = 671
Node 11
TRANSOUTH <= 491.635
STD = 0.015
Avg = 0.064
N = 446
Node 13
H850 <= 1555.500
STD = 0.015
Avg = 0.076
N = 484
> 12.510
Terminal
Node 4
Avg = 0.040
N = 579
Node 6
TRANSOUTH <= -183.555
STD = 0.011
Avg = 0.046
N = 1285
Terminal
Node 5
Avg = 0.043
N = 566
Terminal
Node 6
Avg = 0.049
N = 719
<= 491.635
Terminal
Node 8
Avg = 0.056
N = 177
Terminal
Node 9
Avg = 0.065
N = 494
Node 12
DEVH700 <= 6.100
STD = 0.015
Avg = 0.067
N = 323
Terminal
Node 10
Avg = 0.055
N = 62
Terminal
Node 11
Avg = 0.070
N = 261
Terminal
Node 12
Avg = 0.057
N = 123
Terminal
Node 13
Avg = 0.072
N = 296
Terminal
Node 14
Avg = 0.083
N = 188
Terminal
Node 18
Avg = 0.073
N = 225
Indianapolis
Node 1
TAVGPM <= 79.799
STD = 0.016
Avg = 0.052
N = 10028
<= 79.799
> 79.799
Node 2
RHAVGMID <= 66.545
STD = 0.012
Avg = 0.045
N = 5904
Node 6
TDELTA <= 18.990
STD = 0.014
Avg = 0.063
N = 4124
<= 66.545
> 66.545
<= 18.990
> 18.990
Node 3
TRANSOUTH <= -297.220
STD = 0.011
Avg = 0.049
N = 3823
Node 5
TMAX <= 73.751
STD = 0.011
Avg = 0.037
N = 2081
Node 7
TAVGPM <= 87.080
STD = 0.012
Avg = 0.059
N = 2554
Node 12
TRANDIS <= 383.715
STD = 0.014
Avg = 0.069
N = 1570
> -297.220
Node 4
TAVGPM <= 69.350
STD = 0.011
Avg = 0.053
N = 2211
Terminal
Node 1
Avg = 0.043
N = 1612
Terminal
Node 4
Avg = 0.033
N = 1130
Terminal
Node 5
Avg = 0.042
N = 951
<= 87.080
> 87.080
<= 383.715
Node 8
RHAVGMID <= 70.740
STD = 0.011
Avg = 0.056
N = 1950
Node 11
WSAVG <= 3.760
STD = 0.012
Avg = 0.066
N = 604
Node 13
DEVH500 <= 57.135
STD = 0.014
Avg = 0.074
N = 913
Terminal
Node 14
Avg = 0.063
N = 657
<= 70.740
Terminal
Node 2
Avg = 0.046
N = 645
Node 9
AVG_S_PM <= -1.410
STD = 0.011
Avg = 0.058
N = 1669
Terminal
Node 3
Avg = 0.055
N = 1566
Terminal
Node 9
Avg = 0.047
N = 281
Terminal
Node 10
Avg = 0.070
N = 381
Terminal
Node 11
Avg = 0.060
N = 223
Terminal
Node 12
Avg = 0.070
N = 624
Terminal
Node 13
Avg = 0.082
N = 289
> -1.410
Node 10
RHAVGMID <= 55.265
STD = 0.011
Avg = 0.060
N = 1143
Terminal
Node 6
Avg = 0.053
N = 526
Terminal
Node 7
Avg = 0.064
N = 531
Terminal
Node 8
Avg = 0.056
N = 612
NE Illinois – Lake County/Chiwaukee
Node 1
TMAX <= 75.641
STD = 0.016
Avg = 0.045
N = 8402
<= 75.641
> 75.641
Node 2
DT925 <= -1.956
STD = 0.012
Avg = 0.039
N = 5376
Node 9
TAVGAM <= 77.549
STD = 0.016
Avg = 0.058
N = 3026
<= -1.956
> -1.956
<= 77.549
> 77.549
Node 3
TMAX <= 68.621
STD = 0.010
Avg = 0.036
N = 3496
Node 5
AVG_W_WIN <= -0.965
STD = 0.012
Avg = 0.044
N = 1880
Node 10
AVG_S_PM <= 1.595
STD = 0.013
Avg = 0.053
N = 1927
Node 13
AVG_S_PM <= 2.405
STD = 0.017
Avg = 0.067
N = 1099
<= 68.621
<= -0.965
> -0.965
> 1.595
<= 2.405
> 2.405
Node 4
AVG_W_WIN <= -0.580
STD = 0.010
Avg = 0.033
N = 2458
Node 6
TAVGPM <= 60.404
STD = 0.012
Avg = 0.047
N = 1026
Node 8
TMAX <= 71.681
STD = 0.011
Avg = 0.040
N = 854
Node 11
AVG_W_PM <= -2.405
STD = 0.013
Avg = 0.056
N = 1108
Node 14
DEVH500 <= 49.655
STD = 0.014
Avg = 0.059
N = 452
Node 15
LAKEBREEZE <= 1.500
STD = 0.017
Avg = 0.072
N = 647
Terminal
Node 3
Avg = 0.040
N = 1038
> 60.404
Terminal
Node 1
Avg = 0.037
N = 1290
Terminal
Node 2
Avg = 0.030
N = 1168
Terminal
Node 4
Avg = 0.044
N = 505
Node 7
TRANSOUTH <= -54.830
STD = 0.012
Avg = 0.051
N = 521
Terminal
Node 5
Avg = 0.044
N = 182
Terminal
Node 6
Avg = 0.055
N = 339
Terminal
Node 9
Avg = 0.048
N = 819
<= -2.405
Terminal
Node 7
Avg = 0.037
N = 526
Terminal
Node 8
Avg = 0.045
N = 328
Node 12
TRANSOUTH <= 132.850
STD = 0.013
Avg = 0.060
N = 386
Terminal
Node 10
Avg = 0.055
N = 220
Terminal
Node 11
Avg = 0.067
N = 166
Terminal
Node 12
Avg = 0.053
N = 722
Terminal
Node 13
Avg = 0.054
N = 288
Terminal
Node 14
Avg = 0.067
N = 164
Terminal
Node 15
Avg = 0.066
N = 260
Terminal
Node 16
Avg = 0.076
N = 387
Milwaukee
Node 1
TAVGPM <= 73.976
STD = 0.016
Avg = 0.046
N = 4948
<= 73.976
> 73.976
Node 2
DT925 <= -2.806
STD = 0.011
Avg = 0.040
N = 3124
Node 7
TAVGAM <= 77.567
STD = 0.016
Avg = 0.058
N = 1824
<= -2.806
> -2.806
<= 77.567
> 77.567
Node 3
T925 <= 56.309
STD = 0.009
Avg = 0.036
N = 1780
Node 4
AVG_W_PM <= -0.695
STD = 0.012
Avg = 0.045
N = 1344
Node 8
AVG_S_PM <= 0.395
STD = 0.012
Avg = 0.052
N = 1120
Node 11
AVG_S_PM <= 2.405
STD = 0.017
Avg = 0.066
N = 704
Terminal
Node 1
Avg = 0.034
N = 1330
Terminal
Node 2
Avg = 0.040
N = 450
<= -0.695
> 0.395
<= 2.405
> 2.405
Node 5
TRANSOUTH <= -138.880
STD = 0.011
Avg = 0.047
N = 1071
Node 9
WDAVGPM <= 178.750
STD = 0.012
Avg = 0.055
N = 823
Node 12
DEVH500 <= 63.235
STD = 0.013
Avg = 0.057
N = 276
Node 13
AVG_W_PM <= -1.885
STD = 0.017
Avg = 0.072
N = 428
Terminal
Node 3
Avg = 0.042
N = 313
Terminal
Node 6
Avg = 0.038
N = 273
Terminal
Node 7
Avg = 0.046
N = 297
> -138.880
<= 178.750
Node 6
TAVGPM <= 64.427
STD = 0.011
Avg = 0.049
N = 758
Node 10
TRANSOUTH <= -83.130
STD = 0.013
Avg = 0.059
N = 385
Terminal
Node 4
Avg = 0.045
N = 351
Terminal
Node 5
Avg = 0.052
N = 407
Terminal
Node 8
Avg = 0.050
N = 112
Terminal
Node 10
Avg = 0.051
N = 438
Terminal
Node 11
Avg = 0.053
N = 195
Terminal
Node 12
Avg = 0.066
N = 81
Terminal
Node 9
Avg = 0.063
N = 273
<= -1.885
> -1.885
Node 14
TRANSOUTH <= -25.050
STD = 0.015
Avg = 0.081
N = 181
Node 15
TAVGPM <= 83.012
STD = 0.015
Avg = 0.066
N = 247
Terminal
Node 13
Avg = 0.064
N = 29
Terminal
Node 14
Avg = 0.084
N = 152
Terminal
Node 15
Avg = 0.054
N = 57
Terminal
Node 16
Avg = 0.070
N = 190
St.Louis
Node 1
TAVGPM <= 79.799
STD = 0.017
Avg = 0.050
N = 8753
<= 79.799
> 79.799
Node 2
TAVGPM <= 69.314
STD = 0.013
Avg = 0.040
N = 4566
Node 6
TAVGPM <= 86.567
STD = 0.015
Avg = 0.060
N = 4187
<= 69.314
> 69.314
<= 86.567
> 86.567
Node 3
MHMAX <= 1423.490
STD = 0.011
Avg = 0.034
N = 2167
Node 4
RHAVGMID <= 67.965
STD = 0.012
Avg = 0.045
N = 2399
Node 7
MRMAX <= 14.930
STD = 0.013
Avg = 0.055
N = 2201
Node 12
WNDRUN <= 547.675
STD = 0.016
Avg = 0.066
N = 1986
<= 14.930
> 14.930
<= 547.675
> 547.675
Node 8
TRANSOUTH <= -213.555
STD = 0.012
Avg = 0.059
N = 1184
Node 10
WNDRUN <= 461.145
STD = 0.013
Avg = 0.050
N = 1017
Node 13
TRANDIR <= 209.725
STD = 0.015
Avg = 0.069
N = 1441
Node 15
WSAVG <= 4.795
STD = 0.013
Avg = 0.056
N = 545
<= 67.965
Terminal
Node 1
Avg = 0.032
N = 1665
Terminal
Node 2
Avg = 0.041
N = 502
Node 5
TRANSOUTH <= -289.980
STD = 0.011
Avg = 0.048
N = 1766
Terminal
Node 3
Avg = 0.043
N = 531
Terminal
Node 4
Avg = 0.050
N = 1235
Terminal
Node 5
Avg = 0.038
N = 633
Terminal
Node 6
Avg = 0.051
N = 306
> -213.555
<= 461.145
Node 9
TRANWEST <= 56.105
STD = 0.012
Avg = 0.062
N = 878
Node 11
TDELTA <= 14.020
STD = 0.013
Avg = 0.054
N = 564
Terminal
Node 7
Avg = 0.065
N = 512
Terminal
Node 8
Avg = 0.057
N = 366
Terminal
Node 9
Avg = 0.047
N = 249
Terminal
Node 10
Avg = 0.059
N = 315
<= 209.725
Terminal
Node 11
Avg = 0.046
N = 453
Node 14
TDELTA <= 16.110
STD = 0.016
Avg = 0.072
N = 917
Terminal
Node 12
Avg = 0.067
N = 436
Terminal
Node 13
Avg = 0.077
N = 481
Terminal
Node 14
Avg = 0.064
N = 524
Terminal
Node 15
Avg = 0.061
N = 297
Terminal
Node 16
Avg = 0.051
N = 248
W. Michigan
Node 1
TAVGPM <= 75.299
STD = 0.017
Avg = 0.049
N = 7564
<= 75.299
> 75.299
Node 2
AVG_S_WIN <= 0.365
STD = 0.012
Avg = 0.043
N = 4957
Node 9
AVG_S_AM <= 0.485
STD = 0.017
Avg = 0.062
N = 2607
<= 0.365
> 0.365
<= 0.485
> 0.485
Node 3
RHAVGMID <= 42.785
STD = 0.010
Avg = 0.038
N = 2866
Node 5
TAVGPM <= 68.045
STD = 0.012
Avg = 0.049
N = 2091
Node 10
AVG_S_WIN <= -1.170
STD = 0.012
Avg = 0.050
N = 896
Node 11
TAVGPM <= 82.508
STD = 0.016
Avg = 0.068
N = 1711
Terminal
Node 1
Avg = 0.047
N = 463
> 42.785
<= 68.045
> 68.045
Node 4
AVG_W_PM <= 2.325
STD = 0.009
Avg = 0.037
N = 2403
Node 6
CCAVGPM <= 1.500
STD = 0.010
Avg = 0.044
N = 1030
Node 7
RHAVGMID <= 80.170
STD = 0.012
Avg = 0.053
N = 1061
Terminal
Node 9
Avg = 0.044
N = 342
Terminal
Node 10
Avg = 0.055
N = 554
<= 80.170
Terminal
Node 2
Avg = 0.033
N = 865
Terminal
Node 3
Avg = 0.039
N = 1538
Terminal
Node 4
Avg = 0.050
N = 301
Terminal
Node 5
Avg = 0.041
N = 729
> 82.508
Node 12
CCAVGPM <= 2.500
STD = 0.014
Avg = 0.064
N = 1208
Node 14
AVG_W_PM <= 1.255
STD = 0.016
Avg = 0.080
N = 503
<= 2.500
Node 8
TRANSOUTH <= 10.195
STD = 0.011
Avg = 0.055
N = 895
Terminal
Node 6
Avg = 0.048
N = 239
<= 82.508
Node 13
DEVT850 <= 1.256
STD = 0.013
Avg = 0.068
N = 604
Terminal
Node 8
Avg = 0.044
N = 166
Terminal
Node 7
Avg = 0.058
N = 656
Terminal
Node 11
Avg = 0.059
N = 156
Terminal
Node 13
Avg = 0.060
N = 604
Terminal
Node 14
Avg = 0.069
N = 97
Terminal
Node 12
Avg = 0.071
N = 448
WI Shoreline
Node 1
T925 <= 63.059
STD = 0.016
Avg = 0.047
N = 7549
<= 63.059
> 63.059
Node 2
TRANSOUTH <= -142.780
STD = 0.012
Avg = 0.041
N = 5009
Node 6
AVG_S_PM <= 3.425
STD = 0.018
Avg = 0.058
N = 2540
<= -142.780
> -142.780
<= 3.425
> 3.425
Node 3
RHAVG <= 60.375
STD = 0.009
Avg = 0.036
N = 2468
Node 4
CCAVGPM <= 4.500
STD = 0.012
Avg = 0.046
N = 2541
Node 7
AVG_S_WIN <= -1.095
STD = 0.014
Avg = 0.051
N = 1546
Node 9
RHAVGMID <= 74.625
STD = 0.018
Avg = 0.069
N = 994
<= 4.500
Terminal
Node 1
Avg = 0.042
N = 502
Terminal
Node 2
Avg = 0.034
N = 1966
Node 5
T925 <= 57.830
STD = 0.012
Avg = 0.049
N = 1533
Terminal
Node 5
Avg = 0.041
N = 1008
Terminal
Node 6
Avg = 0.041
N = 279
> -1.095
<= 74.625
> 74.625
Node 8
DEVH700 <= 53.860
STD = 0.014
Avg = 0.053
N = 1267
Node 10
T925 <= 68.819
STD = 0.017
Avg = 0.072
N = 760
Node 13
CCAVGPM <= 1.500
STD = 0.016
Avg = 0.058
N = 234
> 68.819
Terminal
Node 3
Avg = 0.046
N = 912
Terminal
Node 4
Avg = 0.053
N = 621
Terminal
Node 7
Avg = 0.051
N = 979
Terminal
Node 8
Avg = 0.061
N = 288
Node 11
TRANWEST <= 337.425
STD = 0.019
Avg = 0.079
N = 352
Terminal
Node 9
Avg = 0.067
N = 408
<= 337.425
Node 12
RHAVG <= 65.745
STD = 0.018
Avg = 0.082
N = 266
Terminal
Node 10
Avg = 0.094
N = 66
Terminal
Node 11
Avg = 0.078
N = 200
Terminal
Node 12
Avg = 0.069
N = 86
Terminal
Node 13
Avg = 0.067
N = 100
Terminal
Node 14
Avg = 0.052
N = 134
Terminal
Node 15
Avg = 0.082
N = 406
Attachment 2
Trends in Higher Concentration CART Nodes and Ozone Conduciveness Index
Ozone trends in CART nodes (each trend line depicts average ozone concentrations on meteorologically similar days)
and ozone-conducive Index. Blue line shows the ozone index, where higher values mean more days with ozone
conducive conditions and lower values mean fewer days with ozone conducive conditions. The red line plots the 4thhigh ozone concentration each year at the site.