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BRAVO Back-Trajectory Analyses
Why Consider ATAD? History of use at Big Bend - How Good is our past? History of comparison to other wind fields.
ATAD vs Hysplit with EDAS & FNL Wind Fields How different are they and why
Results of preliminary qualitative back-trajectory analyses.
BRAVO Meeting, San Antonio, TX, 23 March 2001
How are ATAD and Hysplit Different?1. Input data Raw sounding data for ATAD Modeled EDAS or FNL wind fields for Hysplit
2. Length of time data is obtainable 1946 - present for ATAD 1997 - present for Hysplit
3. Model methodology Average wind in a transport layer and radius for ATAD “Data following” for Hysplit (other options also)
4. Frequency of Output 4 starts/day, endpoints 8 times/day for ATAD, 5 day max length hourly starts, hourly endpoints for Hysplit, max length > 10 days
74794
71945
78897
78970
70026
70133
70200
70219
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70261
70273
70308
70316
7032670350
70361
70398
70414
7220172202
72206
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7224872249
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7225172261
722657227472293
7230572317
7231872327
723407235772363
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723657237672387
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724027240372426
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72456724697247672489
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7252872558725627257272582
72597 72632
7263472645726497265972662
726727268172694
7271272747
7276472768
727767278672797
74389
7445574560
78526
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7160071603
7172271801
7181171815
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71934
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76225
7638276394
76723 7838478526
78583 78866
78954
78970
UA Sites Used by ATAD on 8/10 0 GMT
ATAD Methodologyfrom Heffter, 1980
EDAS Meteorological Data Archive
The EDAS (Eta Data Assimilation System) data are a product of the NWS' National Centers for Environmental Prediction (NCEP). EDAS is a data assimilation system consisting of successive 3-h Eta model forecasts and Optimum Interpolation (OI) analyses.
•79 by 55 Lambert Conformal grid ~ 80 km resolution.
• 22 vertical layers on constant pressure surfaces from 1000 to 50 mbar
• 3 hour time increment
• Upper Air Data: 3-D winds, Temp, RH
• Surface Data includes: pressure, 10 meter winds, 2 meter Temp & RH, Momentum and heat flux
•Data is available from 1/97 to present. Note Oct. 1999 data is unavailable due to a fire at NCEP
FNL Meteorological Data ArchiveThe FNL data is a product of the Global Data Assimilation System (GDAS), which uses the Global spectral Medium Range Forecast model (MRF) to assimilate multiple sources of measured data and forecast meteorology.
•129 x 129 Polar Stereographic Grid with ~ 190 km resolution.
• 12 vertical layers on constant pressure surfaces from 1000 to 50 mbar
• 6 hour time increment
• Upper Air Data: 3-D winds, Temp, RH
• Surface Data includes: pressure, 10 meter winds, 2 meter Temp & RH, Momentum and heat flux
•Data is available from 1/97 to present.
ATAD vs Hysplit…How Different Can They Be?Begins: Sep. 20, 1999 hr 6 (jd 263)
Duration: 2 Hours
Solid=EDAS, Dash=FNLRed = 2000m
Green = 1000mBlue = 100m
Magenta = 10mBlack=ATAD
0 20 40 60 80 100 120
02
46
810
hours
Hei
ght(
Km
)
Well, at times, pretty different!
Begins: Sep. 15, 1999 hr 18 (jd 258) Duration: 2 Hours
Solid=EDAS, Dash=FNLRed = 2000m
Green = 1000mBlue = 100m
Magenta = 10mBlack=ATAD
0 20 40 60 80 100 120
02
46
810
hours
Hei
ght(
Km
)
And at Other Times…Quite Similar
A common pattern in July & Aug...Begins: Jul. 19, 1999 hr 6 (jd 200)
Duration: 2 Hours
Solid=EDAS, Dash=FNLRed = 2000m
Green = 1000mBlue = 100m
Magenta = 10mBlack=ATAD
0 20 40 60 80 100 120
02
46
810
hours
Hei
ght(
Km
)
7/18-7/28, first few days in August, and end of August
Atad most southerly, EDAS most easterly with FNL in between.
Height Differences Between EDAS & FNL can be large - even on order of Km
Begins: Jul. 24, 1999 hr 12 (jd 205) Duration: 2 Hours
Solid=EDAS, Dash=FNLRed = 2000m
Green = 1000mBlue = 100m
Magenta = 10mBlack=ATAD
0 20 40 60 80 100 120
02
46
810
hours
Hei
ght(
Km
)
Directional Differences Between EDAS & FNL can be large (See 1000m traj.)
Begins: Jul. 18, 1999 hr 6 (jd 199) Duration: 2 Hours
Solid=EDAS, Dash=FNLRed = 2000m
Green = 1000mBlue = 100m
Magenta = 10mBlack=ATAD
0 20 40 60 80 100 120
02
46
810
hours
Hei
ght(
Km
)
Even When Heights match, Directions can Differ Between EDAS & FNL (See 2000 m)
Begins: Aug. 6, 1999 hr 18 (jd 218) Duration: 2 Hours
Solid=EDAS, Dash=FNLRed = 2000m
Green = 1000mBlue = 100m
Magenta = 10mBlack=ATAD
0 20 40 60 80 100 120
02
46
810
hours
Hei
ght(
Km
)
Big Bend Overall Residence Time
0 to 0.0050.005 to 0.010.01 to 0.050.05 to 0.10.1 to 0.50.5 to 11 to 5.5
Percent of Endpoints
Jun 1, 1999 - Sep 30, 1999
Includes All Months
ATAD 5-day trajectories
Big Bend Overall Residence Time
0 to 0.0050.005 to 0.010.01 to 0.050.05 to 0.10.1 to 0.50.5 to 11 to 5.5
Percent of Endpoints
Jun 1, 1999 - Sep 30, 1999
Includes All Months
EDAS 1000m 5-day trajectories
Big Bend Overall Residence Time
0 to 0.0050.005 to 0.010.01 to 0.050.05 to 0.10.1 to 0.50.5 to 11 to 5.5
Percent of Endpoints
Jun 1, 1999 - Sep 30, 1999
Includes All Months
FNL 1000m 5-day trajectories
Overall Residence TimeJune - September, 1999
ATAD, EDAS, FNL
Big Bend Overall Residence Time
0 to 0.0050.005 to 0.010.01 to 0.050.05 to 0.10.1 to 0.50.5 to 11 to 6
Percent of Endpoints
Jun 1, 1999 - Sep 30, 1999
Includes All Months
FNL 2000m 5-day trajectories
Big Bend Overall Residence Time
0 to 0.0050.005 to 0.010.01 to 0.050.05 to 0.10.1 to 0.50.5 to 11 to 5.5
Percent of Endpoints
Jun 1, 1999 - Sep 30, 1999
Includes All Months
FNL 100m 5-day trajectories
Big Bend Overall Residence Time
0 to 0.0050.005 to 0.010.01 to 0.050.05 to 0.10.1 to 0.50.5 to 11 to 5.5
Percent of Endpoints
Jun 1, 1999 - Sep 30, 1999
Includes All Months
EDAS 2000m 5-day trajectoriesBig Bend Overall Residence Time
0 to 0.0050.005 to 0.010.01 to 0.050.05 to 0.10.1 to 0.50.5 to 11 to 7
Percent of Endpoints
Jun 1, 1999 - Sep 30, 1999
Includes All Months
EDAS 100m 5-day trajectories
2 Wind Fields and2 Heights
Correlations between Overall Residence Times 3-Day Trajectories June-Sep 1999
atad EDAS2000 EDAS1000 EDAS100 EDAS10 FNL2000 FNL1000 FNL100 FNL10 atad 1.000 0.732 0.769 0.648 0.662 0.790 0.806 0.653 0.644EDAS2000 0.732 1.000 0.878 0.753 0.787 0.962 0.811 0.714 0.730EDAS1000 0.769 0.878 1.000 0.942 0.945 0.903 0.956 0.933 0.927 EDAS100 0.648 0.753 0.942 1.000 0.994 0.780 0.870 0.973 0.986 EDAS10 0.662 0.787 0.945 0.994 1.000 0.812 0.867 0.955 0.977 FNL2000 0.790 0.962 0.903 0.780 0.812 1.000 0.860 0.751 0.762 FNL1000 0.806 0.811 0.956 0.870 0.867 0.860 1.000 0.893 0.866 FNL100 0.653 0.714 0.933 0.973 0.955 0.751 0.893 1.000 0.989 FNL10 0.644 0.730 0.927 0.986 0.977 0.762 0.866 0.989 1.000
Average DifferencesClosest Comparison to Atad: FNL 1000m
-541 to -22-22 to -7-7 to -2-2 to 88 to 2525 to 9292 to 522
ATAD - FNL1000
June-Sept 1999 Overall Residence Time Differences3-Day Trajectories
EDAS vs FNL 1000m
-424 to -16-16 to -4-4 to -1-1 to 33 to 77 to 2222 to 198
EDAS1000 - FNL1000
June-Sept 1999 Overall Residence Time Differences3-Day Trajectories
EDAS at 2 Heights
-1630 to -19-19 to -6-6 to -2-2 to 33 to 88 to 2222 to 220
EDAS1000 - EDAS100
June-Sept 1999 Overall Residence Time Differences3-Day Trajectories
Which is “Right”? Why? Does it Matter?
1. Transport heights matter. ATAD “transport layer” vs Hysplit vertical wind speed driven transport height. To do “standard” residence time analyses with Hysplit may require 3-D analysis.
2. Tracer concentrations should help on days with large differences.
3. MM5 Winds should help.
4. Qualitative results for some residence-time-type analyses suggest similar results no matter which is used.
180 200 220 240 260 280 300
020
0040
0060
0080
00
Julian Day 1999
ng/m
3
CSU Ion SO4Nov 1Oct 1Sep 1Aug 1Jul 1
90th pctile
50th pctile
10th pctile
10/12
9/1
9/14
9/158/21
7/810/13
10/59/16
9/28/208/22
8/22 9/3
7/187/49/79/6
10/3010/3110/8
Maybe Not Real
180 200 220 240 260 280 300
020
0040
0060
0080
00
Julian Day 1999
ng/m
3
CSU Ion SO4Nov 1Oct 1Sep 1Aug 1Jul 1
90th pctile
50th pctile
10th pctile
10/12
9/1
9/14
9/158/21
7/810/13
10/59/16
9/28/208/22
8/22 9/3
7/187/49/79/6
10/3010/3110/8
Maybe Not Real
TX/MX Border
E. Texas
TX/MX Border with ATAD saying Mexico
Begins: Sep. 1, 1999 hr 12 (jd 244) Duration: 2 Hours
Solid=EDAS, Dash=FNLRed = 2000m
Green = 1000mBlue = 100m
Magenta = 10mBlack=ATAD
0 20 40 60 80 100 120
02
46
810
hours
Hei
ght(
Km
)
Example of “TX/MX Border” Trajectories
Begins: Oct. 12, 1999 hr 12 (jd 285) Duration: 2 Hours
Solid=EDAS, Dash=FNLRed = 2000m
Green = 1000mBlue = 100m
Magenta = 10mBlack=ATAD
0 20 40 60 80 100 120
01
23
45
6
hours
TLD
(Km
)Example of “East Texas” Trajectories
Begins: Aug. 4, 1999 hr 12 (jd 216) Duration: 2 Hours
Solid=EDAS, Dash=FNLRed = 2000m
Green = 1000mBlue = 100m
Magenta = 10mBlack=ATAD
0 20 40 60 80 100 120
02
46
810
hours
Hei
ght(
Km
)Example of ATAD saying Mexico while Hysplit is along the border.
Big Bend High Concentration Source Contribution
0 to 0.630.63 to 1.711.71 to 2.222.22 to 2.92.9 to 3.553.55 to 5.375.37 to 10.7
Res. Time/Equal Prob. Sfc.
Jul 1, 1999 - Oct 31, 1999For CSU.SO4 > 5090.81 ng/m3
Includes Months: 7,8,9,10
ATAD Trajectories
Big Bend High Concentration Source Contribution
0 to 0.130.13 to 0.560.56 to 1.621.62 to 2.722.72 to 4.684.68 to 6.266.26 to 10.36
Res. Time/Equal Prob. Sfc.
Jul 1, 1999 - Oct 31, 1999For CSU.SO4 > 5090.81 ng/m3
Includes Months: 7,8,9,10
EDAS & FNL Hourly 1000m Trajectories
Big Bend High Concentration Source Contribution
0 to 0.080.08 to 0.230.23 to 1.121.12 to 2.462.46 to 4.034.03 to 5.75.7 to 14.74
Res. Time/Equal Prob. Sfc.
Jul 1, 1999 - Oct 31, 1999For CSU.SO4 > 5090.81 ng/m3
Includes Months: 7,8,9,10
FNL Hourly 1000m Trajectories
High Concentration Source Contribution Function for CSU Sulfate Ion, July-Oct,
ATAD, EDAS & FNL started at 1000 m.
Big Bend High Concentration Source Contribution
0 to 0.080.08 to 0.230.23 to 1.121.12 to 2.462.46 to 4.034.03 to 5.75.7 to 14.74
Res. Time/Equal Prob. Sfc.
Jul 1, 1999 - Oct 31, 1999For CSU.SO4 > 5090.81 ng/m3
Includes Months: 7,8,9,10
FNL Hourly 1000m Trajectories
Big Bend High Concentration Source Contribution
0 to 0.640.64 to 1.341.34 to 2.462.46 to 3.523.52 to 5.495.49 to 7.167.16 to 17.83
Res. Time/Equal Prob. Sfc.
Jul 1, 1999 - Oct 31, 1999For CSU.SO4 > 5090.81 ng/m3
Includes Months: 7,8,9,10
FNL Hourly 500m Trajtories
Big Bend High Concentration Source Contribution
0 to 0.470.47 to 0.940.94 to 1.831.83 to 2.882.88 to 4.954.95 to 7.097.09 to 18.31
Res. Time/Equal Prob. Sfc.
Jul 1, 1999 - Oct 31, 1999For CSU.SO4 > 5090.81 ng/m3
Includes Months: 7,8,9,10
FNL Hourly 100 m Trajectories
Big Bend High Concentration Source Contribution
0 to 0.080.08 to 0.160.16 to 0.280.28 to 0.620.62 to 1.451.45 to 3.663.66 to 8.62
Res. Time/Equal Prob. Sfc.
Jul 1, 1999 - Oct 31, 1999For CSU.SO4 > 5090.81 ng/m3
Includes Months: 7,8,9,10
Hourly FNL 2000 m trajectories
Big Bend High Concentration Conditional Probability
0 to 0.060.06 to 0.1090.109 to 0.2140.214 to 0.3530.353 to 0.4650.465 to 0.5860.586 to 1
Probability of ConditionMin endpts/grid= 5
Jul 1, 1999 - Oct 31, 1999For CSU.SO4 > 5090.81 ng/m3
Includes Months: 7,8,9,10
5-day ATAD trajectories
Big Bend High Concentration Conditional Probability
0 to 0.0260.026 to 0.0690.069 to 0.1580.158 to 0.2780.278 to 0.3910.391 to 0.5370.537 to 1
Probability of ConditionMin endpts/grid= 5
Jul 1, 1999 - Oct 31, 1999For CSU.SO4 > 5090.81 ng/m3
Includes Months: 7,8,9,10
EDAS & FNL Hourly 1000m Trajectories
Big Bend High Concentration Conditional Probability
0 to 0.020.02 to 0.040.04 to 0.0790.079 to 0.1380.138 to 0.290.29 to 0.4390.439 to 1
Probability of ConditionMin endpts/grid= 5
Jul 1, 1999 - Oct 31, 1999For CSU.SO4 > 5090.81 ng/m3
Includes Months: 7,8,9,10
FNL Hourly 1000m Trajectories
High Concentration Conditional Probability
Big Bend High Concentration Conditional Probability
0 to 0.020.02 to 0.040.04 to 0.0790.079 to 0.1380.138 to 0.290.29 to 0.4390.439 to 1
Probability of ConditionMin endpts/grid= 5
Jul 1, 1999 - Oct 31, 1999For CSU.SO4 > 5090.81 ng/m3
Includes Months: 7,8,9,10
FNL Hourly 1000m Trajectories
Big Bend High Concentration Conditional Probability
0 to 0.0350.035 to 0.0680.068 to 0.1170.117 to 0.2060.206 to 0.3160.316 to 0.4470.447 to 1
Probability of ConditionMin endpts/grid= 5
Jul 1, 1999 - Oct 31, 1999For CSU.SO4 > 5090.81 ng/m3
Includes Months: 7,8,9,10
FNL Hourly 500m Trajectories
Big Bend High Concentration Conditional Probability
0 to 0.0330.033 to 0.0580.058 to 0.0920.092 to 0.1360.136 to 0.2020.202 to 0.3560.356 to 1
Probability of ConditionMin endpts/grid= 5
Jul 1, 1999 - Oct 31, 1999For CSU.SO4 > 5090.81 ng/m3
Includes Months: 7,8,9,10
FNL Hourly 100 m Trajectories
Big Bend High Concentration Conditional Probability
0 to 0.0380.038 to 0.0780.078 to 0.1380.138 to 0.2120.212 to 0.3330.333 to 0.5480.548 to 1
Probability of ConditionMin endpts/grid= 5
Jul 1, 1999 - Oct 31, 1999For CSU.SO4 > 5090.81 ng/m3
Includes Months: 7,8,9,10
Hourly FNL 2000 m trajectories
Mean Concentration
0 to 500500 to 10001000 to 20002000 to 30003000 to 40004000 to 50005000 to 8569
CSU.SO4 ng/m3
Jul 1, 1999 - Oct 31, 1999
Includes Months: 7,8,9,10
EDAS & FNL Hourly 1000m Trajectories Mean Concentration
0 to 500500 to 10001000 to 20002000 to 30003000 to 40004000 to 50005000 to 6908
CSU.SO4 ng/m3
Jul 1, 1999 - Oct 31, 1999
Includes Months: 7,8,9,10
ATAD Trajectories
Mean Concentration
0 to 500500 to 10001000 to 15001500 to 20002000 to 30003000 to 40004000 to 7776
CSU.SO4 ng/m3
Jul 1, 1999 - Oct 31, 1999
Includes Months: 7,8,9,10
FNL Hourly 1000m Trajectories
Mean Concentration
0 to 500500 to 10001000 to 15001500 to 20002000 to 30003000 to 40004000 to 5293
CSU.SO4 ng/m3
Jul 1, 1999 - Oct 31, 1999
Includes Months: 7,8,9,10
FNL Hourly 100 m Trajectories
-482 to -42-42 to -12-12 to -3-3 to 33 to 99 to 40.540.5 to 448
FNL1000 - EDAS1000
Difference in High Residence TimeCSU Sulfate Ion
-1817.669 to -112.216-112.216 to -23.811-23.811 to -4.141-4.141 to 6.8946.894 to 20.43520.435 to 3030 to 87
ATAD - FNL1000
Difference in High Residence TimeCSU Sulfate Ion
What’s Next?1. To use Hysplit in the “usual” ATAD residence time-type analyses requires some consideration of trajectory height. 3-D residence time?
2. If ATAD’s directions are wrong, choices….. Modify ATAD to use EDAS and/or FNL winds Switch to Hysplit with some height consideration. Abandon ATAD in favor of Monte Carlo model
3. Further analyses of BRAVO data, measured sfc & upper air winds, tracer, MM5 winds, spatial patterns in chem data should all help in deciding which model to use and why.
4. Continue with analyses of other species and other types of trajectory-based analyses.