DISCOVER-AQ Trajectory Analysis - Version R0 (Last modified on 02/08/12)

Back trajectories are an useful way of determing the source regions of air masses 
transported into a region of interest. For DISCOVER-AQ 72 hour, three-dimensional 
kimematic back trajectories were computed for every spiral over the 6 profile sites 
using NOAA ARL's Hybrid Single Particle Lagrangian Integrated Trajectory Model 
(HYSPLIT), version 4 (July 2011 release). The 40km Eta Data Assimilation System 
(EDAS) meteorological data was used to compute the back trajectories at 7 levels 
for each profile (500, 1000, 1500, 2000, 2500, 3000, and 3500 m above ground level). 


TEXT FILES (.CSV FILES)

There are separate files for each of the profile sites and for each file, all the 
profiles for that site is included. The profiles are numbered according to the 
numbering system from Gao Chen's Vertical Profile Summary spreadsheet 
(http://www-air.larc.nasa.gov/missions/discover-aq/Profiles/DISCOVER-AQ-Profile-Summary.xls)

Column Descriptions
1. Date - Date of flight (YYYYMMDD format)
2. Jday - Julian Day
3. Flight - Science Flight Number (1-14)
4. UTC_start - Profile Start Time, UTC Seconds
5. UTC_stop - Profile Stop Time, UTC Seconds
6. SiteID - ID Number accoring to Gao Chen's spreadsheet (1-6 for the profile sites)
7. ProflSeqN - Profile Sequence Number according to Gao Chen's spreadsheet
8. Lat - Latitude of the Profile Site, decimal degrees
9. Lon - Longitude of the Profile Site, decimal degrees
10. ElaspHr - Elasped Hour Backwards in time (0 = initiation time through -72 = 3 days backwards in time)
11. Lat_500m - Latitude (decimal degrees) of the back trajectory released at 500m AGL at the current ElaspHr
12. Lon_500m - Longitude (decimal degrees) of the back trajectory released at 500m AGL at the current ElaspHr
13. Alt_500m - Altitude (meters) of the back trajectory released at 500m AGL at the current ElaspHr
14. Pr_500m - Pressure (mb) of the back trajectory released at 500m AGL at the current ElaspHr
15. Lat_1000m - Latitude (decimal degrees) of the back trajectory released at 1000m AGL at the current ElaspHr
16. Lon_1000m - Longitude (decimal degrees) of the back trajectory released at 1000m AGL at the current ElaspHr
17. Alt_1000m - Altitude (meters) of the back trajectory released at 1000m AGL at the current ElaspHr
18. Pr_1000m - Pressure (mb) of the back trajectory released at 1000m AGL at the current ElaspHr
19. Lat_1500m - Latitude (decimal degrees) of the back trajectory released at 1500m AGL at the current ElaspHr
20. Lon_1500m - Longitude (decimal degrees) of the back trajectory released at 1500m AGL at the current ElaspHr
21. Alt_1500m - Altitude (meters) of the back trajectory released at 1500m AGL at the current ElaspHr
22. Pr_1500m - Pressure (mb) of the back trajectory released at 1500m AGL at the current ElaspHr
23. Lat_2000m - Latitude (decimal degrees) of the back trajectory released at 2000m AGL at the current ElaspHr
24. Lon_2000m - Longitude (decimal degrees) of the back trajectory released at 2000m AGL at the current ElaspHr
25. Alt_2000m - Altitude (meters) of the back trajectory released at 2000m AGL at the current ElaspHr
26. Pr_2000m - Pressure (mb) of the back trajectory released at 2000m AGL at the current ElaspHr
27. Lat_2500m - Latitude (decimal degrees) of the back trajectory released at 2500m AGL at the current ElaspHr
28. Lon_2500m - Longitude (decimal degrees) of the back trajectory released at 2500m AGL at the current ElaspHr
29. Alt_2500m - Altitude (meters) of the back trajectory released at 2500m AGL at the current ElaspHr
30. Pr_2500m - Pressure (mb) of the back trajectory released at 2500m AGL at the current ElaspHr
31. Lat_3000m - Latitude (decimal degrees) of the back trajectory released at 3000m AGL at the current ElaspHr
32. Lon_3000m - Longitude (decimal degrees) of the back trajectory released at 3000m AGL at the current ElaspHr
33. Alt_3000m - Altitude (meters) of the back trajectory released at 3000m AGL at the current ElaspHr
34. Pr_3000m - Pressure (mb) of the back trajectory released at 3000m AGL at the current ElaspHr
35. Lat_3500m - Latitude (decimal degrees) of the back trajectory released at 3500m AGL at the current ElaspHr
36. Lon_3500m - Longitude (decimal degrees) of the back trajectory released at 3500m AGL at the current ElaspHr
37. Alt_3500m - Altitude (meters) of the back trajectory released at 3500m AGL at the current ElaspHr
38. Pr_3500m - Pressure (mb) of the back trajectory released at 3500m AGL at the current ElaspHr

PICTURE FILES (.GIF FILES)

There are separate GIF files for each profile done during DISCOVER-AQ (about 250). 
They follow this naming convention: 
   discoveraq-trajectories_model_ProfileName_ProfSeqNumber_Date.gif. 
So for example, the first profile at Beltsville is named:
   discoveraq-trajectories_model_Beltsville_1001_20110701.gif. 

ACKNOWLEDGEMENTS
These data were created by Nathan Walker, a student from Christopher Newport University working in 
NASA's DEVELOP program under the supervision of Lee Thornhill. If you have any questions, comments, 
or concerns about the data, please contact Lee at 757-864-4278 or email at Kenneth.L.Thornhill@NASA.gov 
for assistance.