[Note that the question and the answer below are recreated from a HYSPLIT FAQ site that predates this forum site. The original posting date is unknown.]
Question: I am trying to better understand what the best approach is for calculating the HYSPLIT trajectories I need. I have mostly looked at using the EDAS data, but it has a lot of holes in it for the period I am interested in, so we wind up with trajectories truncated or not calculatable. I tried to fill in the holes with the FNL data. However, in one case when I calculated 120-hour backward trajectories from Potsdam, NY at 1800 on April 8, 1999 using both the EDAS and FNL data bases, I found that the EDAS data suggested the air was in the upper midwest 5 days prior, but the FNL put it into northern Quebec. Why the difference?
Answer: Although all meteorological models use the same observations, there are three significant differences between EDAS and FNL: horizontal, vertical, and temporal resolution. EDAS has better resolution in all categories. For the case you sent me I re-ran the EDAS trajectory using starting heights of 300, 400, and 500 m agl. There are large differences in the first 24 hours. The 400 m trajectory corresponds more with your 500 m FNL. EDAS vertical resolution is every 25 hPa, FNL resolution is limited to mandatory surfaces: 1000, 925, 850 hPA etc. The usual procedure should be to run trajectories at several heights and locations about the point of interest — if the trajectories are similar then the confidence level is high — if they diverge then there is more uncertainty.
Roland Draxler
I am trying to better understand what the best approach is for calculating the HYSPLIT trajectories I need. I have mostl
-
- Posts: 360
- Joined: May 8th, 2019, 1:31 pm
- Registered HYSPLIT User: Yes
Return to “General questions on meteorological data needed for HYSPLIT”
Jump to
- HYSPLIT
- ↳ Users
- ↳ Developers
- ↳ Bugs
- ↳ Announce
- ↳ General Comments
- ↳ Trajectory Model
- ↳ Dispersion Model
- ↳ User Applications
- ↳ In-line WRF-HYSPLIT coupling
- HYSPLIT Platform Specific
- ↳ HYSPLIT for PCs
- ↳ HYSPLIT for Mac OS X
- ↳ HYSPLIT for LINUX
- ↳ HYSPLIT on the READY Server
- Meteorological Data
- ↳ General questions on meteorological data needed for HYSPLIT
- ↳ Conversion programs
- ↳ Repositories of HYSPLIT formatted data
- ↳ MeteoInfo Software
- HYSPLIT Research
- ↳ Volcanic Ash
- ↳ Wildfire Smoke
- ↳ Dust
- ↳ Chemicals
- ↳ Radiological
- ↳ Cluster Analysis
- HYSPLIT Workshop
- ↳ 2022 HYSPLIT Workshop Questions
- ↳ 1. Installing HYSPLIT
- ↳ 2. Testing the installation
- ↳ 3. Gridded meteorological data files
- ↳ 4. Trajectory calculations
- ↳ 5. Trajectory options
- ↳ 6. Trajectory statistics
- ↳ 7. Air concentration calculations
- ↳ 8. Configuring the CAPTEX simulation
- ↳ 9. Air concentration parameter sensitivity
- ↳ 10. Alternate display options
- ↳ 11. Pollutant transformations and deposition
- ↳ 12. Air concentration uncertainty
- ↳ 13. Source attribution methods
- ↳ 14. Wildfire smoke and dust storms
- ↳ 15. Radioactive pollutants and dose
- ↳ 16. Volcanic eruptions with gravitational settling
- ↳ 17. Custom simulations
- ↳ 2021 HYSPLIT Workshop Questions
- ↳ 1. Installing HYSPLIT
- ↳ 2. Testing the installation
- ↳ 3. Gridded meteorological data files
- ↳ 4. Trajectory calculations
- ↳ 5. Trajectory options
- ↳ 6. Trajectory statistics
- ↳ 7. Air concentration calculations
- ↳ 8. Configuring the CAPTEX simulation
- ↳ 9. Air concentration parameter sensitivity
- ↳ 10. Alternate display options
- ↳ 11. Pollutant transformations and deposition
- ↳ 12. Air concentration uncertainty
- ↳ 13. Source attribution methods
- ↳ 14. Wildfire smoke and dust storms
- ↳ 15. Radioactive pollutants and dose
- ↳ 16. Volcanic eruptions with gravitational settling
- ↳ 17. Custom simulations
- ↳ 2020 HYSPLIT Workshop Questions
- ↳ 1. Installing HYSPLIT
- ↳ 2. Testing the installation
- ↳ 3. Gridded meteorological data files
- ↳ 4. Trajectory calculations
- ↳ 5. Trajectory options
- ↳ 6. Trajectory statistics
- ↳ 7. Air concentration calculations
- ↳ 8. Configuring the CAPTEX simulation
- ↳ 9. Air concentration parameter sensitivity
- ↳ 10. Alternate display options
- ↳ 11. Pollutant transformations and deposition
- ↳ 12. Air concentration uncertainty
- ↳ 13. Source attribution methods
- ↳ 14. Wildfire smoke and dust storms
- ↳ 15. Radioactive pollutants and dose
- ↳ 16. Volcanic eruptions with gravitational settling
- ↳ 17. Custom simulations
- ↳ 2019 HYSPLIT Workshop Questions