**Appendix F**

**Analysis Using HYSPLIT Trajectories for Days with Largest Contribution to Haze by Various Species of Particles**  Contents of Appendix F Discussion of trajectories and results Summary of trajectories (Table 3

- 4 from the FIP) Maps of trajectories Procedure used for trajectories Discussion of trajectories and results Where do the particles come from that affect visibility in the Virgin Islands National Park? The HYSPLIT model plots paths taken by particles blown by

the wind through the air. The HYSPLIT model has historical meteorological data , to see where the air traveled enroute to the IMPROVE monitor, located on St. John, near Cruz Bay , on day s when visibility was worst as measured b y the samples taken b y the IMPROVE monitor

. Explorers travel ing b y balloon us e trajectory models to find the most favorable winds to get them where they want to go. By calculating trajectories, we can test our suppositions about where the various kinds of particles come from. For example, i f the major cause of obstruction to visibility on a given day is due to sulfates or nitrates, and sulfates and nitrates are products of combustion, trajectories on those day s would be likely to come through areas with lots of sources of combustion on the way to affecting visib ility

at the IMPROVE site. HYSPLIT model uses weather data measured every three hours at the surface and twice a day aloft. These data are converted to a grid of values of wind direction and speed and other weather factors for each hour of the day

. The user specifies the starting point (in our case, the IMPROVE monitoring site on St. John), how long to run the model (2 weeks) and the height above ground at the monitoring site. We used the model to go backwards from the IM PROVE site to see where the ai r came from. We started at three different heights above the monitoring site within the well

- mixed tropical surface layer, since tropical air is well mixed over land at these heights . But wind can change direction at different altitudes and give different trajectories, even on the same day

. Since the trade winds mostly blow from east to west across the Virgin Islands, it is not surprising that when the winds are traced backwards from the sampling site on the western end of St. John, the path that the air takes almost alway s passes eastward over the island of St. John. Many trajectories pass over neighboring islands like Antigua and St. Martin. Some trajectories pass over the British Virgin Islands, located to the northeast of St. John. However, as th e summary of the paths of the air parcels show (see the enclosed table) there is not any particular pattern where days with the highest amounts of light

- scattering particles have trajectories that commonly pass through one or more of these likely sources o f human air pollution. For example, only one of the day s with high levels of haze that may be from combustion has trajectories that pass over St. Croix, home to a major industrial center. These trajectories show that even on day s when visibility is reduced due to sulfates, nitrates, and carbon (likely suspects from sources of combustion), the air affecting the park usually does not pass over St. Croix, St. Thomas, or Puerto Rico. More often, days with high concentrations of fine soil or coarse particulat es in the atmosphere occur when air travels from Africa’s Sahara Desert. For example, Figure 1 shows aset of backward trajectories originating at the Virgin I slands National park for 100 (red) , 500

(blue) , and 1,000 (green) meters above ground level for September 26, 2002, which is ty pical of day s with high visibility

impairment due to fine soils. This illustrates how a significant cause of reduced visibility

in the Virgin Islands National Park is dust transported from the Sahara Desert, located over 5,000 miles away in Africa. The Virgin I slands can also be affected b y other various natural sources, such as sulfate produced b y plankton in the ocean , and ash from the Montserrat Volcano located over 200 miles away to the southe ast. The effects of these natural sources on visibility can be very

noticeable on some day s, especiall y because there are not as many anthropogenic sources of pollution in the I slands in comparison with the more urban areas of the continental United States

.

. **Figure 1**  **. HYSPLIT trajectories for a low visibility day with high concentrations of fine soil.**

**References** Draxler, R.R. and Rolph, G.D., 2012. HYSPLIT (HYbrid Single

-Particle Lagrangian Integrated Trajectory) Model access via NOAA ARL READY Website (http://ready.arl.noaa.gov/HYSPLIT.php). NOAA Air Resources Laboratory, Silver Spring, MD. Rolph, G.D., 2012. Real

- time Environmental Applications and Display sYstem (READY) Website (http:// ready.arl.noaa.gov). NOAA Air Resources Laboratory, Silver Spring, MD.
We gratefully acknowledge the NOAA Air Resources Laboratory (ARL) for the provision of the HYSPLIT transport and dispersion model via the READY website ( http://ready.arl.noaa.gov)used in this analysis. The trajectories were run by Edward Finfer of EPA Region 2, Air Programs Branch and reviewed b y Henry

Feingersh, also from EPA

- R2

- APBThe following maps are HYSPLIT trajectories output as.kmz files and plotted on Google Earth. **Table** Error! No text of specified style in document. **3**
**- 1**  **: Summary of Trajectory Analyses for Top Four Days with the Highest Visibility Impairment for Each Species**  **2000**

**– 2004**  **Species Total** 

**Light Extinct** 

**- ion**  **(b ext**  **) Date**  **Source Region ( Height of Trajectory in**  **Meters Above Ground Level)**

**Local Regional**  **Long**
**- Distance** 

All Aerosols Com bined 79.5 06 23 2004 St. John (100, 500) Anguilla (100) NW Africa (500, 1000) 77.4 08 01 2004 St. John (100, 500, 1000) None NW Africa (1000) 71.8 07 08 2004 St. John (100, 500, 1000) Anguila (500) Central Africa (1000) 71.1 08 01 2003 St. John (100, 500) Anguila (100) St. Martin (500) African Coast (1000)
Fine Soil 19.9 09 26 2002 None None Central Africa (500, 1000)

17.9 08 01 2004 St. John (100, 500, 1000) None NW Africa (1000) 17.3 08 03 2002 None Guadeloupe (100) Central Africa (1000) 16.9 06 14 2004 St. John (1000) Guadeloupe (100, 500) Central Africa (1000) Sea Salt 24.2 03 07 2003 St. John (100, 500, 1000) None None

21.8 03 10 2003 St. John (100) Anguila (100) None 18.9 08 01 2003 St. John (100, 500) Anguila (100) St. Martin (500) African Co a st (1000)
17.9 02 12 2001 St. John (100, 500, 1000) None None Sulfate 42.0 04 24 2003 St. John (100) Puerto Rico (1000) None

34.9 11 21 2001 St. Thomas (100) Puerto Rico (100, 500) Dominican Rep. (1000) Florida (500)
26.8 08 03 2002 None Guadeloupe (100) Central Africa (1000) 26.6 02 27 2004 None Montserrat (500) Western U.S. (1000) Nitrate 5.2 05 09 2003 St. John (100, 500, 1000) Anguila (500) Barbuda (1000) None
4.8 11 15 2001 None St. Martin (100) Barbuda (500) Canada (100, 500, 1000)
4.52 08 01 2003 St. John (100, 500) Anguila (100) St. Martin (500) African Co a st (1000)
4.52 05 21 2003 Puerto Rico (500, 1000) Dominica (100) Guadeloupe (500) None Elemental Carbon 15.5 09 05 2002 St. John (500, 1000) BVI (100) None Central Africa (1000) African Co a st (500) 14.0 01 08 2002 None St. Martin (100) Mideast U.S. (100) Mexico, Florida (500, 1000) 13.3 08 13 2004 None St. Martin (100, 500) None 10.3 11 20 2003 None BVI (100, 500) Canada, N.E. U.S. (100) Organic Carbon 18.4 01 08 2002 None St. Martin (100) Mideast U.S. (100) Mexico, Florida (500, 1000) 17.2 09 05 2002 St. John (500, 1000)

BVI (100) None Central Africa (1000) African Co a st (500) 7.09 10 26 2002 St. John (100, 500, 1000) None Central Africa (1000) 7.05 08 13 2004 None St. Martin (100, 500) None Coarse PM 34.4 09 26 2002 None None Central Africa (500, 1000)

33.4 06 23 2004 St. John (100, 500) Anguilla (100) NW Africa (500, 1000) 30.5 08 08 2001 St. John (100, 500, 1000) BVI (100, 500, 1000) W Africa (100, 500, 1000) 28.8 07 14 2003 St. John (500, 1000) BVI (100, 500) None Dates in italics are days when it was a top four date for more than one species of particles.**Figure 2**  **. Trajectories with tim e and dates for worst haze days 2000** 
**- 2004 for**  **all type**  **s of particle**  **s . See Table 3** 
**- 4 for list of** 

**days and type of particle. Figure**  **3 Sam**  **e as Figure 2**

**– trajectories for worst haze days for all types of particles** 
**- but**  **a wider view,**

**including Puerto Rico and other islands in the area of the Virgin Islands Figure**  **4 . Global view of trajectories in Figure 2**  **for w orst haze days 2000** 
**- 2004 for all types of**  **particles. Figure**  **5. Trajectories for worst visibility days due to sulfate, 2000** 
**- 2004** 

**Figure 6**  **. Global view of trajectories for worst visibility days due to sulfate, 2000**
**- 2004** **P rocedure**  **Used for**  **T rajectories** 

**Trajectories for VI haze plan** for selected IMPROVE monitoring day s 2001

- 2004. 24 hour (midnight to midnight) particulate matter filter sampler using READY HySplit trajectories program, Internet version, click on : http://ready .arl.noaa.gov/hy split

- bin/trajty pe.pl?runty

pe=archive

. Instructions: Click on the box under: **First, select the meteorologcal data:** Select: REANALYSI S met data; Enter latitude: +18.336, and longitude:

- 64.796 Click: Continue S elect Select the reanalysis File For the month and year for the date of the trajectory we want, e.g., RP200205 is year 2002, month 05 (May 2002). Click: Next **Trajectory**

**direction:** backward **Vertical Motion:** model vertical velocity. **Start time (UTC):** Fill in year month and day from the data and hour = 18 (for 1800 UTC, which is 2pm time in the Virgin I slands). **Total run time (hours):** 515 **Start a ne w trajectory**  **every :**  should be 0 **Start 1 latitude (degrees):** should already be 18.336 **S tart 1 longitude (degrees):**  should already be

- 64.796 Leave Start 2 and 3 blank Level 1 height: 100 (meters) Level 2 height: 500 Level 3 height: 1000
Display options: Don’t change any defaults, except for: **GIS output? Click:** Google Earth (kmz)

Clic k: Request trajectory Wait for graphics files. When they are ready, they will look something like this:

HYSPLIT MODEL RESULTS FOR JOB NUMBER 33054

**Model Status:**  Wed May 5 14:13:22 EDT 2010

Th e m odeland gr aphic s ar e now c omplete. Fin is hed gener ating gr aphic s fo r jo b 33054. adding: gr eenball .png ( def lated 1% ) adding: r edball .png ( def lated 0% ) adding: bl ueball .png ( def lated 0% )**RESULTS Click on text link to view images in a new window.** 
**GIF Plots Google Earth Plots**  **Trajectories GIF**  **KMZ**

Right click on **gif** and save in directory with time and date in file name Right click on **km z**  and save in directory with time and date in file name For example, this example can have a file name with the year, month, day , hour, e.g., 2002 05 05 18.gif and 2002 05 05 18.kmz S ave the trajectory

plots

. The gif version should look like this:



### Additional runs can be made for multiple trajectories b y following these directions:Click on the box under: **First, select the meteorologcal data:** Select: REANALYSI S met data;

Enter latitude: +18.336, and longitude:

- 64.796 Click: Continue Select Select the reanalysis File For the month and year for the date of the trajectory we want, Click: Next **Trajectory**

**direction:** backward **Vertical Motion:** model vertical velocity. **Start time (UTC):** Fill in year month and day from the data and hour = 18 (for 1800 UTC, which is 2pm time in the Virgin I slands). But for the day , fill in the day *plus 1 day *, e.g., day

in this case would be **06** instead of 05. Enter a time of **03**
**. Star** **t a ne w trajectory**  **every** : **3** hrs **Maximum number of trajectories: 8**  **Total run time (hours):** 515 **Start a ne w trajectory**  **every :**  should be 0 **Start 1 latitude (degrees):** should already be 18.336 **Start 1 longitude (degrees):** should already be

- 64.796 Leave Star

t 2 and 3 blank Level 1 height: 100 (meters) Level 2 height: blank Level 3 height: blank
Display options: Don’t change any defaults, except for: **GIS output? Click:** Google Earth (kmz)
Click: Request trajectory Wait for graphics files. This file s hould look like the graphic on the next page. Then save the file as ye ar date height e.g., 2002 05 05 100m.gif and the kmz file as 2002 05 05 100m.kmz Then go back and run the same information, changing onl y the Level 1` height to 500 and after you get the maps for that run, change the Level 1 height to 1000 and get the maps for that run.