Create new subfolder named “met”insideyour project folder

Open AermetView

Select ‘New’

Name new Aermetproject file and save in “met” folder

AERMET: Pre-Processing Meteorological Data for Use In the AERMOD Model

Hourly Surface

Observations (*.dat file)

Twice DailyTemperature Soundings (*.ua file)

AERMET program

Hourly SurfaceData File(*.sfc file) Aermod

Dispersion ModelHourly

Vertical Profile File(*.pfl file)

Site Characteristics

Go to Webmet.com, download files into the met subfolder, then unzip them in the met subfolder. Note also for this site the anemometer height = 22 ft and the base elevation = 179 ft.

SCRAM surface file:

Aermet upper air file:

Make sure years match

Select hourly surface data file (.dat file) from met subfolder

The surface met data file will automatically display the appropriate conversion here. In this case, the station recorded the data in local time.

Select the Upper Air Menu

Select hourly upper air data file (.ua file) from met subfolder

The upper air data file will automatically display an adjustment to local time. This is because this data is recorded using Greenwich Mean Time which, in this particular case, is 5 hours ahead of Eastern Standard Time.

Select the Sectors Menu 1. Add Site information by clicking on “Copy from Hourly and Upper Air Data”2. Enter the Anemometer Height (22 feet from the relevant Webmet page)3. Then Select the Sectors and Surface Parameters Tab

1

2

3

1. Make sure ‘wind direction sectors’ = 1 2. Specify annual averages (no seasonal effects

assumed here)3. Then click on the dotted tab and a menu will appear

(see right)’4. Choose the default “Urban” land-use value by

selecting the appropriate row

1. Repeat this process for the Bowen ratio and the surface roughness

Now Run Aermet. AERMET: Pre-Processing Meteorological Data for Use In the AERMOD Model

Hourly Surface

Observations (*.dat file)

Twice DailyTemperature Soundings (*.ua file)

AERMET program

Hourly SurfaceData File(*.sfc file) Aermod

Dispersion ModelHourly

Vertical Profile File(*.pfl file)

Site Characteristics

Now open ISC-Aermod View

Under the File menu, choose “New Project”

Name the ISC-AermodProject file and save it in the project folder

From the “Model” menu, make sure you choose Aermod

These choices are the same as before

Set domain extents to 10,000 meters and SW corner to 0,0

Select the stack tool, place the pointer at a location in the middle of the modeling domain, then click once to set the source location

A menu will pop up asking for details about the source

Enter typical values:Stack height: 100 mEmission rate: 1 g/secExit Velocity: 10 m/sStack Diameter: 3 m

Click on the “Tip”Button for informationon stack gas temperature. Select the Ambient Temperature Option (the program artificially sets the stack temperature to 0K if it is the same as the surroundings).

Chosen source location in modeling domain coordinates

Location of newly created point source

Select polar coordinate system for receptor grid. Point at the source location, then click and drag the pointer away from the source to establish the receptor grid. If the grid is near the source, you can zoom in first using the zoom tool. You can erase the grid anytime.

You can also enter gridvalues with this menu.

The receptor grid is shown here.

To zoom out, select the domain tool modeling domain and click OK on the pop-up menu. This will display the entire domain.

Click and drag a second, larger polar receptor grid over the first one.

Close window to return to main program

The receptor grids are shown in the table. Now choose the met data menu

Load the met files (surface .dat file and upper air .ua file) from your project folder that you created earlier with Aermet.

Specify a base elevation for the measured upper air data. The information is given on the relevant webmet page as being equal to 179 ft.

You can now run the model

Prior to running, a project status menu is displayed. The various tabs allow you to review all the options you have selected.

Then choose run. After the run is complete,Select the Contours option.

This is a contour plot of the maximum 1 hr value for the entire year at each location. You can look at the maximum 3hr and 24 hr values as well.

Erase the point source and select the area source tool and place the pointer at the same location as the point source. Try to match the total emission rate specified for the point source (1 g/sec). Compare maximum downwind values

http://www.weblakes.com/ISCAERMOD/ISC-AER5_ReleaseNotes.pdf

Now includes deposition

Recent updates to Aermod

Including Site Specific Datain AERMET

• Wind direction dependence of albedo, B0 and z0

• Land use vs. site parameters• Temperature and velocity profiles

– alternate method to estimate u* and L– spreadsheet program

AERMET: Pre-Processing Meteorological Data for Use In the AERMOD Model

Hourly Surface

Observations (*.dat file)

Twice DailyTemperature Soundings (*.ua file)

AERMET program

Hourly SurfaceData File(*.sfc file) Aermod

Dispersion ModelHourly

Vertical Profile File(*.pfl file)

Site Characteristics

Select the Sectors Menu

Here we have specified urban conditions in the winter with easterly winds….

Note: the values will change with season

…and a water surface to the west of the site.

Note: the values may change with season

http://www.webgis.com/

http://www.webgis.com/ http://www.webgis.com/

Land use data can be view in ArcMap. Data is available at this site for most urban areas.Select the Upper Air Menu

The upper air data file will automatically display an adjustment to local time. This is because this data is recorded using Greenwich Mean Time which, in this particular case, is 8 hours ahead of Pacific Standard Time.

Select the On-Site Menu

Use same time adjustment as upper air data.

Copy lat/long information from surface station (if nearby) or enter site-specific location.

Additonal temperature and wind speed measurements can be entered here to independently estimate local turbulence parameters

( )kgH

uTcL p

3*0ρ

−=( )

2tan2

21ln

21ln2 1

2 πµµµ +−⎟⎟⎠

⎞⎜⎜⎝

⎛ ++⎟⎠⎞

⎜⎝⎛ +=Ψ −

zref

( )2

tan22

1ln

21

ln2 01

200

0

πµµµ+−⎟⎟

⎠

⎞⎜⎜⎝

⎛ ++⎟

⎠⎞

⎜⎝⎛ +

=Ψ −z

25.0161 ⎟⎟

⎠

⎞⎜⎜⎝

⎛−=

Lzrefµ

25.00

016

1 ⎟⎠⎞

⎜⎝⎛ −=

Lzµ

Iterative Calculation of u* and L for each hour

Independently estimated each hour, as

described previously“Similarity” Functions

Definition of L

⎟⎟⎠

⎞⎜⎜⎝

⎛Ψ+Ψ−

=

00

ln*

zzrefref

ref

zz

kuu

Example for Unstable Case:z1 = 10 m uz1 = 2 m/sz2 = z0 = 0.01m uz2 = 0 m/sz3 = 10 m T3 = 295.4 Kz4 = 2 m T4 = 295.8 K

Solving by trial and error, we obtainL = -3.8 m, u* = 0.15 m/s and H = 81 Watts/m2

Example for Stable Case:z1 = 10 m uz1 = 2 m/sz2 = z0 = 0.01m uz2 = 0 m/sz3 = 10 m T3 = 295.4 Kz4 = 2 m T4 = 295.0 K

Solving by trial and error, we obtainL = 11.1 m, u* = 0.07m/s and H = -3 Watts/m2

This trial and error calculation is performed by the EXCEL spreadsheet entitled “Profile Method” on the course web page

Examples

Met Data:Hour Cloud Cover Wind Speed

(noon = 12) (Octas) (m/sec)

Site Data: 0 0 2.05

Date 31-Aug 1 1 1Site Latitude (deg) 49 2 1 1Albedo (see columns A-L) 0.2 3 1 1Bowen Ratio 0.1 4 1 1Roughness Length (m) 0.03 5 1 1Anemometer height (m) 8 6 1 1Temperature (K) 288 7 1 1Pre-dawn dθ/dz (K/m) 0.01 8 1 1

Source Data: 9 1 1

Hour of Day 0 10 1 1Stack height (m) 2 11 1 1

Stack diameter (m) 3 12 1 1

Stack gas exit velocity (m/s) 10 13 1 1

Stack gas temperature (K) 300 14 1 1

Receptor Location (m): 15 1 1

zr = 310 16 1 1

xr = 1000 17 1 1Yr = 0 18 1 1

19 1 120 1 1

21 1 1

22 1 1

23 1 1

00.10.2

0 3 6 9 12 15 18 21

Hour of Day

u* (m

/s)

Turbulence Parameters

-10

0

10

0 5 1 0 1 5 2 0 2 5L (m

)

0

0.5

1

0 3 6 9 12 15 18 21

w*

(m/s

ec)

Excel Spreadsheet entitled “Aermod”

Site Specific Datain RAMMET

• Dry deposition option• Minimum value of L• Roughness length: measurement vs application site

• Anthropogenic Heat Flux (heat island)