AERMOD View – Reading AERMOD SFC File Headers

AERMET, the meteorological preprocessor used to generate meteorological data for use in the AERMOD air dispersion model, creates two unique files:

• A surface file (*.SFC) containing surface-level variables and turbulence scaling parameters calculated by AERMET, and


• A profile file (*.PFL) containing multi-level variables for boundary layer profile analysis in AERMOD.

Each SFC file contains a single line header which provides information about stations processed by AERMET. That information is described below in detail to assist users in decoding this information.

Station Location

Latitude / longitude coordinates of the Onsite or hourly Surface station processed by AERMET are listed here. Precision to three decimal places is used

Station IDs

Identification numbers for each pathway station processed by AERMET are included. Onsite Pathway station IDs (OS_ID) are typically user-defined values. Surface (SF_ID) and Upper Air (UA_ID) ID numbers are most commonly taken from one of two station databases:

1. WBAN (Weather Bureau Army Navy) – A North American system using 5-digit ID numbers for weather stations in the United States and select stations in Canada.


2. WMO (World Meteorological Organization) – A global system using 6-digit ID numbers where the first number specifies the region (e.g., 0/1 = Europe, 2/3 = Russia, 7 = North America). Only the first 5 digits are shown because AERMET was primarily designed around the WBAN database.

A good reference for these station ID numbers is the Interated Surface Database Station History document found on the National Centers for Environmental Information FTP server: ftp://ftp.ncdc.noaa.gov/pub/data/noaa/isd-history.txt. The first column (USAF) corresponds to the WMO ID while the second column (WBAN) is the WBAN ID.

AERMET Version

The version number of the AERMET model used to process the data is included. AERMOD uses this information to produce a fatal error or warning message if the AERMET version is much older than the version of AERMOD being used. For more information, see our archived Modeling Tip at https://www.weblakes.com/Newsletter/2013/Feb2013.html#tip.

Processing Options

A list of options enabled in AERMET. Options include:

1. ASOS 1-Minute Threshold (THRESH_1MIN) – A threshold applied against AERMINUTE data files containing hourly-averaged wind data from ASOS equipment.


2. Adjusted Surface Friction Velocity (ADJ_U*) – Adjusted surface friction velocity calculation applied


3. MMIF Version #.# – Input data to AERMET generated using the US EPA MMIF utility for processing prognostic model data from WRF or MM5.


4. Bulk Richardson Number (BULKRN) – Bulk Richardson scheme used to process incoming solar radiation and delta-temperature data in lieu of cloud cover.


5. Substituted Cloud Cover (CCVR_Sub) – Default option to use linear interpolation in filling cloud cover gaps of 1-2 hours.


6. Substituted Temperature (TEMP_Sub) – Default option to use linear interpolation in filling temperature gaps of 1-2 hours.