AERMOD View – Understanding AERMOD’s Profile Met File
January 2015
The US EPA AERMOD air dispersion model requires two meteorological data files – a surface file (*.SFC) and a profile file (*.PFL). The profile met file is commonly misunderstood for a variety of reasons. That AERMET, the meteorological preprocessor for AERMOD, requires upper air data as input, implies that the profile file will contain some sort of record of this data for AERMOD to analyze. Some users may be confused to open a profile file only to find a limited amount of information from a single level of measurement.
The profile file was written by the United States Environmental Protection Agency (US EPA) to “[contain] one or more levels (a profile) of winds, temperature and the standard deviation of the fluctuating components of the wind.” However, standard National Weather Service (NWS) hourly observations are only taken at the surface level (approximately 6 to 10 meters above ground). This results in a file which contains only a single level.
The image below is an example of a profile met file with data at multiple levels (2, 10, and 30 meters). Data were sourced from an onsite station with measurement equipment at different heights.
The profile file was written by the United States Environmental Protection Agency (US EPA) to “[contain] one or more levels (a profile) of winds, temperature and the standard deviation of the fluctuating components of the wind.” However, standard National Weather Service (NWS) hourly observations are only taken at the surface level (approximately 6 to 10 meters above ground). This results in a file which contains only a single level.
The image below is an example of a profile met file with data at multiple levels (2, 10, and 30 meters). Data were sourced from an onsite station with measurement equipment at different heights.
The second example shows a more standard profile met file; that is, a profile file containing data from a single-level NWS station.
