Meteorological data

This webpage contains ready-to-run meteorological data suitable for the most recent version of AERMOD (version 16216r).

Meteorological data processed with AERMET version 14134 has been removed from this site. If meteorological data sets are needed for this past version, please send a request to the MPCA Air Modeling email at airmodeling.pca@state.mn.us. In your request, include the surface and upper air station and AERMET version data you would like.

Note that the fulfillment of any request for a meteorological dataset is not an approval for use by MPCA air modeling staff. All meteorological data submittals will be subject to MPCA review. Justification for meteorological site selection should be included as part of the air modeling e-Service protocol or the protocol resubmittal form (AQDM-1.5).

General information for development of AERMOD-ready meteorological data

There are approximately 80 meteorological surface observing stations in the state of Minnesota, consisting of ASOS (Automated Surface Observing System) and AWOS (Automated Weather Observing System) sites. The overwhelming majority of these sites are located on airport property and follow guidelines laid out in the Federal Meteorological Handbook (see Links subpage).

During 2009 through 2011, 87 stations from Minnesota, Wisconsin, South Dakota and North Dakota were examined using preliminary processing to determine usability for modeling purposes. Data usability were based on the amount of missing and calm hours per year for each surface station for the years 2000 – 2008. From the original 87 surface stations examined during that time, 46 stations were then further processed to include site-specific yearly-averaged moisture conditions, corrected locational data, and the years 2009 and 2010. This preliminary processing provided the foundation to our meteorological data and informs which sites are processed in future updates. Currently, there are over 20 surface stations that are suitable for use in current modeling demonstrations.

For any questions regarding the development of the meteorological data sets, please contact Daniel Dix (651-757-2326 or daniel.dix@state.mn.us) or Steve Irwin (651-757-2563 or steve.irwin@state.mn.us).

Surface meteorological data were obtained from the National Centers for Environmental Information (NCEI) Integrated Surface Database (ISD). This database is also referred to as the Integrated Surface Hourly Database (ISHD or ISH) or TD-3505. ISHD and TD-3280 are currently the only active formats after 1995 for National Weather Service (NWS) files. Additionally, most ASOS stations also have 1-minute average wind speed and direction data available to supplement the ISHD data, by using the pre-processing program AERMINUTE.

This data set, referred to as DSI-6405, consists of a running 2-minute average wind speed reported for every minute. These data are then used in Stage 2 of AERMET to either substitute missing on-site winds or replace standard winds from the ISHD file(s).  For more details, see section 2.3.1 of the Addendum to the EPA’s “User’s Guide for the AERMOD Meteorological Preprocessor (AERMET)”, as well as EPA’s “AERMINUTE User’s Instructions.” 

At present, on-site meteorological data are not included on this webpage.

Most stations with a WBAN number of 99999 prior to 2009 changed to their current WBAN number on November 24, 2008, with an exception of Grand Forks, ND (GFK). The WBAN changed from 14916 to 99999 briefly in 2010, and then back to 14916. The USAF number for GFK also changed during this time period, from 727576 to 727570. No changes since 2010 have taken place for any site that MPCA pre-processes with AERMET.

Upper air data (also known as radiosondes or soundings) were obtained from the National Oceanic and Atmospheric Administration (NOAA) and Earth System Research Laboratory (ESRL)’s Radiosonde Database. Data were collected for each individual year, for all sounding times and data levels, with wind units selected as tenths of meters/second. Upper air data were processed separately from the surface data in AERMET, resulting in upper air-specific Stage 1 files for three upper air stations:

  • Aberdeen, SD (WMO #: 72659) (Call sign: ABR)
  • International Falls, MN (WMO #: 72747) (Call sign: INL)
  • Chanhassen, MN (WMO #: 72649) (Call sign: MPX)

Note that in 1995, upper air measurements were discontinued at the St. Cloud station (call sign: STC) and were moved to the NWS Twin Cities office in Chanhassen, MN. In future updates, upper air data from Bismarck, ND (WMO #: 72764) (call sign: BIS) will be considered for processing with our North Dakota and northwestern Minnesota surface stations.

Surface characteristics were determined using the EPA’s AERSURFACE processor, which relies on 1992 Land Use Land Cover (LULC) data for Minnesota, Wisconsin, South Dakota, and North Dakota. Land use was examined around each meteorological surface station’s location, to a radius of 1.0 kilometer. Albedo and Bowen ratio values were also examined using a default area of 10.0 km by 10.0 km.

The use of yearly average moisture conditions using historical precipitation rankings from the Minnesota State Climatology Office in the form of gridded GIS files with precipitation data including the edge of nearby states allowed for detailed ranking determinations. For stations in Minnesota, each individual year for every surface station was categorized as: average, dry, or wet.

AERSURFACE, configured to run with 12 sectors (the maximum allowed) on a monthly basis (12 months), results in 144 values each for albedo, Bowen ratio, and surface roughness. Climatology determined seasonal selections, utilizing spring freeze out dates, autumn first frosts, and snow cover data. Beginning in 2015, MPCA began to utilize snow cover data (snowfall depth) from the National Centers for Environmental Information (NCEI) database. Statewide snow depth measurements from all NWS observed and COOP sites were analyzed in ArcGIS to determine the number of days with snow on the ground for each month and year at each meteorological site. Surface characteristics for months with snow cover were adjusted in post-processing by applying the ratio of the number of days with snow (at least 1” on ground) to days without snow. Equation 1 shows how that snow fraction was used to adjust the albedo, Bowen ratio, and surface roughness values:

SCVadj = ((Sf)(SCVws) + (1 – Sf)(SCVns)) [1]

Where:

SCVadj = The adjusted surface characteristic value
Sf = snow fraction
SCVws = AERSURFACE surface characteristic value with snow
SCVns = AERSURFACE surface characteristic value without snow

This methodology matches what is recommended in the draft Region 5 Meteorological Processing Guidance located in the ‘Documents’ section of this page.

All AERSURFACE outputs, after post-processing, were used in Stage 3 AERMET input files, as-is. The exception to this was the surface station MSP (Minneapolis/St. Paul Int’l Airport, MN). Recent aerial images showed that the land use had changed since 1992, with the addition of a new runway and developing new cargo facilities along Cargo Road. These changes occurred in sectors 7 and 8 of the 1 km surface roughness area. To account for these changes without being able to use a more up-to-date LULC data in AERSURFACE, sector 4’s surface roughness value was used as a surrogate for sectors 7 and 8.

MPCA pre-processed meteorological data for AERMOD

Meteorological data sets are listed by the meteorological surface station’s three-letter call sign. Ex., MSP = Minneapolis/St. Paul Int’l Airport. Currently, each surface station is processed with one of three available upper air stations, based on proximity: MPX (Chanhassen, MN), INL (International Falls, MN), and ABR (Aberdeen, SD).

AERMET version 16216

Meteorological data were processed with AERMET version 16216 (for use with AERMOD versions 16216r), which includes the processors AERMINUTE version 15272 and AERSURFACE version 13016. Data are available for the 5-year period of 2012 – 2016.

Not all meteorological stations that were available for previous versions of AERMET are available for AERMET version 16216. This could be due to data availability, number of missing and calm hours in a dataset, and determination by MPCA of appropriate representative sites. If the dataset you are looking for is not listed below, please contact MPCA air modeling staff at AirModeling.PCA@state.mn.us for further discussion. Note that the processing of a particular meteorological dataset is not an approval for use by MPCA air modeling staff, and any justification for the use of a particular meteorological dataset is still subject to MPCA review and should be included as part of the air modeling protocol.

During 2013, several ASOS sites reported 1-minute wind data only for the months of January to May, instead of for the entire year. This was due to federal budget cuts and affected over a 100 ASOS sites nationwide. Current surface sites that were affected by this include Brainerd (BRD), Hibbing (HIB), International Falls (INL), and Park Rapids (PKD). AERMINUTE version 15272 allows 5-minute ASOS data to be used for June to December. MPCA incorporated these data into the processing of these sites making these approvable for modeling purposes.

As a result of the Appendix W release in December of 2016 where the adjusted surface friction velocity (ADJ_U*) approach has been approved by the EPA for use as a regulatory modeling default, the MPCA has processed AERMET data using ADJ_U* as the default data set.  Use of ADJ_U* for PSD projects will require at least some form of justification and explanation for its use for EPA and MPCA review. An informal process by email notification will be all that is required. For non-PSD, it will be highly recommended to include a similar explanation to accompany the usual justification of a meteorological site to be used as there may be instances where non-ADJ_U* AERMET data is more appropriate. The MPCA also processed an AERMET data set of sites using non-ADJ_U* as an option for projects where it is more appropriate.

Call sign - surface station name, state County Available years   Elevation (m) AERMINUTE? Call sign — upper air station name, state ADJ_U* (Default) Non-ADJ_U*
AXN - Alexandria, MN Douglas 2012-2016   432 Yes MPX - Chanhassen, MN Package icon aq2_101.zip Package icon aq2_101.2.zip
*BRD - Brainerd, MN Crow Wing 2012-2016   372 Yes MPX - Chanhassen, MN Package icon aq2_102.zip Package icon aq2_102.2.zip
DLH - Duluth Int’l Arpt, MN St. Louis 2012-2016   435 Yes INL - International Falls, MN Package icon aq2_103.zip Package icon aq2_103.2.zip
**DYT - Duluth Sky Harbor Arpt, MN St. Louis 2009-2013   186 No INL - International Falls, MN Package icon aq2_104.zip Package icon aq2_104.2.zip
FAR - Fargo Int'l Arpt., ND Cass 2012-2016   272 Yes ABR- Aberdeen, SD Package icon aq2_105.zip Package icon aq2_105.2.zip
FCM - Flying Cloud Arpt, MN Scott 2012-2016   276 Yes MPX - Chanhassen, MN Package icon aq2_106.zip Package icon aq2_106.2.zip
FSD - Sioux Falls Int'l Arpt, SD Minnehaha 2012-2016   433 Yes ABR- Aberdeen, SD Package icon aq2_107.zip Package icon aq2_107.2.zip
GFK - Grand Forks Int'l Arp't Grand Forks 2012-2016   255 Yes ABR- Aberdeen, SD Package icon aq2_108.zip Package icon aq2_108.2.zip
HCO – Hallock, MN Kittson 2012-2016   249 No INL - International Falls, MN Package icon aq2_109.zip Package icon aq2_109.2.zip
*HIB – Hibbing, MN St. Louis 2012-2016   408 Yes INL - International Falls, MN Package icon aq2_110.zip Package icon aq2_110.2.zip
*INL - International Falls, MN Koochiching 2012-2016   353 Yes INL - International Falls, MN Package icon aq2_111.zip Package icon aq2_111.2.zip
LSE - La Crosse, WI La Crosse 2012-2016   292 Yes MPX - Chanhassen, MN Package icon aq2_112.zip Package icon aq2_112.2.zip
MIC - Crystal, MN Hennepin 2012-2016   262 Yes MPX - Chanhassen, MN Package icon aq2_113.zip Package icon aq2_113.2.zip
MJQ – Jackson, MN Jackson 2012-2016   439 No MPX - Chanhassen, MN Package icon aq2_114.zip Package icon aq2_114.2.zip
MML – Marshall, MN Lyon 2012-2016   359 No MPX - Chanhassen, MN Package icon aq2_115.zip Package icon aq2_115.2.zip
MSP - Minneapolis/St. Paul Int’l Arpt, MN Hennepin 2012-2016   256 Yes MPX - Chanhassen, MN Package icon aq2_116.zip Package icon aq2_116.2.zip
OWA, Owatonna, MN Steele 2012-2016   344 No MPX - Chanhassen, MN Package icon aq2_117.zip Package icon aq2_117.2.zip
*PKD - Park Rapids, MN Hubbard 2012-2016   439 Yes MPX - Chanhassen, MN Package icon aq2_118.zip Package icon aq2_118.2.zip
RST – Rochester, MN Olmsted 2012-2016   396 Yes MPX - Chanhassen, MN Package icon aq2_119.zip Package icon aq2_119.2.zip
RWF - Redwood Falls, MN Redwood 2012-2016   311 Yes MPX - Chanhassen, MN Package icon aq2_120.zip Package icon aq2_120.2.zip
STC - St. Cloud, MN Sherburne 2012-2016   310 Yes MPX - Chanhassen, MN Package icon aq2_121.zip Package icon aq2_121.2.zip
STP - St. Paul Downtown Arpt, MN Ramsey 2012-2016   212 Yes MPX - Chanhassen, MN Package icon aq2_122.zip Package icon aq2_122.2.zip
ULM - New Ulm, MN Brown 2012-2016   308 No MPX - Chanhassen, MN Package icon aq2_123.zip Package icon aq2_123.2.zip

* 1-min. data (January-May) and 5-min data (June-December) for the year 2013 (January through May).
** Duluth Sky Harbor (KDYT) METAR AWOS site exceeded EPA Region 5 allowable calms in 2014 making 2012-2016 dataset ineligible for use. The previous AERMET v14134 2009-2013 files will be allowed for use. MPCA will be working with area meteorological data to find a workable solution to best serve the Duluth/Superior (Twin Ports) area and will update and post once available.

Data files contained within each zip file follow the 8-character naming convention of SFCUPAYY (ex., MSPMPX12):

  • The first three characters, SFC, represents the meteorological surface station ID (ex., MSP);
  • The fourth through sixth characters, UPA, represents the upper air station ID (ex., MPX for the Chanhassen, MN upper air station);
  • The last two characters, YY, represents the two digit year (ex., 12 = 2012, 16 = 2016, 5Y = five-year concatenated file, etc.).

Each zip file contains:

  • 5-year wind roses (SFCUPA5Y_windrose_YYYY-YYYY.bmp)
  • 5-year wind frequency counts (SFCUPA5Y_FreqCount_YYYY-YYYY.csv)
  • AERSURFACE outputs for each year (SFC_YYYY_AERSURFACE.out)
  • 5-year concatenated profile file (SFCUPA5Y_YYYYYYYY.pfl)
  • 5-year concatenated surface file (SFCUPA5Y_YYYYYYYY.sfc)
  • 5 subfolders for each individually-processed year, each of which contains:
    • Yearly wind rose (SFCUPAYY_windrose.bmp)
    • AERMET stage 3 input file (SFCUPAYY.in3)
    • Wind frequency counts (SFCUPAYY_FreqCount.csv)
    • AERMET stage 3 message file (SFCUPAYY.ms3)
    • AERMET stage 3 output – profile file (SFCUPAYY.pfl)
    • AERMET stage 1 report file (SFCUPAYY.rp1)
    • AERMET stage 2 report file (SFCUPAYY.rp2)
    • AERMET stage 3 report file (SFCUPAYY.rp3)
    • AERMET stage 3 output – surface file (SFCUPAYY.sfc)

Guidance for selecting the appropriate meteorological data set

40 CFR Part 51, Appendix W, 8.3.a. states that the following should be considered when choosing representative meteorological data:

  • The proximity of the meteorological monitoring site to the area under consideration;
  • The complexity of the terrain;
  • The exposure of the meteorological monitoring site;
  • The period of time during which data are collected.

Section 8.3.c further states that “of paramount importance is the requirement that all meteorological data used as input to AERMOD must be both laterally and vertically representative of the transport and dispersion within the analysis domain.” It also states, “…the surface characteristics input to AERMET should be based on the topographic conditions in the vicinity of the meteorological tower.”

MPCA air dispersion modeling staff has made a detailed effort to make available recent meteorological data, so as to more accurately reflect recent meteorological conditions. In order to determine the most representative meteorological station for use, it is recommended that the subject source consider meteorological sites with similar features. Features to consider include:

  • Wind direction and wind speed patterns
  • Terrain influences on wind patterns
  • Surface characteristics (albedo, Bowen ratios, surface roughness), based on surrounding land use
  • Proximity
  • Time period
  • AERMINUTE (to minimize calm hours) (if applicable, per EPA guidance)

In areas of the state where complex or highly variable terrain occurs (river valleys, lake shores, northeast Minnesota, etc.), it is recommended that a meteorological set be chosen based mainly on surface characteristics, wind patterns, land use, and terrain. In areas of Minnesota where terrain is relatively flat and invariable, then proximity, surface characteristics, land use, and wind patterns are to be examined.

No matter the subject source and the reliance on past meteorological sites, please provide explanation/reasoning for your choice of met sets in the air modeling e-Service protocol.

For any questions regarding the choice of a meteorological data set(s) for your source, please contact MPCA air dispersion modeling staff to discuss.

Documents

Visualizations and figures

  • Updated figures coming soon.

Below is the history of AERMOD and AERMET-related activities. EPA’s recent activities can be found on their SCRAM page (see Links subpage).

  • 2004
    • September – MPCA posted various “trial” documents and “trial” data sets for AERMAP version 02222 and AERMET version 02222 for testing purposes only.
  • 2005
    • October – MPCA posted various “draft” documents and “draft” data sets for AERMAP version 04300 and AERMET version 04300 for testing purposes and conditional regulatory use.
    • November – EPA released AERMOD/AERMAP/AERMET versions 04300.
  • 2006
    • December – EPA released AERMOD/AERMAP/AERMET versions 06341.
  • 2007
    • January – EPA released AERMOD version 07026, which continues to use data processed with AERMAP/AERMET versions 06341.
    • February – MPCA re-processed the aforementioned “draft” meteorological data using AERMET version 06341 for stage 1, stage 2, and stage 3.
  • 2008
    • January – EPA released AERSURFACE version 08009.
  • 2009
    • October – EPA released AERMOD version 09292, which continues to use data processed with AERMAP/AERMET versions 06341, and now AERMAP version 09040.
  • 2011
    • February – EPA released AERMOD/AERMET/AERMINUTE versions 11059.
      • AERMOD version 11059 accepts meteorological data processed with either AERMET version 06341 or 11059. 
      • AERMOD version 11059 will also accept meteorological data processed with AERMINUTE version 11059, which is used in conjunction with AERMET version 11059.
    • April – EPA released AERMOD/AERMAP versions 11103.
    • December – EPA released AERMOD version 11353 and AERMINUTE version 11325. AERMOD continues to use AERMET version 11059.
  • 2012
    • February – EPA released AERMOD version 12060.
    • March – MPCA posted updated pre-processed meteorological data for regulatory use, using AERMET/AERMINUTE versions 11059 and AERSURFACE version 08009.
    • December – EPA released AERMOD/AERMET versions 12345.
      • AERMOD version 12345 only accepts meteorological data processed with AERMET versions 11059 or 12345. 
      • Meteorological data processed with AERMET version 06341 will no longer be useable in AERMOD.
  • 2013
    • January – EPA released AERSURFACE version 13016.
    • December – EPA released AERMOD/AERMET versions 13350. 
      • AERMOD version 13350 only accepts meteorological data processed with AERMET versions 12345 or 13350.
      • In January 2014, EPA reported significant bugs in AERMOD/AERMET versions 13350, and that they intended to address these bugs in the next update.
  • 2014
    • May – EPA released AERMOD/AERMET versions 14134.
      • AERMOD version 14134 accepts meteorological data processed with AERMET versions 12345, 13350, and 14134. 
    • July – MPCA posted updated pre-processed meteorological data for regulatory use, using AERMET version 12345, AERMINUTE version 11325, and AERSURFACE version 13016 for years 2006-2010.
  • 2015
    • July – MPCA posted updated pre-processed meteorological data for regulatory use, AERMET version 14134 and AERMINUTE version 14337 for years 2009-2013.
    • September – EPA released AERMINUTE version 15272 to read in optional 5- minute ASOS files (due to 2013 1min issues at various ASOS sites).
  • 2016
    • December – EPA released AERMOD/AERMET versions 16216 (08/03/2016).
      • AERMOD version 16216 accepts meteorological data processed with AERMET versions 16216, 15181, and 14134.
      • AERMET addressed issue in calculation of adjusted U* (version 15181) in version 16216.
  • 2017
    • January – EPA released AERMOD version 16216r.
      • AERMOD version 16216r accepts meteorological data processed with AERMET versions 16216, *15181 and 14134.
        • (*version no longer approved if processed with adjusted U*)
        • In January, EPA reported issues/bugs with AERMOD version 16216 and published an updated version called 16216r.
      • May – MPCA posted updated pre-processed meteorological data for regulatory use, AERMET version 16216, AERMINUTE version 15272, and AERSURFACE 13016 for years 2012-2016.