An official website of the United States government.

We've made some changes to If the information you are looking for is not here, you may be able to find it on the EPA Web Archive or the January 19, 2017 Web Snapshot.

Support Center for Regulatory Atmospheric Modeling (SCRAM)

Interim Access and Process for Use of 1992 NLCD and NED

In recent years, the Multi-Resolution Land Cover Characteristics (MRLC) Consortium website ( has become the primary source for users of the AERMOD Modeling System to download both land cover data from the 1992 National Land Cover Dataset (NLCD) and elevation data from the National Elevation Dataset (NED) in a format (GeoTIFF) that can be processed directly with the AERSURFACE and AERMAP programs, respectively.  Recently, it was brought to our attention and confirmed by the USGS that the MRLC website is no longer providing either the 1992 NLCD or the NED. In addition, the MRLC website will no longer provide other data products (e.g., more recent NLCD) as GeoTIFF files. Further, the USGS has indicated they are no longer distributing the 1992 NLCD which has been replaced by more recent NLCD products (2001, 2006, and 2011).  The MRLC website has been the only source which we are aware for obtaining the 1992 NLCD. The USGS National Map website ( is their preferred site for acquiring NED data which is maintained and kept up to date.

For AERMOD users in need of obtaining 1992 NLCD and NED data, interim solutions for these changes are being provided until more permanent solutions can be developed.

National Elevation Dataset (NED)  

NED data are maintained and distributed by the USGS on The National Map server (  1 arc-second and 1/3 arc-second NED data can be downloaded for 1 x 1 degree tiles in ArcGrid, GridFloat, and IMG formats for the continental US, Hawaii and Puerto Rico.  Two arc-second data are provided for Alaska as 1 x 1 degree tiles in ArcGrid format.   (Note, additional resolutions are available from The National Map. However, their conversion and processing with AERMAP have not been tested. Historically, 1 arc-second NED data have been sufficient for the continental US, Puerto Rico and Hawaii and 2 arc-second for Alaska.

Provided below are instructions for downloading the 1, 1/3 and 2 arc-second data in ArcGrid format and using the Geospatial Data Abstraction Library (GDAL) to convert the data to a GeoTIFF file that can be processed with AERMAP.

Obtaining 1, 1/3, and 2 arc-second NED Data in ArcGrid Format from The National Map

  1. Follow the provided link to access The National Map (
  2. In the map frame on the right side of the page, zoom to the area of interest.
  3. Click on the “Draw Rectangle” tool on the left side of the map (symbol is black square).
  4. Click and drag to select the area of interest.
  5. Under “Datasets” on the left side of the page, check “Elevation Products (3DEP)” to expand the list of products.
  6. Check “1 arc-second” or “1/3 arc-second” under “All Subcategories,” then check “ArcGrid” under “File Format.”
  7. Click “Find Products” button.
  8. Add the files for the area of interest to the shopping cart.
  9. Click the “View Cart” button to see the contents of your shopping cart.
  10. Download individual tiles using the “Download” links provided.
  11. Unzip to directory of choice.

Conversion from ArcGrid to GeoTIFF for input to AERMAP

As stated above, the instructions for conversion from ArcGrid to GeoTIFF are provided using GDAL, specifically gdal_translate.exe developed for Microsoft Windows systems.

Download x64 compiled GDAL binaries at the following link:

  1. Download the first entry in the table.  “Compiled binaries in a single .zip package.” (
  2. Unzip the file in a folder of your choice.  This will result in the creation of several subdirectories.
  3. Locate gdal_translate.exe under bin\gdal\apps.
  4. Add the absolute path of both the “bin” directory (where the “.dll” files are located) and the “apps”  directory (where “gdal_translate.exe” is located) to your PATH Environment Variable.
  5. Open a Windows command-prompt and set your working directory to the directory of your choice.
  6. At the command-prompt call gdal_translate.exe with the following command-line arguments:
    > gdal_translate  -of GTIFF  -co COMPRESS=NONE   path-to-ArcGrid-data-folder   path\filename-of-geotiff-file

    Note: The ArcGrid-data-folder should be a folder prefixed with “grd” in the folder name. The folder should contain .adf files.

1992 NLCD State Binary Files

With regard to the 1992 NLCD, AERSURFACE was originally developed to process files provided by the USGS and referred to as state binary files (.bin) files for the continental US. That capability was carried forward in the current version of AERSURFACE (v.13016).  Links to zipped archives of these files are provided below. These files should suffice for a majority of AERMOD applications.  The exception may be meteorological tower locations that are within less than 5 km of a state border, in which case the required 10 km domain might extend beyond the data within the file.

These data are being provided to support modeling using the AERMOD Modeling System for regulatory applications while a draft version of AERSURFACE is tested that will process more recent NLCD products.

To use these state binary files, download and unzip the file for the respective state. A few larger states may have multiple files. Run AERSURFACE in a Windows command-prompt. When prompted, enter the path and filename for the state binary (.bin) file. Provide additional information as prompted.

Alabama(ZIP, 29.4 MB)
Arizona(ZIP, 32 MB)
Arkansas(ZIP, 23 MB)
California - North(ZIP, 36.5 MB)
California - South(ZIP, 40.7 MB)
Colorado(ZIP, 36.4 MB)
Connecticut(ZIP, 3.4 MB)
Delaware(ZIP, 1.2 MB)
Florida(ZIP, 33.6 MB)
Georgia(ZIP, 35.8 MB)
Idaho(ZIP, 30.5 MB)
Illinois(ZIP, 21.2 MB)
Indiana(ZIP, 14.4 MB)
Iowa(ZIP, 22.2 MB)
Kansas(ZIP, 34.4 MB)
Kentucky(ZIP, 19.1 MB)
Louisiana(ZIP, 21.3 MB)
Maine(ZIP, 18.1 MB)
Maryland(ZIP, 6.1 MB)
Massachusetts(ZIP, 6 MB)
Michigan(ZIP, 31.9 MB)
Minnesota(ZIP, 34.4 MB)
Mississippi(ZIP, 26.8 MB)
Missouri(ZIP, 33.8 MB)
Montana(ZIP, 47.2 MB)
Nebraska(ZIP, 22.5 MB)
Nevada(ZIP, 22.9 MB)
New Hampshire(ZIP, 5.8 MB)
New Jersey(ZIP, 4.9 MB)
New Mexico(ZIP, 33.4 MB)
New York(ZIP, 25.4 MB)
North Carolina(ZIP, 30.7 MB)
North Dakota(ZIP, 24.6 MB)
Ohio(ZIP, 17.9 MB)
Oklahoma(ZIP, 30.9 MB)
Oregon(ZIP, 33.5 MB)
Pennsylvania(ZIP, 21.5 MB)
Rhode Island(ZIP, 0.8 MB)
South Carolina(ZIP, 19.3 MB)
South Dakota(ZIP, 21 MB)
Tennessee(ZIP, 22.9 MB)
Texas - North(ZIP, 38.2 MB)
Texas - Southeast(ZIP, 59.9 MB)
Texas - Southwest(ZIP, 24.3 MB)
Utah(ZIP, 31.8 MB)
Vermont(ZIP, 5.5 MB)
Virginia(ZIP, 22.2 MB)
Washington DC(ZIP, 0.1 MB)
Washington(ZIP, 28.5 MB)
West Virginia(ZIP, 10.6 MB)
Wisconsin(ZIP, 28.8 MB)
Wyoming(ZIP, 30.4 MB)

Please contact Clint Tillerson of the Air Quality Modeling Group at or 919-0541-2051 with questions related to obtaining or the use of the 1992 NLCD state binary files or NED data with the AERMOD Modeling System.