1. Test Runs Using AERMAP Version 09040 and
the National Elevation Dataset
2009 Annual NESCAUM Permit Modeling Committee Meeting
Mystic, CT
June 24-25, 2009
Dave Healy
New Hampshire Department of Environmental Services
(603)

2. Highlights of AERMAP Version 09040
Can process USGS National Elevation Dataset (NED) data files in
GeoTIFF format
Allows mixed DEM files (i.e. 1-degree and 7.5-minute DEMs can be
used in the same run; can’t mix DEM and NED, however)
User no longer needs to specify a domain (i.e. DOMAINXY and
DOMAINLL keywords are now optional)
User can INCLUDE source and receptor data in external input files

3. USGS National Elevation Dataset
Available for free download using the USGS Seamless
Data Server
Multiple NED data files can be used as input to AERMAP
and they can overlap
Access the National Map Seamless Server at

4. Downloading NED Data from the Seamless Server
button
NED
data
select download area using rectangle or coordinates, etc.

5. Downloading NED Data (Continued)
modify the data request

6. Downloading NED Data (Continued)
select GeoTIFF

7. NED Data Files Downloaded for Modeling in NH

8. AERMAP Test Cases Two Project Locations: Keene, NH Bow, NH
Four Tests (plus the baseline case):
Baseline case = the original unaltered AERMAP run for the project, which
was done with Version and DEM data
Test 1 = Version with DEM data and a specified domain
Test 2 = Version with DEM data and no domain specified
Test 3 = Version with NED data and a specified domain
Test 4 = Version with NED data and no domain specified

9. Summary of AERMAP Test Case Results
Test 1: DEM Data with Domain Specified, Difference from Baseline
Elevation
Controlling Hill Height
Location
Max.
Difference (m)
Ave.
Keene
0.00
2.00
Bow
Both Projects

10. Summary of AERMAP Test Case Results (Continued)
Test 2: DEM Data with No Domain Specified, Difference from Baseline
Elevation
Controlling Hill Height
Location
Max.
Difference (m)
Ave.
Keene*
0.00
2.00
Bow
Both Projects
*With DEM data and no domain specified, there were three “gap” receptors for the Keene project
(elevations are flagged as missing for gap receptors).

11. Summary of AERMAP Test Case Results (Continued)
Test 3: NED Data with Domain Specified, Difference from Baseline
Elevation
Controlling Hill Height
Location
Max.
Difference (m)
Ave.
Keene
18.65
3.26
175.18
2.67
Bow
6.02
0.69
25.59
1.56
Both Projects
1.98
2.11

12. Summary of AERMAP Test Case Results (Continued)
Test 4: NED Data with No Domain Specified, Difference from Test 3
Elevation
Controlling Hill Height
Location
Max.
Difference (m)
Ave.
Keene
0.00
Bow
Both Projects

13. DEM and NED vs. Hard-Copy Topo Map
Receptor
DEM
NED
Topo
Diff.
UTM-E (m)
UTM-N (m)
Elev. (m)
Topo-DEM (m)
Topo-NED (m)
715500
354
343
342
-12 -1
717000
186
179
180 -6 1
716800
198
206
207 9
716400
263
253
252
-11
246
237
236
-10
715400
326
333
336 10 3
715800
359
350
348 -2
340
329
330
218
210 -8 4
349
339
-13 -3
327
318
321
269
260
258
714400
356
346
-14 -4
717600
238
228
714600
259
267
270 11
275
265
264
716200
280
291
294 14
328
310
312
-16 2
362

14. Test Case Conclusions
Test 1 – DEM data with domain: essentially no difference from the
baseline case (a couple receptors in Keene had a 2-meter difference
in controlling hill height)
Test 2 – DEM data with no domain: also essentially no difference from
the baseline case, except that without a domain, three gap receptors
were left in Keene
Test 3 – NED data with no domain: a fairly high maximum difference
from the baseline case (especially in controlling hill height) and a modest
average difference from the baseline
Test 4 – NED data with no domain: results were identical to Test 3
(i.e. specifying a domain has no effect with NED data) and no gap
receptors were left
Note: Baseline case = previous AERMAP version with DEM data

15. Test Case Conclusions (Continued)
For the limited number of receptors that I checked by hand against the
hard-copy topo map, the NED data was closer to the topo than the DEM
data
AERMAP run times were longer with NED data, especially without a
domain specified

16. AERMAP v Test Runs – Keene Landfill Receptors Processed with DEM Data (left) and NED Data (right)
ELEVATIONS

17. CONTROLING HILL HEIGHTS
AERMAP v Test Runs – Keene Landfill Receptors Processed with DEM Data (left) and NED Data (right)
CONTROLING HILL HEIGHTS

18. AERMAP v Test Runs – Blue Seal Feeds Receptors Processed with DEM Data (left) and NED Data (right)
ELEVATIONS

19. CONTROLING HILL HEIGHTS
AERMAP v Test Runs – Blue Seal Feeds Receptors Processed with DEM Data (left) and NED Data (right)
CONTROLING HILL HEIGHTS