# Presentation: 678274

## AERMAP Briefing for the8th Conference on Air Quality ModelingSeptember 22, 2005by Peter EckhoffEnvironmental Scientist, US EPA

## Purpose of AERMAP

- Calculate elevations for sources and receptors
- Adjust coordinates so all under one Datum
- Calculate critical hill height values for receptors
- Output formatted for input to AERMOD control file

## Example AERMAP Output File

- ** AERMAP - VERSION 02222**  Using Durham NW DEM data file                                                                                                   **                                                                                                                                  ** A total of   9  7.5-minute DEM files were used** DOMAINXY  683500.0 3990500.0 17 686500.0 3993500.0 17                                                                            ** ANCHORXY  0.0      0.0     685000.0 3992000.0 17 1                                                                               ** Terrain heights were extracted by default  RE ELEVUNIT METERS   GRIDPOLR POL1 STA                                                                                                                            POL1 ORIG   0.0   0.0                                                                                                               POL1 DIST   100.   200.   300.   500.   1000.                                                                                       POL1 GDIR   36     10.    10.                                                                                              GRIDPOLR POL1     ELEV    1       132.86       137.55       142.49       148.89       136.50   GRIDPOLR POL1     ELEV    2       133.60       138.86       143.26       147.71       136.12   GRIDPOLR POL1     ELEV    3       135.15       139.78       140.59       145.54       133.69     :     :     :   GRIDPOLR POL1     ELEV   34       134.09       136.88       139.40       144.84       136.00   GRIDPOLR POL1     ELEV   35       133.34       134.83       136.01       145.46       134.55   GRIDPOLR POL1     ELEV   36       133.00       135.23       138.18       149.23       130.67   GRIDPOLR POL1     HILL    1  132.86  137.55  142.49  148.89  136.50   GRIDPOLR POL1     HILL    2  133.60  138.86  143.26  147.71  136.12   GRIDPOLR POL1     HILL    3  135.15  139.78  140.59  145.54  133.69     :     :     :   GRIDPOLR POL1     HILL   34  135.00  151.00  151.00  144.84  136.00   GRIDPOLR POL1     HILL   35  133.34  149.00  151.00  145.46  134.55   GRIDPOLR POL1     HILL   36  133.00  135.23  138.18  149.23  130.67   GRIDPOLR POL1 END

## Introduction to Modifications

-    Treatment of Critical Hill Height Receptors
-     Use with SDTS File Format
-     Use with Mixed DEM Datums
-     Ability to Read 7 Digit Northing Coordinates

## Introduction to Modifications –continued

-     Better Error Checking
-     Use of XYZ Terrain Data for Input
-     Use of Various Nodes Spacings
-     Status of Aermap
- 	    Allocatable Arrays
- 	    Testing

## Treatment of Critical Hill Height Receptors

- Public comment:
-       Critical Hill Heights could vary based on
-       domain size which did affect the results
- Response:
-       Search for terrain that breaks through a
-       10% slope from a receptor.

## Treatment of Critical Hill Height Receptors

## Incorporate SDST File Format

-      Public Comment:   Provide ability to read SDTS formats
-      Response:
-     SDTS - Spatial Data Transfer Standard
-                Available on several internet sites for “free”.
-                May find some download restrictions
-     SDTS files are preprocessed and reconstituted into the old
-                “native” DEM file format using the SDTS2DEM program
-     Batch file system being included with AERMAP package.
-                Important to read instructions and comments

## Use with Mixed DEM Datums

- Public Comment:     Want to use AERMAP with two
-                                 different datums
- Response:
- Can process 7.5-minute files with:
- 		North American Datum 1927,
- 	   	North American Datum 1983,
-  		Old Hawiian Datum, and
- 		Puerto Rico and Virgin Island Datum
-      Can process 1-Degree files with:
- 		World Geodetic System 1972, and
- 		World Geodetic System 1984 Datums
- Need to add a Datum code at end of the ANCHOR keyword

## Ability to Read 7-digit Northing Coordinates

- Public Comment:  AERMAP was not able to fully
-                               process the 7-digit Northing
-                               Coordinate
- Response:
- Done by using Double Precision variables
- 	and double to single and single to double
- 	precision functions.

## Better Error Checking

- Public Comment:  There was a need sighted for better error 		        checking of the raw data
- Response:
- Additional error checks were added to AERMAP
- DEM files were scrutinized for problems and better READ algorithms were developed
- Additional debug statements were added
- An additional debug strategy is being	reviewed

## Need to Process XYZ Terrain Data

- Public Comment:  There is a need to be able to read user-
-  	 		 prepared XYZ in a user-specified format
- Response:
- A draft method has been developed where the user copies a DEM file and fills in the appropriate field with their own data.
- The X and Y values must be evenly spaced
- The values can be in UTM or Arc-seconds
- The user needs to understand the USGS “Blue Book” format – copy in AERMAP User’s Guide
- A draft XYZ Terrain User’s Guide has been prepared

## Use of Variable Node Spacings

- Emailed Comment: 	The USGS SDTS files have node
-                                  spacings of 10 meters that cause
-                                  AERMAP to crash
- Response:
- The X, Y, and Z spacing values and units which are found in the DEM file header are now read and utilized in AERMAP.
- These values are used instead of the	previously fixed values.

## Status of AERMAP

- Allocatable Arrays
- Testing