ETOPO & ArcView 3.x

Bathymetry and elevation data provded by the National Geophysical Data Center, NOAA can be downloaded free either as custom grids or raw data. These instructions should help you import the data into ArcView 3.x.

Bathymetry and Elevation

NGDC Web page: http://www.ngdc.noaa.gov/mgg/global/seltopo.html

1. Select the area
2. Choose a Database Option: ETOPO5 5 min grid or TerrainBase 5 min grid (they have differnt ways of compiling the data)
3. For Data Output Option choose ASCII Format and "Lat Lon Datavalue" (this will give you a text file that has 3 rows. One for Latitude, Longitude and Elevation/Depth. Negative values in the Datavalue mean depths.)
4. Choose Comma for Delimiter
5. Click the "Create File" Button
6. Another site will come up in which it tells you the size of the file and asks if you would like to continue. Click Continue.
7. Another page will come up with the link to the file that was created. Place the mouse over the link and do a right click. Choose "Save Target As..." from the pulldown list.
8. Open the txt file file in Notepad. Save as a new txt file. Delete all the file metadata information from the top of the page (Keep the field header information: Lat,Lon,Datavalue). Save.
9. Open the new txt file in Access. Once opened, do an Export to another txt file. For the "Save as Type: " select Text File. In the "File Name" enter the new file name and the extension (.txt) in quotations (i.e. "filename.txt"). Click save. In the next window choose "Delimited". In the next window choose "Comma", check the "Include Field Names on First Row" box and Select "{none}" for the Text Qualifier. In the next window click Finish.
10. Add the new txt file to Arcview as a table. Open a new view and add an event theme. Choose the new txt file as the Table and the appropriate fields for the X and Y Fields. Click Ok. You will see in the view the new point theme. Classify the theme to see the variation in Elevation/Depth. (for future use, convert this event theme into a new Shapefile)