Ansley,
I found the data for county boundaries at nationalatlas.gov. After a bit of searching I discovered IDL can read the GIS shapefile provided by the site so I was able to convert the data into netCDF for use by Ferret. If you are interested, I can send you the file. Others might find it useful, so you might want to include it in a future Ferret release. Right now I have the data in an independent file, but I could see adding the county lat/lon info to the file used by land_detail and then extending that script to include county boundaries for the USA. The filesize is 12 MB. Attached is an example plot for California and Nevada with the counties in black and the states and continents in red:
yes? use counties_usa.nc
yes? show d
currently SET data sets:
1> ./counties_usa.nc (default)
name title I J K L
COUNTY_LON
Longitude of county borders 1:778766 ... ... ...
COUNTY_LAT
Latitude of county borders 1:778766 ... ... ...
yes? plot/vs/line/hlim=-125:-112/vlim=31:42.5 county_lon, county_lat
yes? go land_detail 2,,2,2
-Bill
On 3/11/10 10:20 AM, "Ansley Manke" <Ansley.B.Manke@xxxxxxxx> wrote:
Hi Bill,
The data we download to create the datasets containing outlines is from
the "pscoast" tool in the GMT software, as outlined in the Ferret FAQ
http://ferret.pmel.noaa.gov/FERRET_17sep07/FAQ/graphics/coastlines.html
That source does not include data for outlines of counties, and I'm not
aware of any source for that data. The coastline-extractor mentioned in
our FAQ page contains political boundaries, but I believe that consists
only country and state boundaries as well.As you say, it must be
available somewhere. The data consist of (lon,lat) pairs, separated by
a missing-value where the pen should pick up, so the Ferret command to
plot them is just
plot/vs/line lon_data, lat_data.
Ansley
Gustafson, William I wrote:
> Hi,
>
> I did a quick search of the Ferret archives but did not see anybody asking about this before. Has anybody generated a file that could be used to draw U.S. county lines on a map similar to land_detail for the states and rivers? The data must be out there somewhere.
>
> I've looked at how land_detail handles the state boundaries. I'm assuming it is not trivial to get the lat/lon pairs setup so that all the lines connect at the right places.
>
> Thanks for any suggestions.
>
> -Bill
_______________________________________________
William I. Gustafson Jr., Ph.D.
Scientist
ATMOSPHERIC SCIENCES AND GLOBAL CHANGE DIVISION
Pacific Northwest National Laboratory
P.O. 999, MSIN K9-30
Richland, WA 99352
Tel: 509-372-6110
William.Gustafson@xxxxxxx
http://www.pnl.gov/atmospheric/staff/staff_info.asp?staff_num=5716
http://www.researcherid.com/rid/A-7732-2008
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