[ferret_users] Scale Factor in Polymark

[Jennifer Keene <jennifer.keene@xxxxxxxx>]

I am trying to draw mooring avoidance circles over bathymetry data, and am currently using this command:

! Plot avoidance area for most recent mooring location

GO POLYMARK POLY/OVER/PALETTE=grey_light/NOLABELS Lon[i=1] Lat[i=1] , , circle 9

Is there a way to use actual geographic distances to define the radius of the circle?  For example, I want this circle to have a radius of 3NM.

I adjusted my plot Lat/Lon ranges so that the ratio of degrees per inch on each axis was the same (0.075°/inch).  Then I translated my desired circle radius to inches (3NM = 0.05° = 0.67” on my axis scale).  Now I can’t quite figure out how to translate that to the scale parameter.  Can anyone help me figure out how to do this last step?  Or should I be doing something different?

Thank you,

Jennifer Keene

Research Scientist/Engineer

NOAA Pacific Marine Environmental Lab

7600 Sand Point Way, Bldg. 3

Seattle, WA 98115

(206)526-4805

http://www.pmel.noaa.gov/ocs/