How often is the NED 1 arc second and 1/3 arc second data updated?
A. The NED 1 arc second is updated every other month with any new “best available” elevation data. The NED 1/3 arc second is updated every other month, but the opposite of the NED 1 arc second. An example of the schedule would be NED 1 arc second updated in October 2004 and NED 1/3 arc second November 2004 and so on.
