Date: Wed, 12 Oct 2011 15:09:20 -0600 (MDT) From: Keith Lindsay To: Nancy J. Norton Subject: Re: "fresh eyes"/sanity check review? Nancy, Glad to help. The Arctic front is an artifact of the fill algorithm. It shows up when regridding a dataset that is all missing values in the Arctic. The algorithm iteratively fills from non-land non-missing neighbors, until either there are no non-land values left to be filled, or filling is no longer actually filling in values. For an initially missing Arctic, the key point is that the algorithm does not apply any smoothing to the filled values. What happens is that the initially missing Arctic gets simultaneously filled from the Bering Strait and the North Atlantic, which typically have different values of the field being regridded. When these fill patterns meet, the algorithm stops, leaving the front. Keith On Wed, 12 Oct 2011, Nancy J. Norton wrote: > > Thanks, Keith. The ALK field looks much, much better, > with no spurious zero values along the coasts and > the Arctic filled in with reasonable values. The > only issue that I observed was a visible "front" > in the Arctic, but I'm going to go ahead for now and > see if more reasonably interpolated ICs will eliminate > the present problem. (I'll update my to-do list to > include investigating the Arctic front). > > Thank you for all of your help, > > -- Nancy