The NAO

[weatherwiz]

There is something I have been confused about with regards to the NAO which I have asked several people about before but not sure if I'm exactly clear on the issue. As many may know there are several different methods or several different versions of how the NAO is calculated. You have the method used by the CPC, the method used by Jim Hurrell and the method used by Tim Osborne. I have heard from some that Hurrell's method is more accurate and gives a better depiction of the NAO, I've also heard from some people that the CPC's definition of the NAO is correct and is better to use b/c it's more widely known than Hurrell and Osborne's methods.

My questions is;

Of these three methods which is the best to use or go by? Does each version have it's strengths and weaknesses and if so are there times where one version may be more correct than another?

[ORH_wxman]

I like Hurrell.

CPC uses upper air which is nice, but their domain is too large IMHO...I think Hurrell's values show the pattern better in how we relate to the CONUS. Both have their problems, but I seem to "agree" with Hurrell more when I look at the upper air maps for each month when we are trying to relate this stuff to our own weather....but obviously there are times when the CPC one might score a coup and be better. But in all of my research for NAO stuff, I have used Hurrell.

[weatherwiz]

I like Hurrell.

CPC uses upper air which is nice, but their domain is too large IMHO...I think Hurrell's values show the pattern better in how we relate to the CONUS. Both have their problems, but I seem to "agree" with Hurrell more when I look at the upper air maps for each month when we are trying to relate this stuff to our own weather....but obviously there are times when the CPC one might score a coup and be better. But in all of my research for NAO stuff, I have used Hurrell.

Excellent, thanks! I was hoping you'd see this and respond.