weatherwiz Posted November 26, 2012 Share Posted November 26, 2012 I would really like to construct biweekly (even weekly) values of all the global indices, first I would like to do the NAO. I have daily readings of the NAO from the CPC which are online, I also plan on emailing Dr. Jim Hurrell if he has daily NAO readings archived but I just need to know the process of doing the math in order to construct this. If anyone could give me just a step-by-step process of what to do that would be fantastic! Link to comment Share on other sites More sharing options...
heavy_wx Posted December 3, 2012 Share Posted December 3, 2012 The NAO is generally defined as the first Empirical Orthogonal Function (EOF) of the 500 hPa height anomalies. So the first thing that has to be done is to calculate the weekly or biweekly 500 hPa height anomalies. Various scientific computing packages can then calculate the EOFs from these anomalies. The NCL (NCAR Command Language) has a sample script on their website that calculates yearly values of the NAO, the first link on this page http://www.ncl.ucar.edu/Applications/eof.shtml . The eof_1.ncl script uses slp anomalies which can be modified to use the 500 hPa heights, although the two fields correlate well. The script can also be modified to calculate monthly, biweekly or weekly values of the NAO. Link to comment Share on other sites More sharing options...
weatherwiz Posted December 3, 2012 Author Share Posted December 3, 2012 Thanks for this link! When I get more time to look over it I will. Link to comment Share on other sites More sharing options...
Yeoman Posted December 3, 2012 Share Posted December 3, 2012 Thanks for this link! When I get more time to look over it I will. Sounds good, Bigfoot Link to comment Share on other sites More sharing options...
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