About the calculation of PDO(Pacific Decadal Oscillation)

HI, all

I have a question about how to use ncl to calculate the PDO index. I
searched online but only find the results and method about that.
Below is the method I searched online.

Data used:

* monthly 5x5 Hadley Center SST 1900-93

Method:

1. create monthly anomaly fields for all grid points

2. create a monthly mean global SST anomaly time series for all months,
1900-93, using gridpoints specified in file grid.temp.glob_ocean.977

3. create a "residual SST anomaly" field for the North Pacific by
subtracting out the global mean anomaly from each North Pacific grid point
in file grid.N_Pac_SST.resi.172 (20N-65N, only in Pacific Basin) for all
months and locations

  np_resi(mo,loc)= np_ssta(mo,loc) - global_mean(mo)

4. compute the EOFs of the North Pacific residual SST anomaly fields, and
ignore all missing data point (set them to zeros)

5. the PDO index is the leading PC from the above analysis

6. for PDO index values post 1993, project observed "North Pacific residual
SST anomalies" onto the leading eigenvector (what we call the "PDO pattern"
of ssts) from the EOF analysis done in step 4. We now do this with the
Reynold's and Smith Optimally Interpolated SST (version 2) data.

Is there anyone have the relative script about how to calculate the PDO?
Thanks!

Best,

DK

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Received on Tue Aug 14 03:55:25 2012