The PDO index is derived as the leading principal of monthly SST anomalies in the North Pacific Ocean, poleward of 20N. The monthly mean global average SST anomalies are removed to separate this pattern of variability from any "global warming" signal that may be present in the data.
The NCEI PDO index is based on NOAA's extended reconstruction of SSTs (ERSST Version 4). It is constructed by regressing the ERSST anomalies against the Mantua PDO index for their overlap period, to compute a PDO regression map for the North Pacific ERSST anomalies. The ERSST anomalies are then projected onto that map to compute the NCEI index. The NCEI PDO index closely follows the Mantua PDO index.
Arguments
- use_cache
logical option to save and load from cache. If `TRUE`, results will be cached in memory if `file` is `NULL` or on disk if `file` is not `NULL`.
- file
optional character with the full path of a file to save the data. If `cache` is `FALSE` but `file` is not `NULL`, the results will be downloaded from the internet and saved on disk.
Value
Date: Date object that uses the first of the month as a placeholder. Date formatted as date on the first of the month because R only supports one partial of date time
Month: Month of record
Year: Year of record
PDO: Pacific Decadal Oscillation index
References
Original PDO: https://oceanview.pfeg.noaa.gov/erddap/info/cciea_OC_PDO/index.html