indicesCPC: Calculation of CPC circulation indices from grid.

In SantanderMetGroup/climate4R.indices: Climate Index calculation for climate4R data

Calculation of CPC circulation indices from grid.

Description

Calculate circulation indices of grids or multimember grids.

Usage

indicesCPC(
  grid,
  base = NULL,
  ref = NULL,
  season = NULL,
  index.code,
  match = "spatial",
  n.pcs = 10,
  rot = TRUE,
  members = NULL
)

Arguments

grid	A grid (gridded or station dataset), or multimember grid object of geopotential height or geopotential.
base	Baseline grid to be substracted for the calculation of anomalies. Default: NULL. See ?scaleGrid.
ref	Reference grid to be added for the calculation of anomalies. Default: NULL. See ?scaleGrid.
season	Selected month(s) for the calculation. Default: NULL (i.e. as input grid).
index.code	Circulation index (or vector of indices with same input variables) to be computed. See circIndexShow() for details.
match	Character string with the criterion to be used for the detection of CPC indices. Options "spatial" or "temporal". Default: "spatial". See details.
n.pcs	Integer vector with the number of EOFs to be retained for the CPC indices. Default: 10. See details.
rot	Logical. Should VARIMAX-Rotation be performed? Default: TRUE. This argument is only relevant for CPC indices. See details.
members	Select number of members. Default: NULL (all members of the grid).

Details

CPC indices are obtained, by default, as the first 10 Varimax-rotated EOFs, as explained in https://www.cpc.ncep.noaa.gov/data/teledoc/telecontents.shtml. The core of this function is stats::prcomp including Varimax rotation. The rotated EOFs are obtained from the monthly standardized anomalies of geopotential or geopotential height at 500hPa, with a 3-month moving window. The argument match is used to assign each rEOF to a circulation index and pattern. Matching is based on 'temporal' or 'spatial' correction of the CPC original (NCEP Reanalysis-based) indices.

Value

A list of circulation indices (and members, if applicable) with:

* index: vector with the time series of the teleconnection index. * pattern: matrix with the spatial pattern of the teleconnection. * dates and coordinates as list attributes. * further arguments related to the CPC indices, such as the corresponding (r)EOF and (temporal or spatial, depending on 'match') correlation with the original index.

Examples

## Not run:  
data(NCEP_hgt500_2001_2010)
cpc <- indicesCPC(grid=NCEP_hgt500_2001_2010, index.code = c("NAO", "EA","PNA"), season=1)

## End(Not run)

SantanderMetGroup/climate4R.indices documentation built on July 3, 2023, 11:02 p.m.