Plot proxy stack correlation

Plot the correlation of the spatial average of a certain number of proxy records with the underlying common signal depending on the number of records averaged and their temporal resolution (e.g., as in the firn core analysis of Münch and Laepple, 2018, Fig. 4).

Usage

PlotStackCorrelation(
  data,
  col.pal = NULL,
  label = "",
  xlim = NA,
  ylim = NA,
  xlab = "Number of cores",
  ylab = "Averaging period (yr)",
  xtm = NULL,
  ytm = NULL,
  xtl = NULL,
  ytl = NULL,
  xtm.min = NULL,
  ytm.min = NULL
)

Arguments

data

a list of the correlation data (e.g. as output by ObtainStackCorrelation), which must have two elements: freq and correlation, where freq contains the frequency axis of the underlying proxy dataset (to obtain an axis for the temporal averaging period), and where correlation is a n * m matrix of the correlation values. The number of columns of correlation must match the number of frequency values (i.e. the length of freq), and the row index stands for the number of proxy records averaged.

col.pal

a color palette function to be used to assign colors in the plot; the default NULL means to calculate the palette function internally from ten colours of the diverging RdYlBu palette in the ColorBrewer 2.0 collection.

label

an optional label of the dataset to be displayed at the top of the plot.

xlim

the x limits (x1, x2) of the plot. Set to NA to use default limits calculated from the x data range, or supply a numeric vector of length 2 with custom limits. In the latter case, setting either of the elements to NA results in using the default limit for this element only; see the example.

ylim

as xlim for the y limits of the plot.

xlab

x axis label.

ylab

y axis label.

xtm

x axis tick mark positions; default setting (NULL) uses c(1, 2, 5, 10, 20).

ytm

y axis tick mark positions; default setting (NULL) uses c(2, 5, 10, 20, 50).

xtl

x axis tick mark labels; if NULL determined automatically from xtm, else it must be a vector of labels of the same length as xtm.

ytl

equivalent to xtl for the y axis tick mark labels.

xtm.min

x axis minor tick marks; default setting NULL uses minor tick marks that are adapted to the default x major tick marks. Set to NA to omit minor ticks at all.

ytm.min

as xtm.min for minor y axis tick marks.

References

Münch, T. and Laepple, T.: What climate signal is contained in decadal- to centennial-scale isotope variations from Antarctic ice cores? Clim. Past, 14, 2053–2070, https://doi.org/10.5194/cp-14-2053-2018, 2018.

See also

ObtainStackCorrelation; https://colorbrewer2.org/

Author

Thomas Münch

Examples

# create a toy correlation dataset, which mimicks an increase
# in correlation with timescale and with the number of cores
# averaged, and plot it:

nf <- 20
nc <- 5

data <- list(
  freq = seq(0.01, 0.5, length.out = nf),
  correlation =
    matrix(seq(0.05, 0.9, length.out = nf), nrow = nc, ncol = nf,
           byrow = TRUE) +
    matrix(seq(0, 0.3, length.out = nc), nrow = nc, ncol = nf) +
    matrix(rnorm(nf * nc, sd = 0.02), nrow = nc, ncol = nf)
)
data$correlation[data$correlation > 1] <- 1
data$correlation[data$correlation < 0] <- 0

PlotStackCorrelation(data)