S1: S1 Score, Anomaly Correlation

In SpatialVx: Spatial Forecast Verification

S1 Score, Anomaly Correlation

Description

Calculate the S1 score and anomaly correlation for a verification set.

Usage

S1(x, ...)

## Default S3 method:
S1(x, ..., xhat, gradFUN = "KernelGradFUN")

## S3 method for class 'SpatialVx'
S1(x, ..., xhat, gradFUN = "KernelGradFUN",
    time.point = 1, obs = 1, model = 1)

ACC(x, ...)

## Default S3 method:
ACC(x, ..., xhat, xclim = NULL, xhatclim = NULL)

## S3 method for class 'SpatialVx'
ACC(x, ..., xclim = NULL, xhatclim = NULL,
    time.point = 1, obs = 1, model = 1)

Arguments

x, xhat	m by n matrices giving the verification and forecast fields, resp. For S1.SpatialVx and ACC.SpatialVx, x is an object of class “SpatialVx”.
xclim, xhatclim	m by n matrices giving the climatologies for X and Y, resp. If NULL, the result is simply a usual correlation.
gradFUN	character identifying a function used to calculate the gradient fields for X and Y. The default KernelGradFUN is to use a Laplacian of Gaussian kernel.
time.point	numeric or character indicating which time point from the “SpatialVx” verification set to select for analysis.
obs, model	numeric indicating which observation/forecast model to select for the analysis.
...	optional arguments to the gradFUN function. In the case of the default, the kernel can be changed (e.g., if only “laplacian” is desired), and optional arguments to the kernel2dmeitsjer function (in this case, nx, ny and sigma). Not used by ACC.

Details

The S1 score is given by

S1 = 100*sum(abs(DY_i - DX_i))/sum(max(abs(DY_i),abs(DX_i))),

where DY_i (DX_i)is the gradient at grid point i for the forecast (verification). See Brown et al. (2012) and Thompson and Carter (1972) for more on this score.

The ACC is just the correlation between X - Xclim and Y - Yclim.

Value

single numeric

Author(s)

Eric Gilleland

References

Brown, B.G., Gilleland, E. and Ebert, E.E. (2012) Chapter 6: Forecasts of spatial fields. pp. 95–117, In Forecast Verification: A Practitioner's Guide in Atmospheric Science, 2nd edition. Edts. Jolliffee, I. T. and Stephenson, D. B., Chichester, West Sussex, U.K.: Wiley, 274 pp.

Thompson, J. C. and Carter, G. M. (1972) On some characteristics of the S1 score. J. Appl. Meteorol., 11, 1384–1385.

See Also

kernel2dmeitsjer

Examples

data( "UKobs6" )
data( "UKfcst6" )

S1( UKobs6, xhat = UKfcst6 )
ACC( UKobs6, xhat = UKfcst6 )

## Not run: 
data( "obs0601" )
data( "wrf4ncar0531" )
data( "ICPg240Locs" )

hold <- make.SpatialVx( obs0601, wrf4ncar0531, loc = ICPg240Locs,
    projection = TRUE, map = TRUE, loc.byrow = TRUE,
    field.type = "Precipitation", units = "mm/h",
    data.name = "ICP NSSL/SPC Spring 2005 Cases",
    obs.name = "obs0601", model.name = "wrf4ncar0531" )

plot( hold )

S1( hold )
ACC( hold )

## End(Not run)

SpatialVx documentation built on May 29, 2024, 9:31 a.m.