()scorr
This function calculates the spatial correlation between two variables over an X-Y domain. It returns a single number. The syntax is:
(scorr(expr1, expr2, xdim1, xdim2, ydim1, ydim2
where:
expr1
- any valid grads expression
expr2
- any valid grads expression
xdim1
- starting X dimension expression
xdim2
- ending X dimension expression
ydim1
- starting Y dimension expression
ydim2
- ending Y dimension expression
For global averaging, a shorthand may be used:
scorr(expr1, expr2, global)
or
scorr(expr1, expr2, g)
is the same as
scorr(expr1, expr2, lon=0, lon=360, lat=-90, lat=90)
Usage Note
-
scorr
may be used in conjunction withtloop
ordefine
to create time series or time/height plots.
-
scorr
assumes that the world coordinates are longitude in the X dimension and latitude in the Y dimension, and does weighting in the latitude dimension by the delta of the sin of the latitudes. Weighting is also performed appropriately for unequally spaced grids.
Examples
This example calculates the correlation between the surface temperature and the latent heat flux over the tropical Pacific:
set lat -10 10set lon 120 280d scorr(tsfc, lhtfl, lon=120, lon=280, lat=-10, lat=10)