The format is a list with components:
"longitude" "latitude" "precip" "elevation" "precipSE" "trend" "trendSE" "type" "x.s" "sProjection"
with elevation in meters, longitude as (-180,180), latitude as (-90, 90) and precipitaion in 1/10 mm
( precip/254 converts to inches of rainfall)
precip
is the intercept for 1980.5 when a straight line least squares regression is fit to
each station's record. SE is the companion standard error from the least squares fit.
If the station is complete, then precip
and precipSE
will just be the mean and standard deviation adjusted for a linear trend. The estimated trend trend
and and its standard error trendSE
are also included.
Also due to the centering, for complete data the intercept and trend estimate will be uncorrelated. The component type
indicates whether the station has been "adjusted" (see below) or is still in
"unadjusted" form.
x.s
is a useful transformation of locations into stereographic coordinates that reduces the
inflation of North Canada due to the usual lon/lat coordinates. Specifically it is found by:
library(mapproj)
xStereo<- mapproject( NorthAmericanRainfall$lon,NorthAmericanRainfall$lat, projection="stereographic")
NorthAmericanRainfall$x.s<- cbind( xStereo$x, xStereo$y)
NorthAmericanRainfall$projection<- .Last.projection
Use NorthAmericanRainfall$orientation
to access the stereographic projection orientation.