Home > ERSST, HadSST, Natural Variability > SST Regions: NorthWest Pacific 23N-65N, 120E-180E

SST Regions: NorthWest Pacific 23N-65N, 120E-180E

2011 March 3
I extend the previous work on global and hemispheric fourier analysis with HadSST2 and ERSSTv3b into regional analysis. First up is the NorthWest Pacific as defined by a bounding box 23N-65N, 120E-180E.

I used the ‘crop‘ in the ‘raster‘ package. The crop function takes a raster object and an extent. So I set up a simple function to return cropped rasters and loop through the individual years of the series.

cropRaster <- function (r,r1,r2,c1,c2) {
          return(crop(r, extent(r,rowFromY(r,r1), rowFromY(r,r2), colFromX(r,c1), colFromX(r,c2))))
}

region_hadsst <- stack(cropRaster(raster(hadsst,layer=1),65,23,120,180))
for (i in 2:dim(hadsst)[3]) {
    region_hadsst <- addLayer(region_hadsst,cropRaster(raster(hadsst,layer=i),65,23,120,180))
}

region_ersst <- stack(cropRaster(raster(ersst,layer=1),65,23,120,180))
for (i in 2:dim(ersst)[3]) {
    region_ersst <- addLayer(region_ersst,cropRaster(raster(ersst,layer=i),65,23,120,180))
}

I had to upgrade the spectral threshold value from 0.1 of the max intensity to the 0.2 of the max intensity. The 5.5 freq spike in both sets is interesting. We didn’t see any significant freq with a period of less than 10 years and this high of a relative intensity in the global or hemispheric means.

HadSST2 NWPAC ERSSTv3b NWPAC
[1] 162, 81, 40.5, 27, 20.25, 7.36, 5.59, 3.52, … [1] 160, 80, 53.3, 40, 26.7, 20, 7.6, 6.2, 5.7, 5.5

Code is here: trend-sst-regional-nwpac-fourier.R


Update: 2011 03 07 – Inverted x-axis on Fourier. Formatted freq text on Fourier. Standard color scale. Colors and cuts from HadSST2 map.

Advertisements