File:Northern Hemisphere snow cover.svg

Summary
Self created image from public domain data found at http://climate.rutgers.edu/snowcover/files/wkcov.nhland.txt

Plot was generated by first calculating a simple average (A) for each week over the period 1980-2000. Then the weekly values where converted to anomalies by subtracting A.

The plot was then generated by gnuplot:

set terminal svg set font "Helvetica" set output "plot.svg" set multiplot set xzeroaxis set xlabel "Year" set ylabel "Snow-cover\n5*10**6" set title "Northern Hemisphere snow cover" plot 'plot2' using 1:($2/5e6) with lines title "Anomalies" lt 1,\ 'plot2' using 1:($2/5e6) with lines smooth bezier title "Bezier smooth" lt 3