NASA provides extensive ozone data. I wanted to see what it looks like over time. The following charts describe the following:
The ozone hole area is determined from total ozone satellite measurements. It is defined to be that region of ozone values below 220 Dobson Units (DU) located south of 40°S.
— Link
Note: 1995 and most of 1996 is missing from their data. I delete 1996 entirely for annual average.
Code: ozone.sh
# Zoe Phin
# 2020/12/22
require() { sudo apt-get install curl gnuplot; }
download() { for y in {1979..2020}; do
curl -o y$y.csv "https://ozonewatch.gsfc.nasa.gov/meteorology/figures/ozone/to3areas_${y}_toms+omi+omps.txt"
done; }
daily() { awk '
BEGINFILE { d=0 }
FNR>6 && $2!~/9999/ {
y=substr($1,1,4); d+=1/366
printf "%8.3f %s\n", y+d, $2
}' y*.csv > daily.csv
}
# Run daily() first
annual() { cut -c 1-4,9- daily.csv | awk '{
S[$1]+=$2; N[$1]+=1
} END {
for (y in S) print y" "S[y]/N[y]
}' | sed '/^1996/d' > annual.csv
}
# Arg 1 - 'daily' or 'annual'
plot() { echo "set term png size 740,370
set nokey
set title 'Ozone Hole Area (mil. km²)'
set xrange [1979:2021]
set mxtics 5
set grid ytics
plot '$1.csv' u 1:2 w l lw 1 lc rgb 'blue'
" | gnuplot > $1.png
}
Run it:
$ source ozone.sh
$ require && download
$ daily && annual
$ plot daily
$ plot annualEnjoy 🙂 -Zoe
Doesn’t add up. The hole was first observed using a Dobson Spectrophotometer in the 1950s at Halley Bay.
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This data covers everything south of 40 degrees latitude South, not a single location.
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Isn’t it weird that in 2019 it was almost at its minimum (since 1987), and then in 2020 almost at its maximum…
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…as if legal policy didn’t matter one bit.
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One possibility is that the data from the early years — say, before 1983 — is incomplete. Perhaps the measurement systems were not ironed out or successful?
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I think they rushed to judgment and won’t admit their mistake. Hairspray wasn’t the problem.
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So it’s similar to when they first showed retreating ice-caps?
Ice melts in the summer, and reforms in winter.
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