What is a Dobson Unit?

What is a Dobson Unit?

A dobson unit is the most basic measure used in
ozone research. The unit is named after
G.M.B. Dobson, one of the first scientists to
investigate atmospheric ozone (~1920 - 1960).
He designed the 'Dobson Spectrometer' - the
standard instrument used to measure ozone from
the ground. The Dobson spectrometer measures
the intensity of solar UV radiation at four wavelengths,
two of which are absorbed by ozone and two of
which are not.

[ http://jwocky.gsfc.nasa.gov/dobson.html [

The illustration above shows a column of air,
10 deg x 5 deg, over Labrador, Canada. The amount
of ozone in this column (i.e. covering the 10 x 5 deg
area) is conveniently measured in Dobson Units.

If all the ozone in this column were to be compres-
sed to stp (0 deg C and 1 atmosphere pressure) and
spread out evenly over the area, it would form a
slab approximately 3mm thick.

1 Dobson Unit (DU) is defined to be 0.01 mm
thickness at stp; the ozone layer over Labrador then
is ~300 DU.
NOTE: This page, including the copyrighted graphic,
is based on a page developed by Owen Garrett for the
Centre for Atmospheric Science at Cambridge University,
UK. The center has kindly given us permission to
reproduce it. (Take their excellent Multimedia Ozone
Hole Tour!)
http://www.atm.ch.cam.ac.uk/tour/index.html

http://www.env.go.jp/en/wpaper/1990/eae190023000001.gif

http://www.env.go.jp/en/wpaper/1990/eae190024000001.gif