This picture shows the seasonal average concentrations of tropospheric ozone in Dobson units over the period 1979 to 2000.
13.
That compares to a minimum of 98 Dobson units in 2000, said Bryan Johnson, a scientist with NOAA's Climate Monitoring and Diagnostics Laboratory in Boulder, Colorado.
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Ozone levels are far lower here than in much of the rest of the world, less than 200 Dobson units on the scientific scale of measurement.
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In temperate regions, seasonal variations can produce large swings in ozone levels, reaching as high as 475 Dobson units in some areas, and as low as 300.
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In temperate regions, seasonal variations can produce large swings in ozone levels, reaching as high as 475 Dobson Units in some areas, and as low as 300.
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Per the definition of Dobson Units, we see that 1 DU = 0.01 mm of trace gas when compressed down to sea level at standard temperature and pressure.
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The results are measured in Dobson Units, equal to 10 �m thickness of ozone compressed to Standard conditions for temperature and pressure ( STP ) in the column.
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The ozone hole is the area with total column ozone below 220 Dobson Units, as measured by satellites and balloon-borne ozone measuring instruments launched from the South Pole station.
20.
Heavily ozone-depleted air from the Arctic region settled over England about a month ago, dropping ozone concentrations below 200 Dobson Units for the first time in 17 years of measurement.
