Definition of Dobson unit in US English:

Dobson unit

(also DU)


  • A unit of measurement for the total amount of ozone in the atmosphere above a point on the earth's surface, one Dobson unit being equivalent to a layer of pure ozone 0.01 mm thick at standard temperature and pressure.

    • ‘Ozone measurements from the first week of March already show a region over the North Atlantic with very low ozone levels (<250 Dobson units).’
    • ‘The unit of measure is a Dobson unit, which is equivalent to 1 milli-centimetre atmosphere of column ozone.’
    • ‘Ground-based measurements of ozone for all 3 days were within 8 Dobson units.’
    • ‘The ozone hole area is defined as the size of the region with total ozone below 220 Dobson units.’
    • ‘This ratio changed by less than 1% as column ozone varied by 50 Dobson units, about 300 DU, so for subsequent calculations we used only the ratios computed for the central ozone value.’


1980s: from the name of G. M. B. Dobson (1889–1976), British meteorologist.


Dobson unit

/ˈdäbsən ˌyo͞onit/