Paul Josef Crutzen (1933-2021).

In his Ph.D. thesis work, Crutzen had shown that the choice of the rate constants employed by Hampson and Hunt could not explain the vertical distribution of ozone in the stratosphere and furthermore would result in unrealistically rapid ozone loss in the troposphere. In May 1973, Paul submitted his D.Sc. dissertation entitled, 'On the photochemistry of ozone in the stratosphere and troposphere and pollution of the stratosphere by highflying aircraft' which was again awarded the highest distinction possible. Understanding of tropospheric ozone and its chemical production through organic trace gases and nitrogen oxides, helped clear lingering notions about downward transport of ozone from the stratosphere being the major source of tropospheric ozone. Paul's earthly journey commenced on 3 December 1933 in Amsterdam where he was born to Anna Gurk and Jozef Crutzen. [Extracted from the article]