Richard Assmann and the Discovery of the Stratosphere

In the last decade of the 19th century the invention of the sounding balloon in France allowed temperature measurements well above 10 km and soon lead to a most surprising discovery. On 28 April 1902 Leon Teisserence de Bort announced this discovery of an "isothermal zone", which he later termed "stratosphere", to the French Academy of Science. As little as three days later Richard Assmann made a similar announcement to the German Academy of Science (referring to the existence of an "upper inversion"). Teisserenc de Bort and Assmann had been in close contact about the problem of upper air temperature measurements over the years, but followed quite different scientific approaches. While Teisserenc de Bort focused on collecting a large number of soundings under many different conditions (most importantly at night to prevent radiation errors), Assmann meticulously improved the instrumentation but only collected a small number of soundings.

We present a summary of Assmann's report to the German Academy of Science, which we have recently translated into English. In particular, his report includes the temperature data from the 6 soundings he had collected. We discuss these temperature profiles in light of our current understanding of the structure of the tropopause region and present a comparison to available temperature profiles from the 20th century reanalysis product.