Meteorological observations in the expeditions by H. Clapperton into the interior of Africa, 1822-1827.

The growing evidence of an anthropogenically induced climatic change and the need to compare present day climate with that of past centuries, has boosted the search of early meteorological data from all kind of historical archives. The objective of this work is to present new data from Nigeria corresponding to the 1820s decade. This period coincides with the last years of the so-called ‘Dalton Minimum’, a period of minimum solar activity and intense volcanic eruptions. Data sources are the books describing the expeditions by Hugh Clapperton from 1822 to 1827 into the interior of Africa. Instrumental measurements of temperature and pressure, and qualitative descriptions of the “state of weather” (wind, rain, fog, thunderstorms, cloudiness) in some localities of the country were recorded. These observations are compared with modern instrumental records. Results show an interesting overview on climate conditions in this Sahelian area during the beginning of the 19th century.