Analysis of a newly recovered historical sea level and air pressure dataset in Cap Horn (1882-1883)

As part of the first international polar year (1882-1883), two scientific bases were established in the southern hemisphere by France and Germany. The French settled at the southern tip of South America seventy km northwest of Cape Horn at Orange Bay and the German expedition two thousand km away in the south Atlantic in the South Georgia Islands (Royal Bay). This contrasts with the effort put in the northern hemisphere, where 12 stations were installed during this first international polar year. The Cape Horn mission was organized by the French Science Academy and 140 men were send to the south to set up the scientific base and to carry out meteorological and magnetic operations over the course of a year. During this period, sea level measurements were carried out using a tide pole at the arrival of the expedition and then a floating tide gauge. The 300 original tidal charts (marigrams) of the floating gauge have not yet been found, but about 15000 half-hourly sea level measurements from the tables of the scientific report have been digitized. We have also digitized the barometric pressure records. The recording was almost continuous from September 12, 1882 to August 31, 1883.  This newly recovered dataset is one of the few records of the southern hemisphere's sub-polar regions to cover almost a full year in the 19th century. In particular, this recording enables precise analysis of the tides in this part of the world. In the presentation we will assess the quality of the records and discuss the evolution of the tide in this region.