The first meteorological measurements in the Iberian Peninsula: evaluating the storm of November 1724

Domínguez-Castro F., Trigo R. M., Vaquero J. M.
Climatic Change, 118, 443-455, DOI 10.1007/s10584-012-0628-9

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Early instrumental series can play a key role in the study of recent climate change or assessments of specific extreme events. Unfortunately in the Iberian Peninsula few series are available relative to the 18th century. In this article we retrieved and make available the first daily instrumental series obtained in Iberia. The observations were made in Lisbon between 1 November 1724 and 11 January 1725 by Diogo Nunes Ribeiro. While pressure and temperature values were registered twice a day, the remaining variables, i.e. the state of the sky, wind direction and force, have only one value per day. Despite the relatively short period covered by this series, we were very fortunate to discover that it helps to characterize one of the strongest storms that struck Lisbon since the early 17th century. In particular, the data provide evidence for an outstanding pressure drop of 28.61 hPa from 1010.76 hPa on the 18 November to just 982.15 hPa on the 19 November. Using recently digitized pressure data for Lisbon since 1863, we can state that this 24 h decrease of surface pressure has been surpassed only once on the 28 November 1879. Moreover, the extreme winds associated with this "bomb" affected severely the entire Lisbon area as well as large sections of central and northern Portugal during the afternoon of 19 November and caused important damage in the eastern coast of Madeira the night before (18 November). This storm resembles the rare tropical storms that have reached the Iberian Peninsula as a tropical storm (Vince 2005) or the low intense hurricane that occurred in 1842.