Earliest meteorological readings in San Fernando (Cádiz, Spain)

Abstract

Abstract. Cádiz and San Fernando are two nearby towns with a wealth of meteorological records due to their connection with the Spanish Royal Navy officers and enlightened merchants. Several previous works have already recovered a significant amount of meteorological records of interest in these localities. However, unnoticed previously more than 40,000 daily meteorological observations recorded at the Royal Observatory of the Spanish Navy (located in San Fernando) during the period 1799–1813 remained neither digitized nor studied. Here, we have carried out this important task describing the different steps undertaken to achieve it as well as the results obtained. The dataset is composed by different meteorological variables such as atmospheric pressure, air temperature, precipitation, or state of the sky. As a first step a quality control was carried out to find possible errors in the original data or in the digitization process. Moreover, the antique units were converted to modern units. Also, the metadata and an analysis of the data have been described. Finally, we study in detail the meteorological conditions in October 1805, during the Battle of Trafalgar and to check the possible local effects of the unknown volcanic eruption of 1809. The dataset is freely available to the scientific community and can be download at https://doi.org/10.5281/zenodo.7104289.