The Earliest Pressure Measurements in Bologna: Recovery, Correction, and Homogenization of the 1715–1774 Series

The recovery of measurements from the early instrumental period is crucial for improving the quality of historical climate reconstructions, enhancing model calibration, and increasing the reliability of long-term predictions. The study aims to recover, correct, and analyze the daily pressure observations made in Bologna by Jacopo Bartolomeo Beccari and his pupils from 1715 to 1774. The empirical quantile mapping at monthly level using the Padua series as a reference resulted in the most reasonable correction method. The quality of the reconstruction was assessed through a posteriori data analysis at monthly, seasonal, and annual time scales. The reconstructed Bologna series shows general agreement with the contemporary Padua series, in particular in the day-by-day variability and percentile distribution. Moreover, its main features reflect those of the 1961–1990 reference period. The annual cycle is also consistent with the Milan and Venice series for the overlapping periods. The notable difference between the 18th-century pressure observations in Northern Italy and the paleo-reanalysis dataset ModE-RA (Modern Era Reanalysis) is likely due to the fact that instrumental measurements are only assimilated from the 18th century onward. The paper provides a new 18th-century daily dataset and is part of a broader effort aimed at reconstructing the Bologna pressure series up to the present day.