| Summary: | It has been known for some time that the potential exists to create long daily series of pressure for the cities of London and Paris by piecing together the barometer readings from various observers and institutions. However, most of the readings prior to 1920 have not previously been digitized or converted to modern units. To rectify this, work began in 2006 to locate and digitize these observations and then to correct the data to form homogeneous series of pressure. Observations have been located to span the years 1670–2007 for Paris and 1692–2007 for London, although significant gaps exist for the periods 1726–47 (Paris) and 1717–22 (London) where no daily pressure observations appear to have survived. The barometer observations were subjected to a quality control procedure before being corrected to represent daily means of sea-level pressure at standard conditions. Statistically significant breakpoints were tested and corrected using the RH-test (version 2). This thesis describes the sources of data used in the London and Paris daily pressure series, and how the data were corrected and homogenized. The new series are compared with previous monthly reconstructions of Mean Sea-Level Pressure (MSLP) for London and Paris. In addition to being of a higher resolution (daily) and stretching over a longer time period than the previous data, the new series resolve certain inhomogeneities apparent in the monthly reconstructions. The daily data are used to construct a westerly index for Europe, which extends instrumental North Atlantic Oscillation (NAO) indices back to the eighteenth century. The relationship of this westerly index to surface temperature across Europe is examined. The results support the findings of previous studies that have indicated non-stationary relationships over time between the atmospheric circulation and surface temperature in the region. The London and Paris series are also used to assess the variability of storminess in the English Channel area over the last 300 years.
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