Abstract

Building on the achievements of the CLIWOC project and its use of ships’ logbooks for climatic reconstructions, this thesis examines more closely the conditions over the North Atlantic during the latter half of the eighteenth century. Furthermore, and importantly, this thesis provides additional verification of this largely untapped data source for scientific purposes.
Such is the recent nature of this field that the logbook data required careful translation and manipulation before they could be used in climatological studies and a significant element of the thesis is devoted therefore to the important question of data verification and treatment.
Indices were derived from the logbook data that described the wind patterns in the areas north and south of the Azores anticyclone, taking the form of vectors combining wind force and direction. These indices were developed at monthly resolution (although the original logbook data are presented in daily form on CD1, which accompanies this thesis) and also aggregated up to annual resolution. The indices showed good agreement with accepted climatological theory and the general character of wind flows in the two constituent sub-regions noted above could be identified at this scale of resolution for the very first time. Studies were developed using independently derived indices, including a grid-based North Atlantic Oscillation Index (NAOI), the Central England Temperature series (CET), the England and Wales Precipitation series (EWP) and sunspot number, which were selected for their coverage of the study period at monthly resolution. A number of significant correlations were found between the logbook indices and also between the latter and the ‘independent’ series. Some of these, such as those between airflow and the Central England Temperature series were not unexpected, but welcome nonetheless by conforming to climatological theory. Others, however, especially those suggesting a solar signal in the climate record were new and more challenging. These require additional research, much of it beyond the scope of this thesis, and provide an inviting pointer for future studies using this demonstrably valuable data source.