final_program_abstracts[1]

11 IMSC Session Program
The London and Paris daily pressure series, 1692-2007: The
development and analysis of long pressure series
Tuesday - Parallel Session 8
Richard Cornes
Over the last ten years, daily series of mean sea-level pressure (MSLP) have been
constructed for several sites across Europe that extend back into the mid-eighteenth
century. These series have allowed more detailed analyses of the variability of the
atmospheric circulation in the North Atlantic/Western European area than have
previously been possible with monthly resolution data. However, long daily series of
MSLP have not been constructed for the cities of London and Paris. While MSLP
series have previously been developed for these two sites at the monthly resolution,
many of the daily barometer observations have never been extracted from the original
sources and have remained uncorrected and unhomogenized. To rectify this situation,
the barometer observations recorded by several scientists and organisations based in
the cities of London and Paris have been recovered and corrected. By joining these
data with previously corrected short series, daily series of MSLP have been
constructed for the two sites that extend back to the late seventeenth century (1692 in
the case of London and 1670 for Paris). Given that these series consist of the
instrumental readings from several observers and extend over a considerable length of
time, the homogenization of the data has been an important and major component of
the project. This process has been helped by the fact that many of the observations
were recorded by leading scientists or scientific institutions, and a remarkable amount
of information about the observations is available, even for the seventeenth and
eighteenth centuries. Through the application of suitable corrections, these pressure
data are able to yield important information about the state of the atmospheric
circulation in previous times, and how the circulation has varied over the past 300
years. Most notably, the MSLP series permit the construction of a westerly index on a
near-continuous basis back to 1748 and on a more fragmented basis back to 1692.
Abstracts 147