The development of a daily historical European-North Atlantic mean sea level pressure dataset (EMSLP) for 1850-2003 on a 5°latitude by longitude grid is described. This product was produced using 86 continental and island stations distributed over the region 25°-70°N, 70°W-50°E blended with marine data from the International Comprehensive Ocean-Atmosphere Data Set (ICOADS). The EMSLP fields for 1850-80 are based purely on the land station data and ship observations. From 1881, the blended land and marine fields are combined with already available daily Northern Hemisphere fields. Complete coverage is obtained by employing reduced space optimal interpolation. Squared correlations (r 2 ) indicate that EMSLP generally captures 80%-90% of daily variability represented in an existing historical mean sea level pressure product and over 90% in modern 40-yr European Centre for Medium-Range Weather Forecasts Re-Analyses (ERA-40) over most of the region. A lack of sufficient observations over Greenland and the Middle East, however, has resulted in poorer reconstructions there. Error estimates, produced as part of the reconstruction technique, flag these as regions of low confidence. It is shown that the EMSLP daily fields and associated error estimates provide a unique opportunity to examine the circulation patterns associated with extreme events across the European-North Atlantic region, such as the 2003 heat wave, in the context of historical events.

Tree-rings can provide continuous yearly paleoclimatic records for regions or periods of time with no instrumental climate data. However, different species respond to different climate parameters with, for example, some sensitive to moisture and others to temperature. Here, we describe four common species growing in Northern Ireland and their suitability for climate reconstruction.Our results suggest that beech and ash are the most sensitive to climate, with tree-ring widths more strongly influenced by precipitation and soil moisture in early summer than by temperature or sunshine. Oak is also sensitive to summer rainfall, whereas Scots pine is sensitive to maximum temperature and the soil temperature.We find that the moisture-related parameters, rainfall and the Palmer Drought Severity Index (PDSI), and to a lesser extent, maximum and mean temperatures, can be reconstructed. Reconstructions of climate parameters with tree-rings as proxies may be relatively stable for some seasons such as May-July. We find that combinations of species are more successful in reconstructing climate than single species.

We have analysed the trends in four long meteorological time series from Armagh Observatory and compared them with series available from other Irish sites. We find that although maximum and minimum temperatures have risen in line with global averages, minima have risen faster than maxima, thereby reducing the daily temperature range. The total number of hours of bright sunshine has fallen since 1885 at the four sites studied, which is consistent with both a rise in cloudiness and the fall in the daily temperature range. Over the past century, soil temperatures at both 30cm and 100cm depths have risen twice as fast as air temperature.Wavelet analysis has found significant cycles with periods of 7Á 8 years, 20Á 23 years and 30 Á 33 years in the seasonal and annual meteorological series from Armagh. Some of these cycles are clearly linked to the North Atlantic Oscillation.