Precipitation at Armagh Observatory 1838-1997

The meteorological series maintained at Armagh Observatory began in 1795 an d are the longest in Ireland and among the longest in the British Isles. He re we present the monthly mean daily precipitation recorded at Armagh since 1838. Variations in the distribution of the rainfall during the year, over this period, are apparent, with a tendency for drier summers in recent dec ades. We find a significant correlation between the mean seasonal rainfall and the North Atlantic Oscillation index during autumn and winter, and ther e appears to be a negative correlation between the summer rainfall and the North Atlantic Oscillation index for the previous winter. A search for peri odicities has been made and Ilo evidence of an eleven-year cycle similar to the Sunspot cycle has been found. However, Fourier analysis reveals an app roximate seven-year cycle in summer rainfall. We examine the evidence that this cycle may be linked either to the Taurid meteor stream or to the North Atlantic Oscillation.