EVIDENCE FOR SOLAR-CYCLE FORCING AND SECULAR VARIATION IN THE ARMAGH-OBSERVATORY TEMPERATURE RECORD (1844-1992)

A prominent feature of previous long-term temperature studies has been the appearance of warming since the 1880s, this often being taken as evidence for anthropogenic-induced global warming. In this investigati on, the long-term, annual, mean temperature record (1844-1992) of the Armagh Observatory (Armagh, North Ireland), a set of temperature data based on maximum and minimum thermometers that predates the 1880s and correlates well with northern hemispheric and global standards, is exa mined for evidence of systematic variation, in particular, as related to solar-cycle forcing and secular variation. Indeed, both appear to b e embedded within the Armagh data. Removal of these effects, each cont ributing about 8% to the overall reduction in variance, yields residua ls that are randomly distributed. Application of the 10-year moving av erage to the residuals, furthermore, strongly suggests that the behavi or of the residuals is episodic, inferring that (for extended periods of time) temperatures at Armagh sometimes were warmer or cooler (than expected), while at other times they were stable. Comparison of cyclic averages of annual mean temperatures against the lengths of the assoc iated Hale cycles (i.e., the length of two, sequentially numbered, eve n-odd sunspot cycle pairs) strongly suggests that the temperatures cor relate inversely (r = -0.886 at <2% level of significance) against the length of the associated Hale cycle. Because sunspot cycle 22 ended i n 1996, the present Hale cycle probably will be shorter than average, implying that temperatures at Armagh over this Hale cycle will be warm er (about 9.31 +/- 0.23 degrees C at the 90% confidence level) than av erage (= 9.00 degrees C).