Abstract
AbstractThree independent mean temperature series for Armagh Observatory, covering the period 1796–2002 have been calibrated and corrected for the time of reading and exposure. Agreement between the three series is good in regions of overlap. With a short gap in the Armagh data from 1825 to 1833 filled by data from two stations in Dublin, the resulting series is the longest for the island of Ireland and one of the longest for any single site in the British Isles.Over the past 207 years, we note that temperatures in Armagh, in all seasons, show a gradual overall trend upwards. However, there are seasonal differences: summer and spring temperatures have increased by only half as much as those in autumn and winter. This is partly due to the exceptionally cold winters and autumns experienced prior to 1820. Relative to the overall trend, warm periods occurred in Ireland, as in other parts of Europe, in the mid‐19th century, in the mid‐20th century and at the end of the 20th century. Relatively cool temperatures prevailed in the early 19th century, in the 1880s and in the 1970s. Thus, if the baseline against which current temperatures are compared were moved from the late 19th century to include the earlier warm period, the apparent warming at the end of the late 20th century would be correspondingly reduced.A gradual decline in the daily temperature range at Armagh since 1844 may have resulted from higher minimum temperatures associated with increased cloudiness.A 7.8 year periodicity is identified in winter and spring mean temperatures at Armagh, which is probably a consequence of the North Atlantic oscillation. Copyright © 2005 Royal Meteorological Society
Highlights
Our instrumental knowledge of climate change prior to the mid-19th century relies heavily on a few long meteorological series, most of which are from Europe
For each of the three temperature series maintained at Armagh Observatory with which we are concerned here, namely Series I, II and III, we have investigated the various instrumental and exposure effects and, where necessary, we have made corrections
This has been done in the present instance using the mean diurnal temperature curves for Armagh for each day of the year, based on the hourly temperature data recorded at Armagh from 1868 to 1882 by the self-recording thermograph (SRT) of the automatic weather station (AWS) (see Figure 1 and Report of the Meteorological Committee of the Royal Society (1867))
Summary
Our instrumental knowledge of climate change prior to the mid-19th century relies heavily on a few long meteorological series, most of which are from Europe. Some long series (e.g. central England; Manley, 1974; Parker et al, 1992) are composite series, containing data from a number of sites. This can be an advantage in the sense that climate is being measured over a larger area than a single location, it can be a disadvantage if the same distribution of sites is not maintained (i.e. different sites are used at different times). The series presented here are almost entirely from a single location, namely the Armagh Observatory. Preliminary mean annual temperature data for Armagh have been published previously by Butler and Johnston (1996). We give the mean monthly temperature, based on a new and more complete standardization of the three daily temperature series
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