Examination of the Armagh Observatory Annual Mean Temperature Record, 1844–2004 Robert M
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National Aeronautics and NASA/TP—2006–214434 Space Administration IS20 George C. Marshall Space Flight Center Marshall Space Flight Center, Alabama 35812 Examination of the Armagh Observatory Annual Mean Temperature Record, 1844–2004 Robert M. Wilson and David H. Hathaway Marshall Space Flight Center, Marshall Space Flight Center, Alabama July 2006 The NASA STI Program Office…in Profile Since its founding, NASA has been dedicated to • CONFERENCE PUBLICATION. Collected the advancement of aeronautics and space papers from scientific and technical conferences, science. The NASA Scientific and Technical symposia, seminars, or other meetings sponsored Information (STI) Program Office plays a key or cosponsored by NASA. part in helping NASA maintain this important role. • SPECIAL PUBLICATION. 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Hathaway Marshall Space Flight Center, Marshall Space Flight Center, Alabama Natonal Aeronautcs and Space Admnstraton Marshall Space Flght Center • MSFC, Alabama 35812 July 2006 Acknowledgments The authors thank C.J. Butler and colleagues (Armagh Observatory, College Hll, Armagh, Northern Ireland, Unted Kngdom) for provdng access to the long-term temperature records at Armagh Observatory, whch are now avalable onlne at <http://clmate.arm.ac.uk/calbrated.html>. Avalable from: NASA Center for AeroSpace Informaton Natonal Techncal Informaton Servce 7121 Standard Drve 5285 Port Royal Road Hanover, MD 21076–1320 Springfield, VA 22161 301–621–0390 703–487–4650 TABLE OF CONTENTS 1. INTRODUCTION .......................................................................................................................... 1 2. RESULTS AND DISCUSSION ..................................................................................................... 2 3. CONCLUSION ............................................................................................................................... 12 REFERENCES .................................................................................................................................... 14 v LIST OF FIGURES 1. Annual mean varaton of Armagh Observatory temperature, T (lower panel); the aa-geomagnetc ndex, aa (mddle panel); and sunspot number, R (upper panel). The thn lnes are the annual means and the thck lnes are the 10-year movng averages. The numbers 9–23 n the upper panel refer to sunspot cycles 9–23. See text for addtonal remarks ................................................................................................................ 3 2. The resdual T10 – T10(aa10) (lower panel) and T10 – T10(R10) (upper panel), where T10 s the 10-year movng average of temperature and T10(aa10) and T10(R10) are the regression fits T( 10 versus aa10 and T10 versus R10). See text for detals ................. 4 3. Variation of temperature <T> (lower panel), the aa-geomagnetc ndex <aa> (mddle panel), and sunspot number <R> (upper panel) averaged over each sunspot cycle 9–23. The thn lne s the cyclc average and the thck lne s a 2-cycle movng average. See text for detals ..................................................................................... 5 4. Scatterplots of <T> versus <aa> (lower-left panel), <T> versus <R> (lower-rght panel), <T>2 versus <aa>2 (upper-left panel) and <T>2 versus <R>2 (upper-rght panel). See text and nomenclature for detals ................................................................................... 6 5. The resdual <T> – <T>aa (lower panel), <T>2 – <T>aa2 (lower-mddle panel), <T> – <T>R (upper-mddle panel), and <T>2 – <T>R2 (upper panel), where <T>aa is the regression fit for T< > versus <aa>, <T>aa2 is the regression fit for <T>2 versus <aa>2, <T>R is the regression fit for T< > versus <R> and <T>R2 s the regression fit for <T>2 versus <R>2. See text and nomenclature for detals ........................ 8 6. Scatterplots of average temperature for even-odd Hale cycle groupngs versus temperature for the even-leadng cycle (left panel) and temperature for odd-even Hale cycle groupngs versus temperature for the odd-leadng cycle (rght panel). See text and nomenclature for detals ................................................................................... 9 7. Cyclc varaton of average temperature <<T>> (lower panel), the aa-geomagnetc ndex <<aa>> (mddle panel) and sunspot number <<R>> (upper panel) for Hale cycles 1–7, usng the preferred even-odd groupng of sunspot cycles. See text for detals ................................................................................................................ 10 8. Scatterplots of <<T>> versus <<aa>> (left panel), <<T>> versus <<R>> (mddle panel) and <<T>> versus Hale cycle length n years. See text and nomenclature for detals ......... 11 v NOMENCLATURE aa annual aa-geomagnetc ndex aa10 10-year movng average of the aa-geomagnetc ndex <aa> average aa over a sunspot cycle <<aa>> average aa over a Hale cycle <aa>2 2-cycle movng average of <aa> °C degrees Centgrade cl confidence level r coefficient of correlation r2 coefficient of determination (amount of variance explained by the inferred regression) R annual sunspot number R10 10-year movng average of sunspot number <R> average R over a sunspot cycle <<R>> average R over a Hale cycle <R>2 2-cycle movng average of <R> se standard error of estmate t the t-statstc for ndependent samples T annual mean temperature at Armagh Observatory T10 10-year movng average of T <T> average T over a sunspot cycle <T>aa the nferred regresson for <T> versus <aa> v NOMENCLATURE (Continued) <T>aa2 the nferred regresson for <T>2 versus <aa>2 <T>R the nferred regresson for <T> versus <R> <T>R2 the nferred regresson for <T>2 versus <R>2 <<T>> the average T over a Hale cycle <T>2 2-cycle movng average of <T> T10(aa10) the nferred regresson of T10 versus aa10 T10(R10) the nferred regresson of T10 versus R10 x the ndependent varable y the dependent varable v v TECHNICAL PUBLICATION EXAMINATION OF THE ARMAGH OBSERVATORY ANNUAL MEAN TEMPERATURE RECORD, 1844–2004 1. INTRODUCTION The Armagh Observatory temperature record s one of the longest avalable for study.1–3 Mean temperature readngs based on maxmum and mnmum thermometers extend from 1844 to the present, where mean temperature is defined as the mean of the daily maximum and minimum temperatures. Armagh Observatory3 les about 1 km northeast of the center of the ancent cty of Armagh n Northern Ireland, being located at latitude 54°21.2́N and longitude 6°38.9́W and situated about 64 m above mean sea level at the top of a small hll n an estate of natural woodland and parkland that measures about 7 ha. Studes have shown that ts rural envronment has ensured that the observatory suffers from lttle or no urban mcroclmatc effects4 and that the temperature readngs can be used as a proxy for studyng long-term trends n annual mean temperature for the northern hemsphere and globe.2,3 The purpose of ths study, then, s to examne the extended Armagh Observatory annual mean temperature record spannng 1844–2004, nvestgatng trends n the data ndcatve of clmatc change. In partcular, ths study updates a prevous one that was based on the Armagh data spannng 1844–1992.2 1 2. RESULTS AND DISCUSSION Fgure 1 dsplays