Spatial variability of δ 18 O during the past 1000 years in Northern Greenland
Motivation
To reconstructclimatechangesitisneccessaryto haveregionallyrepresentative dataset. StablewaterisotoperecordsfromtheNGT coresareusedto better understandthespatialvariabilityof theclimatein Northern Greenland.
Questions:
•Howrepresentativeisa singlerecord?
•Whatist thecorrelationbetweenthesitesin Northern Greenland?
References
B. Mieding(2005) Rconstructionof millenialaerosol-chemicalicecorerecordsfromthenortheastGreenland: Quantificationof temporal changesin atmosphericcirculation, emissionand deposition, PhD-theses
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Data
• AWI traverse in Northern Greenland(NGT) between 1993-1995
• 100-150 m longfirn cores
• δ18O measuredin 2-3 cm depth resolution
• annualdatedbylayercounting afterback diffusion
Spatial correlations
• relativelylowcorrelationcoefficients
• negative correlationwithB19
• differencesin accumulationratesarenotthereasonfor differencesin loadof traceelements(Mieding2005)
Conclusion
•
the quality of correlation is independent on distance between the core sites
•
the isotope records reflect high spatial variability in the Northern Greenland‘s climate
•
it is difficult to find a representative record for climate in Greenland
Outlook
•
to analyze spatio-temporal variability
Time series
• NGT coresdo not showthesameδ18O- variability
• isotoperecordsfrom lowaccumulationsites aremoresmoothedby diffusion(B19)
• coresiteshave different sourcesof moisture
• influenceof volcanic and global climate eventsisevident
• forsometime slots coresarehighly correlated, forothers not
Fig. 5 Lowerpannel:
Thescattermatrixof the5 yearsbox averageof theannualδ18O values.
Thered linesin thescatter plotsshowthelinear regressionline.
Upper pannel:
Significantpearson correlationcoefficientsas usedin fig. 1.
5 yearsbox averageddata usded, because correlationincreases increaseswithaveraging.
Black numbersare significanton 95% level, bluenumberson 90%.
Fig. 2 Time seriesof δ18O in theNGT cores DACA 2013
FR-70_A2.3
Principal components
• PCA-analysisshowsthatthereisno dominant signalforthecores
• eachcore has othermaininfluencingfactor
• climaticmeaningof theprincipalcomponentsisunclear
B16 B18 B19 B21 B22 B26 B29 B30 Accumulationrates(mm w. e. a-1)
144 106 102 108 159 161 152 177
Hight(m WGS 84)
3040 2508 2234 2185 2242 2598 2874 2947
a b
LoadingPC 1 LoadingPC 5
Fig. 4 LoadingsfortheNGT coresof thefirstprincipalcomponent(a) and fifthcomponent(b) Fig.3 First principalcomponent(PC) fromNGT cores
Loadingsof thefirstPC
Stefanie Weißbach | Anna Wegner| Hans Oerter| Frank Wilhelms | Sepp Kipfstuhl|(stefanie.weissbach@awi.de)
Fig.1 Correlationmapbetweenthecoresof NGT Solid lines: r>0.2, p=0.05, dashedlines: r<0.2, p=0.1,
blueline: negative correlation, r>0.2, p=0.05
ModifiedafterF. Wilhelms
