Graf, W.

Lambrecht, A.

Meyer, Hanno

Oerter, Hans

Wilhelms, Frank

English

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Age (yr B.P.)d(!18O)/dt = 0.16±0.06 o/oo/kan=400, r= 0.26a0 2000 4000 6000          -47-46-45-44-43-42          δ 18O (‰)European Research Conference „Polar Regions and Quaternary Climate“, San Feliu de Guixols, Spain, 4-9 October 2003layout: hans oerter, 2003EPICA ice core Dronning Maud Land: Results from stable isotopemeasurements back to the LGMHans Oerter, Hanno Meyer, Anja Lambrecht, Sepp Kipfstuhl,  Frank Wilhelms Alfred-Wegener-Institute for Polar and Marine Research, Bremerhaven & Potsdam, GermanyWolfgang Graf,  Willibald Stichler, GSF-Institute for Hydrology, Neuherberg, GermanyThis work is a contribution to the “European Project forIce Coring in Antarctica” (EPICA), a joint EuropeanScience Foundation/European Commission (EC)scientific programme, funded by the EC under theEnvironment and Climate Programme and by nationalcontributions from Belgium, Denmark, France, Germany,Italy, The Netherlands, Norway, Sweden, Switzerland,and U.K.. Additional funding by DeutscheForschungsgemeinschaft (projects Oe130/5-1&STI207/1-1) is gratefully acknowledged.hoerter@awi-bremerhaven.deIntroductionThe European Project for Ice Coring in Antarctica(EPICA) focuses on the drilling of two deep icecores, the first at Dome C in the Indian/Pacific sector,and the second in Dronning Maud Land in theAtlantic sector of Antarctica. We focus on DronningMaud Land and the isotope record from the EDML(EPICA Dronning Maud Land) ice core drilledthere. The drilling of EDML started in the 2001/2002season at Kohnen station (75º00’S, 0º04’E, 2882 ma.s.l.) and reached in the 2002/03 season a depth of1564 m recovering approx. 55,000 year old ice.References:Fuji, Y. et al.  (1999): Thephra layers in the Dome Fuji (Antarctica) deep ice core. Ann. Glac.29, 126-130.Johnsen S. J. et al. (1997) The 18O record along the Greenland Ice Core Project deep ice core and theproblem of possible Eemian climatic instability. J. Geophys. Res. 102, 26397-26410.Jouzel, J. et al. (2001) A new 27 ky high resolution East Antarctic climate record. Geophys. Res. Lett. 28,3199-3202.Steinhage, D., et al. (2003). Internal structure of the ice sheet between Kohnen Station and Dome Fujirevealed by airborne radio-echo sounding, 7th Intern. Symp. Antarctic Glaciology, 25-29/08/2003, Milano.Watanabe, O. et al. (2003): Homogenous climate variability across East Antarctica over the past threeglacial cycles. Nature, 422, 509-512.EuropeanProjectforIce CoringinAntarctica(EPICA)δ18O and DEP high resolution-48-46-44-42546.0545.5545.0544.5544.0222120191817161514δ18 O (‰-SMOW)DEP conductivity   (µS/m)Depth below surface (m)DEPδ18O30.7 a/m   or  0,032 m/ad (o/o o)!18O (o/oo)R (18O - d )!18O (o/oo)d (o/o o)1999-2000 year period1994-1995 year periodmonth delay [month]R (18O - d )0 6 12 18 24           0 6 12 18 24            0 3 6 9 12     0 3 6 9 12          -50-48-46-44-42-40-38 0 2 4 6     -48-46-44-42-40-38 2 4 6 81012     -1.0-0.5 0.0 0.5 1.0     -1.0-0.5 0.0 0.5 1.0Depth (m Firn)0.0 0.5 1.0 1.5 2.0    0.0 0.5 1.0 1.5 2.0          -48-44-40-36      0 4 81216d (‰)δ 18O (‰)The near surface snow and its isotopic compositionTimes series of 18O contents (10-year,300-years means)Times series of 18O contents (10-year means) deduced fromthe ice cores B32 and EDML, which were drilled atslightly different positions and supplement each other. Thesmoothed curve (thick line) has been calculated usingGaussian low-pass filter over 300 years. Generally, thestable isotope profiles (18O, 2H) are characterized byHolocene stable climate and show only low variability.But, in the last 4000 years (based on a preliminary timescale) the δ18O values decrease continuously and thedeuterium excess values d increase in the same time byabout 0.5 ‰. Both trends could indicate climate cooling inthis part of Antarctica. The depth section of the EDMLcore (123-173m) for which higher resolution measurementsare available is marked by arrows and a yellow bar.EDML ice core: δ18O 5cm samplesca. 30 a/m-460-440-420-400-38025201510Age (kyrs BP)-52-50-48-46-44-4212001000800600Depth (m)-44-42-40-38-36-34-3225201510Age (kyrs BP)Dome CJ. Jouzel et al. , GRL (2001)EDMLGRIPS.J. Johnsen et al., JGR (1997)δ18 O (‰-SMOW)δ18 O (‰-SMOW)δ2H (‰-SMOW)??EDML ice core: δ18O and DEPd18O (‰-SMOW)-54-52-50-48-46-44-421600140012001000800600400200222018161412δ18 O (‰-SMOW)DEP conductivity   (µS/m)Depth below surface (m)Dust/ash layervisible in thecoreδ18O,10-m running averageδ18O,50-cm samplesδ18O,Single samplesDEP,10-m average296.6 808.2 939.8 1053.9 1292.6 1463.0 1558.9mtransition D/O 8 12 ?ACR„8.2 ky“eventdecreasingtrendδ18O und deuteriumexcess profiles, plottedagainst the depth, at theposition of the snow pitSS0203, close to theEDML drilling site. Thevertical lines indicate theannual layering andmark the austral summer(Dec/Jan).Cross-correlations between the 18Ocontent and the d values in thesnow cover at SS0203, sampled18.12.2002. To perform thecorrelation, the profile data wereconverted to monthly resolvedtime series using 18O stratigraphyfor dating and assuming equalaccumulation rates throughout theyear-48-46-44-42570565560555550545540535530Depth (m below surface)-48-46-44-42160155150145140135130125δ18 O (‰-SMOW)δ18 O (‰-SMOW)50cm resolution 5 cm resolution Mean ±sdev50cm resolution 5 cm resolution Mean ±sdev ca. 16 a/mca. 30 a/m„8.2 kyr“ eventδ18O profiles for two core sections (123-164m and 529-569m) where5cm samples were available. In the upper profile the annual layerthickness corresponds to ca. 6.2cm, in the lower profile to ca. 3.3cm.The lower profiles originates from the time around the socalled “8.2kyr” event. An exact dating of the EDML is still missing.δ18O and DEP profiles in the centre of the “8.2 kyr” event. The DEPprofile (depth resolution 5mm) still shows variations which indicateannual layers (grey lines). The variations of the δ18O values are inthe order of a decade.Profile of δ18O values along the EDML core down to the depthof 1564 m: Shown are values measured at 50cm samples (singlevalues grey, 10-m running mean thick red line) and at 4cmsamples with a spacing of 10 m (red circles connected by lines).The blue lines are 10-m averages of DEP measurements,showing good correlation with the isotope values. The dating ofthe core is still under discussion. The isotope profile available sofar shows a decreasing trend from around 270 m to the surface(cf. Figure above), a clear cooling event is indicated around thedepth of 545 m (“8.2 kyr” event; cf. Figures left) as well as theAntarctic Cold Reversal (ACR). It looks whether the transitionzone is steeper than known from the Dome C, Dome F or Vostokcores (Watanabe et al., 2003) (cf. Figure right). The dust/ashlayers which can be seen in the EDML core are indicated bylines. There is indication from air-borne radar survey (Steinhageet al., 2003) that the layers at 939.8m and 1053.9m correspond tovisible tephra layers in the Dome F core at a depth of 505.8mand 573.9m (Fuji et al., 1999). According to Watanabe et al.(2003) those layers in the Dome F core correspond to appr. 19.5kyr and 24.5 kyr.69,9

EPICA ice core Dronning Maud Land: first results from stable isotope measurements back to the LGM

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