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Rasmussen, Sune Olander; Abbott, Peter M; Blunier, Thomas; Bourne, Mark; Brook, Edward J; Buchardt, Susanne L; Buizert, Christo; Chappellaz, Jérôme A; Clausen, Henrik Brink; Cook, Eliza; Dahl-Jensen, Dorthe; Davies, Siwan M; Guillevic, Myriam; Kipfstuhl, Sepp; Laepple, Thomas; Seierstad, Inger K; Severinghaus, Jeffrey P; Steffensen, Jørgen Peder; Stowasser, Christopher; Svensson, Anders M; Vallelonga, Paul T; Vinther, Bo M; Wilhelms, Frank; Winstrup, Mai (2013): Concentration of hydrogen ions measured with the Electrical Conductivity Method (ECM) on the NGRIP ice core. PANGAEA,, In supplement to: Rasmussen, SO et al. (2013): A first chronology for the North Greenland Eemian Ice Drilling (NEEM) ice core. Climate of the Past, 9(6), 2713-2730,

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Source data set:
Dahl-Jensen, Dorthe; Rasmussen, Sune Olander; Clausen, Henrik Brink; Steffensen, Jørgen Peder; Svensson, Anders M; Vallelonga, Paul T; Vinther, Bo M; Winstrup, Mai (2013): NGRIP ice core ECM Data. World Data Center for Paleoclimatology, Boulder and NOAA Paleoclimatology Program,
Latitude: 75.100000 * Longitude: -42.320000
Date/Time Start: 1996-07-01T00:00:00 * Date/Time End: 1996-07-01T00:00:00
Minimum DEPTH, ice/snow: 9.84 m * Maximum DEPTH, ice/snow: 3084.99 m
NGRIP * Latitude: 75.100000 * Longitude: -42.320000 * Date/Time: 1996-07-01T00:00:00 * Elevation: 2925.0 m * Campaign: NGRIP * Basis: Sampling/drilling ice * Method/Device: Ice drill (ICEDRILL)
The ECM data has been temperature corrected to a standard temperature of -14 °C, according to an Arrhenius relationship using an activation energy of 0.23 eV. Subsequently, the measured current has been converted to ice acidity using the relationship suggested by Hammer (1980). For more information on the calibration procedure see Rasmussen et al, 2013.
Due to the manual approach of the applied ECM technique depth assignment is only accurate to within 1-2 cm. Data in areas of breaks have been removed from the resulting data sets, and data has been downsampled to 1 cm resolution.
The ECM data was obtained in the field during the NGRIP field seasons. It consists of data from NGRIP1 (9.84-1371.69 m depth) and NGRIP2 (1346.41-3084.99 m depth). The NGRIP1 core reaches down to a depth of 1372 m. The NGRIP2 core (drilled 20 meters away from the NGRIP1 core) reaches from surface to bedrock, but high-resolution measurements have only been carried out downwards from 1346 m. In the 26 m overlap zone, the cores are offset by 0.43 m on average, probably due to uncertainties in the logging procedure (see Schøtt Hvidberg et al., Ann. Glac. 35, 2002). Thus, the same features appear at larger depths in the NGRIP1 than in the NGRIP2 core. When combining NGRIP1 and NGRIP2 data, the recommended switching point from NGRIP1 to NGRIP2 is the year 9830b2k (NGRIP1 depth: 1371.47 m, NGRIP2 depth 1371.070 m).
#NameShort NameUnitPrincipal InvestigatorMethod/DeviceComment
1DEPTH, ice/snowDepth ice/snowmGeocode
2Hydrogen ion concentrationH+µeq/kgDahl-Jensen, DortheElectrical conductivity method, ECM (Hammer, 1980)NGRIP1
3Hydrogen ion concentrationH+µeq/kgDahl-Jensen, DortheElectrical conductivity method, ECM (Hammer, 1980)NGRIP2
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