Greenland NGRIP2 Ice-Core annual layer markings

Annual markers forming the GICC05 time scale for NGRIP1, NGRIP2, GRIP, and DYE-3 where data was available and sufficiently resolved to allow annual dating. The markers are placed in the winter and spring depending on the availability of data (e.g. using the winter d18O minimum, winter Sodium concentration maximum, spring dust/Calcium concentration maximum, or visual stratigraphy grey-scale peaks in the deepest parts). Across data gaps, markers are placed by interpolation or using other impurity species with different seasonality (e.g. using summer Ammonium or Nitrate peaks). Therefore, the criteria for where the annual markers are places vary between sections, and care should be taken when interpreting data on annual scale. Ages are reported as years before A.D. 2000 / 2000 CE, abbreviated b2k. Depths (in meter) are true depths below the undisturbed surface the year when drilling started