Document DetailsThe NorthGRIP deep drilling programme
|Authors:||Dahl-Jensen D, Gundestrup NS, Miller H, Watanabe O, Johnsen SJ, Steffensen JP, Clausen HB, Svensson A and Larsen LB|
|Periodical/Journal:||Annals of Glaciology|
The North Greenland Icecore Project (NorthGRIP) was initiated in 1995 as a joint international programme involving Denmark, Germany,Japan, Belgium, Sweden, Iceland, the U.S.A., France and Switzerland. The main goal was to obtain undisturbed high-resolution information about the Eemian climatic period (115-130 kyr BP). The records from the Greenland Icecore Project (GRIP) and Greenland Ice Sheet Project 2 (GISP2) in central Greenland are different and disturbed down in the ice covering this period. Internal radio-echo sounding layers show that NorthGRIP, placed 325 km northnorthwest of GRIP at the Summit of the Greenland ice sheet, is located on a gently sloping ice ridge with very flatbedrock and internal layers found so high that an undisturbed Eemian record is possible. Internal layers much farther above bedrock than their apparent counterparts at GRIP suggest that conditions are favourable for recovery of an undisturbed Eemian record. So far, a 1351m deep ice core (NorthGRIP1)and a 3001m deep ice core (NorthGRIP 2) have been recovered.The ice thickness is expected to be 3080 m, and the ice temperature at 3001m is -5.6 degrees C, so we expect basal melting at the bedrock. Most of the Eemian ice will be melted away, leaving only the last part and the transition between the Eem and the Last Glacial Period. At 3001m the age of the ice is 110kyr BP and the annual layers are of the order 1cm.With modern methods the annual layers can be resolved, resulting in detailed information on the decline of the warm Eemian period into the Last Glacial Period.