A correlation estimation algorithm adapted to irregular sampling applied to ice core and speleothem time series

(1) Potsdam Institute for Climate Impact Research, PO Box 601203, 14412 Potsdam, Germany, (2) Department of Physics, Humboldt University Berlin, Newtonstr. 15, 12489 Berlin, Germany, (3) Institute of Environmental Physics, Ruprecht-Karls-Universitat Heidelberg, Im Neuenheimer Feld 229, 69120 Heidelberg, Germany, (4) Laboratoire de Glaciologie et Geophysique de l’Environnement, CNRS,BP 96, F-38402 St. Martin d’Heres, France, (5) Climate Geology, Dept. of Earth Sciences, Swiss Federal Institute of Science and Technology (ETH), CH-8092, Zurich, Switzerland