ATLANTIC CORE-TOP CALIBRATION OF THE U-37(K) INDEX AS A SEA-SURFACE PALEOTEMPERATURE INDICATOR

A field calibration of the U-37(K) index with sea surface temperature is discussed, through analysis of an extensive suite of surface sedime nts (n = 109) from the northeastern Atlantic (2 degrees S-75 degrees N ). Values of U-37(K) are compared with sea surface temperatures for ov erlying waters measured at different depths and seasons, to obtain a c orrelation suitable for palaeotemperature reconstructions. The best fi t is obtained using surface (0 m) temperatures corresponding to calori c winter and autumn months. However, the annual average, spring and su mmer surface temperature equations also have high correlation coeffici ents, and are also appropriate for climatic studies. The results furth er validate the general applicability of the U-37(K) as a climatic pro xy, because the calibration equations are valid over a wide range of s urface water temperatures (0-28 degrees C) for different algal populat ions and are representative of the average contribution of alkenones t o sediments, as found in sediment cores.