Evaluation of reconstructed sea surface temperatures based on U37k′ from sediment surface samples of the North Pacific

摘要: Abstract The alkenone unsaturation index ( U 37 k ′ ) as proxy for sea surface temperature (SST) is an important tool in paleoclimatology reconstructing past ocean variability. Typically, recorded marine sediments shows a linear correlation with modern mean annual SST. However, high-latitude oceanic regions, such the subpolar Pacific, -based SSTs do overestimate by up to 6 °C, potentially leading obscured paleoclimatic information drawn from stratigraphic -records. reason this “warm bias” still not well understood. Here, we present compilation of 97 sediment samples Multicores collected Bering Sea, Okhotsk Sea and North Pacific evaluate alkenone-temperature against observational data Pacific. Sediment were analysed alkenones derived -indices converted water temperatures using different calibration equations established literature. then compared instrumental SST data, flux traps Our results confirm that most are 2–6 °C too warm calibrations applied. uncertainty at level ±1.5 °C or less reconstructed fit quite autumn north Subarctic Front (SAF), when maximum export seafloor indicated trap data. South SAF, largely mimic signal less, which likely due attenuation seasonality longer growth season coccolithophorids according study further demonstrates , production known considered, able provide reasonable estimates settings. We conduct case available time-series core south-western better understand potential effect on -record indicates even small shift may lead strongly biased broader regional implications paleoclimate reconstructions