Seasonality of UK′37 temperature estimates as inferred from sediment trap data

The seasonality of sea surface temperatures (SST) estimated from the alkenone- UK′37 index has been a debated issue since the development of the proxy. Using a compilation of sediment trap time series data from 34 sampling locations, we show that the seasonality of maximum alkenone flux in sediment traps varies markedly across the oceans, depending not only on latitude and light availability but also on local oceanographic conditions. The seasonality of the alkenone flux to sediments may also be shaped by the complexity of sedimentation processes and a consistent, globally applicable, seasonal pattern is not apparent. Nevertheless, UK′37 values display a world ocean scale correlation with mean annual SSTs (0 m) that closely resembles the standard calibration equation now established for modern surface sediment records. Thus, with a few notable exceptions at oceanographic locations proximate to major hydrographic fronts, it can be concluded that the integrated sedimentation patterns for UK′37 measured in sediment trap time series provide a measure of annual mean SST.