Limited lateral transport bias during export of sea surface temperature
proxy carriers in the Mediterranean Sea
Abstract
Some lipid-biomarker-based sea surface temperature (SST) proxies applied
in the modern Mediterranean Sea exhibit large offsets from expected
values, generating uncertainties in climate reconstructions. Lateral
transport of proxy carriers along ocean currents prior to burial can
contribute to this offset between reconstructed and expected SSTs above
the burial site and at the particle’s origin in the surface ocean. We
perform virtual particle tracking experiments to simulate transport
during sinking and derive a quantitative estimate of transport bias for
alkenones and glycerol dibiphytanyl glycerol tetraethers (GDGTs), which
form the basis of the UK’37 and
TEX86 paleothermometers, respectively. We use sinking
speeds appropriate for the export of various proxy carriers (6, 12, 25,
50, 100, 250, 500, and 1000 m d-1). For the assessed
sinking speeds, lateral transport bias is generally small (always
<0.75 °C) within the Mediterranean Sea and does not
substantially contribute to the uncertainties in
UK’37- or TEX86-based
SSTs.