scholarly journals Comparing historical and modern methods of sea surface temperature measurement – Part 2: Field comparison in the central tropical Pacific

Ocean Science ◽  
2013 ◽  
Vol 9 (4) ◽  
pp. 695-711 ◽  
Author(s):  
J. B. R. Matthews ◽  
J. B. Matthews
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Cooling Water ◽  
Unknown Origin ◽  
Tropical Pacific ◽  
Temperature Gradients ◽  
Sea Surface ◽  
Near Surface ◽  
Modern Methods ◽  
Hadley Centre

Abstract. Discrepancies between historical sea surface temperature (SST) datasets have been partly ascribed to use of different adjustments to account for variable measurement methods. Until recently, adjustments had only been applied to bucket temperatures from the late 19th and early 20th centuries, with the aim of correcting their supposed coolness relative to engine cooling water intake temperatures. In the UK Met Office Hadley Centre SST 3 dataset (HadSST3), adjustments have been applied over its full duration to observations from buckets, buoys and engine intakes. Here we investigate uncertainties in the accuracy of such adjustments by direct field comparison of historical and modern methods of shipboard SST measurement. We compare wood, canvas and rubber bucket temperatures to 3 m seawater intake temperature along a central tropical Pacific transect conducted in May and June 2008. We find no average difference between the temperatures obtained with the different bucket types in our short measurement period (∼1 min). Previous field, lab and model experiments have found sizeable temperature change of seawater samples in buckets of smaller volume under longer exposure times. We do, however, report the presence of strong near-surface temperature gradients day and night, indicating that intake and bucket measurements cannot be assumed equivalent in this region. We thus suggest bucket and buoy measurements be considered distinct from intake measurements due to differences in sampling depth. As such, we argue for exclusion of intake temperatures from historical SST datasets and suggest this would likely reduce the need for poorly field-tested bucket adjustments. We also call for improvement in the general quality of intake temperatures from Voluntary Observing Ships. Using a physical model we demonstrate that warming of intake seawater by hot engine room air is an unlikely cause of overly warm intake temperatures. We suggest that reliable correction for such warm errors is not possible since they are largely of unknown origin and can be offset by real near-surface temperature gradients.

scholarly journals Comparing historical and modern methods of Sea Surface Temperature measurement – Part 2: Field comparison in the Central Tropical Pacific

2012 ◽  
Vol 9 (5) ◽  
pp. 2975-3019 ◽  
Author(s):  
J. B. R. Matthews ◽  
J. B. Matthews
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Cooling Water ◽  
Tropical Pacific ◽  
Sea Surface ◽  
Near Surface ◽  
Engine Cooling ◽  
Modern Methods ◽  
Hadley Centre ◽  
The Uk

Abstract. Discrepancies between historical Sea Surface Temperature (SST) datasets have been partly ascribed to use of different adjustments for variable measurement methods. Until recently adjustments had only been applied to bucket temperatures from the late 19th and early 20th century, with the aim of correcting their supposed coolness relative to engine cooling water intake temperatures (EIT). In the UK Met Office Hadley Centre SST 3 dataset (HadSST3) adjustments are applied to observations over its full duration, including those obtained by other methods. Here we evaluate such adjustments by direct field comparison of historical and modern methods of SST measurement. We compare wood, canvas and rubber bucket temperatures to 3 m seawater intake temperature along a Central Tropical Pacific transect conducted in May and June 2008. In contrast to the prevailing view we find no average differences between bucket temperatures obtained with different bucket types. Moreover, we observe strong near-surface temperature gradients day and night, indicating intake and bucket temperatures cannot be considered equivalent in this region. We suggest engine intake temperatures are unreliable as a source of SST given that they are often obtained by untrained non-scientist observers with low precision, inaccurate instruments at unknown intake depth. Using a physical model we demonstrate that warming of intake seawater by engine room air is unlikely a cause of negative average bucket-intake temperature differences, as sometimes suggested. We propose removal of intake temperatures and bucket adjustments from historical SST records and posit this will lead to their better capture of real long-term trends.

scholarly journals Comparing historical and modern methods of sea surface temperature measurement – Part 1: Review of methods, field comparisons and dataset adjustments

Ocean Science ◽  
2013 ◽  
Vol 9 (4) ◽  
pp. 683-694 ◽  
Author(s):  
J. B. R. Matthews
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Temperature Measurement ◽  
Field Experiments ◽  
Cooling Water ◽  
Field Studies ◽  
Sea Surface ◽  
Near Surface ◽  
Engine Cooling

Abstract. Sea surface temperature (SST) has been obtained from a variety of different platforms, instruments and depths over the past 150 yr. Modern-day platforms include ships, moored and drifting buoys and satellites. Shipboard methods include temperature measurement of seawater sampled by bucket and flowing through engine cooling water intakes. Here I review SST measurement methods, studies analysing shipboard methods by field or lab experiment and adjustments applied to historical SST datasets to account for variable methods. In general, bucket temperatures have been found to average a few tenths of a °C cooler than simultaneous engine intake temperatures. Field and lab experiments demonstrate that cooling of bucket samples prior to measurement provides a plausible explanation for negative average bucket-intake differences. These can also be credibly attributed to systematic errors in intake temperatures, which have been found to average overly-warm by >0.5 °C on some vessels. However, the precise origin of non-zero average bucket-intake differences reported in field studies is often unclear, given that additional temperatures to those from the buckets and intakes have rarely been obtained. Supplementary accurate in situ temperatures are required to reveal individual errors in bucket and intake temperatures, and the role of near-surface temperature gradients. There is a need for further field experiments of the type reported in Part 2 to address this and other limitations of previous studies.

scholarly journals Sea-surface temperature records of Termination 1 in the Gulf of California: Challenges for seasonal and interannual analogues of tropical Pacific climate change

2012 ◽  
Vol 27 (2) ◽  
pp. n/a-n/a ◽  
Author(s):  
Erin L. McClymont ◽  
Raja S. Ganeshram ◽  
Laetitia E. Pichevin ◽  
Helen M. Talbot ◽  
Bart E. van Dongen ◽  
...  
Keyword(s):  
Climate Change ◽  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Gulf Of California ◽  
Tropical Pacific ◽  
Sea Surface ◽  
Temperature Records

Oligocene sea-surface temperature gradients in the Southern Ocean related to Tasmanian Gateway widening: New TEX86 paleothermometry, dinoflagellate cyst data and climate model comparisons

2021 ◽  
Author(s):  
Frida Hoem ◽  
Suning Hou ◽  
Matthew Huber ◽  
Francesca Sangiorgi ◽  
Henk Brinkhuis ◽  
...  
Keyword(s):  
Southern Ocean ◽  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Climate Model ◽  
Temperature Gradients ◽  
Ocean Currents ◽  
Sea Surface ◽  
Dinoflagellate Cyst ◽  
Frontal Systems ◽  
Dsdp Site

<p>The opening of the Tasmanian Gateway during the Eocene and further deepening in the Oligocene is hypothesized to have reorganized ocean currents, preconditioning the Antarctic Circumpolar Current (ACC) to evolve into place. However, fundamental questions still remain on the past Southern Ocean structure. We here present reconstructions of latitudinal temperature gradients and the position of ocean frontal systems in the Australian sector of the Southern Ocean during the Oligocene. We generated new sea surface temperature (SST) and dinoflagellate cyst data from the West Tasman margin, ODP Site 1168. We compare these with other records around the Tasmanian Gateway, and with climate model simulations to analyze the paleoceanographic evolution during the Oligocene. The novel organic biomarker TEX<sub>86</sub>- SSTs from ODP Site 1168, range between 19.6 – 27.9°C (± 5.2°C, using the linear calibration by Kim et al., 2010), supported by temperate and open ocean dinoflagellate cyst assemblages. The data compilation, including existing TEX<sub>86</sub>-based SSTs from ODP Site 1172 in the Southwest Pacific Ocean, DSDP Site 274 offshore Cape Adare, DSDP Site 269 and IODP Site U1356 offshore the Wilkes Land Margin and terrestrial temperature proxy records from the Cape Roberts Project (CRP) on the Ross Sea continental shelf, show synchronous variability in temperature evolution between Antarctic and Australian sectors of the Southern Ocean. The SST gradients are around 10°C latitudinally across the Tasmanian Gateway throughout the early Oligocene, and increasing in the Late Oligocene. This increase can be explained by polar amplification/cooling, tectonic drift, strengthening of atmospheric currents and ocean currents. We suggest that the progressive cooling of Antarctica and the absence of mid-latitude cooling strengthened the westerly winds, which in turn could drive an intensification of the ACC and strengthening of Southern Ocean frontal systems.</p>

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