NOAA OCEAN CLIMATE STUDY BEGINS IN EQUATORIAL PACIFIC

Abstract. Water isotope-enabled coupled atmosphere/ocean climate models allow for exploration of the relative contributions to coral stable oxygen isotope (δ18Ocoral) variability arising from Sea Surface Temperature (SST) and the isotopic composition of seawater (δ18Osw). The unforced behaviour of the isotope-enabled HadCM3 Coupled General Circulation Model affirms that the extent to which inter-annual δ18Osw variability contributes to that in model δ18Ocoral is strongly spatially dependent, ranging from being negligible in the eastern equatorial Pacific to accounting for 50% of δ18Ocoral variance in parts of the western Pacific. In these latter cases, a significant component of the inter-annual δ18Osw variability is correlated to that in SST, meaning that local calibrations of the effective local δ18Ocoral–SST relationships are likely to be essential. Furthermore, the relationship between δ18Osw and SST in the central and western equatorial Pacific is non-linear, such that the interpretation of model δ18Ocoral in the context of a linear dependence on SST alone may lead to overestimation (by up to 20%) of the SST anomalies associated with large El-Niño events. Intra-model evaluation of a salinity-based pseudo-coral approach shows that such an approach captures the first-order features of the model δ18Osw behaviour. However, the utility of the pseudo-corals is limited by the extent of spatial variability seen within the modelled slopes of the temporal salinity–δ18Osw relationship.

Download Full-text

Assessment of Quality and Reliability of Measurements with XBT Sippican T5 and T5/20

Journal of Atmospheric and Oceanic Technology ◽

10.1175/jtech-d-18-0043.1 ◽

2018 ◽

Vol 35 (10) ◽

pp. 1935-1960 ◽

Cited By ~ 3

Author(s):

Franco Reseghetti ◽

Lijing Cheng ◽

Mireno Borghini ◽

Igor M. Yashayaev ◽

Giancarlo Raiteri ◽

...

Keyword(s):

Laboratory Tests ◽

World Ocean ◽

Field Trials ◽

Matched Pairs ◽

Temperature Profiles ◽

Fall Rate ◽

Ocean Climate ◽

The World ◽

Quality And Reliability ◽

Climate Study

AbstractThe T5 expendable bathythermographs reach the greatest depth within the current XBT family. Since the early 1970s, in several areas they have been providing a significant part of available temperature profiles below 1000 m and therefore represent an important resource for ocean climate study. In this paper we present new results from laboratory tests of Sippican T5 and T5/20 probes and analyses of more than 350 XBT–CTD matched pairs from our own field trials and the World Ocean Database (WOD), and we propose an improved fall rate equation (coefficients: A = 6.720 ± 0.025 m s−1, B = 0.001 60 ± 0.000 15 m s−2, Offset = 1.00 ± 0.65 m). Possible influences of probe physical characteristics and initial launch conditions on the probe motion have also been investigated with launching height and probe weight being identified as important factors. Analyses also confirm that fall speed and pure temperature error increase with water temperature, as previously reported for other XBT types. The uncertainties in depth and temperature measurements are then calculated. Finally, a new correction for a global T5 dataset is proposed, with an update of the currently available schemes.

Download Full-text