Atmospheric histories, growth rates and solubilities in seawater and other natural waters of the potential transient tracers HCFC-22, HCFC-141b, HCFC-142b, HFC-134a, HFC-125, HFC-23, PFC-14 and PFC-116 Ocean Science DOI 10.5194/os-15-33-2019 11 January 2019 Use of CFCs as oceanic transient tracers is difficult for recently ventilated water masses as their atmospheric mole fractions have been decreasing. To explore novel tracers, we synthesized consistent annual mean atmospheric histories of HCFC-22, HCFC-141b, HCFC-142b, HFC-134a, HFC-125, HFC-23, PFC-14 (CF4) and PFC-116 in both hemispheres and reconstructed their solubility functions in water and seawater. This work is also potentially useful for tracer studies in a range of natural waters. HCFC-22, HCFC-141b, HCFC-142b, HFC-134a, HFC-125, HFC-23, PFC-14 and PFC-116">Read more
What can seabirds tell us about the tide? Ocean Science DOI 10.5194/os-14-1483-2018 29 November 2018 This paper describes a feasibility study carried out to determine if information gathered for one discipline could berepurposedto provide insight in another. Data gathered during a study of bird distribution were used to investigate whether these same data could be used to measure tidal current velocities and direction. The paper concludes that there is potential to use GPS-tagged birds asdrifters of opportunityand that interdisciplinary sharing of data can provide additional insight. Read more
World Ocean Circulation Experiment – Argo Global Hydrographic Climatology Ocean Science DOI 10.5194/os-14-1127-2018 27 September 2018 The new gridded WOCE-Argo Global Hydrographic Climatology (WAGHC) is described and compared with the NOAA WOA13 atlas. The monthly fields of temperature and salinity for 65 depth levels have a 1/4° spatial resolution. Two versions of the climatology were produced and differ with respect to the spatial interpolation performed on isobaric or isopycnal surfaces, respectively. The climatology characterizes the thermohaline state of the world ocean for the time period from 2008 to 2012. Read more
Technical note: Two types of absolute dynamic ocean topography Ocean Science DOI 10.5194/os-14-947-2018 4 September 2018 Two types of marine geoid exist with the first type being the average level of sea surface height if the water is at rest (classical definition), and the second type being satellite-determined with the condition that the water is usually not at rest. The associated absolute dynamic ocean topography (DOT) also has two types. Horizontal gradients of the two DOTs are different with the 1st (2nd) type representing the absolute (relative) surface geostrophic currents. Read more
Overflow of cold water across the Iceland–Faroe Ridge through the Western Valley Ocean Science DOI 10.5194/os-14-871-2018 27 August 2018 The Western Valley is one of the passages across the Iceland–Scotland Ridge through which a strong overflow of cold, dense water has been thought to feed the deep limb of the Atlantic Meridional Overturning Circulation (AMOC), but its strength has not been known. Based on a field experiment with instruments moored across the valley, we show that this overflow branch is much weaker than previously thought and that this is because it is suppressed by the warm countercurrent in the upper layers. Read more
On the role of the North Equatorial Counter Current during a strong El Niño Ocean Science DOI 10.5194/os-14-633-2018 11 July 2018 Results from a high-resolution ocean model show that during the strong El Niños of 1983 and 1998, transport of warm water in the equatorial Pacific was dominated by the North Equatorial Counter Current and not by equatorial Kelvin waves. The results show why the NECC fails to do this in most years and how stronger than normal annual Rossby waves near the Equator can both trigger the El Niño in the western Pacific and help to ensure that the warm water arrives off South America around Christmas. Read more
Electromagnetic characteristics of ENSO Ocean Science DOI 10.5194/os-14-515-2018 25 June 2018 The study finds that changes in seawater temperature due to El Niño and La Niña, anomalous warm and cold events, are in principle detectable by means of the oceanic tidally induced magnetic field. Furthermore, subsurface processes in the onset of those anomalous events lead the surface processes by several months. This causes a lead in the oceanic tidally induced magnetic field signals over sea-surface temperature signals. ENSO">Read more
Acoustic mapping of mixed layer depth Ocean Science DOI 10.5194/os-14-503-2018 22 June 2018 The ocean surface mixed layer depth (MLD) is an important parameter within several research disciplines, as variations in the MLD influence air–sea CO2 exchange and ocean primary production. A new method is presented in which acoustic mapping of the MLD is done remotely by means of echo sounders. This method allows for observations of high-frequency variability in the MLD, as horizontal and temporal resolutions can be increased by orders of magnitude compared to traditional in situ measurements. Read more
High-resolution diapycnal mixing map of the Alboran Sea thermocline from seismic reflection images Ocean Science DOI 10.5194/os-14-403-2018 6 June 2018 The Alboran Sea is a dynamically active region. The interaction between Mediterranean and Atlantic water originates a set of sub-mesoscale structures and a complex sequence of processes that entail mixing close to the thermocline. Here we present a high-resolution map of the diapycnal diffusivity around the thermocline depth obtained using acoustic data recorded with a high-resolution multichannel seismic system. The map revels a patchy thermocline, with areas of strong diapycnal mixing. Read more
Consideration of various aspects in a drift study of MH370 debris Ocean Science DOI 10.5194/os-14-387-2018 4 June 2018 To assist in establishing the most likely location of the crash site of MH370, a Boeing 777 aircraft that went missing on March 7, 2014, a drift study was conducted by means of numerical modelling. Three elements were considered: (a) the efficacy of the aerial search; (b) water temperatures along the path of the flaperon; © beached debris distribution. The results obtained indicate the crash site is likely located between 25.5° S and 30.5° S along the so-called seventh arc in the Indian Ocean. Read more
