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Altimetry-derived synthetic temperature and salinity profiles between 20°S and 34.5°S are used to estimate the Meridional Overturning Circulation (MOC) and meridional heat transport (MHT), which are assessed against estimates obtained from expendable bathythermograph (XBT) measurements. Consistent with studies from XBTs and Argo data, both the geostrophic and Ekman contributions to the MOC exhibit annual cycles and play an equal role in the MOC seasonal variations. The strongest variations on seasonal and interannual time scales in our study region are found at 34.5°S. The dominance of the geostrophic and Ekman components on the interannual variations in the MOC and MHT varies with time and latitude, with the geostrophic component being dominant during 1993-2006 and the Ekman component dominant between 2006 and 2011 at 34.5°S.

[1] The Brazil Current is a weak western boundary current, the southwest component of the South Atlantic subtropical gyre, which is the main conduit of upper ocean waters in the region. The objective of this work is to report on observed low frequency variability of the Brazil Current front using satellite-derived sea height anomaly and sea surface temperature observations during the 1993-2008 period. The variability of the front is studied in terms of the separation of the Brazil Current front from the continental shelf break. During the study period, estimates of this parameter vary 6 degrees in latitude, and the mean monthly estimates exhibit a shift to the south of approximately 1.5 degrees. Statistically significant changes are not observed in the geostrophic transport of the Brazil and Malvinas currents, suggesting that the low-frequency changes of the Brazil Current front are governed by different mechanisms than the seasonal variability of these surface currents. Surface drifter trajectories and simulations using synthetic drifters are consistent with the observed shift to the south of the Brazil Current front. Trends of eddy kinetic energy, sea height anomaly, sea surface temperature and wind stress curl are also in agreement with the variability reported here. Wavelet transform analysis revealed interesting changes in the periodicity of the latitude of separation of the Brazil Current front from the continental shelf break, with periods ranging from semiannual to biannual. Longer records, together with comprehensive numerical experiments, will ultimately be needed to determine the origin of these changes.

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The variability of mesoscale circulation structures in the Gulf of Mexico (GOM) was examined using satellite altimeter data collected between 1992 and 2008, and linkages between ocean circulation and the spatial distribution of larval fish were assessed. The abundance and distribution of the larvae of 5 pelagic fish taxa (Auxis spp., Euthynnus alleteratus, Thunnus thynnus, other Thunnus spp., and Coryphaena spp.) were estimated from surveys conducted by the National Oceanic and Atmospheric Administration National Marine Fisheries Service each spring between 1993 and 2007. We observed a tendency for higher northward extension of the Loop Current (LC) during spring each year, with maximum northern penetration in summer, although the exact location of the LC varied from year to year. Generally, higher total larval abundances occurred during years of high northward penetration in a region that was crossed by the LC during its excursions. However, the interannual variability of the LC was not mirrored in a general increase or decrease of larval fish densities in the water masses out of the LC front. Further, the results show that larvae of T. thynnus and Auxis spp. were more abundant within the boundaries of anticyclonic features (usually between 148 to 158 cm of sea surface height) and within GOM common waters, defined as the background waters in between the boundaries of mesoscale features. Our findings suggest that the position and strength of anticyclone mesoscale features in the GOM define a favorable spawning habitat for the species examined. KEY WORDS: Fisheries oceanography · Mesoscale variability · Fronts and eddies · Loop Current · Ichthyoplankton distribution · Thunnus thynnusResale or republication not permitted without written consent of the publisher

Expendable bathythermograph (XBT) data were the major component of the ocean temperature profile observations from the late 1960s through the early 2000s, and XBTs still continue to provide critical data to monitor surface and subsurface currents, meridional heat transport, and ocean heat content. Systematic errors have been identified in the XBT data, some of which originate from computing the depth in the profile using a theoretically and experimentally derived fall-rate equation (FRE). After in-depth studies of these biases and discussions held in several workshops dedicated to discussing XBT biases, the XBT science community met at the Fourth XBT Science Workshop and concluded that XBT biases consist of 1) errors in depth values due to the inadequacy of the probe motion description done by standard FRE and 2) independent pure temperature biases. The depth error and temperature bias are temperature dependent and may depend on the data acquisition and recording system. In addition, the depth bias also includes an offset term. Some biases affecting the XBT-derived temperature profiles vary with manufacturer/probe type and have been shown to be time dependent. Best practices for historical XBT data corrections, recommendations for future collection of metadata to accompany XBT data, impact of XBT biases on scientific applications, and challenges encountered are presented in this manuscript. Analysis of XBT data shows that, despite the existence of these biases, historical XBT data without bias corrections are still suitable for many scientific applications, and that bias-corrected data can be used for climate research

During October 2014, Hurricane Gonzalo traveled within 85 km from the location of an underwater glider situated north of Puerto Rico. Observations collected before, during, and after the passage of this hurricane were analyzed to improve our understanding of the upper ocean response to hurricane winds. The main finding in this study is that salinity potentially played an important role on changes observed in the upper ocean; a near‐surface barrier layer likely suppressed the hurricane‐induced upper ocean cooling, leading to smaller than expected temperature changes. Poststorm observations also revealed a partial recovery of the ocean to prestorm conditions 11 days after the hurricane. Comparison with a coupled ocean‐atmosphere hurricane model indicates that model‐observations discrepancies are largely linked to salinity effects described. Results presented in this study emphasize the value of underwater glider observations for improving our knowledge of how the ocean responds to tropical cyclone winds and for tropical cyclone intensification studies and forecasts.

We study triatomic systems in the regime of large negative scattering lengths which may be more favorable for the formation of condensed trimers in trapped ultracold monoatomic gases as the competition with the weakly bound dimers is absent. The manipulation of the scattering length can turn an excited weakly bound Efimov trimer into a continuum resonance. Its energy and width are described by universal scaling functions written in terms of the scattering length and the binding energy, $B_3$, of the shallowest triatomic molecule. For $a^{-1}<-0.0297 \sqrt{m B_3/\hbar^2}$ the excited Efimov state turns into a continuum resonance.Comment: 4 pages, 4 figure