Modification of turbulent dissipation rates by a deep Southern Ocean eddy

This is the final version. Available from AGU via the DOI in this recordAll data used in this study are available by communication with the author and will be archived at British Oceanographic Data CentreThe impact of a mesoscale eddy on the magnitude and spatial distribution of diapycnal ocean mixing is investigated using a set of hydrographic and microstructure measurements collected in the Southern Ocean. These data sampled a baroclinic, middepth eddy formed during the disintegration of a deep boundary current. Turbulent dissipation is suppressed within the eddy but is elevated by up to an order of magnitude along the upper and lower eddy boundaries. A ray tracing approximation is employed as a heuristic device to elucidate how the internal wave field evolves in the ambient velocity and stratification conditions accompanying the eddy. These calculations are consistent with the observations, suggesting reflection of internal wave energy from the eddy center and enhanced breaking through critical layer processes along the eddy boundaries. These results have important implications for understanding where and how internal wave energy is dissipated in the presence of energetic deep geostrophic flows.DIMES is supported by the Natural Environment Research Council (NERC) grants NE/E007058/1 and NE/E005667/1 and U.S. National Science Foundation grants OCE‐1231803, OCE‐0927583, and OCE‐1030309. K.L.S. and J.A.B. are supported by NERC

Continued glacial retreat linked to changing macronutrient supply along the West Antarctic Peninsula

At the West Antarctic Peninsula (WAP), continued atmospheric and oceanic warming is causing significant physical and biogeochemical changes to glaciers and the marine environment. We compare sediment sources and drivers of macronutrient distributions at two bays along the WAP during austral summer 2020, using radioactive radium and stable oxygen isotopes to trace sedimentary influences and quantify different freshwater inputs. In the Ryder Bay, where the Sheldon Glacier is marine-terminating, radium activities at the sediment-water interface indicate considerable benthic mixing. Using radium isotope activity gradients to resolve radium and macronutrient fluxes, we find buoyant meltwater proximal to the glacier drives vigorous mixing of sediment and entrainment of macronutrient deep waters, on the order of 2.0 × 105 mol d− 1 for nitrate. Conversely, in the Marian Cove, where the Fourcade Glacier terminates on land, low salinities and oxygen isotopes indicate a meltwater-rich surface layer <1 m thick and rich in sediment, and strong vertical mixing to the seafloor. A continued shift to land-terminating glaciers along the WAP may have a significant impact upon nutrient and sediment supply to the euphotic zone, with impacts upon primary productivity and carbon uptake efficiency. The future of primary production, carbon uptake, and food web dynamics is therefore linked to glacier retreat dy�namics in the many fjords along the WAP

Stabilization of dense Antarctic water supply to the Atlantic Ocean overturning circulation

The lower limb of the Atlantic overturning circulation is resupplied by the sinking of dense Antarctic Bottom Water (AABW) that forms via intense air–sea–ice interactions next to Antarctica, especially in the Weddell Sea. In the last three decades, AABW has warmed, freshened and declined in volume across the Atlantic Ocean and elsewhere, suggesting an ongoing major reorganization of oceanic overturning. However, the future contributions of AABW to the Atlantic overturning circulation are unclear. Here, using observations of AABW in the Scotia Sea, the most direct pathway from the Weddell Sea to the Atlantic Ocean, we show a recent cessation in the decline of the AABW supply to the Atlantic overturning circulation. The strongest decline was observed in the volume of the densest layers in the AABW throughflow from the early 1990s to 2014; since then, it has stabilized and partially recovered. We link these changes to variability in the densest classes of abyssal waters upstream. Our findings indicate that the previously observed decline in the supply of dense water to the Atlantic Ocean abyss may be stabilizing or reversing and thus call for a reassessment of Antarctic influences on overturning circulation, sea level, planetary-scale heat distribution and global climate

Tracer-derived freshwater composition of the Siberian continental shelf and slope following the extreme Arctic summer of 2007

We investigate the freshwater composition of the shelf and slope of the Arctic Ocean north of the New Siberian Islands using geochemical tracer data (delta O-18, Ba, and PO4*) collected following the extreme summer of 2007. We find that the anomalous wind patterns that partly explained the sea ice minimum at this time also led to significant quantities of Pacific-derived surface water in the westernmost part of the Makarov Basin. We also find larger quantities of meteoric water near Lomonosov Ridge than were found in 1995. Dissolved barium is depleted in the upper layers in one region of our study area, probably as a result of biological activity in open waters. Increasingly ice-free conditions compromise the quantitative use of barium as a tracer of river water in the Arctic Ocean. Citation: Abrahamsen, E. P., M. P. Meredith, K. K. Falkner, S. Torres-Valdes, M. J. Leng, M. B. Alkire, S. Bacon, S. W. Laxon, I. Polyakov, and V. Ivanov (2009), Tracer-derived freshwater composition of the Siberian continental shelf and slope following the extreme Arctic summer of 2007, Geophys. Res. Lett., 36, L07602, doi:10.1029/2009GL037341

Does Screening for Pain Correspond to High Quality Care for Veterans?

Routine numeric screening for pain is widely recommended, but its association with overall quality of pain care is unclear. To assess adherence to measures of pain management quality and identify associated patient and provider factors. A cross-sectional visit-based study. One hundred and forty adult VA outpatient primary care clinic patients reporting a numeric rating scale (NRS) of moderate to severe pain (four or more on a zero to ten scale). Seventy-seven providers completed a baseline survey regarding general pain management attitudes and a post-visit survey regarding management of 112 participating patients. We used chart review to determine adherence to four validated process quality indicators (QIs) including noting pain presence, pain character, and pain control, and intensifying pharmacological intervention. The average NRS was 6.7. Seventy-three percent of charts noted the presence of pain, 13.9% the character, 23.6% the degree of control, and 15.3% increased pain medication prescription. Charts were more likely to include documentation of pain presence if providers agreed that “patients want me to ask about pain” and “pain can have negative consequences on patient’s functioning”. Charts were more likely to document character of pain if providers agreed that “patients are able to rate their pain”. Patients with musculoskeletal pain were less likely to have chart documentation of character of pain. Despite routine pain screening in VA, providers seldom documented elements considered important to evaluation and treatment of pain. Improving pain care may require attention to all aspects of pain management, not just screening

The Role of Medical Language in Changing Public Perceptions of Illness

This study was designed to investigate the impact of medical terminology on perceptions of disease. Specifically, we look at the changing public perceptions of newly medicalized disorders with accompanying newly medicalized terms (e.g. impotence has become erectile dysfunction disorder). Does using “medicalese” to label a recently medicalized disorder lead to a change in the perception of that condition? Undergraduate students (n = 52) rated either the medical or lay label for recently medicalized disorders (such as erectile dysfunction disorder vs. impotence) and established medical conditions (such as a myocardial infarction vs. heart attack) for their perceived seriousness, disease representativeness and prevalence. Students considered the medical label of the recently medicalized disease to be more serious (mean = 4.95 (SE = .27) vs. mean = 3.77 (SE = .24) on a ten point scale), more representative of a disease (mean = 2.47 (SE = .09) vs. mean = 1.83 (SE = .09) on a four point scale), and have lower prevalence (mean = 68 (SE = 12.6) vs. mean = 122 (SE = 18.1) out of 1,000) than the same disease described using common language. A similar pattern was not seen in the established medical conditions, even when controlled for severity. This study demonstrates that the use of medical language in communication can induce bias in perception; a simple switch in terminology results in a disease being perceived as more serious, more likely to be a disease, and more likely to be a rare condition. These findings regarding the conceptualization of disease have implications for many areas, including medical communication with the public, advertising, and public policy