Where three oceans meet : the Algulhas retroflection region

Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution September 1988The highly energetic Agulhas Retroflection region south of the African continent lies at the junction of the South Indian, South Atlantic, and Circumpolar Oceans. A new survey of the Agulhas Retroflection taken in March 1985, plus historical hydrographic data, allow its dynamical and water-mass characteristics, and its role in exchanging mass, tracers, and vorticity between the three oceans, to be extensively characterized. The 1985 survey is composed of three independent, synoptic elements: a grid of closely-spaced, full-water-depth hydrographic stations (the first entirely full-water-column survey in this area), including several transects of the Agulhas and Agulhas Return Currents; a continuous survey of the path of the currents (the first such survey in the Agulhas); and a contemporaneous and relatively cloud-free sea surface temperature image derived from satellite infrared measurements. Mass transport balances within the closed grid boxes of the 1985 hydrographic survey provide information about current transport, recirculation (transport in excess of estimated returning interior ocean transport), and the overall Retroflection transport pattern. The current transport values exceed by as much as a factor of 1.5 the maximum interior transport computed from observed wind-stress curl and linear theory. Agulhas Current transports ranged from 56 to 95 x 106 m s-l at four 1985 transects crossing the current. Agulhas Return Current transports at the two 1985 transects were 54 and 65 x 106 m s-l. These transports are computed relative to 2400 dbar, which lies below the deep oxygen minimum emanating from the South Indian Ocean, and above the North Atlantic Deep Water salinity maximum. The current retroflected in two distinct branches in 1985, with a cold ring and a partially isolated warm recirculation cell found between the two branches. The satellite-derived sea surface temperature (SST) image, in agreement with the in situ measurements, showed that the cold ring lacked a cold SST anomaly; that the subsurface current path, as represented by a survey of the 15 C isotherm and 200 dbar surface intersection, was closely followed by a sharp front in sea surface temperature; and that most of the Agulhas's surface warm core retroflected upstream of the second retroflection branch. Anticyclonic curvature vorticity at sharp turns in the subsurface current path was found to exceed the maximum allowed by gradient wind balance, indicating that at these locations time-dependence and cross-frontal flow are important. The current's density field is found to meet necessary conditions for baroclinic and barotropic instability. These instability mechanisms may play a role in ring formation and current meandering. Top-to-bottom cross-stream spatial and isopycnal water-mass layering in the Agulhas Current, Agulhas Return Current, and associated rings are presented in two sets of sections, one contoured with pressure and the other with potential density as vertical coordinate. Temperature, salinity, oxygen, potential density and velocity sections are shown contoured versus pressure; and pressure, salinity, oxygen, and planetary potential vorticity are shown contoured versus potential density. These sections clearly illustrate water-mass structure both in space and relative to isopycnal surfaces. Strong salt, oxygen, and potential vorticity fronts on isopycnals in the upper -300 m across the Agulhas and Agulhas Return Current are observed, as are deep western boundary filaments of (i) salty, low oxygen water at intermediate depths traceable to Red Sea Water influences, and (ii) salty North Atlantic Deep Water close round the tip of Africa. The 1985 cold-core ring is the first cold-cored isolated feature to be observed within the Retroflection itself. Its transport was 64 x 106 m s-1, its integrated kinetic and available potential energy anomalies were 8.3 and 61 x 1015 J respectively, and its integrated planetary potential vorticity anomaly was 2.8 x 10-12 m-1 s-1. The potential vorticity flux associated with the exchange of 25 warm ring/cold ring pairs per year between the South Indian and Southern Oceans would balance the potential vorticity input by the wind to the entire South Indian Ocean. Interbasin flow of warm thermocline water (warmer than 8 C) from the South Indian to the South Atlantic Ocean is reconsidered in light of the 1985 hydrographic data. Thermocline water flow from the South Indian Ocean into the South Atlantic in the 1985 and historical observations is found to range from 2.8 to <9.6 x 106 m s-I. These values are less than the S;10 x 106 m s·1 needed to balance the Atlantic Ocean export of deep water, and implies that the deep water export is balanced in part by water colder than 8 C.Funding was provided by the Office of Naval Research under contract numbers NOOOI4-84-C-OI34 (NR083-400), NOOOI4-85-C-OOOl (NR083-004), and NOOOI4-87-K-0007 (NR083-004)

Where three oceans meet : the Agulhas retroflection region

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmosphere and Planetary Sciences, 1988.Vita.Includes bibliographical references.by Sara Louise Bennett.Ph.D

Characterizing Psychological Management Practices of College and University Athletic Trainers in Orange, California

An increase in the prevalence, types, and severity of psychological disorders among adolescents and young adults is being recognized. A multidisciplinary team approach to address mental health concerns among student-athletes, including well-developed referral and management plans, is important in the health care setting. Athletic trainers are often the first to notice subtle changes indicative of psychopathology, and have the ability to appropriately intervene and refer student-athletes as necessary. The purpose of this study was to investigate the psychological management practices of college and university athletic trainers in Orange, California. A descriptive exploratory online questionnaire was used to obtain information regarding psychological management protocols, multidisciplinary health care teams, experience with psychological concerns among student-athletes and education programs about mental concerns for staff and students. Analysis of data included descriptive percentages of the total sample. Results compared the psychological management practices of participants to the gold standard outlined by the National Athletic Trainer’s Association Inter-Association Recommendations for Developing a Plan to Recognize and Refer Student-Athletes With Psychological Concerns at the Collegiate Level: An Executive Summary of a Consensus Statement. Findings of the study concluded the compliance level of college and university athletic trainers in Orange, California to the recommendations set out by NATA. Furthermore, the study outlined the clinical implications for athletic trainers and identified areas of improvement for the profession

Building the field of health policy and systems research: framing the questions.

In the first of a series of articles addressing the current challenges and opportunities for the development of Health Policy & Systems Research (HPSR), Kabir Sheikh and colleagues lay out the main questions vexing the field

Multiple COVID-19 Outbreaks Linked to a Wedding Reception in Rural Maine — August 7–September 14, 2020

Summary What is already known about this topic? Large gatherings pose a high risk for SARS-CoV-2 transmission. What is added by this report? A wedding reception with 55 persons in a rural Maine town led to COVID-19 outbreaks in the local community, as well as at a long-term care facility and a correctional facility in other counties. Overall, 177 COVID-19 cases were linked to the event, including seven hospitalizations and seven deaths (four in hospitalized persons). Investigation revealed noncompliance with CDC’s recommended mitigation measures. What are the implications for public health practice? To mitigate transmission, persons should avoid large gatherings, practice physical distancing, wear masks, stay home when ill, and self-quarantine after exposure to a person with confirmed SARS-CoV-2 infection

Moored current meter, AVHRR, CTD, and drifter data from the Agulhas Current and Retroflexion region (1985-1987) Volume XLII

Stored in the Archives of the Woods Hole Oceanographic Institution is the floppy disk on which can be found the one-day average currents, the path of the Agulhas Current, CTD stations in "Live Atlas" format, SST frontal analyses (Chassignet and Olson, personal communcation) as well as programs written in QuickBASIC which allow one to access and display these observations. The programs are stored in ASCII and can be run under the Microsoft QuickBasic (Version 4.0 or higher). Instructions for running the programs can be found in a file entitled "read.me" on the disk.Data are presented from an experiment designed to explore the spatial and temporal structure of the Agulhas Current and Retroflexion by direct means. Included are the current meter results from 10 moorings in the Retroflexion region, CTD stations occupied on the deployment cruise in 1985, data from satellite tracked (ARGOS) freely during surface buoys and numerous images of the sea surface temperature.Funding was provided by the Office of Naval Research through Contract Nos. NOOO14-84C-O134, NOO014-85-C-0001, and NOOO14-87-K-0007

Building the Field of Health Policy and Systems Research: An Agenda for Action

In the final article in a series addressing the current challenges and opportunities for the development of Health Policy and Systems Research (HPSR), Sara Bennett and colleagues lay out an agenda for action moving forward

Dynamic Ocean Management: Defining and Conceptualizing Real-Time Management of the Ocean

Most spatial marine management techniques (e.g., marine protected areas) draw stationary boundaries around often mobile marine features, animals, or resource users. While these approaches can work for relatively stationary marine resources, to be most effective marine management must be as fluid in space and time as the resources and users we aim to manage. Instead, a shift towards dynamic ocean management is suggested, defined as management that rapidly changes in space and time in response to changes in the ocean and its users through the integration of near real-time biological, oceanographic, social and/or economic data. Dynamic management can refine the temporal and spatial scale of managed areas, thereby better balancing ecological and economic objectives. Temperature dependent habitat of a hypothetical mobile marine species was simulated to show the efficiency of dynamic management, finding that 82.0 to 34.2 percent less area needed to be managed using a dynamic approach. Dynamic management further complements existing management by increasing the speed at which decisions are implemented using predefined protocols. With advances in data collection and sharing, particularly in remote sensing, animal tracking, and mobile technology, managers are poised to apply dynamic management across numerous marine sectors. Existing examples demonstrate that dynamic management can successfully allow managers to respond rapidly to changes on-the-water, however to implement dynamic ocean management widely, several gaps must be filled. These include enhancing legal instruments, incorporating ecological and socioeconomic considerations simultaneously, developing ‘out-of-the-box’ platforms to serve dynamic management data to users, and developing applications broadly across additional marine resource sectors

Better Guidance Is Welcome, but without Blinders

David Peters and Sara Bennett provide a critical perspective on a three-part series on health systems guidance that examines how evidence should be used to strengthen health systems and improve the delivery of global health interventions

Addressing the Gender Gap in Distinguished Speakers at Professional Ecology Conferences

Keynote and plenary speakers at professional conferences serve as highly visible role models for early-career scientists and provide recognition of scientific excellence. This recognition may be particularly important for women, who are underrepresented in senior positions in the biological sciences. To evaluate whether conferences fulfill this potential, we examined distinguished speakers at North American ecology conferences between 2000 and 2015 and compared these data with the percentage of women ecologists at diverse career stages. We found that 15%–35% (x = 28%, n = 809) of the distinguished speakers were women, which is significantly lower than the percentage of female ecology graduate students (x = 55%, n = 26,802) but consistent with the percentage of women in assistant- and associate-faculty positions. We recommend that conference organizers institute policies to enhance speaker gender balance, to provide support for speakers with family responsibilities, and to actively monitor gender-related trends in their societies to achieve the equitable representation of women in distinguished speaking roles