Temperature-Salinity Data from mooring M3, northwest Weddell Sea, 1999-2019

This project maintains an array of oceanographic moorings south of the South Orkney Islands in the Northwest Weddell Sea to provide a time series of the properties of the combined outflow of Antarctic Deep and Bottom Water drawn from various sites within the Weddell Sea. The goal of this project is to observe the properties of the Weddell deep and bottom waters as they exit the Weddell system. The data obtained over the course of a decade and more can be used to better understand deep water formation and long term changes in ocean circulation and their relation to the climate system

Data from the INSTANT Makassar Strait moorings, 2004-2006: current meter, temperature, and salinity sensor records

This archive contains time series data records from two moorings in Makassar Strait, Indonesia, deployed during the International Nusantara Stratification and Transport program (INSTANT), 2004-2006. Raw and processed data from current meter, temperature and salinity sensors on the moorings are available. Raw and processed, gridded data from acoustic doppler current profilers (ADCP) on the two moorings are also available. A complete description of the project and archive contents can be found in the accompanying document file (Data_INSTANT-Makassar_Description.pdf)

Small-scale variability of the cross-shelf flow over the outer shelf of the Ross Sea

The importance of cross-shelf transport across the Ross Sea on local and remote processes has been well documented. In the Ross Sea, mid-water intrusions of Circumpolar Deep Water (CDW) are modified by shelf water near the shelf break to form Modified Circumpolar Deep Water (MCDW). In 2010–2011, we deployed multi-platform technologies focused on this MCDW intrusion in the vicinity of Mawson and Pennell Banks to better understand its role in ecosystem processes across the shelf. The high-resolution time and space sampling provided by an underwater glider, a short-term mooring, and a ship-based survey highlight the scales over which these critical cross-shelf transport processes occur. MCDW cores were observed as small-scale well-defined features over the western slopes of Pennell and Mawson Banks. The mean transport along Pennell Bank was estimated to be about 0.24 Sv but was highly variable in time (hours to days). The observations suggest that the core of MCDW is transported by a predominately barotropic flow that follows topography around the banks toward the south until the slope of the bank flattens and the warmer water moves up and over the bank. This pathway is shown to link the source MCDW with an area of high productivity over the shallows of Pennell Bank

Bottom water export from the western Ross Sea, 2007 through 2010

Bottom water export from the Ross Sea, February 2007 to January 2011, exhibits seasonal and interannual variability. Temperature minima coupled to salinity maxima in late austral summer, into the fall, indicate input from High-Salinity Shelf Water (HSSW). Secondary temperature minima lacking the high-salinity trait, characteristic of Low-Salinity Shelf Water (LSSW), appear in the spring. Warmer bottom water similar to modified Circumpolar Deep Water (mCDW) is observed in winter and in early summer. The LSSW and mCDW may be drawn from the Drygalski Basin, as the HSSW pool retreats poleward from the shelf break in response to increased winter polar easterlies allowing these less dense overlying waters to spill into the deep ocean within the benthic layer. Bottom salinity decreased from 2007 to 2011 by 0.007 year−1 significantly higher than regional decadal trends, which we propose is a result of HSSW retreat induced by strengthening polar easterlies

Quasi-Elastic Scattering, Random Fields and phonon-coupling effects in PbMg1/3Nb2/3O3

The low-energy part of the vibration spectrum in PbMg$_{1/3}$Nb$_{2/3}$O$_3$ (PMN) relaxor ferroelectric has been studied by neutron scattering above and below the Burns temperature, T$_d$. The transverse acoustic and the lowest transverse optic phonons are strongly coupled and we have obtained a model for this coupling. We observe that the lowest optic branch is always underdamped. A resolution-limited central peak and quasi-elastic scattering appear in the vicinity of the Burns temperature. It is shown that it is unlikely that the quasi-elastic scattering originates from the combined effects of coupling between TA and TO phonons with an increase of the damping of the TO phonon below T$_d$. The quasi-elastic scattering has a peak as a function of temperature close to the peak in the dielectric constant while the intensity of the central peak scattering increases strongly below this temperature. These results are discussed in terms of a random field model for relaxors

Gateways to the Ocean: A Symposium Celebrating Arnold Gordon's Contributions to Physical Oceanography

The global ocean circulation affects our climate in myriad ways and plays a central role in mediating the planet’s response to climate change. A key aspect of this circulation is the importance of specific localized gateways (or choke points) which control the strength, structure and basin connectivity of the circulation. Examples of such gateways are the Indonesian Throughflow, the Agulhas retroflection, and outflows from the Ross and Weddell Seas to name a few. These systems often consist of multiple strong jets that vary over a range of space and time scales and so remain extremely challenging to observe, model and predict. Given the rapid development of new observing technologies, and the emergence of a new class of high-resolution global ocean models that are critical for understanding the accelerating rate of climate change, the time is ripe to assess the state of knowledge in the field of ocean gateways and define key challenges for future research. A two-day symposium to bring together distinguished and early-career researchers from across the world, including observationalists, theoreticians and modelers to address these topics was convened at Scripps Institution of Oceanography in San Diego, 13-14 February, the week prior to the 2020 AGU Ocean Science meeting. The symposium coincided with the 80th birthday of Prof. Arnold L. Gordon, a pioneer in the field of ocean gateways. Professor Gordon’s singular research career, spanning over 50 years, has transformed our understanding of ocean gateways and their role in climate. The conveners and attendees celebrated Prof. Gordon’s contributions over the two-day symposium, held in John Martin House, an intimate forum on the SIO campus that fostered interaction and lively discussion among attendees. Attendance was limited to about 50 participants per day, in keeping with the occupancy limit of the venue. In an effort to cultivate the next generation of leaders in the field of ocean gateways, invitations were extended to early career researchers and members of underrepresented groups in addition to well-established researchers in the field. The symposium presentations are archived here as pdf files, organized by session. An introduction, including the two-day agenda, is included in the Session_01 compilation of files. Symposium Organizing Committee: Ryan Abernathey, Bruce Huber (Lamont-Doherty Earth Observatory/Columbia University) Janet Sprintall (Scripps Institution of Oceanography) Martin Visbeck (GEOMAR Helmholtz Centre for Ocean Research Kiel) The symposium was funded by the US National Science Foundation, grant number OCE 2006148

Makassar Strait Throughflow Seasonal and Interannual Variability: An Overview

The Makassar Strait throughflow of ~12–13 Sv, representing ~77% of the total Indonesian Throughflow, displays fluctuations over a broad range of time scales, from intraseasonal to seasonal (monsoonal) and interannual scales. We now have 13.3 years of Makassar throughflow observations: November 1996 to early July 1998; January 2004 to August 2011; and August 2013 to August 2017. Strong southward transport is evident during boreal summer, modulated by an ENSO interannual signal, with weaker southward flow and a deeper subsurface velocity maximum during El Niño; stronger southward flow with a shallower velocity maximum during La Niña. Accordingly, the southward heat flux, a product of the along‐channel current and temperature profiles, is significantly larger in summer and slightly larger during La Niña. The southward flow relaxed in 2014 and more so in 2015/2016, similar though not as extreme as during the strong El Niño event of 1997. In 2017, the throughflow increased to ~20 Sv. Since 2016, the deep layer, 300‐ to 760‐m southward transport increases, almost doubling to ~7.5 Sv. From mid‐2016 into early 2017, the transports above 300 m and below 300 m are about equal, whereas previously, the ratio was about 2.7:1. Near zero or northward flow occurs in the upper 100 m during boreal winter, albeit with interannual variability. Particularly strong winter reversals were observed in 2014/2015 and 2016/2017, the latter being the strongest winter reversal revealed in the entire Makassar time series

SuperCDMS Cold Hardware Design

We discuss the current design of the cold hardware and cold electronics to be used in the upcoming SuperCDMS Soudan deployment. Engineering challenges associated with such concerns as thermal isolation, microphonics, radiopurity, and power dissipation are discussed, along with identifying the design changes necessary for SuperCDMS SNOLAB. The Cryogenic Dark Matter Search (CDMS) employs ultrapure 1-inch thick, 3-inch diameter germanium crystals operating below 50 mK in a dilution cryostat. These detectors give an ionization and phonon signal, which gives us rejection capabilities regarding background events versus dark matter signals.United States. Dept. of Energy (Grant DEAC02-76SF00515)United States. Dept. of Energy (Contract DC-AC02-07CH11359)National Science Foundation (U.S.) (Awards 0705052, 0902182, 1004714 and 0802575