Deep circulation in the Lau Basin and Havre Trough of the western South Pacific Ocean from floats and hydrography

A system of meridional ridges in the western South Pacific Ocean frame the Lau Basin and Havre Trough, and form a barrier to direct communication between the far western South Pacific basins and the interior South Pacific Ocean. The eastern side of this system comprises the Tonga and Kermadec Ridges, the location of the main deep western boundary current entering the Pacific Ocean. Observations from floats released in the Lau Basin as part of the RIDGE2000 program suggested the presence of a western boundary current along the Lau Ridge exiting into the North Fiji Basin. Those observations, together with Argo sub-surface float data and repeat hydrographic sections, confirm and expand the boundary current observations along the Lau Ridge throughout the Lau Basin and into the Havre Trough, along the Colville Ridge. The observations also reveal two previously unrecognized westward flowing jets bisecting the Lau Basin and Havre Trough. Using an extension to the classic Stommel-Arons abyssal circulation model, the predicted strength and location of these boundary currents and their bifurcation is compared with the float observations. The model provides a simplified view of the dynamics controlling the boundary current structure in the deep basins. A comparison of transport within the western boundary current derived from float data, hydrographic sections, and the idealized analytical model indicates that roughly 4 Sv (below 1,000 db) is transported northward through the Lau Basin, exiting into the North Fiji Basin

Genesis of the Antarctic Slope Current in West Antarctica

The stability of the West Antarctic Ice Sheet (WAIS) depends on ocean heat transport toward its base and remains a source of uncertainty in sea level rise prediction. The Antarctic Slope Current (ASC), a major boundary current of the ocean's global circulation, serves as a dynamic gateway for heat transport toward Antarctica. Here, we use observations collected from the Bellingshausen Sea to propose a mechanistic explanation for the initiation of the westward‐flowing ASC. Waters modified throughout the Bellingshausen Sea by ocean‐sea‐ice and ocean‐ice‐shelf interactions are exported to the continental slope in a narrow, topographically steered western boundary current. This focused outflow produces a localized front at the shelf break that supports the emerging ASC. This mechanism emphasizes the importance of buoyancy forcing, integrated over the continental shelf, as opposed to local wind forcing, in the generation mechanism and suggests the potential for remote control of melt rates of WAIS' largest ice shelves

Novel High Frequency Silicon Carbide Static Induction Transistor-Based Test-Bed for the Acquisition of SiC Power Device Reverse Recovery Characteristics

A test system is presented that utilizes a high-frequency Silicon Carbide (SiC) Static Induction Transistor (SIT) in place of the traditional MOSFET to test reverse recovery characteristics for the new class of SiC power diodes. An easily implementable drive circuit is presented that can drive the high-frequency SIT. The SiC SIT is also compared to a commonly used Si MOSFET in the test circuit application

Ice‐shelf meltwater overturning in the Bellingshausen Sea

Hydrographic data are analyzed for the broad continental shelf of the Bellingshausen Sea, which is host to a number of rapidly‐thinning ice shelves. The flow of warm Circumpolar Deep Water (CDW) onto the continental shelf is observed in the two major glacially‐carved troughs, the Belgica and Latady troughs. Using ship‐based measurements of potential temperature, salinity and dissolved oxygen, collected across several coast‐to‐coast transects over the Bellingshausen shelf in 2007, the velocity and circulation patterns are inferred based on geostrophic balance and further constrained by the tracer and mass budgets. Meltwater was observed at the surface and at intermediate depth toward the western side of the continental shelf, collocated with inferred outflows. The maximum conversion rate from the dense CDW to lighter water masses by mixing with glacial meltwater is estimated to be 0.37±0.1 Sv in both depth and potential density spaces. This diapycnal overturning is comparable to previous estimates made in the neighboring Amundsen Sea, highlighting the overlooked importance of water mass modification and meltwater production associated with glacial melting in the Bellingshausen Sea

Pacific anthropogenic carbon between 1991 and 2017

© The Author(s), 2019. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Carter, B. R., Feely, R. A., Wanninkhof, R., Kouketsu, S., Sonnerup, R. E., Pardo, P. C., Sabine, C. L., Johnson, G. C., Sloyan, B. M., Murata, A., Mecking, S., Tilbrook, B., Speer, K., Talley, L. D., Millero, F. J., Wijffels, S. E., Macdonald, A. M., Gruber, N., & Bullister, J. L. Pacific anthropogenic carbon between 1991 and 2017. Global Biogeochemical Cycles, 33(5), (2019):597-617, doi:10.1029/2018GB006154.We estimate anthropogenic carbon (Canth) accumulation rates in the Pacific Ocean between 1991 and 2017 from 14 hydrographic sections that have been occupied two to four times over the past few decades, with most sections having been recently measured as part of the Global Ocean Ship‐based Hydrographic Investigations Program. The rate of change of Canth is estimated using a new method that combines the extended multiple linear regression method with improvements to address the challenges of analyzing multiple occupations of sections spaced irregularly in time. The Canth accumulation rate over the top 1,500 m of the Pacific increased from 8.8 (±1.1, 1σ) Pg of carbon per decade between 1995 and 2005 to 11.7 (±1.1) PgC per decade between 2005 and 2015. For the entire Pacific, about half of this decadal increase in the accumulation rate is attributable to the increase in atmospheric CO2, while in the South Pacific subtropical gyre this fraction is closer to one fifth. This suggests a substantial enhancement of the accumulation of Canth in the South Pacific by circulation variability and implies that a meaningful portion of the reinvigoration of the global CO2 sink that occurred between ~2000 and ~2010 could be driven by enhanced ocean Canth uptake and advection into this gyre. Our assessment suggests that the accuracy of Canth accumulation rate reconstructions along survey lines is limited by the accuracy of the full suite of hydrographic data and that a continuation of repeated surveys is a critical component of future carbon cycle monitoring.The data we use can be accessed at CCHDO website (https://cchdo.ucsd.edu/) and GLODAP website (https://www.glodap.info/). This research would not be possible without the hard work of the scientists and crew aboard the many repeated hydrographic cruises coordinated by GO‐SHIP, which is funded by NSF OCE and NOAA OAR. We thank funding agencies and program managers as follows: U.S., Australian, Japanese national science funding agencies that support data collection, data QA/QC, and data centers. Contributions from B. R. C., R. A. F., and R. W. are supported by the National Oceanic and Atmospheric Administration Global Ocean Monitoring and Observing Program (Data Management and Synthesis Grant: N8R3CEA‐PDM managed by Kathy Tedesco and David Legler). G. C. J. is supported by the Climate Observation Division, Climate Program Office, National Oceanic and Atmospheric Administration (NOAA), U.S. Department of Commerce and NOAA Research (fund reference 100007298), grant (N8R1SE3‐PGC). B. M. S was supported by the Australian Government Department of the Environment and CSIRO through the Australian Climate Change Science Programme and by the National Environmental Science Program. N. G. acknowledges support by ETH Zurich. This is JISAO contribution 2018‐0149 and PMEL contribution 4786. We fondly remember John Bullister as a treasured friend, valued colleague, and dedicated mentor, and we thank him for sharing his days with us. He is and will be dearly missed

Fc-mediated functions of nirsevimab complement direct respiratory syncytial virus neutralization but are not required for optimal prophylactic protection

IntroductionNirsevimab is an extended half-life (M252Y/S254T/T256E [YTE]-modified) monoclonal antibody to the pre-fusion conformation of the respiratory syncytial virus (RSV) Fusion protein, with established efficacy in preventing RSV-associated lower respiratory tract infection in infants for the duration of a typical RSV season. Previous studies suggest that nirsevimab confers protection via direct virus neutralization. Here we use preclinical models to explore whether fragment crystallizable (Fc)-mediated effector functions contribute to nirsevimab-mediated protection.MethodsNirsevimab, MEDI8897* (i.e., nirsevimab without the YTE modification), and MEDI8897*-TM (i.e., MEDI8897* without Fc effector functions) binding to Fc γ receptors (FcγRs) was evaluated using surface plasmon resonance. Antibody-dependent neutrophil phagocytosis (ADNP), antibody-dependent cellular phagocytosis (ADCP), antibody-dependent complement deposition (ADCD), and antibody-dependent cellular cytotoxicity (ADCC) were assessed through in vitro and ex vivo serological analyses. A cotton rat challenge study was performed with MEDI8897* and MEDI8897*-TM to explore whether Fc effector functions contribute to protection from RSV.ResultsNirsevimab and MEDI8897* exhibited binding to a range of FcγRs, with expected reductions in FcγR binding affinities observed for MEDI8897*-TM. Nirsevimab exhibited in vitro ADNP, ADCP, ADCD, and ADCC activity above background levels, and similar ADNP, ADCP, and ADCD activity to palivizumab. Nirsevimab administration increased ex vivo ADNP, ADCP, and ADCD activity in participant serum from the MELODY study (NCT03979313). However, ADCC levels remained similar between nirsevimab and placebo. MEDI8897* and MEDI8897*-TM exhibited similar dose-dependent reduction in lung and nasal turbinate RSV titers in the cotton rat model.ConclusionNirsevimab possesses Fc effector activity comparable with the current standard of care, palivizumab. However, despite possessing the capacity for Fc effector activity, data from RSV challenge experiments illustrate that nirsevimab-mediated protection is primarily dependent on direct virus neutralization

Variability in the meridional overturning circulation at 32°S in the Pacific Ocean diagnosed by inverse box models

The meridional circulation and transport at 32°S in the Pacific Ocean in 1992 and 2017 are compared with analogous data from 2003 and 2009 computed by Hernández-Guerra and Talley (2016). The hydrographic data come from the GO-SHIP database and an inverse box model has been applied with similar constraints as in Hernández-Guerra and Talley (2016). In 1992, 2003 and 2017 the pattern of the overturning streamfunction and circulation are similar, but in 2009 the pattern of the circulation changes in the whole water column. The horizontal distribution of mass transports at all depths in 1992 and 2017 resembles the familiar shape of the “classical gyre” also observed in 2003 and is notably different to the “bowed gyre” found in 2009. The hydrographic data have been compared with data obtained from the numerical modelling outputs of ECCO, SOSE, GLORYS, and MOM. Results show that none of these models properly represents the “bowed gyre” circulation in 2009, and this change in circulation pattern was not observed during the entire length of model simulations. Additionally, the East Australian Current in the western boundary presents higher mass transport in the hydrographic data than in any numerical modelling output. Its poleward mass transport ranges from −35.1 ± 2.0 Sv in 1992 to −54.3 ± 2.6 Sv in 2003. Conversely, the Peru-Chile Current is well represented in models and presents an equatorward mass transport from 2.3 ± 0.8 Sv in 2009 to 4.4 ± 1.0 Sv in 1992. Furthermore, the Peru-Chile Undercurrent presents a more intense poleward mass transport in 2009 (−3.8 ± 1.2 Sv). In addition, the temperature and freshwater transports in 1992 (0.42 ± 0.12 PW and 0.26 ± 0.08 Sv), 2003 (0.38 ± 0.12 PW and 0.25 ± 0.02 Sv), and 2017 (0.42 ± 0.12 PW and 0.34 ± 0.08 Sv) are similar, but significantly different from those in 2009 (0.16 ± 0.12 PW and 0.50 ± 0.03 Sv, respectively). To clarify the causes of these different circulation schemes, a linear Rossby wave model is adopted, which includes the wind-stress curl variability as remote forcing and the response to sea surface height changes along 30°S.This study was supported by the SAGA project (RTI2018-100844-B-C31) funded by the Ministerio de Ciencia, Innovación y Universidades of the Spanish Government. This article is a publication of the Unidad Océano y Clima from Universidad de Las Palmas de Gran Canaria, an R&D&I CSIC-associate unit. The wind data were collected from NCEP Reanalysis Derived data (http://www.eslr.noaa.gov/psd/). Hydrographic data were collected from the CCHDO website in the frame of International WOCE and GO-SHIP projects (https://cchdo.ucsd.edu/). We gratefully acknowledge the major efforts of the WOCE/GO-SHIP program’s chief scientists that collected these transect data: H. L. Bryden, M. McCartney, J. Toole M. Fukasawa, S. Watanabe, Y. Yoshikawa, A. Macdonald, R. Curry, S. Mecking, and K. Speer. ECCO data are available for download at https://ecco.jpl.nasa.gov/. MOM data are available at https://www.gfdl.noaa.gov/mom-ocean-model/. SOSE data are available at http://sose.ucsd.edu. GLORYS data are available for download at https://resources.marine.copernicus.eu/. The SSHA data were collected from the Aviso database (http://las.aviso.oceanobs.com). The authors declare no competing interests. This work has been completed as part of C. Arumí-Planas work at IOCAG, in the doctoral program in Oceanography and Global Change. C. Arumí-Planas acknowledges the Agencia Canaria de Investigación, Innovación y Sociedad de la Información (ACIISI) grant program of “Apoyo al personal investigador en formación” TESIS2021010028.Peer reviewe

Reducing Binge Drinking? The Effect of a Ban on Late-Night Off-Premise Alcohol Sales on Alcohol-Related Hospital Stays in Germany

Excessive alcohol consumption among young people is a major public health concern. On March 1, 2010, the German state of Baden-Württemberg banned the sale of alcoholic beverages between 10pm and 5am at off-premise outlets (e.g., gas stations, kiosks, supermarkets). We use rich monthly administrative data from a 70 percent random sample of all hospitalizations during the years 2007-2011 in Germany in order to evaluate the short-term impact of this policy on alcohol-related hospitalizations. Applying difference-in-differences methods, we find that the policy change reduces alcohol-related hospitalizations among adolescents and young adults by about seven percent. There is also evidence of a decrease in the number of hospitalizations due to violent assault as a result of the ban

The North American tree-ring fire-scar network

Fire regimes in North American forests are diverse and modern fire records are often too short to capture important patterns, trends, feedbacks, and drivers of variability. Tree-ring fire scars provide valuable perspectives on fire regimes, including centuries-long records of fire year, season, frequency, severity, and size. Here, we introduce the newly compiled North American tree-ring fire-scar network (NAFSN), which contains 2562 sites, >37,000 fire-scarred trees, and covers large parts of North America. We investigate the NAFSN in terms of geography, sample depth, vegetation, topography, climate, and human land use. Fire scars are found in most ecoregions, from boreal forests in northern Alaska and Canada to subtropical forests in southern Florida and Mexico. The network includes 91 tree species, but is dominated by gymnosperms in the genus Pinus. Fire scars are found from sea level to >4000-m elevation and across a range of topographic settings that vary by ecoregion. Multiple regions are densely sampled (e.g., >1000 fire-scarred trees), enabling new spatial analyses such as reconstructions of area burned. To demonstrate the potential of the network, we compared the climate space of the NAFSN to those of modern fires and forests; the NAFSN spans a climate space largely representative of the forested areas in North America, with notable gaps in warmer tropical climates. Modern fires are burning in similar climate spaces as historical fires, but disproportionately in warmer regions compared to the historical record, possibly related to under-sampling of warm subtropical forests or supporting observations of changing fire regimes. The historical influence of Indigenous and non-Indigenous human land use on fire regimes varies in space and time. A 20th century fire deficit associated with human activities is evident in many regions, yet fire regimes characterized by frequent surface fires are still active in some areas (e.g., Mexico and the southeastern United States). These analyses provide a foundation and framework for future studies using the hundreds of thousands of annually- to sub-annually-resolved tree-ring records of fire spanning centuries, which will further advance our understanding of the interactions among fire, climate, topography, vegetation, and humans across North America