755 research outputs found

    The Effects of Rotation and River Discharge on Net Mixing in Small-Mouth Kelvin Plumes

    Get PDF
    Small-mouth Kelvin number plumes, or plumes with a source width smaller than the deformation radius, are characterized by near-field plume regions of rapid lateral expansion and strong vertical mixing. Net plume mixing, or the dilution of a plume by ocean water between the estuary mouth and the far-field plume, is examined using idealized numerical experiments with the Regional Ocean Modeling System (ROMS). The density anomaly of plume water entering the far field is determined from isohaline analysis of the modeled salinity field. The experiments indicate that when estuarine discharge increases, net plume mixing decreases in a rotating environment but increases in a nonrotating environment. Scaling analysis supports that this opposite trend in behavior is related to rotation turning the plume, limiting the lateral expansion and suppressing shear mixing. The results of this study explain different trends in net plume mixing reported in previous studies and compare favorably to observations of the Fraser River plume

    Multivariable statistical regression models of the areal extent of hypoxia over the Texas-Louisiana continental shelf

    Get PDF
    Observations of the areal extent of seasonal hypoxia over the Texas-Louisiana continental shelf from 1985 to 2010 are correlated with a variety of physical and biogeochemical forcing mechanisms. Significant correlation is found between hypoxic area and both nitrogen load (r(2) = 0.24) and east-west wind speed (r(2) = 0.16). There is also a significant increasing trend in the areal extent of hypoxia in time; a linearly increasing trend over the entire record (r(2) = 0.17), a step increase in area for the years 1994 and beyond (r(2) = 0.21), and a step increase for 1993 and beyond (r(2) = 0.29) were all found to be significantly correlated with area. The year 1988, often included in other studies, was found to be a statistical outlier, in that the statistical regression properties are strongly modified when this year is included. The exclusion of any other year does not have as great an effect as excluding 1988 from the record. The year 1989 is also excluded, as this year had no full shelf survey, for a total of 24 years of data for the record. Multivariable regression models using all possible combinations of the forcing variables considered were calculated. The best performing models included east-west wind, either a linear trend in time or step in time (1994 and beyond), and either nitrogen load or river discharge combined with nitrogen concentration. The range of adjusted correlation coefficients ranged from r(2) = 0.47 to 0.67. The best model (east-west wind, a step increase in time 1994 and beyond, river discharge, and nitrogen concentration) has a standard error of 3008 km(2)

    Cross-frontal entrainment of plankton into a buoyant plume: The frog tongue mechanism

    Get PDF
    A mechanism for the cross-frontal entrainment of plankton by a buoyant plume influenced by wind stress is described and tested using an idealized numerical model. Under the right circumstances, plankton may enter a buoyant plume during an upwelling wind stress, then be transported shoreward during a subsequent downwelling wind stress. In order for the plankton to enter the plume, they must swim upward at a velocity (wp) bounded by Hplume/T \u3c wp \u3c Îș/ Hmix where Hplume is the thickness of the buoyant plume, Hmix is the thickness of the upper oceanic mixed layer (Hmix \u3e Hplume), Îș is the magnitude of vertical mixing within the mixed layer, and T is the time between upwelling and downwelling events. In words, this equation states that the plankton must swim slow enough so that they are evenly distributed through the mixed layer, so that the buoyant plume may override the plankton patch during upwelling. Once the plume has overridden the patch, in order to enter the plume, the plankton must swim fast enough to be able to enter the plume in the time while it is over them. These two bounds on the swimming rate suggest that, given various physical parameters, there may be a range of swimming speed that will maximize entrainment into a plume. Numerical experiments corroborate the feasibility of the proposed mechanisms and associated scaling

    Psychiatric Diagnoses Differ Considerably in Their Associations With Alcohol/Drug-Related Problems Among Adolescents. A Norwegian Population-Based Survey Linked With National Patient Registry Data

    Get PDF
    The aim of this study was to examine alcohol/drug use and problems across psychiatric diagnoses and to what extent associations between each psychiatric diagnosis and alcohol/drug use and problems were independent from the potential confounding effects of psychiatric comorbidity, socioeconomic status, sex and age. We used a dataset comprising a linkage between a large population-based and cross-sectional study among Norwegian adolescents (the youth@hordaland conducted in 2012) and national registry-based data on specialist mental health care use during the 4 years prior to the survey (2008 to 2011). The study sample included 16 to 19 year olds who participated in the youth@hordaland survey and consented to the linkage with patient registry data (n = 9,408). Among these, 853 (9%) had received specialist mental health care and comprised the clinical group, while the rest (n = 8,555) comprised the comparison group. The main outcome variables were several self-reported indicators for alcohol/drug use, including any alcohol use, frequent alcohol intoxication, high-level alcohol consumption, and lifetime illicit drug use, as well as one indicator for potential alcohol/drug-related problems: a positive CRAFFT-score. Adolescents receiving specialist mental health care (n = 853) reported more frequently alcohol/drug use and problems compared to adolescents not receiving these services (Cohens d’s ranging from 0.09 to 0.29, all p ≀ 0.01). Anxiety, depression, conduct disorders, eating disorders, ADHD, and trauma-related disorders were all associated with single measures of alcohol/drug use and problems, with odds ratios (ORs) ranging from 1.58 to 4.63, all p < 0.05) in unadjusted models. Trauma-related disorders, depression and conduct disorders were also positively associated with higher scores on a combined indicator of alcohol/drug use and problems (ORs ranging from 1.89 to 3.15, all p < 0.01), even after the full adjustment from psychiatric comorbidity and sociodemographic variables (adjusted odds ratios ranging from 1.61 to 2.79, p < 0.05). These results suggest that alcohol/drug use and problems were slightly more common among adolescents who received specialist mental health care during the past 4 years compared with the general adolescent population, and adolescents with trauma-related disorders, depression and conduct disorders were high-risk groups for alcohol/drug use and problems.publishedVersio

    An Open Access Policy at Texas A&M University

    Get PDF
    An information sheet on a proposed open access policy at Texas A&MOpen access scholarly literature is “digital, online, free-of-charge, and free of most copyright and licensing restrictions”1. An Open Access Policy reserves Open access policies directly support the mission of land grant universities by making publically supported research openly available. Universities around the world have created Open access policies to share their research so that society has equitable access to published scholarship. These policies generally allow authors to archive a copy of their publication in an institutional repository or published in an open access journal, in ways that help address both the price barriers and the permission barriers that undermine global access to the products of a university’s scholarly and creative work. Over six hundred universities and research institutions worldwide, including more than half of our peer institutions (as defined by Vision 2020), have an open access policy2. The Faculty Senate Research sub-committee recommends that TAMU adopt an Open Access Policy. An open access policy at TAMU would be managed by the TAMU Libraries, who would provide the support to TAMU authors so they can archive an open access copy of their publication in our institutional repository so that the burden on the authors would be minimal. We are proposing the Faculty Senate as a whole vote on a resolution to recommend that the President’s office implement such a policy.Texas A&M Faculty Senat

    Development, Operation, and Results From the Texas Automated Buoy System

    Get PDF
    The Texas Automated Buoy System (TABS) is a coastal network of moored buoys that report near-real-time observations about currents and winds along the Texas coast. Established in 1995, the primary mission of TABS is ocean observations in the service of oil spill preparedness and response. The state of Texas funded the system with the intent of improving the data available to oil spill trajectory modelers. In its 12 years of operation, TABS has proven its usefulness during realistic oil spill drills and actual spills. The original capabilities of TABS, i.e., measurement of surface currents and temperatures, have been extended to the marine surface layer, the entire water column, and the sea floor. In addition to observations, a modeling component has been integrated into the TABS program. The goal is to form the core of a complete ocean observing system for Texas waters. As the nation embarks on the development of an integrated ocean observing system, TABS will continue to be an active participant of the Gulf of Mexico Coastal Ocean Observing System (GCOOS) regional association and the primary source of near-surface current measurements in the northwestern Gulf of Mexico. This article describes the origin of TABS, the philosophy behind the operation and development of the system, the resulting modifications to improve the system, the expansion of the system to include new sensors, the development of TABS forecasting models and real-time analysis tools, and how TABS has met many of the societal goals envisioned for GCOOS

    Insights on Simulating Summer Warming of the Great Lakes: Understanding the Behavior of a Newly Developed Coupled Lake-Atmosphere Modeling System

    Get PDF
    The Laurentian Great Lakes are the world\u27s largest freshwater system and regulate the climate of the Great Lakes region, which has been increasingly experiencing climatic, hydrological, and ecological changes. An accurate mechanistic representation of the Great Lakes thermal structure in Regional Climate Models (RCMs) is paramount to studying the climate of this region. Currently, RCMs have primarily represented the Great Lakes through coupled one-dimensional (1D) column lake models; this approach works well for small inland lakes but is unable to resolve the realistic hydrodynamics of the Great Lakes and leads to inaccurate representations of lake surface temperature (LST) that influence regional climate and weather patterns. This work overcomes this limitation by developing a fully two-way coupled modeling system using the Weather Research and Forecasting model and a three-dimensional (3D) hydrodynamic model. The coupled model system resolves the interactive physical processes between the atmosphere, lake, and surrounding watersheds; and validated against a range of observational data. The model is then used to investigate the potential impacts of lake-atmosphere coupling on the simulated summer LST of Lake Superior. By evaluating the difference between our two-way coupled modeling system and our observation-driven modeling system, we find that coupled-lake atmosphere dynamics can lead to a higher LST during June-September through higher net surface heat flux entering the lake in June and July and a lower net surface heat flux entering the lake in August and September. The unstratified water in June distributes the entering surface heat flux throughout the water column leading to a minor LST increase, while the stratified waters of July create a conducive thermal structure for the water surface to warm rapidly under the higher incoming surface heat flux. This research provides insight into the coupled modeling system behavior, which is critical for enhancing our predictive understanding of the Great Lakes climate system

    Thank you to our 2017 peer reviewers

    Get PDF
    Author Posting. © American Geophysical Union, 2018. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Oceans 123 (2018): 6042-6052, doi:10.1029/2018JC014410.Similar to the construction of physical ships and laboratory buildings, scientific knowledge is built incrementally and requires solid components of data, theory, and methodology at each phase of the “construction.” The peer‐review process provides the necessary “inspection” and the assurance that every step of the construction is solid, particularly in regard to the proper use of the scientific method. The peer‐review process helps improve the published work by providing constructive suggestions and by safeguarding against scientific work that could later be found to be built on shaky foundations. Because no single scientist has intimate knowledge of today's many aspects of the Ocean Sciences, we rely on each other's expertise to serve as unbiased “inspectors” of published articles. Your considerable time and effort, spent reviewing JGR‐Oceans manuscript(s) during 2017, are sincerely appreciated by our editorial board and by the Ocean Science community at large. We thank you for rising to this professional challenge and for your wisdom, commitment, skill, and service.2019-03-1

    Psychiatric Diagnoses Differ Considerably in Their Associations With Alcohol/Drug-Related Problems Among Adolescents. A Norwegian Population-Based Survey Linked With National Patient Registry Data

    Get PDF
    The aim of this study was to examine alcohol/drug use and problems across psychiatric diagnoses and to what extent associations between each psychiatric diagnosis and alcohol/drug use and problems were independent from the potential confounding effects of psychiatric comorbidity, socioeconomic status, sex and age. We used a dataset comprising a linkage between a large population-based and cross-sectional study among Norwegian adolescents (the youth@hordaland conducted in 2012) and national registry-based data on specialist mental health care use during the 4 years prior to the survey (2008 to 2011). The study sample included 16 to 19 year olds who participated in the youth@hordaland survey and consented to the linkage with patient registry data (n = 9,408). Among these, 853 (9%) had received specialist mental health care and comprised the clinical group, while the rest (n = 8,555) comprised the comparison group. The main outcome variables were several self-reported indicators for alcohol/drug use, including any alcohol use, frequent alcohol intoxication, high-level alcohol consumption, and lifetime illicit drug use, as well as one indicator for potential alcohol/drug-related problems: a positive CRAFFT-score. Adolescents receiving specialist mental health care (n = 853) reported more frequently alcohol/drug use and problems compared to adolescents not receiving these services (Cohens d’s ranging from 0.09 to 0.29, all p ≀ 0.01). Anxiety, depression, conduct disorders, eating disorders, ADHD, and trauma-related disorders were all associated with single measures of alcohol/drug use and problems, with odds ratios (ORs) ranging from 1.58 to 4.63, all p &lt; 0.05) in unadjusted models. Trauma-related disorders, depression and conduct disorders were also positively associated with higher scores on a combined indicator of alcohol/drug use and problems (ORs ranging from 1.89 to 3.15, all p &lt; 0.01), even after the full adjustment from psychiatric comorbidity and sociodemographic variables (adjusted odds ratios ranging from 1.61 to 2.79, p &lt; 0.05). These results suggest that alcohol/drug use and problems were slightly more common among adolescents who received specialist mental health care during the past 4 years compared with the general adolescent population, and adolescents with trauma-related disorders, depression and conduct disorders were high-risk groups for alcohol/drug use and problems
    • 

    corecore