A Cross Scale Model For 3d Baroclinic Circulation In Estuary Plume Shelf Systems 2 Application To The Columbia River

This article is the second of a two-part paper on ELCIRC, an Eulerian-Lagrangian finite difference/finite volume model designed to simulate 3D baroclinic circulation across river-to-ocean scales. In part one (Zhang et al., 2004), we described the formulation of ELCIRC and assessed its baseline numerical skill. Here, we describe the application of ELCIRC within CORIE, a coastal margin observatory for the Columbia River estuary and plume. We first introduce the CORIE modeling system and its multiple modes of simulation, external forcings, observational controls, and automated products. We then focus on the evaluation of highly resolved, year-long ELCIRC simulations, using two variables (water level and salinity) to illustrate simulation quality and sensitivity to modeling choices. We show that, process-wise, simulations capture well important aspects of the response of estuarine and plume circulation to ocean, river, and atmospheric forcings. Quantitatively, water levels are robustly represented, while salinity intrusion and plume dynamics remain challenging. Our analysis highlights the benefits of conducting model evaluations over large time windows (months to years), to avoid significant localized biases. The robustness and computational efficiency of ELCIRC has proved invaluable in identifying and reducing non-algorithmic sources of errors, including parameterization (e.g., turbulence closure and stresses at the air- water interface) and external forcings (e.g., ocean conditions and atmospheric forcings).

Semi-Lagrangian Advection Methods and Their Applications in Geoscience provides a much-needed resource on semi-Lagrangian theory, methods, and applications. Covering a variety of applications, the book brings together developments of the semi-Lagrangian in one place and offers a comparison of semi-Lagrangian methods with Eulerian-based approaches. It also includes a chapter dedicated to difficulties of dealing with the adjoint of semi-Lagrangian methods and illustrates the behavior of different schemes for different applications. This allows for a better understanding of which schemes are most efficient, stable, consistent, and likely to introduce the minimum model error into a given problem. Beneficial for students learning about numerical approximations to advection, researchers applying these techniques to geoscientific modeling, and practitioners looking for the best approach for modeling, Semi-Lagrangian Advection Methods and Their Applications in Geoscience fills a crucial gap in numerical modeling and data assimilation in geoscience. Provides a single resource for understanding semi-Lagrangian methods and what is involved in its application Includes exercises and codes to supplement learning and create opportunities for practice Includes coverage of adjoints, examining the advantages and disadvantages of different approaches in multiple coordinate systems and different discretizations Includes links to numerical datasets and animations to further enhance understanding

The tragedy of the 2004 Indian Ocean tsunami has led to a rapid expansion in science directed at understanding tsunami and mitigating their hazard. A remarkable cross-section of this research was presented in the session: Tsunami Generation and Hazard, at the International Union of Geodesy and Geophysics XXIV General Assembly in Perugia, held in July of 2007. Over one hundred presentations were made at this session, spanning topics ranging from paleotsunami research, to nonlinear shallow-water theory, to tsunami hazard and risk assessment. A selection of this work, along with other contributions from leading tsunami scientists, is published in detail in the 28 papers of this special issue of Pure and Applied Geophysics: Tsunami Science Four Years After the Indian Ocean Tsunami. Part I of this issue includes 14 papers covering the state-of-the-art in tsunami modelling and hazard assessment. Another 14 papers are published in Part II focusing on observations and data analysis.

In Part 2 of our application of the Navy coastal ocean model (NCOM) to the Atchafalaya Bay system, we examine the wind- and tide-forced three-dimensional baroclinic circulation of the Lower Atchafalaya and Wax Lake Outlet river plumes. The salinity and the current velocity are examined during a time period when three cold fronts passed over the region. The baroclinic circulation of NCOM was validated for the same time period in Part 1 of this study (Cobb, Keen, and Walker, 2008. Modeling the circulation of the Atchafalaya Bay region, 1: Model description and validation. Journal of Coastal Research, this issue). We find that the westward transport of plume water and the offshore cold-front induced circulation are determined to a large extent by the alongshore and cross-shore bathymetric structure. Wind-driven plume water moves parallel to the alongshore bathymetric contours unless forced to mix. with higher salinity water by strong cross-shore directed winds. The mixing of plume water with offshore water occurs over bathymetric shoals during periods of strong post-frontal winds. This mixing process involves the offshore transport of plums water over the entire water column in addition to the strong surface transport. The model results for offshore circulation are in qualitative agreement with past observations. In addition, the hydrodynamic processes that control the salinity fronts in Vermilion and West Cote Blanche Bays, areas where the model salinity was validated in Part 1, are examined as well.

Published by the American Geophysical Union as part of the Coastal and Estuarine Sciences, Volume 4. The AGU Monograph Series on Coastal and Estuarine Regimes provides timely summaries and reviews of major process and regional studies, both observational and theoretical, and of theoretical and numerical models. It grew out of an IAPSO/SCOR/ECOR working group initiative several years ago intended to enhance scientific communications on this topic. The series' authors and editors are drawn from the international community. The ultimate goal is to stimulate bringing the theory, observations, and modeling of coastal and estuarine regimes together on the global scale.