New River Inlet DRI: Observations and Modeling of Flow and Material Exchange

LONG-TERM GOALS: The goal of our effort is to understand river and inlet fluid dynamics through in situ field observations and model validation.N0001411WX20962; N0001412WX20498; N000141010409, N00014101037

New River Inlet DRI: Observations and Modeling of Flow and Material Exchange & Field and Numerical Study of the Columbia River Mouth

LONG-TERM GOALS: The goal of our effort is to understand river and inlet fluid dynamics through in situ field observations and model validation.N0001411WX20962; N0001412WX20498; N0001413WX20480; N000141110376, N000141010379, N00014131018

Riverine Flow Observations and Modeling- Sensitivity of Delft3D River Model to Bathymetric Variability

Long-term goals: The goal of our effort is to understand river and inlet fluid dynamics through in situ field observations and model validation.NPS Award Number: (N0001410WX21049; N0001411WX20962)UM Award Number: (N000141010379

Riverine Flow Observations and Modeling- Sensitivity of Delft3D River Model to Bathymetric Variability

Long-term goals: The goal of our effort is to understand river and inlet fluid dynamics through in situ field observations and model validation.NPS Award Number: (N0001410WX21049; N0001411WX20962)UM Award Number: (N000141010379

Responses of Swimmers Caught in Rip Currents: Perspectives on Mitigating the Global Rip Current Hazard

Rip currents are the primary mechanism on many of the world’s beaches associated with rescues and drownings and have long been the focus of beachgoer education and awareness strategies. Traditional approaches to mitigating the rip current hazard typically provide information on escape procedures for beachgoers caught in a rip current. Several of these approaches are now being challenged by new scientific findings leading to uncertainty and debate amongst scientists and beach safety practitioners. This paper suggests that future research efforts on mitigating the rip current hazard should focus on quantifying the physical and behavioral responses of beachgoers who have been caught in rip currents. Descriptions of new approaches adopted recently in Australia by a joint collaboration between the University of New South Wales and Surf Life Saving Australia are presented

Field and Numerical Study of the Columbia River Mouth

LONG-TERM GOALS: The overall goal is to improve the predictive capability and skill of Delft3D to simulate complex hydrodynamics in an inlet setting in which tides, river discharge, winds, waves, and bottom friction are all important.N0001413IP200

Dynamique de la zone de swash : influence de la marée et de la morphologie sur les paramètres du run-up

The impact of tide and morphology on run-up parameters in dissipative conditions is assessed, using high-frequency video observations. The infragravity run-up is dominant and shows variations of about 60% during an entire tidal cycle. This behavior cannot be explained by the evolution of offshore wave conditions. Wave conditions in the surf zone and the beach slope are tidally modulated and significantly correlated to the runup. The role of the shape of the beach profile is also investigated

State-Space Analysis Of Model Error: A Probabilistic Parameter Estimation Framework with Spatial Analysis of Variance

Long-term goals: An over-arching goal in prediction science is to objectively improve numerical models of nature. Meeting that goal requires objective quantification of deficiencies in our models. The structural differences between a numerical model and a true system are difficult to ascertain in the presence of multiple sources of error. Numerical weather prediction (NWP) is subject to temporally and spatially varying error, resulting from both imperfect atmospheric models and the chaotic growth of initial- condition (IC) error. The aim of our work is to provide a method that begins to systematically disentangle the model inadequacy signal from the initial condition error signal.N0001410WX2005

Fortnightly tides and subtidal motions in a choked inlet

This paper is not subject to U.S. copyright. The definitive version was published in Estuarine, Coastal and Shelf Science 150, Pt.B (2014): 325-331, doi:10.1016/j.ecss.2014.03.025.Amplitudes of semi-diurnal tidal fluctuations measured at an ocean inlet system decay nearly linearly by 87% between the ocean edge of the offshore ebb-tidal delta and the backbay. A monochromatic, dynamical model for a tidally choked inlet separately reproduces the evolution of the amplitudes and phases of the semi-diurnal and diurnal tidal constituents observed between the ocean and inland locations. However, the monochromatic model over-predicts the amplitude and under-predicts the lag of the lower-frequency subtidal and fortnightly motions observed in the backbay. A dimensional model that considers all tidal constituents simultaneously, balances the along-channel pressure gradient with quadratic bottom friction, and that includes a time-varying channel water depth, is used to show that that these model-data differences are associated with nonlinear interactions between the tidal constituents that are not included in non-dimensional, monochromatic models. In particular, numerical simulations suggest that the nonlinear interactions induced by quadratic bottom friction modify the amplitude and phase of the subtidal and fortnightly backbay response. This nonlinear effect on the low-frequency (subtidal and fortnightly) motions increases with increasing high-frequency (semi-diurnal) amplitude. The subtidal and fortnightly motions influence water exchange processes, and thus backbay temperature and salinity.We thank the Office of Naval Research (N0001411WX20962; N0001412WX20498) for funding

Assimilating Lagrangian data for parameter estimation in a multiple-inlet system

© The Author(s), 2017. This is the author's version of the work. It is posted here under a nonexclusive, irrevocable, paid-up, worldwide license granted to WHOI. It is made available for personal use, not for redistribution. The definitive version was published in Ocean Modelling 113 (2017): 131-144, doi:10.1016/j.ocemod.2017.04.001.Numerical models of ocean circulation often depend on parameters that must be tuned to match either results from laboratory experiments or field observations. This study demonstrates that an initial, suboptimal estimate of a parameter in a model of a small bay can be improved by assimilating observations of trajectories of passive drifters. The parameter of interest is the Manning's n coefficient of friction in a small inlet of the bay, which had been tuned to match velocity observations from 2011. In 2013, the geometry of the inlet had changed, and the friction parameter was no longer optimal. Results from synthetic experiments demonstrate that assimilation of drifter trajectories improves the estimate of n, both when the drifters are located in the same region as the parameter of interest and when the drifters are located in a different region of the bay. Real drifter trajectories from field experiments in 2013 also are assimilated, and results are compared with velocity observations. When the real drifters are located away from the region of interest, the results depend on the time interval (with respect to the full available trajectories) over which assimilation is performed. When the drifters are in the same region as the parameter of interest, the value of n estimated with assimilation yields improved estimates of velocity throughout the bay.This work was supported by: Department of Defense Multidisciplinary University Research Initiative (MURI) [grant N000141110087], administered by the Office of Naval Research; the National Science Foundation (NSF); the National Oceanic and Atmospheric Administration (NOAA); NOAA's Climate Program Office; the Department of Energy's Office for Science (BER); and the Assistant Secretary of Defense (Research & Development)