Hernan G. Arango

Hernan G. Arango
Rutgers, The State University of New Jersey | Rutgers · Department of Marine and Coastal Sciences

Ph.D. Physical Oceanography, Texas A&M University (1990)

About

66
Publications
12,356
Reads
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6,384
Citations
Introduction
My current research interest is to design, develop, test, and maintain ocean community models (ROMS) for diverse scientific and operational applications, and to develop adjoint-based algorithms for variational data assimilation, ensemble forecasting, observation impact and observation sensitivity, and circulation stability analysis.
Additional affiliations
October 1995 - present
Rutgers, The State University of New Jersey
Position
  • Ocean Modeler
Description
  • Develop and Maintain ROMS (Regional Ocean Modeling System) Framework
September 1992 - October 1995
Harvard University
Position
  • Research Associate
Description
  • Further develop and maintain Harvard Ocean Prediction System (HOPS)
August 1990 - September 1992
Harvard University
Position
  • PostDoc Position
Description
  • Real-time Ocean Prediction
Education
August 1987 - August 1990
Texas A&M University
Field of study
  • Physical Oceanography
September 1984 - August 1987
Texas A&M University
Field of study
  • Physical Oceanography

Publications

Publications (66)
Article
This paper explores the impact of the individual components of a coastal ocean observing system on estimates of the circulation derived from a state-of-the-art analysis and forecast system for the Mid-Atlantic Bight and Gulf of Maine. The foundation of these activities is the Regional Ocean Modeling System 4-dimensional variational (4D-Var) data as...
Article
The efficacy of an ocean observing, analysis, and forecasting system for the Mid-Atlantic Bight and the Gulf of Maine is explored using the concept of array modes. The analysis-forecast system is based on a triply nested configuration of the Regional Ocean Modeling System (ROMS) in conjunction with 4-dimensional variational (4D-Var) data assimilati...
Article
The Regional Ocean Modeling System (ROMS) 4-dimensional variational (4D-Var) data assimilation system was used to compute ocean state estimates of the Mid-Atlantic Bight (MAB). A three-level nested grid configuration was employed with horizontal resolution successively enhanced from 7 km down to 800 m at the innermost nest. This captures the dynami...
Article
The properties of the expected analysis and forecast error covariance matrices are explored using a novel method based on the tangent linearization and adjoint of a 4-dimensional variational (4D-Var) data assimilation system. The method is applied to the mesoscale circulation that develops in the presence of a baroclinically unstable mid-latitude o...
Article
A nested configuration of the Regional Ocean Modeling System (ROMS) comprising three grids was used in conjunction with a 4-dimensional variational (4D-Var) data assimilation system to compute ocean state estimates of the Mid-Atlantic Bight (MAB). The three nested grids have a horizontal resolution ranging from ∼7 km to ∼0.8 km and capture circulat...
Article
The performance of two common approaches to data assimilation, an Ensemble Adjustment Kalman Filter (EAKF) and a 4-dimensional variational (4D-Var) method, is quantified in a popular community ocean model, the Regional Ocean Modeling Systems (ROMS). Two distinct circulation environments are considered: the California Current System (CCS), which is...
Article
Full-text available
Turbidity currents deliver sediment rapidly from the continental shelf to the slope and beyond; and can be triggered by processes such as shelf resuspension during oceanic storms; mass failure of slope deposits due to sediment-and wave-pressure loadings; and localized events that grow into sustained currents via self-amplifying ignition. Because th...
Article
This paper explores the impact of the individual components of a coastal ocean observing system on estimates of the circulation derived from a state-of-the-art analysis and forecast system for the Mid-Atlantic Bight and Gulf of Maine. The foundation of these activities is the Regional Ocean Modeling System 4-dimensional variational (4D-Var) data as...
Article
Full-text available
Ocean data assimilation is increasingly recognized as crucial for the accuracy of real-time ocean prediction systems and historical re-analyses. The current status of ocean data assimilation in support of the operational demands of analysis, forecasting and reanalysis is reviewed, focusing on methods currently adopted in operational and real-time p...
Article
The information content of the ocean observing array spanning the U.S. west coast is explored using the reduced-rank array modes (RAMs) derived from a 4-dimensional variational (4D-Var) data assimilation system covering a period of three decades. RAMs are an extension of the original formulation of array modes introduced by Bennett [1985] but in th...
Article
Aiming to achieve systematic ocean forecasting for the southeastern Brazilian coast, an incremental 4D-Var data assimilation system is applied to a regional ocean model focused mainly in the Santos Basin region. This implementation is performed within the scope of The Santos Basin Ocean Observing System (or Project Azul), a pilot project designed t...
Article
Experience in numerical weather prediction suggests that singular value decomposition (SVD) of a forecast can yield useful a priori information about the growth of forecast errors. It has been shown formally that SVD using the inverse of the expected analysis error covariance matrix to define the norm at initial time yields the Empirical Orthogonal...
Article
The summertime eastward jet (SEJ) located around 12°N, 110°-113°E, as the offshore extension of the Vietnam coastal current, is an important feature of the South China Sea (SCS) surface circulation in boreal summer. Analysis of satellite-derived sea level and sea surface wind data during 1992-2012 reveals pronounced interannual variations in its su...
Article
Full-text available
A data assimilative ocean circulation model is used to hindcast the interaction between a large Gulf Stream Warm Core Ring (WCR) with the Mid-Atlantic Bight (MAB) shelf and slope circulation. Using the recently developed Incremental Strong constraint 4D Variational (I4D-VAR) data assimilation algorithm, the model assimilates mapped satellite sea su...
Article
Variational data assimilation problems arising in meteorology and oceanography require the solution of a regularized nonlinear least-squares problem. Practical solution algorithms are based on the incremental (Truncated Gauss-Newton) approach, which involves the iterative solution of a sequence of linear least-squares (quadratic minimization) sub-p...
Chapter
In this chapter we will describe a comprehensive 4-dimensional variational ocean data assimilation system that is currently being used in the Regional Ocean Model System for the production of both near real-time and historical ocean analyses of the California Current circulation. The main focus of this article is on the practical aspects of the dat...
Article
A two-equation turbulence model (one equation for turbulence kinetic energy and a second for a generic turbulence length-scale quantity) proposed by Umlauf and Burchard [J. Marine Research 61 (2003) 235] is implemented in a three-dimensional oceanographic model (Regional Oceanographic Modeling System; ROMS v2.0). These two equations, along with sev...
Article
We present the feasibility of a prototype, near real-time assimilation and ensemble prediction system for the Intra-Americas Sea run autonomously aboard a ship of opportunity based on the Regional Ocean Modeling System (ROMS). Predicting an ocean state depends upon numerical models that contain uncertainties in their modeled physics, initial condit...
Article
The dynamics of the seasonal surface circulation in the Philippine Archipelago (117°E–128°E, 0°N–14°N) are investigated using a high-resolution configuration of the Regional Ocean Modeling System (ROMS) for the period of January 2004–March 2008. Three experiments were performed to estimate the relative importance of local, remote and tidal forcing....
Article
ROMS is a versatile, state-of-the-art, free-surface, hydrostatic primitive equation ocean circulation model developed at Rutgers University and UCLA. As its predecessors, ROMS is terrain-following, and is discretized in space on an orthogonal curvilinear, Arakawa C-grid. System attributes include extensive restructuring for sustained performance on...
Article
A method is presented in which the adjoint of a four-dimensional variational data assimilation system (4DVar) was used to compute the expected analysis and forecast error variances of linear functions of the ocean state vector. The power and utility of the approach are demonstrated using the Regional Ocean Modeling System configured for the Califor...
Article
One of the many applications of data assimilation is the estimation of adequate initial conditions for model forecasts. In this work we evaluate to what extent the Incremental, Strong constraint, 4-dimensional Variational (IS4DVAR) data assimilation can improve prediction of mesoscale variability in the East Australia Current (EAC) using the Region...
Article
The option for surface forcing correction, recently developed in the 4D-Variational (4DVAR) data assimilation systems of the Regional Ocean Model System (ROMS), is presented. Assimilation of remotely-sensed (satellite sea surface height anomaly and sea surface temperature) and in situ (from mechanical and expendable bathythermographs, Argo floats a...
Article
The Regional Ocean Modeling System (ROMS) is one of the few community ocean general circulation models for which a 4-dimensional variational data assimilation (4D-Var) capability has been developed. The ROMS 4D-Var capability is unique in that three variants of 4D-Var are supported: a primal formulation of incremental strong constraint 4D-Var (I4D-...
Article
A data assimilative, coupled physical–biological model for the Coastal Gulf of Alaska (CGOA) is used to investigate the extent to which improvements to oceanic circulation yield improvements to lower trophic level ecosystem predictions, especially in relation to mesoscale variability at the shelfbreak. The ocean circulation component is an implemen...
Article
This article discusses the challenges of developing a regional ocean prediction model for the Philippine Archipelago, a complex area in terms of geometry, bathymetry-dominated dynamics and variability, and strong local and remote wind forcing, where there are limited temporal and spatial ocean measurements. We used the Regional Ocean Modeling Syste...
Article
Four-dimensional variational data assimilation (4DVAR) in the Regional Ocean Modeling System (ROMS) is used to produce a best-estimate analysis of ocean circulation in the New York Bight during spring 2006 by assimilating observations collected by a variety of instruments during an intensive field program. An incremental approach is applied in an o...
Article
We investigate the processes that influence residence time in a partially mixed estuary using a three-dimensional circulation model. The complex geometry of the study region is not optimal for a structured grid model and so we developed a new method of grid connectivity. This involves a novel approach that allows an unlimited number of individual g...
Article
The Incremental Strong constraint 4D-Variational (IS4DVAR) system of the Regional Ocean Model System (ROMS) for data assimilation is presented. It has been applied to the California Current System (CCS) to assimilate remotely-sensed and in situ oceanic observations. Results from both twin and realistic experiments are presented. The IS4DVAR control...
Article
Adjoint sensitivity analysis is used to study the New York Bight circulation for three idealized situations: an unforced buoyant river plume, and upwelling and downwelling wind forcing. A derivation of adjoint sensitivity is presented that clarifies how the method simultaneously addresses initial, boundary, and forcing sensitivities. Considerations...
Article
Adjoint methods of sensitivity analysis were applied to the California Current using the Regional Ocean Modeling Systems (ROMS) with medium resolution, aimed at diagnosing the circulation sensitivity to variations in surface forcing. The sensitivities of coastal variations in SST, eddy kinetic energy, and baroclinic instability of complex time-evol...
Article
Full-text available
In this paper, we present the feasibility of a prototype autonomous ship-board, near real-time assimilation and ensemble prediction system for the Intra-Americas Sea. Predicting an atmosphere or ocean state depends upon numerical models that contain uncertainties in their modeled physics, initial conditions, and model state errors. We use an advanc...
Article
Full-text available
LONG-TERM GOAL The long-term goal of this project is to improve our capability to predict the inherent spatial and temporal variability near the Philippine Straits, and thus contribute to the development of reliable prediction systems. OBJECTIVES The primary focus is to provide a comprehensive understanding of the remote and local factors that cont...
Article
We present the background, development, and preparation of a state-of-the-art 4D variational (4DVAR) data assimilation system in the Regional Ocean Modeling System (ROMS) with an application in the Intra-Americas Sea (IAS). This initial application with a coarse model shows the efficacy of the 4DVAR methodology for use within complex ocean environm...
Article
Full-text available
The prediction of spectral water leaving radiance and remote sensing reflectance from a coupled physical/ecological/optical simulation is one of the goals of the ONR Hyperspectral Coastal Ocean Dynamics Experiment (HyCODE). This goal requires coupling a high-resolution circulation model (ROMS) to provide realistic physical forcing to a dynamic ecol...
Article
We are developing a three-dimensional numerical model that implements algorithms for sediment transport and evolution of bottom morphology in the coastal-circulation model Regional Ocean Modeling System (ROMS v3.0), and provides a two-way link between ROMS and the wave model Simulating Waves in the Nearshore (SWAN) via the Model-Coupling Toolkit. T...
Article
The Inverse Ocean Modeling (IOM) System is a modular system for constructing and running weak-constraint four-dimensional variational data assimilation (W4DVAR) for any linear or nonlinear functionally smooth dynamical model and observing array. The IOM has been applied to four ocean models with widely varying characteristics. The Primitive Equatio...
Article
Decadal fluctuations in salinity, nutrients, chlorophyll, a variety of zooplankton taxa, and fish stocks in the Northeast Pacific are often poorly correlated with the most widely-used index of large-scale climate variability in the region - the Pacific Decadal Oscillation (PDO). We define a new pattern of climate change, the North Pacific Gyre Osci...
Article
Systematic improvements in algorithmic design of regional ocean circulation models have led to significant enhancement in simulation ability across a wide range of space/time scales and marine system types. As an example, we briefly review the Regional Ocean Modeling System, a member of a general class of three-dimensional, free-surface, terrain-fo...
Article
We describe the development and preliminary application of the inverse Regional Ocean Modeling System (ROMS), a four dimensional variational (4DVAR) data assimilation system for high-resolution basin-wide and coastal oceanic flows. Inverse ROMS makes use of the recently developed perturbation tangent linear (TL), representer tangent linear (RP) and...
Article
The barotropic Rossby wave field in the North Atlantic Ocean is studied in an eddy-resolving ocean model simulation. The meandering model Gulf Stream radiates barotropic Rossby waves southward through preferred corridors defined by topographic features. The smoother region between the Bermuda Rise and the mid-Atlantic Ridge is a particularly striki...
Conference Paper
The adjoint of the tangent linear version of the Regional Ocean Modeling System (ROMS) coupled to a four component nitrogen-based trophic model (NPZD) has been used to explore the sensitivity of various physical and biological aspects of the southern arm of the California Current system to linear variations in the physical and biological attributes...
Article
A coastal ocean forecasting system was developed for the Long-term Ecosystem Observatory (LEO) on New Jersey's inner shelf. The forecast system comprised an ocean model, the Regional Ocean Modeling System, forced by a high-resolution atmospheric forecast, with assimilation of ocean data from ships and coastal radar systems. The forecasts were used...
Article
The regional ocean modelling system (ROMS) is a new generation ocean general circulation model that is rapidly gaining favour in the ocean modelling community. The tangent linear and adjoint versions of ROMS have recently been developed, and a new suite of tools that utilize these models for a variety of applications are now available to the ocean...
Article
Full-text available
During the course of developing new numerical algorithms for a terrain-following ocean modeling system (TOMS), different numerical aspects have been evaluated through a comparison between two widely used community ocean models, the Princeton ocean model (POM) and the regional ocean modeling system (ROMS). While both models aim at modeling coastal t...
Article
A primitive equation ocean circulation model in nonlinear terrain-following coordinates is applied to a decadal-length simulation of the circulation in the North Atlantic Ocean. In addition to the stretched sigma coordinate, novel features of the model include the utilization of a weakly dissipative, third-order scheme for tracer advection, and a c...
Article
A primitive equation, hydrostatic, terrain-following coordinate ocean general circulation model (OGCM) is used to investigate the mean water mass pathways from the subtropics to the tropics in the Atlantic Ocean. The OGCM is used in a fully realistic configuration of the Atlantic, from 30°S to 65°N, with realistic bathymetry. Surface forcings are p...
Article
The results of an intercomparison experiment performed with five numerical ocean models of different architecture are presented. While all models are able to simulate the large-scale characteristics of the North Atlantic circulation with a fair degree of realism, they also exhibit differences that can be attributed to the choices made in vertical c...
Article
This is the first part of a three-part study on the circulation, dynamics, and mesoscale forecasting of the western North Atlantic. The overall objective of this series of studies is threefold: 1) to present a methodology for deriving a dynamically balanced regional climatology that maintains the synoptic structure of the permanent fronts embedded...
Chapter
An overview of ongoing research efforts for regional nowcasts, forecasts and hindcasts of physical, biogeochemical and acoustical fields is given. The estimation of oceanic fields is carried out using a modular and flexible system approach, intended to optimize data and model contact, facilitating a unified approach to interdisciplinary research. R...
Chapter
An observational network, dynamical models and data assimilation schemes are the three components of an ocean prediction system. Its configuration for a regional real-time forecasting system proceeds in three phases, based on previous knowledge and experience of the area. In the initial (exploratory) phase, identification of dominant scales (synopt...
Article
Real-time operational shipboard forecasts of Iceland-Faeroe frontal variability were executed for the first time with a primitive equation mode. High quality, intensive hydrographic surveys during August 1993 were used for initialization, updating, and validation of the forecasts. Vigorous and rapid synoptic events occurred over several-day timesca...
Article
Using initialization and validation conditions from hydrographie surveys of the Iceland-Faroe Front in August 1993, shipboard quasi-geostrophic model forecasts executed in real time are evaluated for quantitative skill in terms of anomaly correlation coefficient and rms error. The prototype dynamical forecasts are synoptically initialized from two...
Article
Using a hydrocast survey of the Iceland-Faroe Front (IFF) from October 1992, quasigeostrophic forecasts are studied to validate their efficacy and to diagnose the physical processes involved in the rapid growth of a cold tongue intrusion. Explorations of 1) the choice of initial objective analysis parameters, 2) the depth of the unknown level of no...
Article
Full-text available
Using data sets of known quality as the basis for comparison, a recent experiment explored the Gulf Stream Region at 27°-47°N and 80°-50°W to assess the nowcast/forecast capability of specific ocean models and the impact of data assimilation. Scientists from five universities and the Naval Research Laboratory/Stennis Space Center participated in th...
Article
A major difficulty with two-layer ocean models, except in the linear approximation, is encountered in situations where the interface intersects the seabed. For the single mode, reduced-gravity version it is assumed that a passive deep lower layer exists everywhere, which in fact precludes any influence by bathymetry. These restrictions can be remov...
Article
Using initialization and validation conditions from hydrographic surveys of the Iceland-Faroe Front in August 1993, ship-board quasigeostrophic model forecasts executed in real-time are evaluated for quantitative skill in terms of anomaly correlation coefficient and rms error. The prototype dynamical forecasts are synoptically initialized from two...
Chapter
The Regional Ocean Modeling System (ROMS) is a new generation ocean general circulation model that is rapidly gaining favor in the ocean modeling community. The tangent linear and adjoint versions of ROMS have recently been developed, and a new suite of tools that utilize these models for a variety of applications are now available to the ocean mod...

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