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A 1/32° global ocean nowcast/forecast system has been developed by the Naval Research Laboratory at the Stennis Space Center. It started running at the Naval Oceanographic Office in near real-time on 1 Nov. 2003 and has been running daily in real-time since 1 Mar. 2005. It became an operational system on 6 March 2006, replacing the existing 1/16° system which ceased operation on 12 March 2006. Both systems use the NRL Layered Ocean Model (NLOM) with assimilation of sea surface height from satellite altimeters and sea surface temperature from multi-channel satellite infrared radiometers. Real-time and archived results are available online at http://www.ocean.nrlssc.navy.mil/global_nlom . The 1/32° system has improvements over the earlier system that can be grouped into two categories: (1) better resolution and representation of dynamical processes and (2) design modifications. The design modifications are the result of accrued knowledge since the development of the earlier 1/16° system. The improved horizontal resolution of the 1/32° system has significant dynamical benefits which increase the ability of the model to accurately nowcast and skillfully forecast. At the finer resolution, current pathways and their transports become more accurate, the sea surface height (SSH) variability increases and becomes more realistic and even the global ocean circulation experiences some changes (including inter-basin exchange). These improvements make the 1/32° system a better dynamical interpolator of assimilated satellite altimeter track data, using a one-day model forecast as the first guess. The result is quantitatively more accurate nowcasts, as is illustrated by several model-data comparisons. Based on comparisons with ocean color imagery in the northwestern Arabian Sea and the Gulf of Oman, the 1/32° system has even demonstrated the ability to map small eddies, 25–75 km in diameter, with 70% reliability and a median eddy center location error of 22.5 km, a surprising and unanticipated result from assimilation of altimeter track data. For all of the eddies (50% small eddies), the reliability was 80% and the median eddy center location error was 29 km. The 1/32° system also exhibits improved forecast skill in relation to the 1/16° system. This is due to (a) a more accurate initial condition for the forecast and (b) better resolution and representation of critical dynamical processes (such as upper ocean – topographic coupling via mesoscale flow instabilities) which allow the model to more accurately evolve these features in time while running in forecast mode (forecast atmospheric forcing for the first 5 days, then gradually reverting toward climatology for the remainder of the 30-day forecast period). At 1/32° resolution, forecast SSH generally compares better with unassimilated observations and the anomaly correlation of the forecast SSH exceeds that from persistence by a larger amount than found in the 1/16° system.

A 1/8° global version of the Navy Coastal Ocean Model (NCOM) is used for simulation of upper-ocean quantities on interannual time scales. The model spans the global ocean from 80°S to a complete Arctic cap, and includes 19 terrain-following σ- and 21 fixed z-levels. The global NCOM assimilates three-dimensional (3D) temperature and salinity fields produced by the Modular Ocean Data Assimilation System (MODAS) which generates synthetic temperature and salinity profiles based on ocean surface observations. Model-data intercomparisons are performed to measure the effectiveness of NCOM in predicting upper-ocean quantities such as sea surface temperature (SST), sea surface salinity (SSS) and mixed layer depth (MLD). Subsurface temperature and salinity are evaluated as well. An extensive set of buoy observations is used for this validation. Where possible, the model validation is performed between year-long time series obtained from the model and time series from the buoys. The statistical analyses include the calculation of dimensionless skill scores (SS), which are positive if statistical skill is shown and equal to one for perfect SST simulations. Model SST comparisons with year-long SST time series from all 83 buoys give a median SS value of 0.82. Model subsurface temperature comparisons with the year-long subsurface temperature time series from 24 buoys showed that the model is able to predict temperatures down to 500 m reasonably well, with positive SS values ranging from 0.18 to 0.97. Intercomparisons of MLD reveal that the model MLD is usually shallower than the buoy MLD by an average of about 15 m. Annual mean SSS and subsurface salinity biases between the model and buoy values are small. A comparison of SST between NCOM and a satellite-based Pathfinder data set demonstrates that the model has a root-mean-square (RMS) SST difference of 0.61 °C over the global ocean. Spatial variations of kinetic energy fields from NCOM show agree with historical observations. Based on these results, it is concluded that the global NCOM presented in this paper is able to predict upper-ocean quantities with reasonable accuracy for both coastal and open ocean locations.

A 1/8� global version of the Navy Coastal Ocean Model (NCOM) is described with details of its formulation, implementation, and configuration of the vertical coordinate. NCOM is a baroclinic, hydrostatic, Boussinesq, free-surface ocean model that allows its vertical coordinate to consist of r coordinates for the upper layers and z-levels below a user-specified depth. This flexibility allows implementation of a hybrid r–z coordinate system that is expected to mitigate some of the weaknesses that can be associated with either pure coordinate option. For the global NCOM application, the r–z coordinate is used to allow terrain-following r coordinates in the upper ocean, providing better resolution and topographic fidelity in shelf regions where flow is most sensitive to its representation. Including z coordinates for deeper regions efficiently maintains high near-surface vertical resolution in the open ocean. Investigation into the impact of the selected coordinate system focuses on differences between atmospherically-forced free-running (no assimilation) global solutions using r–z and pure z coordinates. Comparisons with independent temperature observations indicate that global NCOM using the r–z coordinate has improved skill relative to its z coordinate implementation. Among other metrics, we show that in comparison with time series of surface temperature from National Oceanic Data Center (NODC) buoys, mostly located in coastal regions, root mean squared differences (RMSD) improved for 63% and correlation improved for 71% of the stations

The first real-time eddy resolving nearly global ocean nowcast/forecast system has been running daily at the Naval Oceanographic Office (NAVOCEANO) since 18 October 2000 and it became an operational system on 27 September 2001. Thirty-day forecasts are made once a week. The system, which was developed at the Naval Research Laboratory (NRL), uses the NRL Layered Ocean Model (NLOM) with 1/16j resolution and seven layers in the vertical, including a Kraus–Turner type bulk mixed layer. Sea surface temperature (SST) from satellite IR and satellite altimeter sea surface height (SSH) data from TOPEX/ POSEIDON (T/P), ERS-2 and Geosat-Follow-On (GFO), provided via NAVOCEANO’s Altimeter Data Fusion Center (ADFC), are assimilated into the model. The large size of the model grid (4096 � 2304 � 7) and operational requirements make it necessary to use a computationally efficient ocean model and data assimilation scheme. The assimilation consists of an optimum interpolation (OI) based scheme that uses an OI deviation analysis with the model as a first guess, a statistical inference technique for vertical mass field updates, geostrophic balance for the velocity updates outside of the equatorial region and incremental updating of the model fields to further reduce inertia–gravity wave generation. A spatially varying mesoscale covariance function determined from T/P and ERS-2 data is used in the OI analysis. The SST assimilation consists of relaxing the NLOM SST to the Modular Ocean Data Assimilation System (MODAS) SSTanalysis, which is performed daily at NAVOCEANO. Realtime and archived results from the model can be viewed at the NRL web site http://www.ocean.nrlssc.navy.mil/global_nlom. This includes many zoom regions, nowcasts and forecasts of SSH, upper ocean currents and SST, forecast verification statistics, subsurface temperature cross-sections, the amount of altimeter data used for each nowcast from each satellite and nowcast comparisons with unassimilated data. The results show that the model has predictive skill for mesoscale and other types of variability lasting at least 1 month in most regions and when calculated globally. D 2003 Elsevier Science B.V. All rights reserved.

The global ocean has its own "weather" phenomena, although with greatly different time and space scales compared to the atmosphere. Oceanic mesoscale eddies are typically about 100 km in diameter which makes them 20?30 times smaller than comparable atmospheric highs and lows. The ocean's "jet streams" are the western boundary currents and their extensions into the interior ocean. The currents have speeds on the order of 1 m/s compared to atmospheric speeds that can be 100 times this value. The space scales of the meanders on these high-speed streams are similar to those for the eddies mentioned above. Knowing and predicting these oceanic mesoscale features have numerous naval applications which include tactical planning, optimum track ship routing, search and rescue and supplying boundary conditions for high resolution coastal models, to name a few.

he ocean is changing vigorously on a wide range of time and space scales. This variability leads to substantial problems in observing and modeling (simulating) the rapidly changing flow field, the ocean's temperature distribution, and more generally the consequences of those changes on a wide variety of scientific, military, and societal problems, including climate research, fisheries management, coastal pollution (spill) predictions, or ship routing. As an example, the ocean carries roughly 50% of the heat from the low latitudes to mid and high latitudes, where it is released to the atmosphere and moderates our climate. Any significant variation in this heat transport will necessarily lead to a perturbation of the climate system. Among the goals of the present ocean research are therefore to measure, understand, and eventually predict these variations by combining ocean data and ocean models.

This paper illustrates the value of SeaWiFS ocean color imagery in assessing the ability of three data-assimilative ocean models (configured in five prediction systems) to map mesoscale variability in the Gulf of Mexico (i.e., the Loop Current and associated warm and cold eddies) and in helping to diagnose specific strengths and weaknesses of the systems. In addition, the study clearly illustrates that biological responses of the surface waters are strongly linked to the physical events and processes.

The purpose of this User's Manual (UM) is to describe the components, order of execution, setup and operational run of the Global Ocean Forecast System (GOFS) version 2.6. The emphasis of the document is on the additions to the system, mainly Naval Coupled Data Assimilation System (NCODA), and the coupling with PIPS 3.0. Flowcharts are included to describe the global NCOM inputs, execution, outputs, and the launch of the PIPS 3.0 system. Information on obtaining the GOFS through a Subversion repository is also included.

The version 4 series of the Navy Coastal Ocean Model (NCOM) has been developed at the Naval Research Laboratory (NRL) and transitioned to the Navy Oceanographic Office. New capabilities include a general vertical coordinate (GVC) option in addition to the sigma-z coordinate vertical grid, Earth System Modeling Framework (ESMF) compliance, and several other compile time options that increase the flexibility of the model code. NRL has also begun maintaining NCOM in version control using a Subversion repository. This User's Manual documents the setup and execution of the NCOM version 4.0 series.

The version 4 series of the Navy Coastal Ocean Model (NCOM) has been developed at the Naval Research Laboratory (NRL) and transitioned to the Navy Oceanographic Office. New capabilities include a general vertical coordinate (GVC) option in addition to the sigma-z coordinate vertical grid, Earth System Modeling Framework (ESMF) compliance, and several other compile time options that increase the flexibility of the model code. NRL has also begun maintaining NCOM in version control using a Subversion repository. This User's Manual documents the setup and execution of the NCOM version 4.0 series.

The purpose of this Software Design Description (SDD) is to describe the software design and code of the Navy Coastal Ocean Model Version 4.0 (NCOM). It includes flow charts and descriptions of the NCOM programs, subprograms, and common blocks. This document, along with the User's Manual and two Validation Test Reports forms a comprehensive documentation package for the NCOM 4.0. A User's Manual for the Global Ocean Prediction System (GOPS) is also available.

The global Naval Coastal Ocean Model (NCOM) is a 1/8 degree global application of NCOM developed by the Naval Research Laboratory (NRL) for use at the Naval Oceanographic Office (NAVOCEANO) as part of an assimilative ocean model nowcast/forecast system. Global NCOM is the first operational global ocean model that has sufficient resolution to be eddy-permitting. Global NCOM supports predictions of ocean currents, temperatures, salinity, sea surface height, and sound speed both directly and by providing initial and boundary conditions for higher-resolution nested ocean models. The forecast system addresses Navy requirements for Numerical Modeling (METOC 9801), High Resolution Surface and Subsurface Currents (METOC 9308), Littoral Salinity Prediction (METOC 9902), and Air-Sea Drift Prediction (METOC 9115). This validation test report describes global NCOM, its use in an assimilative forecast system, and evaluation of assimilative and non-assimilative products using independent climatologies and observations.

This DoD HPC challenge project is a crucial component of an effort to develop a data-assimilative 1/32/spl deg/ global ocean nowcast/forecast system, which includes the associated basic research and exploratory development. The need for 1/32/spl deg/ resolution (/spl sim/3.5 km at midlatitudes) has been demonstrated through extensive research, including essential contributions from our FY97 and FY98-00 DoD HPC Challenge projects. The ocean model, after 30 years of climatological spinup, was run interannually spanning the period 1979-present. Data assimilation experiments are currently underway. Transition of this system to operational use at the Naval Oceanographic Office (NAVO) is planned.

A real-time eddy-resolving global ocean nowcast/forecast system has been running at the Naval Oceanographic Office (NAVOCEANO) since 18 October 2000 and it became an operational product on 27 September 2001. The system, which was developed at the Naval Research Laboratory (NRL), uses the NRL Layered Ocean Model (NLOM) with 1/16/spl deg/ resolution and seven layers in the vertical. Real-time satellite altimeter sea surface height (SSH) from TOPEX/Poseidon, ERS-2 and Geosat-Follow-On provided by NAVOCEANO's Altimeter Data Fusion Center, are assimilated into the model. The large size of the model grid (4906/spl times/2304/spl times/7) and operational requirements makes it necessary to use a computationally efficient ocean model and assimilation scheme. The assimilation consists of an optimum interpolation (OI) deviation analysis of SSH with the model as a first guess, a statistical inference technique for vertical mass field updates, geostrophic balance for the velocity updates outside the equatorial region and an incremental updating of the model fields to further reduce gravity wave generation. A spatially varying mesoscale covariance function determined from TOPEX/Poseidon and ERS-2 data is used in the OI analysis. The sea surface temperature (SST) assimilation consists of relaxing the NLOM SST to the Modular Ocean Data Assimilation System (MODAS) SST analysis which is performed daily at NAVOCEANO. Real-time and archived results from the model can be viewed at the NRL Website http://www.ocean.nrlssc.navy.mil/global/spl I.bar/nlom. This includes many zoom regions, nowcasts and forecasts of SSH, upper ocean currents and SST, forecast verification statistics, subsurface temperature cross-sections, the amount of altimeter data used for each nowcast from each satellite and nowcast comparisons with unassimilated data. The results show that the model has predictive skill of the mesoscale variability for at least one month.

The Oceanography Division of the Naval Research Laboratory (NRL) conducts a coordinated program of research and development (R&D) that results in Navy operational ocean nowcast and prediction capabilities. This R&D covers domains from global scales down to local surf zone scales with both military and civilian applications. It includes sophisticated primitive-equation ocean circulation models on global and nested regional and local domains designed for high performance computing platforms at the Naval Oceanographic Office (NAVOCEANO) and Fleet Numerical Meteorology and Oceanography Center (FNMOC). It also includes less sophisticated, but operationally-relevant models designed to run on workstations and personal computers at the Navy's regional Meteorology and Oceanography Centers (METOCCEN) and on-scene. These latter capabilities, while capable of stand-alone operations, are specifically designed to accept initial and boundary conditions available from the central site products. This paper presents an overview of NRL R&D efforts in global and regional nowcast and prediction capabilities that provide these initial and boundary conditions. These efforts combine primitive equation models with optimal interpolation assimilation techniques using both in situ and remotely-sensed temperature and altimetry data. Assimilation of altimetry data via statistical models that relate surface height to subsurface density structure is the key to mesoscale nowcast and prediction skill, especially for deeper water. Second, this paper presents and overview of the current, rapidly-relocateable local area nowcast and forecast capabilities for temperature, salinity, currents and surface waves for NAVOCEANO as well as the METOCCEN and on-scene applications.

Summary form only given. The Oceanography Division of the Naval Research Laboratory conducts a coordinated program of research and development (R&D) supporting Navy operational ocean nowcast and prediction. This R&D program covers domains from global scales down to local surf zone scales. Included in these efforts are sophisticated primitive equation ocean circulation models on global, basin, and regional domains run on high performance computing platforms at the Naval Oceanographic Office (NAVO) and at the Fleet Numerical Meteorology and Oceanography Center (FNMOC). These efforts combine primitive equation models with observations using various assimilation techniques such as optimal interpolation using both in situ and satellite temperature and altimetry data. In addition to large scale and computationally significant models run at the Navy's central sites are the operationally relevant models designed to run on workstations and personal computers at the Navy's regional Meteorology and Oceanography Centers (METOCCEN) as well as on-scene. These latter capabilities can run stand-alone but also are designed to accept initial and boundary conditions available from the central site products. This allows for rapid relocatability to provide local area nowcasts and forecasts of temperature, salinity, currents, tides and surface waves for the METOCCEN and for on-scene applications. This paper provides an overview on the present NRL R&D nowcast and prediction capabilities from global to local scales.

The long-term goal is to use a HYbrid Coordinate Ocean Model (HYCOM) with data assimilation in an eddy-resolving, fully global ocean prediction system with transition to the Naval Oceanographic Office (NAVO) at .08 equatorial resolution in 2006 and with .04 resolution by the end of the decade. Equatorial resolution of .08 (.04 ) increases from 9 km (4.4 km) at the equator to 6 km (3 km) at 47 latitude. The Arctic is covered by a bipolar PanAm grid. At 59 N it matches the spherical grid covering the rest of the global ocean. The model will include shallow water to a minimum depth of 10- 20 m and will provide boundary conditions to finer resolution coastal models that may use HYCOM or a different ocean model.

A 1/16 deg Pacific Ocean model north of 20 deg S and a 1/4 deg global ocean model are used to assimilate satellite altimeter data and then to perform month-long forecasts initialized from the data assimilative states. The results constitute a feasibility demonstration of ocean model eddy-resolving nowcast/forecast skill using altimeter data. In particular they demonstrate: (1) that satellite altimetry is an effective observing system for mesoscale oceanic features, (2) that an ocean model with high enough resolution can be a skillful dynamical interpolator for satellite altimeter data in depicting mesoscale oceanic variability, and (3) that the high resolution ocean model can provide skillful forecasts of mesoscale variability for at least a month, when model assimilation of the altimeter data is used to define the initial state.

The components of OCEANS 1.0 are described in this report. They consist of the marginally eddy-resolving 1/4 deg global, reduced gravity NRL (Naval Research Laboratory) Layered Ocean Model (NLOM) and the Pacific West Coast (PWC) model. The reduced gravity version of NLOM is capable of accurately depicting the large-scale oceanic circulation, but there are a few exceptions. The version of NLOM described here is wind-forced only, with no assimilation of altimeter or infrared frontal data. Thus, it cannot be expected to produce accurate hindcasts of sea surface height or upper layer velocities in regions dominated by mesoscale flow instabilities. Maps are provided to show the relative importance of direct wind forcing (deterministic) versus flow instabilities (nondeterministic). NLOM has mixed success in hindcasting sea level variations when compared to observed tide gauges; however, some of its highest correlations are at stations within the PWC domain. A comparison between observed and NLOM simulated drifting buoys has also been made. Ensemble forecasts of four model simulations generally produce an average simulated track that is closer to the observed drifter than any single simulation. However, the model cannot consistently beat a persistence forecast due to the large amount of nondeterminism in the upper layer velocity fields. NLOM will also provide boundary conditions for the PWC model. Two PWC simulations were run, one using climatologically wind-forced NLOM boundary conditions and one using climatologically wind-forced NLOM boundary conditions. The latter case showed improved sea level correlation over the former case. Satellite altimetry assimilation and a refinement in the boundary condition implementation should further improve the results.

An eddy-resolving nowcast/forecast system for the global ocean with embedded basin-scale systems (1/16 deg Pacific north of 20 deg S and 1/32 deg Atlantic subtropical gyre, 9 deg-51 deg N, which includes the Intra- Americas Sea) and a global model with progressively increasing resolution, 1/4 deg, 1/8 deg and ultimately 1/32 deg resolution. These systems will include data assimilation of satellite altimetry, sea surface temperature and in-situ data.

The Geosat Follow On altimeter will provide valuable information to the warfighter on scene. This real time knowledge of the ocean environment is critical to making intelligent decisions in the field. In particular, the acoustic environment depends on the synoptic mesoscale density distribution which is retrievable from the altimeter. Surface geostrophic currents are inferred from the altimeter data, and these allow calculation of mine drift paths. Altimeter data also provides key data for forecasting tidally generated heights and currents throughout the world. For numerical ocean models, it represents the most useful source of operational oceanic data for nowcasting and forecasting of ocean frontal locations, meandering currents and mesoscale eddies as well as larger scale oceanic analysis.

With the ongoing development of ocean circulation models and real-time observing systems, routine estimation of the synoptic state of the ocean is becoming feasible for practical and scientific purposes. The models can assist in ocean monitoring and regional dynamics studies, but only after they have been validated. For the first time, beginning 1 November 2004, independent ocean model estimates of the Florida Current (FC) volume transport are available, in real time, for cross validation with observed transport variations forced by cold front passages, tropical cyclones, and other weather systems. The FC flows poleward through the Straits of Florida and ultimately becomes the Gulf Stream. The FC originates from both the large-scale, wind-driven circulation of the North Atlantic subtropical gyre and the trans-equatorial Atlantic thermohaline overturning circulation (i.e., the “global conveyor belt”). The FC is constrained by Florida to the north and/or west and by Cuba and the Bahamas to the south and east, respectively (Figure 1).

The large variability of the Gulf of Mexico wind field indicates that high-resolution wind data will be required to represent the weather systems affecting ocean circulation. This report presents methods and results of the calculation of a corrected geostrophic wind data set with high temporal and spatial resolution. Corrected geostrophic wind was calculated from surface pressure analyses compiled by the Fleet Numerical Oceanography Center. The correction factors for wind magnitude and direction were calculated using linear regressions of observed Gulf buoy winds and geostrophic winds derived at the buoys. The regressions were performed for each month to determine the seasonal variability of the correction factors. The magnitude correction was found to be nearly constant (0.675) throughout the year, but the direction correction varied seasonally from 8.5 to 26.5 degrees. The corrected geostrophic wind was calculated twice daily store 1967–1982 on a spherical grid over the Gulf, together with the ...

The metabolites of hexazinone [3-cyclohexyl-6-(dimethylamino)-1-methyl-1,3,5-triazine-2,4(1H,3H)-dione ] obtained in the rat and in plants were identified by mass spectrometry. Rat urine metabolites were identified from direct probe spectra obtained on metabolites separated by thin-layer chromatography. Sugarcane metabolites were identified by gas chromatography mass spectrometry of the trimethylsilyl derivatives. The major metabolic routes were found to be hydroxylation of the cyclohexyl group and demethylation. All identifications were confirmed by synthesis and direct comparison of chromatographic data and mass spectra. Hexazinone is metabolized quickly and extensively in the biological systems studied, and is relatively nonpersistent in the environment.

The Naval Research Laboratory (NRL) at Stennis Space Center has developed a global implementation of the Navy Coastal Ocean Model (NCOM). Global NCOM encompasses the open ocean to 5 m depth in a curvilinear global model grid with 1/8 degree grid spacing at 45/spl deg/N, extending from 80/spl deg/S to a complete Arctic cap with grid singularities mapped into Canada and Russia. The model employs 40 vertical sigma-z levels, with sigma in the upper ocean and coastal regions, and z in the deeper ocean. The real-time system uses Navy Operational Global Atmospheric Prediction System (NOGAPS) 3-hourly wind stresses and heat fluxes. Operationally available sea surface temperature (SST) and altimetry (SSH) data are incorporated into NAVOCEANO Modular Ocean Data Assimilation System (MODAS) and Navy Layered Ocean Model (NLOM) analyses and forecasts of SSH and SST. These in turn are combined with the MODAS synthetic database to yield three-dimensional fields of temperature and salinity for assimilation into global NCOM. We describe the analysis and forecast system, present selected evaluations of the model performance, and discuss planned upgrades to the model and data assimilation methods.