COMIT Publications 2021 - 2026

Rubiano, C., Hapke, C.J., Naar, D.F., Graham, A.G.C. 2026. Continental Shelf Research, 302. https://doi.org/10.1016/j.csr.2026.105762

Abstract: Global sea level history capturing the rise in sea levels since the Last Glacial Maximum, about 20,000 years ago, is generally well-resolved to the scale of millennia. However, when examining this record at a finer scale of hundreds of years, discrepancies remain particularly as it pertains to the timing of accelerated periods of sea level rise caused by outsized glacial meltwater events (or pulses). We present here an inventory of sea level indicators in the form of submerged paleoshorelines that have been identified across the west Florida shelf for the depth range of 45-90 m. The region’s well-preserved carbonate sedimentary record coupled with its tectonic stability provides a setting in which sea level changes since ∼20 ka have been recorded to a remarkable degree of resolution in the form of paleoshoreline features that formed during still stands or slowdowns of sea level rise. In total, 27 paleoshorelines were identified based on geomorphic identifiers and used as paleo-sea level indicators to put forth a hypothetical scenario for sea level history between 14.2 ka – 11.2 ka. In all, our findings describe 15 previously unidentified features and present new constraints to the sequence of meltwater pulses in the Gulf of Mexico, which challenge current estimates. We suggest that in the periods preceding and in between meltwater pulses (MWP)-1A and -1B, rates of sea level rise were slow enough for the formation of shorelines to occur; followed by periods of rapid sea level rise (MWP-1A and -1B) which were sufficiently high enough to drown and preserve these shorelines in place.

Download PDF

San, S-C., Liu, Y., Weisberg, R. H., Xu, H., Qiao, K., Lae, J., Zheng, L., John, S., Murawski, S. A., Gilbert, S., Mitchum, G. T., Frazer, T. K. and Pe’eri, S. 2026. Ocean Modeling, 202. https://doi.org/10.1016/j.ocemod.2026.102734

Abstract: Hurricane Ian impacted the west Florida coastal ocean and adjacent estuarine waters as it moved northeastward across the broad West Florida Shelf from September 28 to 30, 2022. To investigate the role of wave–current interaction in storm surge simulation during this extreme weather event, we coupled the West Florida Coastal Ocean Model (WFCOM) with two surface wave modules: the Mellor–Donelan–Oey (MDO) wave model (MDO-Wave) and SWAVE. Incorporating wave–current interaction improved peak surge simulations, with wave set-up enhancing surge by up to 0.41 m – approximately 22 % of the peak surge height. However, this contribution exhibited pronounced spatial and temporal variability, with maximum enhancement occurring along the right-front quadrant of the storm track and improvements primarily evident during the peak storm period. Tide–surge interaction played a minimal role in modulating peak positive and negative storm surges, contributing <5 % to the water level changes during the peak surge period. Process-oriented experiments further revealed that while both MDO-Wave and SWAVE produced comparable offshore wave characteristics, they demonstrated notable differences in nearshore wave effects. MDO-Wave simulated approximately 57 % higher nearshore wave set-up than SWAVE, resulting in greater storm surges within coastal and estuarine areas. These findings highlight the importance of wave–current coupling for accurately modeling hurricane-induced storm surge.

Download PDF

Weisberg, R.H. and Liu, Y. 2025. Oceanography, 38:1. https://doi.org/10.5670/oceanog.2025e107

Abstract: The central portion of the west Florida continental shelf is the epicenter for blooms of the harmful alga Karenia brevis, which tends to form at mid-shelf under nutrient depleted, or oligotrophic, conditions. Whether or not the shelf is conducive to such bloom formation in any given year appears to be related to when and where the Gulf of Mexico Loop Current, a western boundary current, interacts with the shelf slope. If this occurs in the southwest corner, where shallow isobaths wrap around the Florida Keys at the Dry Tortugas, then the entire west Florida shelf may be set into a protracted upwelling circulation that can both reset water properties and transport mid-shelf materials to the shoreline within the bottom Ekman layer. The 2018 K. brevis bloom provides one such example, as described via a coordinated program of coastal ocean observing and modeling. Both the elevation of K. brevis cell counts along the coast and their eventual cessation may be largely accounted for by the coastal ocean circulation, as driven, in part, by the Loop Current’s interaction with the shelf slope.

Download PDF

Nickerson, A. K., Zhang, J. A., Weisberg, R.H. and Liu, Y. 2025. Journal of Geophysical Research: Atmospheres,130:13. https://doi.org/10.1029/2024JD042024

Abstract: Initially a Category 3 storm, Hurricane Ian (2022) rapidly intensified on the West Florida Shelf reaching Category 5 over the course of about 12 hr. Intensification occurred despite inhibiting factors such as high axial tilt, high vertical wind shear, low atmospheric moisture, and transit over a relatively shallow continental shelf. Using a high-resolution simulation of Hurricane Ian from the Hurricane Weather Research Forecasting (HWRF) model, we examine the factors that both hindered and supported rapid intensification (RI) by blending various methods. We show that an increase in diabatic heating in the eyewall led to an inward radial advection of momentum, seen in both the absolute angular momentum budget and in the azimuthal wind budget. Analysis of the moist static energy budget indicates that the substantial latent heat flux from the surface was enough to balance heat losses through storm outflow. For instance, surface latent heat fluxes exceeded 1,500 W m−2 on the West Florida Continental Shelf. As suggested by actual ocean temperature observations that substantially exceeded those in the HWRF simulation, the latent heating may have even been larger. Physical explanations for discrepancies between the simulated Hurricane Ian and observations are provided, particularly those pertaining to the coastal ocean at the time of Ian’s passage. This research provides a comprehensive explanation of the RI of a hurricane using momentum budget analyses as part of a coupled air-sea analysis. Our findings demonstrate the importance of in situ oceanic air-sea measurements in evaluating the performance of coupled models, especially for hurricanes.

Download PDF

Murawski, S.A., Gilbert, S., Hommeyer, M., Liu, Y., Lembke, C., Grasty, S., English, D., Hu, C., Dixon, T. 2025. Marine Technology Journal, 59:62-77. https://doi.org/10.4031/MTSJ.59.2.6

Abstract: Shallow waters (< 30 c.a. m deep) represent at once the most accessible region of the world’s oceans and coasts, but its most challenging in terms of efficient broad-scale, high-resolution mapping, hazard identification, and habitat characterization. Hazards to navigation are primarily a coastal threat and thus the requirement for high-resolution (< 1 m) maps are critical for well-traveled parts of the coastal ocean. Traditional sonar mapping approaches rely on acoustic swath widths that are proportionally wider with increasing water depths. High-resolution landscape-scale maps in shallow waters thus require numerous closely spaced transects that may be prohibitive in ship time and data processing costs. Alternatives to multibeam, single beam, and side scan sonar include satellite-derived bathymetry, airborne Light-Detection and Ranging, autonomous surface and underwater vehicles, and, increasingly, the use of crowd-sourced bathymetry to gather and disseminate depth sounder data from community participant vessels. Each of these approaches has its advantages (e.g., resolution, synopticity, calibration/validation, utility in turbid waters, efficiency for repeat measurements) and drawbacks (e.g., costs, platform availability and logistical considerations). Local requirements, challenges, conditions, and capacities will dictate which techniques or combinations render adequate resolution. As an alternative to a single technology solution, we advocate multisource coupling to blend information from multiple mapping approaches with the overall goal being a synthesized map explicitly depicting uncertainties in bathymetry due to differences in observational characteristics of technologies employed. Higher resolution technologies can be deployed where the accuracy of the map is commensurate with elevated threats/interests. Principles of multiplatform data acquisition, data processing, and display for shallow water bathymetry are illustrated using data collected during the Tampa Bay (USA) Bathymetry Experiment (TBBEx) conducted in 2021‐2022.

Download PDF

Meyers, S.D., Arias, M.E., Kramer, M. and Luther, M.E. 2025. Final Report to The Tampa Bay Estuary Program, Oct. 25, 2025. https://drive.google.com/file/d/1_xrxiM9TVqpv9meVR3ZpdJ7vElPC7tLe/view

Summary: Erosion of the shoreline around MacDill Air Force Base presents a long-term threat to the
sustainability of base operations. The primary mechanism behind this erosion is generally
understood to be ocean waves and the strong, erratic currents they generate. These waves can be
generated by winds or large ships transiting the nearby shipping channel. Designing effective
protective measures for the shoreline requires specialized understanding of these waves such as
their height, period, and duration, but there has never been a quantitative study of the wave
environment in the vicinity of the base. The primary objective of this study was to reduce this
knowledge gap by deploying wave-measuring devices off the southeast shore of the base. These
instruments measured the water level (yielding wave height and frequency) and the speed and
direction of the currents. The instruments operated in a fixed position about 150 m (492 ft)
offshore for a few weeks. The water was deep enough that the instruments were always
submerged even at low tide, so the water level sensors were always functioning. Wake statistics
along with estimates of the erosion generated by tides, wind waves, and wakes were computed
based on these measurements. Information on the nearby vessel traffic was obtained from the
Automatic Identification System and correlated with the wave measurements.
Significant findings from analysis of the data from these instruments include:

• The average duration of a ship wake was a little over 1 hr
• Large wakes often led to wave breaking that greatly elevated turbulence in the water and
  enhanced erosion
• Living shorelines to be installed must be able to withstand this turbulent environment
• Wave-induced currents were much more erosive than tidal currents and almost 50% more
  erosive than typical wind-driven waves
• As the waves move onshore from the study site they will tend to increase in height, and
  generate more wave breaking, turbulence, and erosion
• Most of the ships moving in and out of port were large (> 100 m or 330 ft)
• Cargo, cruise liner, and tanker vessels were most frequently associated with large wakes
• The large wakes were generated by these ships displacing a significant fraction of water
  out of the channel
• Adaption and protection rather than regulation appeared to be the method most likely to
  protect the shoreline around MacDill
• Future studies should include direct measurements of sediment resuspension

Access Full Report

Meyers, S.D., Weisberg, R.H., Beckwith, S., Donovan, J.C., Law, J.A., Lembke, C., Luther, M.E., Merz, C.R., Liu, Y. 2025. Chapter 7 in A Meta-Analysis of Marine Benthic Data and Metadata Standards: A Florida Perspective, the final report of FLRACEP, edited by V. Lecours and A.E. Braswell. P. 101 – 118, January 2025. https://doi.org/10.5281/zenodo.14046427

Download PDF

Meyers, S.D., Day, S., and Luther, M.E. 2025. Applied Sciences, 15:9. https://doi.org/10.3390/app15094807

Abstract: Characterizing the coastal wave environment, typically composed of wind-driven waves and boat wakes, and its interaction with built infrastructure is essential for planning sustainable and resilient shoreline development and protection. Objectively identifying and measuring non-stationary wave features, particularly boat wakes, in longer data records remains a challenge. A wave gauge array of four pressure sensors was deployed for several weeks in the northernmost section of urbanized Tampa Bay, FL, a sheltered, shallow (mean depth 1.2 m) region with frequent recreational small-boat activity. New methods for analyzing these measurements were explored. The array had a square geometry, allowing the calculation of directional spectra. Most prior studies of boat wakes could only examine amplitude spectra. A nearby seawall was found to be a significant source of wave reflection. Additionally, a novel empirical method for identifying wakes, distinguishing them from wind-driven waves, and providing an estimate of their duration and amplitude was developed. The method was found to reliably identify most primary wakes but not reflected wakes. Reflected boat wakes were identified manually, and only during times of relatively high water levels when the shoreline in front of the seawall was flooded.

Download PDF

Liu, Y., Weisberg, R.H., Sorinas, L., Law, J.A., Nickerson, A.K. 2025. Geophysical Research Letters, 52. https://doi.org/10.1029/2024GL113192

Abstract: Hurricane Ian rapidly intensified from Category 3 to 5 as it transited the wide West Florida Shelf (WFS). This is ascribed to heating by the anomalously warm shelf waters, despite the water depth being shallow when compared to the thicker, mixed layer areas of the deeper ocean. By examining temperature from long-term moorings, we found that the sea surface and subsurface temperatures exceeded the climatologies by 1–2°C and 2–3°C, respectively. Additionally, these anomalously high temperatures in summer/fall of 2022 were related to the absence of Gulf of Mexico Loop Current interactions with the WFS slope at its “pressure point”. Without such offshore forcing to induce an upwelling circulation, the warmer waters on the shelf were not flushed and replaced by colder waters of deeper ocean origin. This work highlights the importance of subsurface temperature and ocean circulation monitoring on shallow continental shelves, which are largely overlooked in hurricane-related ocean heat content observational programs.

Download PDF

Khazaei, B., Moghimi, S., Kurapov, A., Mani, S., Myers, E., Zhang, Y. J., and Liu, Y. 2025. Journal of Hydrologic Engineering, 31:1. https://doi.org/10.1061/JHYEFF.HEENG-6624

Abstract: The escalating frequency of extreme coastal events, exemplified by hurricanes and floods, underscores the necessity of robust monitoring and flood prediction tools. Given the limitations of observations, numerical models offer opportunities to address these gaps, yet their predictive efficiency is prone to uncertainties. Coastal models require several inputs, including bathymetry, which is a first-order forcing and an important boundary condition. However, bathymetric information is susceptible to inaccuracy due to the constraints of underwater topography measurement technologies; therefore, it can be a significant source of uncertainty in ocean models. Moreover, nearshore bathymetry is subject to frequent variability due to its highly dynamic seafloor morphology, especially during storm events. In this study, we investigate the sensitivity of a 3D tributary-estuary-ocean hydrodynamic model and its ability to forecast flood inundation under bathymetric uncertainty, focusing on Delaware Bay—a major estuarine system in the eastern US that Hurricane Irene profoundly impacted in August 2011. Bathymetry uncertainty is quantified based on NOAA’s Category Zone of Confidence (CATZOC) and a random perturbation process that represents errors in the estimation of topobathy data based on vertical and horizontal length scales. Our results indicate that bathymetric errors can lead to model uncertainties of about 24% and 28% differences between original bathymetry and average ensemble conditions, respectively, for water level and currents predictions at locations of interest. Also, we observed standard deviations of 30 cm and 0.35  m/s for water level and currents in the perturbed conditions, which exceed acceptable error thresholds of NOAA’s operational forecast models. Additionally, simulated currents showed more sensitivity in deeper regions, while water levels were more affected nearshore. These findings highlight the importance of accounting for input data uncertainty in marine operations and flood risk assessments, and support the development of resilient coastal planning strategies.

Download PDF

Gilbert, S., Murawski, S.A., Luther, M.E., Silverman, A., Hommeyer, M., Vistocci, R., Chernoch, S. Clark, H., Grasty, S., and Erickson, K. 2025. Marine Technology Journal, 59:51-61. https://doi.org/10.4031/MTSJ.59.2.9

Abstract: Efficient and effective mapping of bathymetry in coastal regions requires sustained effort from a diverse set of stakeholders. These contributors include federal and state organizations, industry, and private citizens. A research priority of the Center for Ocean Mapping and Innovative Technologies, an academic-government mapping center funded by National Oceanic and Atmospheric Administration’s Office of Coast Survey, is to address the complexities of collecting bathymetry in shallow water areas that are consistently in flux. This paper discusses the development of a regional crowdsourced bathymetry (CSB) program in the Tampa Bay region of Florida that capitalizes on the broadly termed boating “crowd” to harvest opportunistic depth sounding data from participating vessels and return those data to participants via a transparent and accessible process. One of the key ingredients in making a CSB program possible and sustainable is the development and maintenance of a stakeholder engagement program. Here, we discuss the makeup of Tampa Bay’s “crowd,” our current processes and structure, and plans to expand this regional CSB effort. The goal of this pilot project is to realize a fully developed, operational, and transferable CSB program based on the Tampa Bay region.

Download PDF

Fujisaki-Manome, A., Seroka, G., Kelley, J., et al. (31 co-authors including Liu, Y.). 2025. NOAA NOS Coastal Survey Development Laboratory, 37 pages, April 2025. NOAA Technical Memorandum NOS, 37, https://repository.library.noaa.gov/view/noaa/69898.

Executive Summary: This report documents the second round of the model evaluation effort of the National Oceanic
and Atmospheric Administration (NOAA) Unified Forecast System (UFS) Coastal Application
Team (CAT) Marine Navigation Sub-Application. The effort follows the 1) the first phase of the
project, which included gathering user requirements, generating an initial list of oceanographic
models to evaluate, and defining skill assessment guidelines for the future model evaluation
(Seroka et al. 2022), and 2) the first round of the second phase of the project– the model
evaluation (Seroka et al. 2024). The project has worked toward the major goals of UFS CAT,
which are 1) to evaluate potential coastal ocean models for the coastal ocean model
components of the UFS and 2) to train the next generation of coastal modelers to accelerate the
Research-to-Operations (R2O) process within the National Ocean Service (NOS).

Similarly to the first round of the model evaluation, two coastal ocean models were used for
evaluation: 1) Finite Volume Community Ocean Model (FVCOM); and 2) Semi-implicit Cross-
scale Hydroscience Integrated System Model (SCHISM). These two ocean models to date have
demonstrated sufficient skill to meet NOS forecast skill requirements. Therefore, specific model
results are not shown in this report; some testers’ results can be found in journal publications
that have resulted from this work. Instead, the report focuses on successes, challenges, and
lessons learned that aid future advancement of these models in NOAA Readiness Levels as
potential candidates for the UFS’ operational coastal ocean model components.

In the second round, the researchers participating in the evaluation effort (i.e., testers) refined
the model mesh for 3D simulations and incorporated atmospheric forcing in a 3D (multiple
vertical layers) baroclinic mode whereas the first round focused on 2D simulations and tidal
forcing only. The testers used atmospheric forcing from commonly used models [i.e., NOAA’s
High Resolution Rapid Refresh (HRRR), Global Forecast System (GFS), and/or the ECMWF
Reanalysis v5 (ERA5)]. In addition, the testers used output from NOAA’s Global Real-Time
Ocean Forecast System (G-RTOFS) or datasets from Copernicus Marine Environment
Monitoring Service (CMEMS) and Hybrid Coordinate Ocean Model (HYCOM) in order to create
subtidal ocean lateral boundary conditions. For river boundary conditions, testers used river
discharge observations at U.S. Geological Survey (USGS) river gauges. The model predictions
were evaluated against available water levels, currents, temperature, and salinity observations
during January 1 – March 31, 2022 and July 1 – September 30, 2021.

The key steps of this round two model evaluation include:

• Refine mesh for three-dimensional baroclinic simulations
• Conduct baseline simulations
• Compare model results with observations (water levels, water currents required; water
  temperature and salinity optional)
• Explore additional results to each tester’s baseline simulation
• Conduct skill assessment based on NOAA’s model evaluation guidance
  

Successes from the second round include continued training of the next generation of ocean
modelers, testers’ learning of the models and their exposure to NOAA’s operational processes,
skill assessment using multiple metrics, and multiple conference presentations and publications
out of the effort. Beyond improving collaboration and cooperation between modeling groups
within the government and academic partners, the UFS CAT was able to promote an evaluation
approach that uses multiple hydrodynamic models. By working together and building a coalition,
the UFS CAT team members were able to track, support, and assess new technological
advancements and algorithms pertaining to oceanographic models. Challenges include
ensuring consistency and troubleshooting support among the testers while each tester has their
own baseline, issues with Digital Elevation Models (DEMs), and the need for local knowledge to
interpret both the inputs (e.g. DEMs) and outputs (i.e. simulations results) accurately. These
successes and challenges prompted three lessons learned: 1) gap analysis (i.e. evaluating gaps
in each model’s performance and skill to bring the models to a “level playing field” for NOAA
operations), 2) realistic expectations (i.e. testers have focused so far on setting up/learning
model configurations and gaining simulation accuracy, with a lack of attention to model
efficiency, requiring co-leads to adapt and emphasize efficiency in subsequent rounds), and 3)
update to skill assessment software (i.e. further motivation for the ongoing effort of NOS’s
development of a next generation skill assessment software to have more consistency and
usability, and allow for process-based skill assessment). These lessons learned will be
implemented in the next rounds that focus on incorporating wave and hydrologic processes in
the simulations, and testing of the UFS-Coastal infrastructure.

Overall, the work with the second round helped the UFS CAT team and NOAA’s operational
coastal ocean forecasting enterprise make substantial progress toward NOAA’s central goals of
“Building a Weather Ready Nation” and “Accelerating Growth in an Information-Based Blue
Economy.”

Access Full Report

Azevedo, L., Marcon, G., Labourdette, E., Meyers, S.D., Luther, M.E. 2025. Ocean Dynamics, 75:52, 19pp, https://doi.org/10.1007/s10236-025-01697-0.

Abstract: A comparative analysis of rogue wave occurrence was conducted by examining reported eye-witness incidents against ERA5 reanalysis data and ECMWF CY47R1 wave model hindcast data. The study utilized a unique dataset of 440 rogue wave incidents, analyzing sea state conditions within a 72-hour window surrounding each event, due to the challenge of pinpointing the exact time of occurrence. A marked discrepancy was observed between the datasets, with ERA5 identifying 25 rogue waves and ECMWF CY47R1 identifying 301 rogue waves, defined as waves with maximum height at least twice the significant wave height. This difference may be attributed to the sensitivity of the hindcast data to its wave-focused modeling and finer spatial resolution. Spectral characteristics related to rogue waves such as kurtosis, peakedness, skewness, and the Benjamin-Feir Index, while showing low correlation between the models, did not significantly diverge in absolute values, suggesting an underlying consistency. The study highlights the robustness of the crest-trough correlation parameter in identifying rogue waves, aligning with theories of linear superposition. These insights are pivotal for enhancing rogue wave prediction models and maritime safety assessments, with broader implications for the reliability of reanalysis and model data as detectors of rogue wave occurrence.

Download PDF

Azevedo, L., Marcon, G., Meyers, S., Luther, M. 2025. EGUsphere, 2025:1-29; https://doi.org/10.5194/egusphere-2025-2031.

Abstract: Rogue waves pose substantial risks to maritime operations and offshore infrastructure, yet their formation mechanisms and predictability remain poorly understood. This study analyses real rogue wave occurrences using in situ observations from CDIP wave buoys from the Filtered Ocean Wave Data (FOWD) dataset and model-based estimates from ERA5 reanalysis and the ECMWF CY47R1 high-resolution hindcast. Seasonal distributions, wave height comparisons, and spectral analyses reveal that models systematically underestimate extreme wave events due to spectral smoothing and spatial averaging. A key finding is that rogue waves are usually preceded by a sharp decrease in crest-trough correlation below 0.5, followed by a rapid increase above 0.6, indicating a transition to a more structured wave field. This pattern, accompanied by spectral bandwidth narrowing and increased relative energy in the 0.25–1.5 Hz range, suggests energy focusing mechanisms play a critical role. Analysis of rogue wave events at four CDIP buoy stations show that the crest-trough correlation parameter alone is not a good rogue wave indicator, but its temporal variability is. These results highlight the need for improved modelling by integrating dynamic wave field specific parameters and high-resolution numerical models to enhance rogue wave risk assessments on a global scale.

Download PDF

Nguyen, B.V.V., Liu, Y., Stallings, C.D., Breitbart, M., Murawski, S.A., Weisberg, R.H., Kerr, M., Bonnelycke, E.-M. S., Peebles, E.B. 2024. Fisheries Oceanography, 33:e12655. https://doi.org/10.1111/fog.12655

Abstract: To help determine whether planktonic eggs of fishes on the West Florida Shelf (WFS) are retained locally or exported elsewhere, we collected fish eggs by plankton net from 17 locations (stations) and identified them using DNA barcoding. We then entered the station coordinates into the West Florida Coastal Ocean Model (WFCOM) and simulated the trajectories of the passively drifting eggs over 2 weeks at three depths (surface, midwater, and near bottom). The results indicated there were two groups of trajectories: a nearshore group that tended to be retained and an offshore group that tended toward export and potential long-distance dispersal. We also found evidence of a relationship between retention and higher fish-egg abundance; nearshore stations were associated with higher fish-egg abundances and higher retention. We suggest this is the result of (1) increased spawning in high-retention areas, (2) increased drift convergence in high-retention areas, or both processes acting together. Community analysis using SIMPROF indicated the presence of a depth-related (retention-related) difference in species assemblages. Fish-egg species were also categorized as pelagics or non-pelagics; there was no evidence of pelagic species being more likely to be exported.

Download PDF

Mussett, M. E., Naar, D. F., Caress, D., Conrad, T., Graham, A. G. C., Kaufmann, M. and Maia, M. 2024. Journal of Marine Science Engineering, 12(12). https://doi.org/10.3390/jmse1212232

Abstract: We show that analyzing archived and future multibeam backscatter and bathymetry data, in tandem with regional environmental parameters, can help to identify polymetallic nodule fields in the world’s oceans. Extensive archived multibeam transit data through remote areas of the world’s oceans are available for data mining. New multibeam data will be made available through the Seabed 2030 Project. Uniformity of along- and across-track backscatter, backscatter intensity, angular response, water depth, nearby ground-truth data, local slope, sedimentation rate, and seafloor age provide thresholds for discriminating areas that are permissive to nodule presence. A case study of this methodology is presented, using archived multibeam data from a remote section of the South Pacific along the Foundation Seamounts between the Selkirk paleomicroplate and East Pacific Rise, that were collected during the 1997 Foundation–Hotline expedition on R/V Atalante. The 12 kHz Simrad EM12D multibeam data and the other forementioned data strongly suggest that a previously unknown nodule occurrence exists along the expedition transit. We also compare the utility of three different backscatter products to demonstrate that scans of printed backscatter maps can be a useful substitute for digital backscatter mosaics calculated using primary multibeam data files. We show that this expeditious analysis of legacy multibeam data could characterize benthic habitat types efficiently in remote deep-ocean areas, prior to more time-consuming and expensive video and sample acquisition surveys. Additionally, utilizing software other than specialty sonar processing programs during this research allows an exploration of how multibeam data products could be interrogated by a broader range of scientists and data users. Future mapping, video, and sampling cruises in this area would test our prediction and investigate how far it might extend to the north and south.

Download PDF

Liu, Y., Weisberg, R.H., Zheng, L., Sun, Y., Chen, J., Law, J.A., Hu, C., Cannizzaro, J.P., Frazer, T.K. 2024. Marine Pollution Bulletin, 198. https://doi.org/10.1016/j.marpolbul.2023.115840

Abstract: An emergency discharge of nutrient-rich effluent from the defunct Piney Point fertilizer stack into Tampa Bay at Port Manatee occurred from 30 March–8 April 2021. This resulted in a pollutant plume that evolved over time and space across the entire bay, including its environmentally sensitive marine preserves, and out onto the adjacent continental shelf. As a rapid response to environmental concerns, the plume evolution was simulated using the high resolution, unstructured grid, Tampa Bay Coastal Ocean Model (TBCOM) nowcast/forecast system, with an embedded tracer module that included realistic point discharge rates. Normalized tracer distributions were automatically updated each day, providing 1-day hindcasts and 3.5-day forecasts. Due to mixing and advection, tracer concentration was quickly reduced by two or more orders of magnitude as the plume spread out. Highest tracer concentrations hugged the southeastern Tampa Bay shoreline during the first week. Lower tracer concentrations were gradually advected to the western side of Tampa Bay, and the tracer was slowly flushed out of the bay to be transported primarily northward along the coast. The modeled plume evolution served as principal guidance for coordinating environmental monitoring by state, local and academic personnel. The model results also provide a basis for future multidisciplinary studies.

Download PDF

Law, J. A., Weisberg, R. H., Liu, Y., Mayer, D. A., Donovan, J. C. 2024. Deep Sea Research Part II, 213. https://doi.org/10.1016/j.dsr2.2023.105346

Abstract: Time series from a moored array of current velocity and surface meteorological sensors, some with record lengths as long as 25 years, are used to describe both the long-term mean circulation and its seasonal variations on the West Florida Continental Shelf (WFS). The moorings are part of the University of South Florida’s Coastal Ocean Monitoring and Prediction System (USF-COMPS), a network of ocean observing assets along with numerical circulation models, all used to describe and understand physical and ecological processes on the WFS. These USF-COMPS observations reveal a coherent, shelf-wide mean circulation pattern with depth-averaged flow directed alongshore and down-coast. The vertical structure and the seasonal variations further describe an inner-shelf, wind-driven upwelling region separated from a deeper-ocean influenced offshore downwelling region by a coastal jet. By adding to the record lengths from previous analyses, the statistics are shown to be robust, with the inferences drawn from shorter records being borne out by the present longer-term analyses.

Download PDF

Helber, R.W., Liu, Y., He, R., Wang, C. 2024. Deep-Sea Research Part II, 218. https://doi.org/10.1016/j.dsr2.2024.105414

Download PDF

Vasbinder, K., Ainsworth, C.H., Liu, Y., Weisberg, R.H. 2023. Deep-Sea Research Part II, 211. https://doi.org/10.1016/j.dsr2.2023.105323

Abstract: We developed a Lagrangian larval dispersal model to estimate trajectories for eleven fish taxa inhabiting the Gulf of Mexico (GOM). Dispersal models are at family level resolution for Scaridae, Lutjanidae, Scombridae, Labridae, Ophichthidae, and Ophidiidae, at genus level resolution for Hemanthias, and at species level resolution for Trachurus lathami, Decapterus punctatus, Katsuwonus pelamis, and Euthynnus alleteratus. Hydrodynamics are provided by the West Florida Coastal Ocean Model (WFCOM). Larval samples are from the spring and fall SEAMAP ichthyoplankton surveys from 2007 to 2011. The Lagrangian model was run backwards/forwards in time from the sampling event to estimate spawning/settlement locations. Results were used to update larval dispersal dynamics in the GOM Atlantis ‘end-to-end’ ecosystem model for twelve functional groups. We compare dispersal and non-dispersal scenarios in the Gulf of Mexico Atlantis model and find differences in stock abundance and distribution of fish. This highlights that the abundance and distribution of fishery resources are sensitive to changing circulation patterns. This work takes an interdisciplinary approach to understanding larval dynamics and their impacts on ecosystems at the intersection of predictive statistical modeling, hydrodynamic modeling, and ecosystem modeling.

Download PDF

Sorinas, L., Weisberg, R.H., Liu, Y., Law, J. 2023. Deep-Sea Research Part II, 212. https://doi.org/10.1016/j.dsr2.2023.105341

Abstract: Twenty-three years of surface meteorological and oceanographic data sampled from moored buoys are used to study the seasonal and interannual variations of ocean–atmosphere heat exchange and its influence on West Florida Continental Shelf (WFS) water temperature and stratification. The data are from the University of South Florida’s Coastal Ocean Monitoring and Prediction System (COMPS), part of the Southeast Coastal Ocean Observing Regional Association (SECOORA). Observed are incoming short and longwave radiation, air and sea surface temperatures (AT and SST), barometric pressure, relative humidity, wind velocity, water column velocity profiles, and water column temperature at discrete depths. These data are used to estimate net shortwave and longwave radiation and sensible and latent heat fluxes via the COARE 3.6 algorithm. When combined, these radiative and turbulent heat flux influences are compared with the heating and cooling of the WFS water column and SST. On seasonal average, heating starts in February and lasts through August, with a maximum rate of change in May, while cooling starts in September and lasts through January, with the maximum rate of change in October. Also on seasonal average, SST varies from 18.4 °C in February to 30.4 °C in August at mooring C10 (at the 25 m isobath) and from 20.1 °C in February to 30.2 °C in August at mooring C12 (at the 50 m isobath), the differences in the seasonal range being due to increased ocean circulation influence in deeper water. Both the spring and fall transition onsets, February and August, respectively, occur when the sign of the net heat flux changes. The water column begins to stratify in March, peaking in June–July and lagging the surface heating by one or two months, then decreasing through September at C10 and October at C12. Stratification is also modified by persistent upwelling when the Gulf of Mexico Loop Current (LC) interacts with the WFS slope at its southwest corner near the Dry Tortugas. Interannual temperature anomalies from the seasonal cycle are also related to how the LC interacts with the WFS slope.

Download PDF

Nickerson, A.K., Weisberg, R.H., Zheng, L., Liu, Y. 2023. Deep-Sea Research Part II, 211. https://doi.org/10.1016/j.dsr2.2023.105321

Abstract: Sea surface temperatures for Tampa Bay, the West Florida Continental Shelf (WFS) and the adjacent deep Gulf of Mexico are examined for trends. Data sets are from stations maintained by the Hillsborough County Environmental Protection Commission, buoys maintained by the University of South Florida Coastal Ocean Monitoring and Prediction System and the National Oceanic and Atmosphere Administration (NOAA) National Data Buoy Center, the Optimum Interpolation Sea Surface Temperature analyses by the NOAA National Centers for Environmental Information, and the Hadley Centre Sea Surface Temperature. These various data sets, each with different record lengths, require the consideration of trends both on the basis of record length and start time. Tampa Bay shows a warming trend, but with considerable inter-annual variability and start time bias resulting in a lack of statistical significance in more recent years. The WFS is also generally warming, and its inter-annual variability is largely controlled by the upwelling of cooler, deeper Gulf of Mexico water across the shelf break. The deep GOM shows statistically significant warming in most of the data except for the “gappy” records from buoys, both along the continental shelf and in the deep water. Trends in the Gulf of Mexico are mostly between 0.1 and 0.5 °C/decade, somewhat larger than the secular rise found globally, although within the range of the observed decadal variability.

Download PDF

Liu, Y., Weisberg, R.H., Zheng, L., Hubbard, K.A., Muhlbach, E.G., Garrett, M.J., Hu, C., Cannizzaro, J.P., Xie, Y., Chen, J., John, S., Liu, L.Y. 2023. Deep-Sea Research Part II, 212. https://doi.org/10.1016/j.dsr2.2023.105335

Abstract: Blooms of the toxic dinoflagellate Karenia brevis, also known as harmful algal blooms (HABs) or red tides, occur almost annually on the west coast of Florida, killing fish and other marine life, threatening public health and adversely impacting local economies. Mitigating such effects requires improved red tide forecast capabilities on the West Florida Shelf. A short-term Lagrangian trajectory forecast tool is developed to help federal, state, and local end users monitor and manage red tides on the west coast of Florida. The forecast products are based on the West Florida Coastal Ocean Model (WFCOM) and the Tampa Bay Coastal Ocean Model (TBCOM) nowcast/forecast systems. Observed K. brevis cell count data are uploaded daily into the models to generate 3.5-day forecasts of the bloom trajectories both on the shelf and in the estuaries. The tracking tool displays modeled bloom trajectories at the surface and near-bottom with five categories of cell concentrations (each approximately representing an order of magnitude difference in concentration). More general and user-friendly maps are also produced to provide red tide advisories along the coast, including those integrated with satellite imagery.

Download PDF

Ilich, A., Misiuk, B., Lecours, V., Murawski, S. A. 2023. Transactions in GIS, 27(4), 1164-1204. https://doi.org/10.1111/tgis.13067

Abstract: Digital terrain models (DTMs) are datasets containing altitude values above or below a reference level, such as a reference ellipsoid or a tidal datum over geographic space, often in the form of a regularly gridded raster. They can be used to calculate terrain attributes that describe the shape and characteristics of topographic surfaces. Calculating these terrain attributes often requires multiple software packages that can be expensive and specialized. We have created a free, open-source R package, MultiscaleDTM, that allows for the calculation of members from each of the five major thematic groups of terrain attributes: slope, aspect, curvature, relative position, and roughness, from a regularly gridded DTM. Furthermore, these attributes can be calculated at multiple spatial scales of analysis, a key feature that is missing from many other packages. Here, we demonstrate the functionality of the package and provide a simulation exploring the relationship between slope and roughness. When roughness measures do not account for slope, these attributes exhibit a strong positive correlation. To minimize this correlation, we propose a new roughness measure called adjusted standard deviation. In most scenarios tested, this measure produced the lowest rank correlation with slope out of all the roughness measures tested. Lastly, the simulation shows that some existing roughness measures from the literature that are supposed to be independent of slope can actually exhibit a strong inverse relationship with the slope in some cases.

Download PDF

Chen, J., Weisberg, R. H., Liu, Y., Zheng, L. 2023. Estuarine, Coastal and Shelf Science, https://doi.org/10.1016/j.ecss.2023.108213.

Abstract: With a large salinity gradient existing between the rivers and the ocean, the saline environment of an estuary is crucial to its ecosystem functionality. For Tampa Bay, the Howard F. Curren Advanced Wastewater Treatment Plant (HFCAWTP) presently yields an outflow of nearly freshwater to the Hillsborough Bay portion of Tampa Bay. In order to estimate the potential impact that the removal of this outflow may have on the salinity and flow fields of Hillsborough Bay, as part of the Tampa Augmentation Project, both numerical circulation model and Knudsen theorem applications are made. The numerical model study compares the instantaneous and nontidal, mean estuarine circulation and salinity distributions for the Hillsborough Bay on the basis of the HFCAWTP outflow being either included with, or excluded from, the freshwater inflows. It is found that the potential reduction of the treated reclaimed water inflow to the bay from the HFCAWTP will not significantly affect the circulation or the salinity distributions of Hillsborough Bay or of the larger Tampa Bay. The estimation through a Knudsen theorem application shows an 0.13 psu increase of salinity after removing the HFCAWTP outflow when averaged within Hillsborough Bay. Thus, both approaches demonstrate that the effects of HFCAWTP outflow removal are very small when compared with variations that occur naturally.

Download PDF

Chen, J., Liu, Y., Weisberg, R. H., Murawski, S., Gilbert, S., Naar, D., Zheng, L., Hommeyer, M., Dietrick, C., Luther, M., Hapke, C., Meyers, E., Moghimi, S., Allen, C., Tang, L., Khazaei, B., Pe’eri, S. Wang, P. 2023. Deep Sea Research II, 212, https://doi.org/10.1016/j.dsr2.2023.105344.

Abstract: Bathymetric changes within estuarine and coastal waters can alter the hydrodynamic evolution of sea level and currents, which in turn can influence the ecosystem by altering material property distributions. Here we apply the Tampa Bay Coastal Ocean Model (TBCOM), with an unstructured, high-resolution grid to investigate the hydrodynamic response to bathymetric changes at the periphery of the Tampa Bay mouth over a relatively small area when compared to the whole model domain. Two separate numerical experiments are conducted with the same forcing, one using the original bathymetry and the other employing a revised synthetic bathymetry. The simulated sea level, amplitude and phase of the M2 tide, and associated currents are compared for the two experiments. Significant changes in water level (up to+/-10 cm) and current velocities (up to 20 cm/s) are found in the shallow peripheral area with the two different bathymetric data sets. These bathymetric influences are not limited to the locations where the bathymetric changes occur; they also extend to remote areas of the bay. Since Tampa Bay bathymetry varies with storm-induced sediment redistributions and human actives such as shipping channel dredging and beach nourishment, these findings emphasize the need for accurate and updated bathymetry for coastal ocean modeling and applications.

Download PDF

Chen, J., Weisberg, R. H., Liu, Y., Zheng, L., Law. J., Gilbert, S., Murawski, S. 2023. Deep Sea Research II, 211, 105322.

Abstract: As a partially mixed estuary, Tampa Bay is influenced both by its connections to the adjacent Gulf of Mexico (GOM) and what occurs locally within the estuary. To assist in addressing the many scientific questions arising from various environmental factors, a very high resolution Tampa Bay Coastal Ocean Model (TBCOM) is modified to downscale from the deep GOM, across the continental shelf and into Tampa Bay to provide daily, automated nowcasts and forecasts. Veracity tests are provided for sea levels and currents forced by tides, synoptic weather variations and for extreme events. The model is also demonstrated to reproduce the net estuarine circulation through comparisons between in situ observations and model simulations. With demonstrated accuracy, TBCOM forecast sea levels are provided online as a reference for navigation support and for extreme events such as hurricane storm surge. Model simulations, even with a perfect model, are subject to errors by the forcing functions. For Tampa Bay, the NOAA NAM winds used to force the model are found to underestimate the actual winds, suggesting that additional wind observations for assimilation into operational weather forecast models may offer further improvements. This finding highlights the need for further coordination between coastal ocean observing systems and the ocean and atmosphere modeling communities. With coastal ocean and estuary material properties determined largely by the circulation, most ecological applications require accurate and timely circulation information, which the TBCOM Nowcast/Forecast System for Tampa Bay endeavors to provide.

Download PDF

Weisberg, R. H. and Liu, Y. 2022. Frontiers in Marine Science, 9. https://doi.org/10.3389/fmars.2022.863227

Abstract: We review the evolution of knowledge on the forcing of the west Florida continental shelf by a combination of local winds and deep-ocean influences, and we provide application examples regarding the relationships between the shelf responses to these forcing functions and certain ecological phenomena, including blooms of the harmful alga, Karenia brevis, recruitment of gag juveniles and how Deepwater Horizon hydrocarbons may have affected west Florida reef fish and the shoreline. Our approach employs a coordinated set of observations and numerical circulation model simulations, wherein the observations, by providing reasonable veracity checks on the model simulations, allow for further dynamical analyses that would otherwise be unavailable from the observations alone. For the case of local forcing only, we provide two dynamically consistent definitions of the inner-shelf and outer-shelf regions, and for the case of deep-ocean forcing, we show how the west Florida shelf geometry (with regard to certain geophysical fluid dynamics principles) can result in the entire shelf region being impacted by the Gulf of Mexico Loop Current. Thus, we help to explain why the west Florida shelf experiences large inter-annual variations in shelf ecology, providing impetus for further interdisciplinary study.

Download PDF

Meyers, S., Yilmaz, Y., Luther, M. E. 2022. Ocean Engineering, 264. https://doi.org/10.1016/j.oceaneng.2022.112367

Abstract: The Automatic Identification System (AIS) provides essential services in support of maritime domain awareness. Accurate AIS values for hull dimension and type are often critical for safe and efficient management of ship traffic, and for development of new artificial intelligence maritime algorithms. AIS variables are subject to faults from multiple sources, ranging from bad weather to human error. New heuristic methods for correcting ship draft, beam, and class were developed and evaluated, using AIS data in the vicinity of large Florida ports as a test bed. Novel low order polynomials for 8 broad functional vessel classes yielded predicted values for draft and beam as functions of vessel length. The majority of relative differences between predicted and reported values were <0.1. A logistic regression (LR) multiclass classification scheme using the residuals from these polynomial predictions generally showed good agreement between estimated and reported vessel class. The LR scheme demonstrated skill in verifying AIS-transmitted classification, detecting incorrectly classified vessels, and flagging those with incorrect draft or operating near an extreme draft. A diagnostic of reports whose classification had very low and very high confidence suggested directions for further improvement of the algorithm. A new hierarchy for processed AIS data is proposed.

Download PDF

Liu, Y., Weisberg, R. H., Zheng, L., Heil, C. A., Hubbard, K. 2022. Estuarine, Costal and Shelf Science, 272. https://doi.org/10.1016/j.ecss.2022.107901

Abstract: The 2018 Karenia brevis harmful algal bloom experienced along the west coast of Florida was the worst red tide occurrence there since 2005. Cell concentrations peaked in early fall of 2018, lessened in winter, and disappeared early in 2019. Here we examine the termination of this red tide event by using hindcast simulations of the West Florida Coastal Ocean Model, a numerical ocean circulation model that downscales from the deep Gulf of Mexico, across the continental shelf and into the estuaries. The underlying hypothesis is that without an offshore source of K. brevis cells, a nearshore bloom may quickly dissipate under the influence of a persistent upwelling circulation. To test this hypothesis, we used a passive tracer (without consideration of biological growth or decay) in the model to virtually indicate K. brevis cells. The tracer, inputted along the central West Florida coast where highest bloom concentrations were observed, was subsequently transported southward along the coast and offshore, significantly reducing the tracer concentrations over the three-month-long experimental duration, as was observed for the actual K. brevis cell concentrations. Whereas modeled tracer concentrations decreased over most of the West Florida coast, relatively higher concentrations remained just south of Sanibel Island, trapped there by the sharp bend in the coastline. Longer residence time for this area has important K. brevis implications. Lake Okeechobee nutrient flux through the Caloosahatchee River was thought to contribute to red tide in this region, and while these inputs may be a factor, a persistent upwelling circulation may also play a contributing role.

Download PDF

Hapke, C. J., Baumstark, R., Druyor, R., Fredericks, X., Kramer, P., Jackson, K., McEachon, L. 2022. Ocean and Coastal Management, 216. https://doi.org/10.1016/j.ocecoaman.2021.105942

Abstract: The Florida Coastal Mapping Program (FCMaP) is a consortium of State, Federal and academic partners that is undertaking the coordination of the collection and dissemination of consistent, high-resolution seafloor data for Florida’s coastal zone. The coastal zone in the context of FCMaP refers to the area extending from the shoreline to the 200-m isobath. The high-resolution data is critical for a myriad of ocean and coastal resource management applications.

An existing data gap analysis revealed that less than 20% of Florida’s coastal waters have been mapped using modern bathymetric methods (multibeam sonar or airborne lidar), and in some areas, less than 5% of the seafloor has modern data; where data do exist, they often date to the 1800s. Addressing the need for a more comprehensive modern map of the seafloor will take an enormous amount of effort and funding, coordination and prioritization will be critical to success.

FCMaP also undertook a formal statewide seafloor mapping prioritization to solicit input from a variety of stakeholders. The results provide the first statewide perspective of user and stakeholder mapping prioritization needs for the State of Florida. The prioritization dataset identifies specific locations that would benefit the most users or stakeholders, which can help to refine targeted mapping strategies. We found that new, consistent data would greatly support and improve multiple management activities. The approach used for this effort demonstrates an effective and replicable approach to addressing the need for seafloor mapping.

Download PDF

Xie, S., Chen, J., Dixon, T. H., Weisberg, R. H., Zumberge, M. A. 2021. JGR Oceans, 126, 11. https://doi.org/10.1029/2021JC017734

Abstract: Conventional tide gauges are usually housed along the coast. Satellite altimetry works well in the open ocean but poorly near the coast due to signal contamination by land returns. These limitations lead to an observational gap in the transition zone between the coast and open ocean. Using data collected by a GPS installed on top of an anchored spar-buoy in Tampa Bay, we retrieved water levels through a combination of precise positioning and interferometric reflectometry. Individual water level retrievals agree with a nearby acoustic tide gauge (19.5 km distance) at ∼15 cm level. Amplitude and phase of the major tidal constituents are well recovered by the GPS spar-buoy measurements. Over a 2.9-year period, agreement of de-tided daily mean sea levels measured by the GPS spar-buoy and the nearby acoustic tide gauge is 4.4 cm. When sea level data measured by the GPS spar-buoy are included in the local coastal ocean circulation model, low-frequency error propagated from the open boundary is significantly reduced.

Download PDF