Open Access Publications

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Open access publications by faculty, postdocs, and graduate students in the College of Earth, Ocean, and Environment.

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Characterizing Storm-Induced Coastal Flooding Using SAR Imagery and Deep Learning
(IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, 2025-01-21) Edwing, Deanna; Meng, Lingsheng; Lv, Suna; Yan, Xiao-Hai
Flooding is among the most common yet costly worldwide annual disasters. Previous studies have proven that synthetic aperture radar (SAR) is an effective tool for flooding observation due to its high-resolution and timely observations, and deep learning-based models can accurately extract water bodies from SAR imagery. However, many previous flood analyses do not account for influences of tides and permanent water bodies, and the comprehensive characteristics of coastal storm flooding are still not fully understood. This study therefore presents a novel approach for isolating storm-induced flood waters in coastal regions from SAR imagery through the identification and removal of permanent water bodies and tidal inundation. This methodology is applied to the Delaware Bay region, with ancillary geospatial data used to determine resulting landcover impacts. Results indicate that flooding primarily impacts agricultural and marsh regions, as well as urban areas like airports and road systems adjacent to rivers or large inland bays. The sensitivity impacts of tides on flood estimates reveals that estimates significantly increase if included in analysis, highlighting the importance of their removal prior to flood identification. Finally, exploration into intense coastal storm events in the Delaware Bay region reveal the importance of storm characteristics like high water levels, wind, and precipitation in generating extreme flooding conditions. The case study presented here has important implications for other coastal regions and provides an innovative and comprehensive approach to coastal storm flood identification and characterization which can benefit coastal managers, emergency responders, coastal communities, and researchers interested in coastal flood hazards.
Knowledge-Informed Deep Learning Model for Subsurface Thermohaline Reconstruction From Satellite Observations
(IEEE Transactions on Geoscience and Remote Sensing, 2024-12-02) Wang, An; Su, Hua; Huang, Zhanchao; Yan, Xiao-Hai
3-D ocean temperature and salinity data are the basis for studying ocean dynamic processes and warming. Satellite remote sensing observations on the ocean surface are abundant and full-coverage, while in situ observations in the ocean interior are very sparse and unevenly distributed. Currently, the remote sensing inversion models of temperature and salinity in the ocean interior are unable to learn both global and local detail information, and modeling layer-by-layer blocks the connection between vertical depth levels, resulting in poor accuracy. In this study, we proposed a novel clustering-guided and knowledge-distillation network (CGKDN) model based on the ocean knowledge-driven model. The model introduced K-means clustering for the partitions of ocean processes, knowledge distillation (KD) fusing global and local detail information, and adaptive depth gradient loss linking the vertical depth dimension, which enhanced the interpretability and accuracy of the model. Comparison of the reconstructions with the existing major publicly available datasets through the validation of 10% EN4 in situ profile observations from 2001 to 2020 reveals that the reconstructions are more accurate. Concretely, the average root mean square error (RMSE) (°C) across time-series and vertical levels of CGKDN/Institute of Atmospheric Physics (IAP)/OCEAN5 ocean analysis-reanalysis (ORAS5)/deep ocean remote sensing (DORS) ocean subsurface temperature (OST) is 0.590/0.598/0.690/0.723, and the average RMSE (PSU) of CGKDN/IAP/ORAS5 ocean subsurface salinity (OSS) is 0.101/0.103/0.106, respectively. Furthermore, the downscaled quarter-degree reconstructions present more mesoscale detail signals, consistent with the ARMOR3D data. This study not only improves the estimation accuracy of subsurface temperature and salinity but also serves the study of ocean interior dynamic processes and variabilities and provides valuable references for reconstructing other ocean subsurface physical variables.
Synthetic Aperture Radar for Geosciences
(Reviews of Geophysics, 2024-09-03) Meng, Lingsheng; Yan, Chi; Lv, Suna; Sun, Haiyang; Xue, Sihan; Li, Quankun; Zhou, Lingfeng; Edwing, Deanna; Edwing, Kelsea; Geng, Xupu; Wang, Yiren; Yan, Xiao-Hai
Synthetic Aperture Radar (SAR) has emerged as a pivotal technology in geosciences, offering unparalleled insights into Earth's surface. Indeed, its ability to provide high-resolution, all-weather, and day-night imaging has revolutionized our understanding of various geophysical processes. Recent advancements in SAR technology, that is, developing new satellite missions, enhancing signal processing techniques, and integrating machine learning algorithms, have significantly broadened the scope and depth of geosciences. Therefore, it is essential to summarize SAR's comprehensive applications for geosciences, especially emphasizing recent advancements in SAR technologies and applications. Moreover, current SAR-related review papers have primarily focused on SAR technology or SAR imaging and data processing techniques. Hence, a review that integrates SAR technology with geophysical features is needed to highlight the significance of SAR in addressing challenges in geosciences, as well as to explore SAR's potential in solving complex geoscience problems. Spurred by these requirements, this review comprehensively and in-depth reviews SAR applications for geosciences, broadly including various aspects in air-sea dynamics, oceanography, geography, disaster and hazard monitoring, climate change, and geosciences data fusion. For each applied field, the scientific advancements produced because of SAR are demonstrated by combining the SAR techniques with characteristics of geophysical phenomena and processes. Further outlooks are also explored, such as integrating SAR data with other geophysical data and conducting interdisciplinary research to offer comprehensive insights into geosciences. With the support of deep learning, this synergy will enhance the capability to model, simulate, and forecast geophysical phenomena with greater accuracy and reliability. Key Points - Synthetic Aperture Radar (SAR) for geosciences is comprehensively reviewed broadly including oceanography, geography, hazards, and climate change - Scientific advances contributed by SAR techniques for each topic are overviewed in-depth with recent developments and frontiers highlighted - Data, techniques, and scientific insights of SAR are summarized and prospected, highlighting the role of machine learning Plain Language Summary Synthetic aperture radar (SAR) uses microwaves to remotely see the Earth's surface under all weather conditions, day and night. SAR has been providing high-resolution images for many decades and they have been applied to many fields in geosciences. Several SAR sensors have been launched in recent years, significantly increasing the SAR data volume and leading to great developments in SAR technology, thereby improving our understanding of geophysical phenomena and processes. This work comprehensively overviews the application of SAR in geosciences, including oceanography, geography, geodesy, climatology, seismology, meteorology, and environmental science. Moreover, this review paper highlights the significance of SAR in various aspects of geosciences, summarizes recent advancements in SAR technology, and demonstrates unique insights and important contributions of SAR in understanding and solving geophysical questions. Future directions and outlooks include integrating SAR with other geophysical data and interdisciplinary applications for complex questions. This review serves as an up-to-date guide to the cutting-edge uses of SAR technology in comprehensive geophysical studies. It is aimed at researchers and practitioners in geosciences, as well as policymakers and stakeholders interested in leveraging SAR for geosciences.
Bacteria-Produced Algicide for Field Control of Toxic Dinoflagellates Does Not Cause a Cortisol Stress Response in Two Estuarine Fish Species
(Marine Biotechnology, 2025-01-14) Simons, Victoria E.; Targett, Timothy E.; Gaffney, Patrick M.; Coyne, Kathryn J.
Application of algicides produced by naturally occurring bacteria is considered an environmentally friendly approach to control harmful algal blooms. However, few studies assess the effects of bacterial algicides on non-target species, either independently or with other stressors. Here, we measured sub-lethal effects of dinoflagellate-specific algicide IRI-160AA on the estuarine fish Fundulus heteroclitus and Menidia menidia in laboratory experiments. Plasma cortisol levels were measured to test whether a neuroendocrine stress response was induced in these fish following exposure to the algicide alone, and in combination with diel-cycling hypoxia and/or pH, at 25 and 30 °C. Results show that exposure to IRI-160AA does not significantly affect cortisol levels in either species, at either temperature tested, whether exposure occurs independently or with co-occurring hypoxia and/or pH cycles as potential multiple stressors. These results support the application of IRI-160AA as an environmentally friendly approach to control harmful algal blooms in estuarine environments.
A Universal Electric Vehicle Outlet and Portable Cable for North America
(World Electric Vehicle Journal, 2024-08-06) Kempton, Willett; McGee, Rodney T.; Ejzak, Garrett A.
For electric vehicle (EV) charging in North America, three AC connectors are standardized, resulting in a proliferation of charging stations which can only charge one of the three types of EV. We propose a “Universal EV Outlet” that works with an EV “carry along” charging cable—one end of the cable has a connector specific to that user’s EV, the other a plug for the Universal EV Outlet. This proposal does not interfere with, nor require change to, any existing charging stations. It does not require any new types of inlets on EVs. The components are already standardized. Eight use cases are examined to illustrate the advantages, and some limitations, of the Universal EV Outlet. The use cases illustrate how this solution: resolves the problem of multiple AC charging connectors, makes today’s “EV Ready” building codes more adaptable, lowers capital and maintenance costs, creates a solution to curbside and urban charging, increases energy efficiency, enables higher power three-phase AC charging for heavy vehicles, and facilitates use of EVs for building backup power and for vehicle-to-grid. Finally, we propose a standards-based active cable used with the Universal EV Outlet, which would allow fast and secure EV identification for curbside or other shared charging locations, usable today without modifications to current EVs.
Spatiotemporal patterns in habitat use of natal and non-natal adult Atlantic sturgeon in two spawning rivers
(Animal Biotelemetry, 2024-04-24) White, Shannon; Breece, Matthew; Fox, Dewayne; Kazyak, David; Higgs, Amanda; Park, Ian; Busch, Cassia; Lubinski, Barbara; Johnson, Robin; Welsh, Amy
Background Monitoring movement across an organism’s ontogeny is often challenging, particularly for long-lived or wide-ranging species. When empirical data are unavailable, general knowledge about species’ ecology may be used to make assumptions about habitat use across space or time. However, inferences about habitat use based on population-level ecology may overlook important eco-evolutionary contributions from individuals with heterogenous ethologies and could diminish the efficacy of conservation and management. Methods We analyzed over a decade of acoustic telemetry data to understand individual differences in habitat use of federally endangered adult Atlantic sturgeon (Acipenser o. oxyrinchus) in the Delaware and Hudson rivers during spawning season. In particular, we sought to understand whether sex or natal origin could predict patterns in habitat use, as there is a long-held assumption that adult Atlantic sturgeon seldom stray into non-natal rivers. Results In both rivers, migration timing, spawning habitat occupancy, and maximum upstream migration distance were similar between natal and non-natal individuals. While non-natal individuals represented only 13% of fish detected in the Hudson River, nearly half of all tagged fish detected in the Delaware River were non-natal and generally occupied freshwater habitats longer than natal individuals. In both systems males had more heterogenous patterns of habitat use and longer duration of occupancy than did females. Conclusions This study demonstrates the importance of non-natal rivers for fulfilling ontogenetic habitat requirements in Atlantic sturgeon. Our results may also highlight an opportunity to improve conservation and management by extending habitat designations to account for more heterogenous patterns in individual habitat use in non-natal freshwater environments.
Retrieving Global Ocean Subsurface Density by Combining Remote Sensing Observations and Multiscale Mixed Residual Transformer
(IEEE Transactions on Geoscience and Remote Sensing, 2024-01-05) Su, Hua; Qiu, Junlong; Tang, Zhiwei; Huang, Zhanchao; Yan, Xiao-Hai
Subsurface density (SD) is a crucial dynamic environment parameter reflecting a 3-D ocean process and stratification, with significant implications for the physical, chemical, and biological processes of the ocean environment. Thus, accurate SD retrieval is essential for studying dynamic processes in the ocean interior. However, complete spatiotemporally accurate SD retrieval remains a challenge in terms of the equation of state and physical methods. This study proposes a novel multiscale mixed residual transformer (MMRT) neural network method to compensate for the inadequacy of the existing methods in dealing with spatiotemporal nonlinear processes and dependence. Considering the spatial correlation and temporal dependence of dynamic processes within the ocean, the MMRT addresses temporal dependence by fully using the transformer’s processing of time-series data and spatial correlation by compensating for deficiencies in spatial feature information through multiscale mixed residuals. The MMRT model was compared with the existing random forest (RF) and recurrent neural network (RNN) methods. The MMRT model achieves the best accuracy with an average determination coefficient ( R2 ) of 0.988 and an average root mean square error (RMSE) of 0.050 kg/m3 for all layers. The MMRT model not only outperforms the RF and RNN methods regarding reliability and generalization ability when estimating global ocean SD from remote sensing data but also has a more interpretable encoding process. The MMRT model offers a new method for directly estimating SD using multisource satellite observations, providing significant technical support for future remote sensing super-resolution and prediction of subsurface parameters.
Rapid Sea Level Rise in the Tropical Southwest Indian Ocean in the Recent Two Decades
(Geophysical Research Letters, 2023-12-27) Huang, Lei; Zhuang, Wei; Lu, Wenfang; Zhang, Yang; Edwing, Deanna; Yan, Xiao-Hai
It has been reported that the sea level falls in the tropical Southwest Indian Ocean (SWIO) from the 1960s to the early 2000s. However, a rising trend of 4.05 ± 0.56 cm/decade has occurred during the recent two decades with our analysis showing that manometric sea level contributes 41% to this sea level rise. 30% of this rise is due to steric sea level (SSL) change in the upper 2,000 m with SSL rise in the upper 300 m of secondary importance. Conversely, thermal expansion below the thermocline (300–2,000 m), likely caused by water mass spread from the Southern Ocean, induces major contribution to SSL changes. Compared to existing studies demonstrating the contribution of thermal variations above the thermocline to sea level variability in the tropical SWIO, this study emphasizes the importance of ocean mass and deeper ocean changes in a warming climate. Key Points - Rapid sea level rise occurs in the tropical Southwest Indian Ocean (SWIO) since the early 2000s - The ocean mass addition and the upper 2,000 m ocean warming contribute significantly to the total sea level rise - The upper 2,000 m ocean warming is primarily attributed to thermal expansion below the thermocline associated with the spread of water masses Plain Language Summary Global ocean sea level change is spatially and temporally nonuniform due to oceanic and atmospheric dynamics. The tropical Southwest Indian Ocean (SWIO) experienced a sea level fall from the 1960s to the early 2000s. However, a rapid sea level rise has occurred over the last two decades in the tropical SWIO that is faster than the global average. The ocean mass increase due to extra water input leads to an essential impact on sea level rise in the tropical SWIO. Compared to previous studies demonstrating the effect of thermal expansion in the upper 300 m, this study shows larger contributions from deeper ocean (300–2,000 m) warming over the past two decades. Overall, this study highlights the importance of ocean mass and deeper water thermal structure in regulating tropical SWIO sea level rise in a changing climate, as well as the need for observations and direct assessment of the abyssal ocean beneath 2,000 m.
Retrieving Ocean Surface Winds and Waves from Augmented Dual-Polarization Sentinel-1 SAR Data Using Deep Convolutional Residual Networks
(Atmosphere, 2023-08-11) Xue, Sihan; Meng, Lingsheng; Geng, Xupu; Sun, Haiyang; Edwing, Deanna; Yan, Xiao-Hai
Sea surface winds and waves are very important phenomena that exist in the air–sea boundary layer. With the advent of climate change, cascade effects are bringing more attention to these phenomena as warmer sea surface temperatures bring about stronger winds, thereby altering global wave conditions. Synthetic aperture radar (SAR) is a powerful sensor for high-resolution surface wind and wave observations and has accumulated large quantities of data. Furthermore, deep learning methods have been increasingly utilized in geoscience, especially the inversion of ocean information from SAR imagery. Here, we propose a method to invert various parameters of ocean surface winds and waves using Sentinel-1 SAR IW mode data. To ensure this method is more robust and scalable, we augmented the input data with dual-polarized SAR imagery, an incident angle, and a more constrained homogeneity test. This method adopts a deeper structure in order to retrieve more wind and wave parameters, and the use of residual networks can accelerate training convergence and improve regression accuracy. Using 1600 training samples filtered by a novel homogeneity test and with significant wave heights between 0 and 10 m, results from error parameters including the root mean square error (RMSE), scatter index (SI), and correlation coefficient (COR) show the great performance of this proposed method. The RMSE is 0.45 m, 0.76 s, and 1.90 m/s for the significant wave height, mean wave period, and wind speed, respectively. Furthermore, the temporal variation and spatial distribution of the estimates are consistent with China–France Oceanography Satellite (CFOSAT) observations, buoy measurements, WaveWatch3 regional model data, and ERA5 reanalysis data.
Quasi-Decadal Temperature Variability in the Intermediate Layer of Subtropical South Indian Ocean During the Argo Period
(Journal of Geophysical Research: Oceans, 2023-07-28) Huang, Lei; Zhuang, Wei; Wu, Zelun; Zhang,Yang; Meng, Lingsheng; Edwing, Deanna; Yan, Xiao-Hai
It has been reported that the subtropical South Indian Ocean (SIO) has been rapidly warming over the past two decades and can therefore be characterized as one of the major heat accumulators among the oceanic basins. However, this strong warming is not uniformly distributed in the vertical direction. In comparison to the decade-long warming in the upper layer (0–300 m) in 2004–2013, the intermediate layer (300–1,000 m) displays a shorter warming during 2004–2009 and an intense cooling during 2010–2016. By decomposing temperature variations into heaving and spice components, and performing a heat budget analysis, we show that temperature variations in the intermediate layer during these two periods are primarily contributed by isopycnal migrations driven by local wind forcing. Local wind change in the subtropical SIO can be explained by the Indian Ocean Dipole and El Niño–Southern Oscillation during 2004–2016, while Southern Annular Mode (SAM) favors anomalous wind change in mid-latitudes and the formation of basin-wide wind change in the SIO. Additionally, wind forcing in the Subantarctic Mode Water (SAMW) formation region, which is closely linked to the SAM, modulates the anomalous spreading of SAMW into the interior of the subtropical SIO. This, therefore, leads to the SAMW intrusion being of secondary importance to the quasi-decadal temperature variability. Our findings demonstrate the independence of wind-driven temperature changes on the quasi-decadal scale in the intermediate layer of the subtropical SIO under the overall warming background of SIO waters. Key Points - Quasi-decadal temperature variations occur in the intermediate layer (300–1,000 m) of subtropical South Indian Ocean (SIO) - Local wind-driven heaving process is the major driver, spice component arising from the Subantarctic Mode Water intrusion is of secondary importance - The local wind change in the subtropical SIO can be well explained by the combined effects of El Niño–Southern Oscillation, Indian Ocean Dipole and Southern Annular Mode Plain Language Summary Compared to the decade-long warming in the upper layer of the South Indian Ocean (SIO), which has been studied extensively, our understanding of temperature change in the intermediate layer is relatively limited. This study reveals a quasi-decadal temperature cycle in the intermediate layer of the subtropical SIO during the Argo period, which is characterized by a shorter warming period during 2004–2009 and subsequent cooling during 2010–2016. Decomposition of temperature changes suggests that this quasi-decadal temperature variability is primarily driven by the heaving component, which is tightly associated with local wind variability driven by local and remote forcings, whereas the spice change largely contributed by the SAM-related water mass transmission from higher latitudes, is of secondary importance. Thus, this study expands our knowledge of temperature variability in the SIO and demonstrates that the quasi-decadal variability of intermediate layer temperatures in the subtropical SIO serves as a crucial archive for both global and local climate change.
Effects of nitrate and ammonium on assimilation of nitric oxide by Heterosigma akashiwo
(Scientific Reports, 2023-01-12) Healey, Emily M.; Flood, Stacie; Bock, Patience K.; Fulweiler, Robinson W.; York, Joanna K.; Coyne, Kathryn J.
The harmful alga Heterosigma akashiwo possesses a hybrid nitrate reductase (NR) enzyme, NR2-2/2HbN, which has the potential to convert NO to nitrate for assimilation into biomass. In previous research, NR transcription in H. akashiwo was induced by nitrate while NR activity was inhibited by ammonium. Here, the capacity of H. akashiwo to use NO in the presence of nitrate and/or ammonium was investigated to understand the regulation of NO assimilation. Continuous cultures of H. akashiwo were acclimated to growth on nitrate, ammonium, or a mixture of both. Aliquots from these cultures were spiked with 15N-labeled NO. The expression of genes involved in nitrogen assimilation was evaluated, as well as nitrate reductase activity and assimilation of 15N-labeled nitrogen into algal biomass. Results showed that NO induced expression and activity of NR, and upregulated expression of GOGAT regardless of the presence of other inorganic nitrogen sources, while GS expression decreased over time. Furthermore, 15NO uptake and assimilation was significantly higher in cultures acclimated for growth on ammonium compared to cultures acclimated for growth on nitrate alone. Assimilation of NO may provide H. akashiwo with a competitive advantage in N-poor environments or areas with elevated NO.
Block-structured, equal-workload, multi-grid-nesting interface for the Boussinesq wave model FUNWAVE-TVD (Total Variation Diminishing)
(Geoscientific Model Development, 2022-07-18) Choi, Young-Kwang; Shi, Fengyan; Malej, Matt; Smith, Jane M.; Kirby, James T.; Grilli, Stephan T.
We describe the development of a block-structured, equal-CPU-load (central processing unit), multi-grid-nesting interface for the Boussinesq wave model FUNWAVE-TVD (Fully Nonlinear Boussinesq Wave Model with Total Variation Diminishing Solver). The new model framework does not interfere with the core solver, and thus the core program, FUNWAVE-TVD, is still a standalone model used for a single grid. The nesting interface manages the time sequencing and two-way nesting processes between the parent grid and child grid with grid refinement in a hierarchical manner. Workload balance in the MPI-based (message passing interface) parallelization is handled by an equal-load scheme. A strategy of shared array allocation is applied for data management that allows for a large number of nested grids without creating additional memory allocations. Four model tests are conducted to verify the nesting algorithm with assessments of model accuracy and the robustness in the application in modeling transoceanic tsunamis and coastal effects.
Surface impacts of large offshore wind farms
(Environmental Research Letters, 2022-05-25) Golbazi, Maryam; Archer, Cristina L.; Alessandrini, Stefano
Future offshore wind farms around the world will be built with wind turbines of size and capacity never seen before (with diameter and hub height exceeding 150 and 100 m, respectively, and rated power exceeding 10 MW). Their potential impacts at the surface have not yet been studied. Here we conduct high-resolution numerical simulations using a mesoscale model with a wind farm parameterization and compare scenarios with and without offshore wind farms equipped with these 'extreme-scale' wind turbines. Wind speed, turbulence, friction velocity, and sensible heat fluxes are slightly reduced at the surface, like with conventional wind turbines. But, while the warming found below the rotor in stable atmospheric conditions extends to the surface with conventional wind turbines, with extreme-scale ones it does not reach the surface, where instead minimal cooling is found. Overall, the surface meteorological impacts of large offshore wind farms equipped with extreme-scale turbines are statistically significant but negligible in magnitude.
Population Dynamics of Common Nearshore Forage Fishes in the Delaware Inland Bays, USA
(Estuaries and Coasts, 2022-03-13) McGowan, Andrew T.; Hale, Edward A.; Bartow, Dennis H.; Greco, Michael
In the Mid-Atlantic, four species of forage fish, Menidia menidia (Atlantic Silverside), Fundulus heteroclitus (Mummichog), Fundulus majalis (Striped Killifish), and Cyprinodon variegatus (Sheepshead Minnow), account for a large proportion of fish abundance in estuarine environments and are important food sources for state and federally managed predatory species. The population dynamics of these species are poorly understood, and factors affecting their populations are largely unclear or unknown. Seine samples were collected in the Delaware Inland Bays over 9 years (2011–2019), with indices and trends in abundance, as well as climatic and biotic drivers of population changes investigated at both combined estuary and individual bay scales. Average interannual decreases in abundance for all four species at the combined estuary scale ranged between 31.9 and 69.2%, while increases ranged between 65.9 and 178.6%, indicating the extreme variability these species show between years. Standardized models of abundance demonstrated long-term declines in abundance for Mummichog and Sheepshead Minnow at both the combined estuary and individual bay scales. Spring discharge affected Mummichog and Sheepshead Minnow abundance, and Sheepshead Minnow showed a strong negative correlation with Summer Flounder abundance. These data quantify the variability in abundance for an important portion of the forage base in Mid-Atlantic estuaries and should be considered as fisheries management shifts away from single-species approaches and recognizes the forage needs of managed species. Results indicate that even commonly encountered species can consistently vary through time and emphasize the need to examine other important but poorly studied forage species.
Marshaling ports required to meet US policy targets for offshore wind power
(Energy Policy, 2022-02-16) Parkison, Sara B.; Kempton, Willett
We analyze infrastructure needed for offshore wind power targets set by U.S. state and federal policies—specifically, manufacturing, vessels, and offshore wind ports. By examining cost-competitive turbine and project sizes and infrastructure challenges, we identify marshaling ports as a key bottleneck. Through elicitation of requirements from supply chain, port, and vessel experts, we identify the necessary attributes for marshaling ports and calculate the area needed to meet policy targets. US marshaling ports are currently insufficient to meet either state or federal power targets. We calculate state commitments from state contracts and policies: in sum, 40 GW by 2040. Federal targets from the Biden Administration are 30 GW by 2030 and 110 GW by 2050. Either target yields more demand for marshaling area than is currently available or planned. The shortage of marshaling area supply has incorrectly been attributed to lack of suitable U.S. locations. Instead, we attribute it to developers having built ports to support early, smaller projects, and having located them to incentivize state power contracts rather than developing ports for long-term, large-scale, and economically-efficient use. Additional land suitable for marshaling ports exists, but it requires commitment from port authorities and port investors to develop it for this purpose.
Variability and Dynamics of Along-Shore Exchange on the West Antarctic Peninsula (WAP) Continental Shelf
(Journal of Geophysical Research: Oceans, 2022-01-31) Wang, Xin; Moffat, Carlos; Dinniman, Michael S.; Klinck, John M.; Sutherland, David A.; Aguiar-González, Borja
The continental shelf of the West Antarctic Peninsula (WAP) is characterized by strong along-shore hydrographic gradients resulting from the distinct influences of the warm Bellingshausen Sea to the south and the cold Weddell Sea water flooding Bransfield Strait to the north. These gradients modulate the spatial structure of glacier retreat and are correlated with other physical and biochemical variability along the shelf, but their structure and dynamics remain poorly understood. Here, the magnitude, spatial structure, seasonal-to-interannual variability, and driving mechanisms of along-shore exchange are investigated using the output of a high-resolution numerical model and with hydrographic data collected in Palmer Deep. The analyses reveal a pronounced seasonal cycle of along-shore transport, with a net flux (7.0 × 105 m3/s) of cold water toward the central WAP (cWAP) in winter, which reverses in summer with a net flow (5.2 × 105 m3/s) of Circumpolar Deep Water (CDW) and modified CDW (mCDW) toward Bransfield Strait. Significant interannual variability is found as the pathway of a coastal current transporting Weddell-sourced water along the WAP shelf is modulated by wind forcing. When the Southern Annual Mode (SAM) is positive during winter, stronger upwelling-favorable winds dominate in Bransfield Strait, leading to offshore advection of the Weddell-sourced water. Negative SAM leads to weaker upwelling- or downwelling-favorable winds and enhanced flooding of the cWAP with cold water from Bransfield Strait. This process can result in significant (0.5°C below 200 m) cooling of the continental shelf around Palmer Station, highlighting that along-shore exchange is critical in modulating the hydrographic properties along the WAP. Plain Language Summary: The melting of glaciers and the structure of ecosystems along the West Antarctic Peninsula have been influenced by the local temperature and salinity patterns. Our understanding of what controls the spatial structure and temporal variability of these gradients is limited. In this study, we analyze output from a state-of-the-art numerical model and find that there is strongly seasonal and interannual variability in the along-shore exchange processes that control those gradients. The interannual variability of the along-shore exchange is related to the local winds. As the wind conditions vary in response to hemispheric-scale climate processes, the amount of cold water flowing into the central West Antarctic Peninsula from Bransfield Strait varies interannually. We show this is a key process in the evolution of ocean properties in the West Antarctic Peninsula continental shelf.
Seasonal control of Petermann Gletscher ice-shelf melt by the ocean’s response to sea-ice cover in Nares Strait
(Cambridge University Press, 2017-02-02) Shroyer, E. L.; Padman, L.; Samelson, R. M.; Münchow, A.; Stearns, L. A.; E. L. SHROYER, L. PADMAN, R. M. SAMELSON, A. MÜNCHOW, L. A. STEARNS; Münchow, A
Petermann Gletscher drains ∼4% of the Greenland ice sheet (GrIS) area, with ∼80% of its mass loss occurring by basal melting of its ice shelf. We use a high-resolution coupled ocean and sea-ice model with a thermodynamic glacial ice shelf to diagnose ocean-controlled seasonality in basal melting of the Petermann ice shelf. Basal melt rates increase by ∼20% in summer due to a seasonal shift in ocean circulation within Nares Strait that is associated with the transition from landfast sea ice to mobile sea ice. Under landfast ice, cold near-surface waters are maintained on the eastern side of the strait and within Petermann Fjord, reducing basal melt and insulating the ice shelf. Under mobile sea ice, warm waters are upwelled on the eastern side of the strait and, mediated by local instabilities and eddies, enter Petermann Fjord, enhancing basal melt down to depths of 200 m. The transition between these states occurs rapidly, and seasonal changes within Nares Strait are conveyed into the fjord within the same season. These results suggest that long-term changes in the length of the landfast sea-ice season will substantially alter the structure of Petermann ice shelf and its contribution to GrIS mass loss.
Social Network Analysis Reveals Potential Fission-Fusion Behavior in a Shark
(Nature Publishing Group, 9/30/16) Haulsee,Danielle E.; Fox,Dewayne A.; Breece,Matthew W.; Brown,Lori M.; Kneebone,Jeff; Skomal,Gregory B.; Oliver,Matthew J.; Danielle E. Haulsee, Dewayne A. Fox, Matthew W. Breece, Lori M. Brown, Jeff Kneebone, Gregory B. Skomal and Matthew J. Oliver; Oliver, Matthew John
Complex social networks and behaviors are difficult to observe for free-living marine species, especially those that move great distances. Using implanted acoustic transceivers to study the inter-and intraspecific interactions of sand tiger sharks Carcharias taurus, we observed group behavior that has historically been associated with higher order mammals. We found evidence strongly suggestive of fission-fusion behavior, or changes in group size and composition of sand tigers, related to five behavioral modes (summering, south migration, community bottleneck, dispersal, north migration). Our study shows sexually dimorphic behavior during migration, in addition to presenting evidence of a potential solitary phase for these typically gregarious sharks. Sand tigers spent up to 95 consecutive and 335 cumulative hours together, with the strongest relationships occurring between males. Species that exhibit fission-fusion group dynamics pose a particularly challenging issue for conservation and management because changes in group size and composition affect population estimates and amplify anthropogenic impacts.
Projected asymmetric response of Adelie penguins to Antarctic climate change
(Nature Publishing Group, 6/29/16) Cimino,Megan A.; Lynch,Heather J.; Saba,Vincent S.; Oliver,Matthew J.; Megan A. Cimino, Heather J. Lynch, Vincent S. Saba and Matthew J. Oliver; Oliver, Matthew John
The contribution of climate change to shifts in a species' geographic distribution is a critical and often unresolved ecological question. Climate change in Antarctica is asymmetric, with cooling in parts of the continent and warming along the West Antarctic Peninsula (WAP). The Adelie penguin (Pygoscelis adeliae) is a circumpolar meso-predator exposed to the full range of Antarctic climate and is undergoing dramatic population shifts coincident with climate change. We used true presence-absence data on Adelie penguin breeding colonies to estimate past and future changes in habitat suitability during the chick-rearing period based on historic satellite observations and future climate model projections. During the contemporary period, declining Adelie penguin populations experienced more years with warm sea surface temperature compared to populations that are increasing. Based on this relationship, we project that one-third of current Adelie penguin colonies, representing similar to 20% of their current population, may be in decline by 2060. However, climate model projections suggest refugia may exist in continental Antarctica beyond 2099, buffering species-wide declines. Climate change impacts on penguins in the Antarctic will likely be highly site specific based on regional climate trends, and a southward contraction in the range of Adelie penguins is likely over the next century.
Partitioning of Respiration in an Animal-Algal Symbiosis: Implications for Different Aerobic Capacity between Symbiodinium spp.
(Frontiers Media SA, 4/18/16) Hawkins,Thomas D.; Hagemeyer,Julia C. G.; Hoadley,Kenneth D.; Marsh,Adam G.; Warner,Mark E.; Thomas D. Hawkins, Julia C.G. Hagemeyer, Kenneth D. Hoadley, Adam G. Marshand Mark E.Warner; Warner, Mark E
Cnidarian-dinoflagellate symbioses are ecologically important and the subject of much investigation. However, our understanding of critical aspects of symbiosis physiology, such as the partitioning of total respiration between the host and symbiont, remains incomplete. Specifically, we know little about how the relationship between host and symbiont respiration varies between different holobionts (host-symbiont combinations). We applied molecular and biochemical techniques to investigate aerobic respiratory capacity in naturally symbiotic Exaiptasia pallida sea anemones, alongside animals infected with either homologous ITS2-type A4 Symbiodinium or a heterologous isolate of Symbiodinium minutum (ITS2-type B1). In naturally symbiotic anemones, host, symbiont, and total holobiont mitochondrial citrate synthase (CS) enzyme activity, but not host mitochondrial copy number, were reliable predictors of holobiont respiration. There was a positive association between symbiont density and host CS specific activity (mg protein(-1)), and a negative correlation between host- and symbiont CS specific activities. Notably, partitioning of total CS activity between host and symbiont in this natural E. pallida population was significantly different to the host/symbiont biomass ratio. In re-infected anemones, we found significant between-holobiont differences in the CS specific activity of the algal symbionts. Furthermore, the relationship between the partitioning of total CS activity and the host/symbiont biomass ratio differed between holobionts. These data have broad implications for our understanding of cnidarian-algal symbiosis. Specifically, the long-held assumption of equivalency between symbiont/host biomass and respiration ratios can result in significant overestimation of symbiont respiration and potentially erroneous conclusions regarding the percentage of carbon translocated to the host. The interspecific variability in symbiont aerobic capacity provides further evidence for distinct physiological differences that should be accounted for when studying diverse host-symbiont combinations.

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