An official website of the United States government
Abstract Extreme precipitation during Hurricane Florence, which made landfall in North Carolina in September 2018, led to breaches of hog waste lagoons, coal ash pits, and wastewater facilities. In the weeks following the storm, freshwater discharge carried pollutants, sediment, organic matter, and debris to the coastal ocean, contributing to beach closures, algae blooms, hypoxia, and other ecosystem impacts. Here, the ocean pathways of land‐sourced contaminants following Hurricane Florence are investigated using the Regional Ocean Modeling System (ROMS) with a river point source with fixed water properties from a hydrologic model (WRF‐Hydro) of the Cape Fear River Basin, North Carolina's largest watershed. Patterns of contaminant transport in the coastal ocean are quantified with a finite duration tracer release based on observed flooding of agricultural and industrial facilities. A suite of synthetic events also was simulated to investigate the sensitivity of the river plume transport pathways to river discharge and wind direction. The simulated Hurricane Florence discharge event led to westward (downcoast) transport of contaminants in a coastal current, along with intermittent storage and release of material in an offshore (bulge) or eastward (upcoast) region near the river mouth, modulated by alternating upwelling and downwelling winds. The river plume patterns led to a delayed onset and long duration of contaminants affecting beaches 100 km to the west, days to weeks after the storm. Maps of the onset and duration of hypothetical water quality hazards for a range of weather conditions may provide guidance to managers on the timing of swimming/shellfishing advisories and water quality sampling.
more »
« less
This content will become publicly available on December 1, 2025
Model-Based Study of Near-Surface Transport in and around Cape Cod Bay, Its Seasonal Variability, and Response to Wind
Abstract Output from a high-resolution numerical model is used to study near-surface transport in and around Cape Cod Bay using a Lagrangian approach. Key questions include the following: What are the dominant transport pathways? How do they vary in time on seasonal-to-interannual scales? What is the role of wind in driving this variability? Application to a possible release of wastewater into Cape Cod Bay from the recently closed Pilgrim Nuclear Power Station is discussed. Analysis reveals a seasonality in Cape Cod Bay transport patterns, with shorter residence times throughout the bay and an increased probability of outflow waters exiting the bay during spring and summer. Wind-induced Ekman currents are identified as a dominant driver of this variability. Significance StatementThis study is motivated by a possible release of radioisotope-contaminated wastewater into Cape Cod Bay, a region important to fishing, aquaculture, and tourist industries. The specific aim is to better understand near-surface transport patterns and mechanisms in Cape Cod Bay both in general and within the context of a wastewater release from Pilgrim Nuclear Power Station.
more »
« less
- Award ID(s):
- 1923387
- PAR ID:
- 10566247
- Publisher / Repository:
- American Meteorological Society
- Date Published:
- Journal Name:
- Journal of Physical Oceanography
- Volume:
- 54
- Issue:
- 12
- ISSN:
- 0022-3670
- Page Range / eLocation ID:
- 2393 to 2417
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Abstract Severe convection occurring in high-shear, low-CAPE (HSLC) environments is a common cool-season threat in the southeastern United States. Previous studies of HSLC convection document the increased operational challenges that these environments present compared to their high-CAPE counterparts, corresponding to higher false-alarm ratios and lower probability of detection for severe watches and warnings. These environments can exhibit rapid destabilization in the hours prior to convection, sometimes associated with the release of potential instability. Here, we use self-organizing maps (SOMs) to objectively identify environmental patterns accompanying HSLC cool-season severe events and associate them with variations in severe weather frequency and distribution. Large-scale patterns exhibit modest variation within the HSLC subclass, featuring strong surface cyclones accompanied by vigorous upper-tropospheric troughs and northward-extending regions of instability, consistent with prior studies. In most patterns, severe weather occurs immediately ahead of a cold front. Other convective ingredients, such as lower-tropospheric vertical wind shear, near-surface equivalent potential temperature (θe) advection, and the release of potential instability, varied more significantly across patterns. No single variable used to train SOMs consistently demonstrated differences in the distribution of severe weather occurrence across patterns. Comparison of SOMs based on upper and lower quartiles of severe occurrence demonstrated that the release of potential instability was most consistently associated with higher-impact events in comparison to other convective ingredients. Overall, we find that previously developed HSLC composite parameters reasonably identify high-impact HSLC events. Significance StatementEven when atmospheric instability is not optimal for severe convective storms, in some situations they can still occur, presenting increased challenges to forecasters. These marginal environments may occur at night or during the cool season, when people are less attuned to severe weather threats. Here, we use a sorting algorithm to classify different weather patterns accompanying such storms, and we distinguish which specific patterns and weather system features are most strongly associated with severe storms. Our goals are to increase situational awareness for forecasters and to improve understanding of the processes leading to severe convection in marginal environments.more » « less
-
This work utilizes remotely sensed thermal data to understand how the release of thermal pollution from the Brayton Point Power Station (BPPS) affected the temperature behavior of Narragansett Bay. Building upon previous work with Landsat 5, a multi-satellite analysis is conducted that incorporates 582 scenes from Landsat 5, Landsat 7, and Landsat 8 over 1984–2021 to explain seasonal variability in effluent impacts, contrast data after the effluent ceased in 2011, identify patterns in temperature before and after effluent ceased using unsupervised learning, and track how recent warming trends compare to the BPPS impact. Stopping the thermal effluent corresponds to an immediate cooling of 0.26 ± 0.1°C in the surface temperature of Mt. Hope Bay with respect to the rest of Narragansett Bay with greater cooling of 0.62 ± 0.2°C found near Brayton Point; though, cooling since the period of maximal impact (1993–2000) totals 0.53 ± 0.2°C in Mt. Hope Bay and 1.04 ± 0.2°C at Brayton Point. During seasons with lower solar radiation (winter) and lower mean river input (autumn and late summer), the BPPS effluent impact is more prominent. The seasonal differences between the high impact and low impact periods indicate that river input played an important role in the heat balance when emissions were lower, but surface fluxes dominated when emissions were higher. Putting the BPPS effluent in context, Landsat data indicates that Narragansett Bay warmed 0.5–1.2°C over the period of measurement at an average rate of 0.23 ± 0.1°C/decade and that net warming in Mt. Hope Bay is near zero. This trend implies that Narragansett Bay has experienced climatic warming over the past four decades on the scale of the temperature anomaly in Mt. Hope Bay caused by the BBPS effluent.more » « less
-
Abstract Shelf water is influenced by atmospheric forcing, river outflows, and the open ocean. Studying its variability is crucial for understanding anthropogenic impacts on coastal oceans and their transport to the open ocean. In the Middle Atlantic Bight (MAB), the interaction of the Gulf Stream with shelf/slope circulation leads to some of the complex exchanges between the shelf and open ocean along the U.S. East Coast. This study employs a Lagrangian particle tracking approach, grounded in a high‐resolution, data‐assimilative ocean reanalysis, to examine the export pathways of surface shelf water in the MAB. We analyzed over 700 daily images of simulated particle distributions using image clustering techniques. This revealed three distinct export patterns: abrupt entrainment to the Gulf Stream, gradual entrainment, and southern transport. Each pattern was observed roughly equally during the study period from January 2017 to December 2018. The observed export patterns are closely linked to the coastal circulation dynamics near Cape Hatteras. Understanding the timing and duration of these patterns is vital for assessing water quality and predicting the settlement of species that spawn in the region. Our study further underscores the influence of tropical cyclones, including Hurricanes Jose, Maria, and Chris, on these export patterns. These extreme weather events lead to significant shifts in coastal circulation near Cape Hatteras.more » « less
-
Abstract Ocean warming caused by global climate change is driving range expansions and shifts in marine species. The lady crab Ovalipes ocellatus (Herbst, 1799) is generally found south of Cape Cod, Massachusetts, USA with a disjunct population in the southern Gulf of St. Lawrence, Canada, but absent in the Gulf of Maine and Bay of Fundy. Here we present trawl survey data, recent crowd-sourced observations, and temperature data that suggest a range expansion of O. ocellatus north of Cape Cod into the Gulf of Maine and Bay of Fundy after a marine heat wave in 2012. Crowd-sourced observations of lady crabs increased in the Gulf of Maine at the same time that abundances surged after 2000. In the Gulf of Maine, O. ocellatus was found as far north as Freeport, Maine (43°48′17.136″N, 70°6′30.9594″W) and in the Bay of Fundy as far north as Alma, New Brunswick, Canada (45°36′ 13.6794″N, 64°56′29.184″W). We also extend the southern limit of O. ocellatus to St. Augustine, Florida, USA (29°42′9.432″N, 81°13′56.028″ W). The recent observations of O. ocellatus in the northwestern Atlantic and higher abundances combined with continued warming in this area may signal a permanent expansion of this species. If so, a key goal for ecologists and managers will be to understand the effects of O. ocellatus on food webs and fisheries in the Gulf of Maine and Bay of Fundy.more » « less
