A model study of the response of hypoxia to upwelling-favorable wind on the northern Gulf of Mexico shelf

Feng, Yang; Fennel, Katja; Jackson, George A.; DiMarco, Steven F.; Hetland, Robert D.

doi:10.1016/j.jmarsys.2013.11.009

Cited by 71 publications

(77 citation statements)

References 43 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The possible reason for this was that the strong wind from the northwest in the W Jan wind run drove downwelling due to Ekman dynamics, which decreased the concentration of surface chlorophyll and ultimately led to an enhancement of DO through lower decomposition of organic matters. These finds were the same as the results reported in the study conducted in the northern Gulf of Mexico shelf by Feng (2014). Above all, in the W Jan wind run there was almost no hypoxia adjacent to the Yangtze River Estuary in the summer.…”

Section: Wind Forcingsupporting

confidence: 90%

Modeling the impact of river discharge and wind on the hypoxia off Yangtze Estuary

Zheng

Gao

Liu

et al. 2016

Nat. Hazards Earth Syst. Sci.

View full text Add to dashboard Cite

Abstract. The phenomenon of low dissolved oxygen (known as hypoxia) in a coastal ocean system is closely related to a combination of anthropogenic and natural factors. Marine hypoxia occurs in the Yangtze Estuary, China, with high frequency and long persistence. It is related primarily to organic and nutrient enrichment influenced by river discharges and physical factors, such as water mixing. In this paper, a threedimensional hydrodynamic model was coupled to a biological model to simulate and analyze the ecological system of the East China Sea. By comparing with the observation data, the model results can reasonably capture the physical and biochemical dynamics of the Yangtze Estuary. In addition, the sensitive experiments were also used to examine the role of physical forcing (river discharge, wind speed, wind direction) in controlling hypoxia in waters adjacent to the Yangtze Estuary. The results showed that the wind field and river discharge have significant impact on the hypoxia off the Yangtze Estuary. The seasonal cycle of hypoxia was relatively insensitive to synoptic variability in the river discharge, but integrated hypoxic areas were sensitive to the whole magnitude of river discharge. Increasing the river discharge was shown to increase hypoxic areas, while decreasing the river discharge tended to decrease hypoxic areas. The variations of wind speed and direction had a great impact on the integrated hypoxic areas.

show abstract

Section: Wind Forcingsupporting

confidence: 90%

Modeling the impact of river discharge and wind on the hypoxia off Yangtze Estuary

Zheng

Gao

Liu

et al. 2016

Nat. Hazards Earth Syst. Sci.

View full text Add to dashboard Cite

show abstract

“…Feng et al () showed that the wind forcing during summer has a significant impact on water mass transport and hypoxia on the shelf. Episodes of eastward, upwelling‐favorable winds cause an eastward and offshore transport on the shelf.…”

Section: Discussionmentioning

confidence: 99%

Quantifying the Relative Importance of Riverine and Open‐Ocean Nitrogen Sources for Hypoxia Formation in the Northern Gulf of Mexico

2019

Self Cite

View full text Add to dashboard Cite

The Mississippi and Atchafalaya River System discharges large amounts of freshwater and nutrients into the northern Gulf of Mexico (NGoM). These lead to increased stratification and elevate primary production in the outflow region. Consequently, hypoxia (oxygen <62.5 mmol/m3), extending over an area of roughly 15,000 km2, forms every summer in bottom waters. High‐resolution models have significantly improved our understanding of the processes controlling hypoxia formation in the NGoM and have strongly implicated riverine nutrients as the dominant nutrient source. However, the relative importance of different nutrient sources (i.e., the Mississippi and Atchafalaya Rivers and offshore) has not been assessed before now. Here, we combine a high‐resolution model with an element tracing method to directly quantify the relative contributions of nitrogen from the two rivers and the open ocean to primary production and sediment oxygen consumption, which is the main oxygen sink contributing to hypoxia in the NGoM. Our results indicate that, averaged over 2001–2011, Mississippi and Atchafalaya nitrogen support 51 ± 9% and 33 ± 9% of summer sediment oxygen consumption, respectively, while open‐ocean nitrogen supports 16 ± 2%. The higher relative impact of Mississippi inputs results from longer transit times compared to those of Atchafalaya inputs. We also analyze the effect of riverine nitrogen load reductions and a larger diversion of discharge to the Atchafalaya River. These scenario simulations show that nutrient load reductions are most effective in mitigating hypoxia.

show abstract

“…Our results show that the seasonal changes in wind speed and direction significantly influence the shelf‐wide stratification and hence the simulated hypoxia, which are consistent with the mechanism demonstrated by Feng et al . [], but eliminate the confounding effects of a full biogeochemical model. In our simulations, the persistently weak upwelling‐favorable wind continuously expands the lighter and fresher plume water eastward and offshore, which enhances shelf‐wide stratification and promotes widespread hypoxia.…”

Section: Discussionmentioning

confidence: 99%

A modeling study of physical controls on hypoxia generation in the northern Gulf of Mexico

Fennel

Laurent

2015

J. Geophys. Res. Oceans

Self Cite

View full text Add to dashboard Cite

The Louisiana shelf (LA shelf) in the northern Gulf of Mexico experiences hypoxic conditions every summer due to the combination of eutrophication and strong water column stratification. Here we use a three-dimensional circulation model coupled with a simple oxygen model to examine the physical controls on hypoxia generation on the LA shelf. The model assumes a constant oxygen utilization rate in the water column and a sediment oxygen consumption rate that depends on the bottom water oxygen concentration and temperature. Despite its simplicity, the model reproduces the observed variability of dissolved oxygen and hypoxia on the LA shelf, highlighting the importance of physical processes. Model results demonstrate that both river discharge and wind forcing have a strong effect on the distribution of the river plume and stratification, and thereby on bottom dissolved oxygen concentrations and hypoxia formation on the LA shelf. The seasonal cycle of hypoxia is relatively insensitive to the seasonal variability in river discharge, but the time-integrated hypoxic area is very sensitive to the overall magnitude of river discharge. Changes in wind speed have the greatest effect on the simulated seasonal cycle of hypoxia and hypoxic duration, while changes in wind direction strongly influence the geographic distribution of hypoxia. Given that our simple oxygen model essentially reproduces the evolution of hypoxia simulated with a full biogeochemical model and that physical processes largely determine the magnitude and distribution of hypoxia, a full biogeochemical model might not be necessary for short-term hypoxia forecasting.

show abstract

A model study of the response of hypoxia to upwelling-favorable wind on the northern Gulf of Mexico shelf

Cited by 71 publications

References 43 publications

Modeling the impact of river discharge and wind on the hypoxia off Yangtze Estuary

Modeling the impact of river discharge and wind on the hypoxia off Yangtze Estuary

Quantifying the Relative Importance of Riverine and Open‐Ocean Nitrogen Sources for Hypoxia Formation in the Northern Gulf of Mexico

A modeling study of physical controls on hypoxia generation in the northern Gulf of Mexico

Contact Info

Product

Resources

About