Near-Resonant Ocean Response to Sea Breeze on a Stratified Continental Shelf

Zhang, Xiaoqian; DiMarco, Steven F.; Smith, David C.; Howard, Matthew K.; Jochens, Ann E.; Hetland, Robert D.

doi:10.1175/2009jpo4054.1

Cited by 56 publications

(68 citation statements)

References 39 publications

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“…The deployment location of the sediment trap is close to the critical latitude of 30°N, where the local inertial period is approximately 24 h, which is very near to the local diurnal tidal period (DiMarco et al, 2000;Zhang et al, 2009Zhang et al, , 2010. Therefore, the oceanic response is generally inertial with elements of a sub-inertial coupling at periods of about 2-4 days and 5-12 days (Spencer et al, 2016).…”

Section: Currentsmentioning

confidence: 89%

Scales of seafloor sediment resuspension in the northern Gulf of Mexico

Diercks

Dike

Asper

et al. 2018

Elementa: Science of the Anthropocene

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Diercks, A-R, et al. 2018 Scales of seafloor sediment resuspension in the northern Gulf of Mexico. Elem Sci Anth, 6: 32. DOI: https://doi. org/10.1525/elementa.285 IntroductionThe sedimentation of large amounts of oil via marine snow and its accumulation on the deep seafloor (>1,200 m) during and after the Deepwater Horizon (DwH) oil spill (Passow et al., 2012;Valentine et al., 2014;Brooks et al., 2015;Chanton et al., 2015;Daly et al., 2016;Joye, 2016;Joye et al., 2016;Passow, 2016) raised questions regarding the distribution and re-distribution processes of freshly sedimented material (marine snow) on the seafloor. Once on the seafloor, marine snow contributes to unconsolidated fluffy sediment layers (Gardner, 1978;Gardner et al., 1984;1985;Walsh et al., 1988;Pilskaln et al., 1998;Newell et al., 2005) that are subject to resuspension and the production of benthic nepheloid layers (BNLs).Resuspension leads to the re-invigoration of degradation processes, which would impact the degradation rates of the oil associated with marine snow following the DwH accident (Ziervogel et al., 2016). Additionally, resuspension leads to lateral transport and redistribution of the material that sank to the seafloor. After the DwH accident such re-distribution processes make it especially difficult to estimate the total amount of Macondo oil that reached the seafloor (Passow and Hetland, 2016).BNLs, which are formed when the frictional stress of water motion strips sediment off the seafloor, therewith carrying particles into the overlying water layer, exist near the seafloor, but may reach tens to hundreds of meters upward into the water column (McCave et al., 1976). The thickness of the BNL extending above the seafloor scales with the strength of the bottom currents and the particle composition. Bottom currents >10 cm s -1 may cause resuspension events (Gardner et al., 2017), especially when low density phytodetritus or fine silt covers sediments, but large benthic storms reach 20 cm s -1 (Gardner et al., 1985). Besides locally resuspended material, particles in the BNL also include aggregates settling from the upper ocean as Time-series data of size-specific in-situ settling speeds of marine snow in the benthic nepheloid layer (moored flux cameras), particle size distributions (profiling camera), currents (various current meters) and stacked time-series flux data (sediment traps) were combined to recognize resuspension events ranging from small-scale local, to small-scale far-field to hurricane-scale. One smallscale local resuspension event caused by inertial currents was identified based on local high current speeds (>10 cm s -1) and trap data. Low POC content combined with high lithogenic silica flux at 30 m above bottom (mab) compared to the flux at 120 mab, suggested local resuspension reaching 30 mab, but not 120 mab. Another similar event was detected by the changes in particle size distribution and settling speeds of particles in the benthic nepheloid layer. Flux data indicated two other small-scale events, which occurre...

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Section: Currentsmentioning

confidence: 89%

Scales of seafloor sediment resuspension in the northern Gulf of Mexico

Diercks

Dike

Asper

et al. 2018

Elementa: Science of the Anthropocene

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“…Theoretically, the diurnal wind could generate significant inertial oscillations (Craig 1989;Ingel 2015), which have been reported in both ocean (e.g., Simpson et al 2002;Zhang et al 2009;Hyder et al 2011;Dippe et al 2015) and atmosphere (Stockwell et al 2004;Shibuya et al 2014). Here, the inertial oscillation in the surface ocean produced by diurnal winds is investigated.…”

Section: Diurnal Windsmentioning

confidence: 93%

Local inertial oscillations in the surface ocean generated by time-varying winds

Chen

Polton

et al. 2015

Ocean Dynamics

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A new relationship is presented to give a review study on the evolution of inertial oscillations in the surface ocean locally generated by time-varying wind stress. The inertial oscillation is expressed as the superposition of a previous oscillation and a newly generated oscillation, which depends upon the time-varying wind stress. This relationship is employed to investigate some idealized wind change events. For a wind series varying temporally with different rates, the induced inertial oscillation is dominated by the wind with the greatest variation. The resonant wind, which rotates anticyclonically at the local inertial frequency with time, produces maximal amplitude of inertial oscillations, which grows monotonically. For the wind rotating at non-inertial frequencies, the responses vary periodically, with wind injecting inertial energy when it is in phase with the currents, but removing inertial energy when it is out of phase. The wind rotating anticyclonically with time is much more favorable to generate inertial oscillations than the cyclonic rotating wind. The wind with a frequency closer to the inertial frequency generates stronger inertial oscillations. For a diurnal wind, the induced inertial oscillation is dependent on latitude and is most significant at 30°. This relationship is also applied to examine idealized moving cyclones. The inertial oscillation is much stronger on the right-hand side of the cyclone path than on the left-hand side (in the northern hemisphere). This is due to the wind being anti-cyclonic with time on the right-hand side, but cyclonic on the other side. The inertial oscillation varies with the cyclone translation speed. The optimal translation speed generating the greatest inertial oscillations is 2 m/s at the latitude of 10°and gradually increases to 6 m/s at the latitude of 30°.

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“…The regional wind data are from the North America Regional Reanalysis (NARR), which is a high resolution weather data set covering our study period at 3-hr intervals and 0.3 spatial resolution. We smoothed the east-west wind over our spatial domain (87 W to 94 W, 27 N to 31 N), using a 40-hr low-pass filter to remove the influence of the relatively high-frequency diurnal sea breeze signal [Zhang et al, 2009[Zhang et al, , 2010. The duration of wind (t Uwind ) is the number of days with west-to-east winds before the July shelfwide cruise during a defined time interval.…”

Section: Methodsmentioning

confidence: 99%

Relative role of wind forcing and riverine nutrient input on the extent of hypoxia in the northern Gulf of Mexico

Feng¹,

DiMarco

Jackson

2012

Geophysical Research Letters

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[1] Seasonal hypoxia of the northern Gulf of Mexico has been observed for more than 25 years. It is generally accepted that the variation in the areal extent of hypoxia is determined by changes in nutrient addition from the Mississippi River. In this study, we investigate the statistical relation between the hypoxic area and a new variable, the duration of west wind, using the available measurements for the period 1985-2010. Special consideration was paid to the 1993-2010 period, a time when a large shift in the seasonal hypoxia pattern has been reported. When excluding the years in which hurricanes directly impacted the hypoxic area observation, we find that the duration of west wind is correlated with the hypoxic area at r 2 = 0.32 for the 1985-2010 period, and r 2 = 0.52 for the 1993-2010 period. Multilinear regressions using both wind duration and May-June nitrate loading improve the statistical relationships for both periods to r 2 = 0.69 and 0.74 for the long and short time periods, respectively. Mechanistically, the statistical relationships reflect the movement and changes in horizontal river plume position associated with the wind and the influence of stratification on the hypoxic area. Citation: Feng, Y., S. F. DiMarco, and G. A.Jackson (2012), Relative role of wind forcing and riverine nutrient input on the extent of hypoxia in the northern Gulf of Mexico, Geophys. Res. Lett., 39, L09601,

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Near-Resonant Ocean Response to Sea Breeze on a Stratified Continental Shelf

Cited by 56 publications

References 39 publications

Scales of seafloor sediment resuspension in the northern Gulf of Mexico

Scales of seafloor sediment resuspension in the northern Gulf of Mexico

Local inertial oscillations in the surface ocean generated by time-varying winds

Relative role of wind forcing and riverine nutrient input on the extent of hypoxia in the northern Gulf of Mexico

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