Abstract
In August 2014, in situ measurements revealed an intense salinity drop impacting South Florida coral reefs, between Pulley Ridge (Southwest Florida Shelf) and the Florida Keys. The low salinity waters had a surface signal of 32 (down from 35.2) and extended over a 15–20-m deep lens. Satellite observations showed that this abrupt drop in salinity was due to a southeastward export of Mississippi River waters from the Northern Gulf of Mexico (GoM), revealing strong interaction between coastal and oceanic flows. Unlike previous events of marked long-distance Mississippi water export, this episode is not associated with Mississippi flooding conditions, which makes it a unique study case. We have developed a high-resolution (~2 km) comprehensive hydrodynamic numerical model of the GoM to study the conditions that controlled the 2014 Mississippi River water export episode. It is based on the Hybrid Coordinate Ocean Model (HYCOM) and assimilates remotely sensed altimetry and sea surface temperature observations, to ensure that the simulated upper-ocean is realistic. This regional model has a detailed representation of coastal physics (especially river plume dynamics) and employs high-frequency river discharge and atmospheric forcing. The combined use of the simulation and observations reveals a unique pathway that brought Mississippi waters first eastward along the Northern GoM continental shelf, under prevailing winds and the presence of an anticyclonic Loop Current eddy, then southward along the edge of the West Florida Shelf, before reaching the deep GoM. Unlike usually observed, the offshore advection of Mississippi River waters thus took place far from the Delta area, which is another specificity of the 2014 episode. Finally, in the Florida Straits, Mississippi waters were advected from the deep ocean to the continental shelf under the influence of both deep sea (particularly a cyclonic Loop Current frontal eddy) and shelf flows (wind-induced Ekman transport). The simulation, in tandem with data, thus helped analyze processes that are likely to affect the connectivity between reefs in the southern Florida region (Florida Keys, Dry Tortugas, Pulley Ridge) and remote areas (Mississippi Delta), as well as the local connectivity between neighboring reefs.
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Notes
“Understanding Coral Ecosystem Connectivity in the Gulf of Mexico from Pulley Ridge to the Florida Keys” (http://www.coastalscience.noaa.gov/projects/detail?key=63).
References
Androulidakis YS, Kourafalou VH (2013) On the processes that influence the transport and fate of Mississippi water under flooding outflow conditions. Ocean Dyn 63(2–3):143–164. doi:10.1007/s10236-0120587-8
Asselin R (1972) Frequency filter for time integrations. Mon Weather Rev 100(6):487–490
Bleck R (2002) An oceanic general circulation model framed in hybrid isopycnic-Cartesian coordinates. Ocean Model 4:55–88. doi:10.1016/S1463-5003(01)00012-9
Bleck R, Smith L (1990) A wind-driven isopycnic coordinate model of the north and equatorial Atlantic Ocean: 1. Model development and supporting experiments. J Geophys Res 95(C3):3273–3285. doi:10.1029/JC095iC03p03273
Chassignet EP, Smith LT, Halliwell GR, Bleck R (2003) North Atlantic simulations with the Hybrid Coordinate Ocean Model (HYCOM): impact of vertical coordinate choice, reference pressure and thermobaricity. J Phys Oceanogr 33:2504–2526. doi:10.1175/1520-0485(2003)033<2504:NASWTH>2.0.CO;2
Chassignet EP et al (2006) Generalized vertical coordinates for eddy-resolving global and coastal ocean forecasts. Oceanography 19:118–129. doi:10.5670/oceanog.2006.95
Chassignet EP, Hurlburt HE, Metzger EJ, Smedstad OM, Cummings J, Halliwell GR, Bleck R, Baraille R, Wallcraft AJ, Lozano C, Tolman H, Srinivasan A, Hankin S, Cornillon P, Weisberg R, Barth A, He R, Werner C, Wilkin J (2009) U.S. GODAE: global ocean prediction with the HYbrid Coordinate Ocean Model (HYCOM). Oceanography 22:48–59
Counillon F, Bertino L (2009) High-resolution ensemble forecasting for the Gulf of Mexico eddies and fronts. Ocean Dyn 59:83–95
Cowen RK, Guigand CM (2008) In situ ichthyoplankton imaging system (ISIIS): system design and preliminary results. Limnol Oceanogr Methods 6:126–132
Cummings JA (2005) Operational multivariate ocean data assimilation. Q J R Meteorol Soc 131:3583–3604
Cummings JA, Smedstad OM (2013) Variational data assimilation for the global ocean. In: Data assimilation for atmospheric. Oceanic and hydrologic applications, vol 2. Springer Berlin, Heidelberg, pp 303–343. doi:10.1007/978-3-642-35088-7_13
DiMarco SF, Nowlin WD, Reid RO (2005) A statistical description of the velocity fields from upper ocean drifters in the Gulf of Mexico. In: Sturges W, Lugo-Fernandez A (eds) Geophys Monogr Ser, vol 161. AGU, Washington, D. C, pp 101–109
Donohue KA, Watts DR, Hamilton P, Leben R, Kennelly M, Lugo-Fernandez A (2015) Gulf of Mexico loop current path variability. Dyn Atmos Oceans. doi:10.1016/j.dynatmoce.2015.12.003
Dowgiallo MJ (ed.) (1994) Coastal Oceanographic Effects of Summer 1993 Mississippi river Flooding. Special NOAA Report, March 1994, 74pp
Gierach MM, Vazquez-Cuervo J, Lee T, Tsontos VM (2013) Aquarius and SMOS detect effects of an extreme Mississippi River flooding event in the Gulf of Mexico. Geophys Res Lett 40:5188–5193. doi:10.1002/grl.50995
Gilbert PS, Lee TN, Podestá GP (1996) Transport of anomalous low-salinity waters from the Mississippi River flood of 1993 to the Straits of Florida. Cont Shelf Res 16(8):1065–1085
Halliwell GR (2004) Evaluation of vertical coordinate and vertical mixing algorithms in the Hybrid Coordinate Ocean Model (HYCOM). Ocean Model 7:285–322. doi:10.1016/j.ocemod.2003.10.002
Halliwell GR, Barth A, Weisberg RH, Hogan PJ, Smedstad OM, Cummings J (2009) Impact of GODAE products on nested HYCOM simulations of the West Florida Shelf. Ocean Dyn 59:139–155. doi:10.1007/s10236-008-0173-2
Halliwell GR, Srinivasan A, Kourafalou V, Yang H, Willey D, Le Hénaff M, Atlas R (2014) Rigorous evaluation of a fraternal twin ocean OSSE system in the open Gulf of Mexico. J Atmos Ocean Technol 31(1):105–130. doi:10.1175/JTECH-D-13-00011.1
Halliwell GR, Kourafalou V, Le Hénaff M, Shay LK, Atlas R (2015) OSSE impact analysis of airborne ocean surveys for improving upper-ocean dynamical and thermodynamical forecasts in the Gulf of Mexico. Prog Oceanogr 130:32–46. doi:10.1016/j.pocean.2014.09.004
Hamilton P (1992) Lower continental slope eddies in the central Gulf of Mexico. J Geophys Res 97(C2):2185–2200
Hamilton P, Berger TJ, Johnson W (2002) On the structure and motions of cyclones in the northern Gulf of Mexico. J Geophys Res 107(C12):3208. doi:10.1029/1999JC000270
He R, Weisberg RH (2002) West Florida shelf circulation and temperature budget for the 1999 spring transition. Cont Shelf Res 22:719–748
Hu C, Nelson JR, Johns E, Chen Z, Weisberg RH, Müller-Karger FE (2005) Mississippi River water in the Florida Straits and in the Gulf Stream off Georgia in summer 2004. Geophys Res Lett 32, L14606. doi:10.1029/2005GL022942
Justic D, Rabalais NN, Turner RE, Wiseman WJ Jr (1993) Seasonal coupling between riverborne nutrients, net productivity and hypoxia. Mar Pollut Bull 26:184–189
Kourafalou VH, Androulidakis YS (2013) Influence of Mississippi river induced circulation on the deepwater horizon oil spill transport. J Geophys Res 118(8):3823–3842. doi:10.1002/jgrc.20272
Kourafalou VH, Kang H (2012) Florida current meandering and evolution of cyclonic eddies along the Florida keys reef tract: are they inter-connected? J Geophys Res 117, C05028. doi:10.1029/2011JC007383
Kourafalou VH, Lee TN, Oey LY, Wang JD (1996) The fate of river discharge on the continental shelf, 2: transport of coastal low salinity waters under realistic wind and tidal forcing. J Geophys Res 101(C2):3435–3455
Kourafalou VH, Peng G, Kang H, Hogan PJ, Smedstadt OM, Weisberg RM, Baringer MO, Meinen CS (2009) Evaluation of global ocean data assimilation experiment products on South Florida nested simulations with the Hybrid Coordinate Ocean Model. Ocean Dyn 59:47–66. doi:10.1007/s10236-008-0160-7
Kourafalou VH, De Mey P, Le Hénaff M, Charria G, Edwards CA, He R, Herzfeld M, Pascual A, Stanev EV, Tintoré J, Usui N, Van Der Westhuysen AJ, Wilkin J, Zhu X (2015a) Coastal ocean forecasting: system integration and validation. J Oper Oceanogr. doi:10.1080/1755876X.2015.1022336
Kourafalou VH, De Mey P, Staneva J, Ayoub N, Barth A, Chao Y, Cirano M, Fiechter J, Herzfeld M, Kurapov A, Moore AM, Oddo P, Pullen J, van der Westhuysen AJ, Weisberg RH (2015b) Coastal ocean forecasting: science foundation and user benefits. J Oper Oceanogr. doi:10.1080/1755876X.2015.1022348
Large WG, McWilliams JC, Doney SC (1994) Oceanic vertical mixing: a review and a model with a nonlocal boundary layer parameterization. Rev Geophys 32:363–403. doi:10.1029/94RG01872
Le Hénaff M, Kourafalou VH, Morel Y, Srinivasan A (2012a) Simulating the dynamics and intensification of cyclonic loop current frontal eddies in the Gulf of Mexico. J Geophys Res 117(C2), C02034. doi:10.1029/2011JC007279
Le Hénaff M, Kourafalou VH, Paris CB, Helgers J, Aman ZM, Hogan PJ, Srinivasan A (2012b) Surface evolution of the deepwater horizon oil spill patch: combined effects of circulation and wind-induced drift. Environ Sci Technol 46:7267–7273
Le Hénaff M, Kourafalou VH, Dussurget R, Lumpkin R (2014) Cyclonic activity in the eastern Gulf of Mexico: characterization from along-track altimetry and in situ drifter trajectories. Prog Oceanogr 120:120–138
Lumpkin R, Pazos M (2007) Measuring surface currents with surface velocity program drifters: the instrument, its data, and some recent results. In: Griffa A et al (eds) Lagrangian analysis and prediction of coastal and ocean dynamics. Cambridge Univ. Press, Cambridge, pp 39–67
Mezic I, Loire S, Vladimir A, Fonoberov A, Hogan P (2010) A new mixing diagnostic and gulf oil spill movement. Science 330:486–489
Morey SL, Martin PJ, O’Brien JJ, Wallcraft AA, Zavala-Hidalgo J (2003a) Export pathways for river discharged fresh water in the northern Gulf of Mexico. J Geophys Res 108(C10):3303. doi:10.1029/2002JC001674
Morey SL, Schroeder WW, O’Brien JJ, Zavala-Hidalgo J (2003b) The annual cycle of riverine influence in the eastern Gulf of Mexico basin. Geophys Res Lett 30(16):1867. doi:10.1029/2003GL017348
Oey LY, Chen P (1992) A nested-grid ocean model: with application to the simulation of meanders and eddies in the Norwegian coastal current. J Geophys Res 97(C12):20,063–20,086. doi:10.1029/92JC01991
Oke PR, Larnicol G, Jones EM, Kourafalou V, Sperrevik AK, Carse F, Tanajura CAS, Mourre B, Tonani M, Brassington GB, Le Hénaff M, Halliwell GR, Atlas R, Moore AM, Edwards CA, Martin MJ, Sellar AA, Alvarez A, De Mey P, Iskandarani M (2015) Assessing the impact of observations on ocean forecasts and reanalyses: part 2. Regional applications. J Oper Oceanogr. doi:10.1080/1755876X.2015.1022080
Ortner PB, Lee TN, Milne PJ, Zika RG, Clarke ME, Podestá GP, Swart PK, Tester PA, Atkinson LP, Johnson WR (1995) Mississippi River flood waters that reached the Gulf Stream. J Geophys Res 100(C7):13595–13601
Paris CB, Le Hénaff M, Aman ZM, Subramaniam A, Helgers J, Wang DP, Kourafalou VH, Srinivasan A (2012) Evolution of the Macondo well blowout: simulating the effects of the circulation and synthetic dispersants on the subsea oil transport. Environ Sci Technol 46(24):13293–13302
Pascual A, Faugère Y, Larnicol G, Le Traon PY (2006) Improved description of the ocean mesoscale variability by combining four satellite altimeters. Geophys Res Lett L0261:1–4. doi:10.1029/2005GL024633
Prasad TG, Hogan PJ (2007) Upper-ocean response to Hurricane Ivan in a 1/250 nested Gulf of Mexico HYCOM. J Geophys Res 112, C04013. doi:10.1029/2006JC003695
Rabalais NN, Turner RE, Wiseman WJ Jr, Boesh DF (1991) A brief summary of hypoxia on the northern Gulf of Mexico continental shelf: 1985–1988. In: Tyson RV, Pearson TH (eds) Modern and ancient continental shelf anoxia, vol 58. Geological Society of London, Special Publication, London, pp 35–47
Rabalais NN, Turner RE, Wiseman WJ Jr (2002) Gulf of Mexico hypoxia, a.k.a. “the dead zone.”. Annu Rev Ecol Evol Syst 33:235–263. doi:10.1146/annurev.ecolsys.33.010802.150513
Sadourny R (1975) The dynamics of finite-difference models of the shallow-water equations. J Atmos Sci 32(4):680–689
Schiller RV, Kourafalou VH (2010) Modeling river plume dynamics with the hybrid coordinate ocean model. Ocean Model 33(1–2):101–107
Schiller RV, Kourafalou VH (2014) Loop Current impact on the transport of Mississippi River waters. J Coast Res 30(6):1287–1306
Schiller RV, Kourafalou VH, Hogan P, Walker ND (2011) The dynamics of the Mississippi River plume: impact of topography, wind and offshore forcing on the fate of plume waters. J Geophys Res 116(C6), C06029. doi:10.1029/2010JC006883
Schmitz WJ (2005) Cyclones and westward propagation in the shedding of anticyclonic rings from the Loop Current. In: Sturges W, Lugo-Fernandez A (eds) Circulation in the Gulf of Mexico: observations and models, geophys monogr Ser 161. AGU, Washington, D. C., pp 241–261
Sun C, Thresher A, Keeley R et al (2010) The data management system for the global temperature and salinity profile programme. In: Hall J, Harrison DE, Stammer D (eds) Proceedings of OceanObs.09: sustained ocean observations and information for society, vol 2. ESA Publication WPP-306, Venice, Italy. doi:10.5270/OceanObs09.cwp.86
Valentine DL, Mezic I, Macesic S, Crnjaric-Zic N, Ivic S, Hogan PJ, Fonoberov VA, Loire S (2012) Dynamic autoinoculation and the microbial ecology of a deep water hydrocarbon irruption. Proc Natl Acad Sci U S A 109:20286–20291. doi:10.1073/pnas.1108820109
Walker ND (1996) Satellite assessment of Mississippi river plume variability: causes and predictability. Remote Sens Environ 58:21–35. doi:10.1016/0034-4257(95)00259-6
Walker ND, Fardion GS, Rouse LJ, Biggs DC (1994) Circulation of Mississippi River water discharged into the northern Gulf of Mexico by the great flood of summer 1993. EOS Trans Am Geophys Union 75(36):409–415
Walker ND, Huh OK, Rouse LJ Jr, Murray SP (1996) Evolution and structure of a coastal squirt off the Mississippi River delta: Northern Gulf of Mexico. J Geophys Res 101(C9):20643–20655
Walker ND, Leben RR, Balasubramanian S (2005) Hurricane-forced upwelling and chlorophyll a enhancement within cold-core cyclones in the Gulf of Mexico. Geophys Res Lett 32(18), L18610. doi:10.1029/2005GL023716
Walker ND, Pilley C, Raghunathan V, D’Sa E, Leben R, Hoffmann N, Brickley P, Coholan P, Sharma N, Graber H, Turner R (2011) Impacts of loop current frontal cyclonic eddies and wind forcing on the 2010 Gulf of Mexico oil spill. Geophys Monogr 195:103–116
Weisberg RH, He R, Liu Y, Virmani JI (2005) West Florida shelf circulation on synoptic, seasonal, and interannual time scales. In: Sturges W, Lugo-Fernandez A (eds) Geophys Monogr Ser, vol 161. AGU, Washington, D. C, pp 325–347
Winther NG, Evensen G (2006) A Hybrid Coordinate Ocean Model for shelf sea simulation. Ocean Model 13:221–237. doi:10.1016/j.ocemod.2006.01.004
Acknowledgments
This paper is a result of research funded by the National Oceanic and Atmospheric Administration (awards NA11NOS4780045, NA10OAR4320143, and NA12OAR4310073). M. Le Hénaff received partial support for this work from the NOAA Atlantic Oceanographic and Meteorological Laboratory. The MODIS/Aqua satellite images of chlorophyll-a were provided by the Optical Oceanography Lab of USF/CMS (University of South Florida/College of Marine Science). The altimeter products were produced by Ssalto/Duacs and distributed by AVISO (http://www.aviso.altimetry.fr/duacs/), with support from the Centre National d’Etudes Spatiales (CNES). MDT_CNES-CLS13 was produced by the Collecte Localisation Satellites (CLS) Space Oceanography Division and distributed by AVISO (http://www.aviso.altimetry.fr/), with support from CNES. The SMOS L4 data were obtained from the Ocean Salinity Expertise Center (CECOS) of the CNES-IFREMER Centre Aval de Traitemenent des Données SMOS (CATDS), at IFREMER, Plouzané (France). The authors would like to thank the crew and scientists on board the R/V Walton Smith during the Pulley Ridge project cruise (August 13–28, 2014), for collecting and providing in situ data; in particular, the water column salinity vertical profiles using DPI were provided by R. K. Cowen (Oregon State University). The bathymetry used in the 1/50° GoM-HYCOM reanalysis simulation was derived by P. Velissariou (COAPS, Florida State University). Finally, the authors wish to thank two anonymous reviewers for their constructive remarks.
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Responsible Editor: Pierre De Mey
This article is part of the Topical Collection on Coastal Ocean Forecasting Science supported by the GODAE OceanView Coastal Oceans and Shelf Seas Task Team (COSS-TT)
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Le Hénaff, M., Kourafalou, V.H. Mississippi waters reaching South Florida reefs under no flood conditions: synthesis of observing and modeling system findings. Ocean Dynamics 66, 435–459 (2016). https://doi.org/10.1007/s10236-016-0932-4
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DOI: https://doi.org/10.1007/s10236-016-0932-4