The ocean is constantly changing and is full of interesting phenomena. Satellites allow us to view and learn about the ocean on a scale that is not otherwise possible. In this post, I will share information about oceanographic features that can be observed with satellites, current events and projects that utilize CoastWatch/Oceanwatch products. I hope you enjoy learning about our dynamic ocean and satellite oceanography! --Emily


Table of Contents

• The Gulf of Mexico Loop Current

• The Tongue of the Ocean

• A Satellite's View of Coastal Erosion

• Ocean acidification in the Caribbean


The Gulf of Mexico Loop Current

The Gulf of Mexico loop current on April 20, 2016 as shown by the CoastWatch GOES-POES Global Sea Surface Temperature product.
The Gulf of Mexico loop current on April 20, 2016 as shown by the CoastWatch GOES-POES Global Sea Surface Temperature product.

The Gulf of Mexico loop current brings warm Caribbean water northward between the Yucatan Peninsula and Cuba and into the Gulf. The current loops around the Gulf, flows southeastward into the Florida Strait where it serves as a parent to the Florida current and ultimately joins the Gulf Stream.

The loop current is one of the fastest currents in the Atlantic, traveling at speeds of approximately 0.8 m/s, and is typically about 800 m deep. The extent of the loop current's intrusion into the Gulf varies with eddies frequently breaking off when the current stretches far into the Gulf.

    References and Related Reading

    •   Gopalakrishnan, G., B.D. Cornuelle, I. Hoteit, D.L. Rudnick and W.B. Owens. State estimates and forecasts of the loop current in the Gulf of Mexico using the MITgcm and its adjoint. 2013. Journal of Geophysical Research 118(7): 3292-3314.
    •   Hamilton, P. 1990. Deep Currents in the Gulf of Mexico. Journal of Physical Oceanography 20: 1087-1104.
    •   Hamilton, P., G.S. Fargin, and D.C. Biggs. 1998. Loop current eddy paths in the Western Gulf of Mexico. Journal of Physical Oceanography 29: 1180-1207.
    •   Zeng, X., Y. Li, and R. He. Predictability of the loop current variation and eddy shedding process in the Gulf of Mexico using an artificial neural network approach. 2015. Journal of Atmospheric and Oceanic Technology 32: 1098-1111.
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The Tongue of the Ocean

The Tongue of the Ocean is a deep water basin in the Bahamas that is surrounded to the east, west and south by a carbonate bank known as the Great Bahama Bank. The deep blue water of the Tongue is a stark contrast to the shallow turquoise waters of the surrounding Bank. This sheltered region is a popular foraging ground for cetateans including Cuvier's and Blainville's beaked whales.

VIIRS-SNPP True Color Image from 2 May 2016. Image courtesy of NOAA STAR Ocean Color Team.
VIIRS-SNPP True Color Image from 2 May 2016. Image courtesy of NOAA STAR Ocean Color Team.

Water primarily enters the Tongue of the Ocean from the Northwest Providence Channel to the north though water from the Bank is known to intermittently mix into the Tongue's surface waters. In general, the concentration of chlorophyll in this area of the Bahamas are higher in winter months and lower in summer months.

VIIRS-SNPP NOAA Science Quality monthly composite of chlorophyll in the Tongue of the Ocean (August 2015 - left, December 2015 - right)
VIIRS-SNPP NOAA Science Quality monthly composite of chlorophyll in the Tongue of the Ocean (August 2015 - left, December 2015 - right)

    References and Related Reading

    •   Hooper V, J.A., Baringer, M.O., St. Laurent, L.C., and Dewar, D.N. 2016. Dissipation processes in the Tongue of the Ocean. Journal of Geophysical - Oceans.
    •   Condal, A.R., Vega-Moro, A., Ardisson, P.L. 2013. Climatological, annual and seasonal variability in chlorophyll concentration in the Gulf of Mexico, western Caribbean, and Bahamas using NASA colour maps. International Journal of Remote Sensing: 34(5), 1591-1614.
    •   Shonting, D.H. 1970. On the distribution of temperature, salinity and oxygen in the Tongue of the Ocean, Bahamas. Bulletin of Marine Science: 20(1): 35-56.
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A Satellite's View of Coastal Erosion

One expected impact of climate change is an increase in the frequency and severity of storms in the eastern United States. As such, many coastal communities and ecosystems are increasingly vulnerable to the detrimental impacts of coastal erosion. The CoastWatch East Coast node monitors coastal erosion by tracking in-water sediment values. This is done through the calculation of a sediment index based on the amount of red light, a strong indicator of in-water sediment, reflected from coastal waters measured by the VIIRS instrument on-board the Suomi-NPP satellite

As seen in the below sediment index images of the Mid-Atlantic coast before and after the passing of tropical storm Hermine in early September 2016, storms frequently cause coastal erosion and redistribute the coastal sediment offshore.

CoastWatch Sediment Index before (August 27, 2016 - left) and after the passing of tropical storm Hermine (September 6, 2016 - right).
CoastWatch Sediment Index before (August 27, 2016 - left) and after the passing of tropical storm Hermine (September 6, 2016 - right). White depicts high sediment index values and blue depicts low sediment index values. Black represents areas with no data due to land or cloud cover.

    References and Related Reading

    •   Gao, Y., Fu, J.S., Drake, J.B., Liu, Y., Lamarque, J-F. 2012. Projected changes of extreme weather events in the eastern United States based on a high resolution climate modeling system. Environmental Research Letters 7(4).
    •   National Research Council (NRC) Committee on Mitigating Shore Erosion along Sheltered Coasts. 2007.Mitigating Shore Erosion along Sheltered Coasts. National Academies Press, Washington, D.C, USA. ).
    •   Wubbles, D.J., Kunkel, K., Wehner, M., Zobel, Z. 2014. Severe weather in United States under a changing climate. Earth and Space Science News 95(18): 149-150.
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Ocean acidification in the Caribbean

Anthropogenic emissions of carbon dioxide (CO2) have increased dramatically since the Industrial Revolution. The oceans absorb approximately one third of this carbon dioxide. When CO2 is absorbed by seawater, chemical reactions occur that reduce the pH (increase the acidity). "Ocean acidification" refers to this lowering of ocean pH. Among other issues, ocean acidification makes it difficult for calcifying animals, such as corals and shellfish, to grow and thrive. This occurs because sea water at a lower pH has a reduced availability of the carbonate minerals (calcite, aragonite and high-magnesium calcites) these animals use to construct their shells and skeletons.

Coral reefs provide immense ecological and economic benefits to the Caribbean region.
Coral reefs provide immense ecological and economic benefits to the Caribbean region.

In collaboration with the NOAA Atlantic Oceanographic and Meteorological Laboratory's Ocean Chemistry and Ecosystems Division and NOAA Coral Reef Watch , the Caribbean/Gulf of Mexico node of CoastWatch produces an ocean acidification product suite for the greater Caribbean region to track changes in the surface ocean that can be used as an important tool in coral reef research and management.

The suite of ocean acidification products produced by the CoastWatch Caribbean/Gulf of Mexico node and Coral Reef Watch.
The suite of ocean acidification products produced by the CoastWatch Caribbean/Gulf of Mexico node and Coral Reef Watch. Products include SST, SSS, pCO2a, pCO2w, Alk, pH, Ωarg and Ωcal. Source: CoastWatch Caribbean/Gulf of Mexico node.

    References and Related Reading

    •   Wang, W. and R., Ramakrishna. 2016. Dynamic responses of atmospheric carbon dioxide concentration to global temperature changes between 1850 and 2010. Advances in Atmospheric Sciences 33(2): 247-3314.
    •   Glendhill, D.K., R. Wanninkhof, F.J. Millero, and M. Eakin. Ocean acidification of the Greater Caribbean Region 1996-2006. 2008. Journal of Geophysical Research 113: C10031.
    •   Burke, L. and J. Maidens. 2004. Reefs at Risk in the Caribbean. World Resources Institute, Washington, DC.
    •   Sabine, C.L., R.A. Feely, N. Gruber, R.M., Key, K. Lee, J.L. Bullister, R. Wanninkhof, C.S. Wang, D.W.R. Wallace, B. Tilbrook, F.J. Millero, T.H. Peng, A. Kozyr, T. Ono, and A.F. Rios. 2004. Science 305(5682): 367-371.
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