Oceanography The Official Magazine of
The Oceanography Society
Volume 24 Issue 01

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Volume 24, No. 1
Pages 130 - 141


Barrier Layer Control of Entrainment and Upwelling in the Bohol Sea, Philippines

Olivia C. Cabrera Cesar L. VillanoyLaura T. David Arnold L. Gordon
Article Abstract

The Bohol Sea is a relatively unstudied marginal sea located in the southern part of the Philippines. Hydrographic data from the Philippine Straits Dynamics Experiment (PhilEx) cruises reveal a complex three-dimensional circulation composed of two overturning cells that may be referred to as “double-estuarine type.” This type of overturning circulation promotes upwelling of cold, nutrient-rich waters within the Bohol Sea associated with entrainment and eddy processes that promote phytoplankton blooms. Evidence from ocean color imagery supports entrainment in the eastern basin and eddy formation in the southwestern basin. However, PhilEx researchers found that the cyclonic Iligan Bay Eddy in the southwestern basin did not conform to the paradigm of cyclonic eddy upwelling. Although upwelling was evident through doming isotherms within the water column, the surface projection of this signal was suppressed by the presence of a thick barrier layer, particularly during cruises in December 2007 and January 2008, a known La Niña period. Long-term trends in chlorophyll data followed trends in rainfall and the ENSO 3.4 index, with elevated (reduced) chlorophyll during dry El Niño years (wet La Niña years). By promoting stability of surface layer stratification and preventing vertical transport of nutrients, the barrier layer is thus a mechanism by which the El Niño-Southern Oscillation influences phytoplankton biomass in the Bohol Sea.


Cabrera, O.C., C.L. Villanoy, L.T. David, and A.L. Gordon. 2011. Barrier layer control of entrainment and upwelling in the Bohol Sea, Philippines. Oceanography 24(1):130–141, https://doi.org/10.5670/oceanog.2011.10.


Alejandrino, A.A., M.L. Diaz, R.C. Bruce, A.P. Basilio, C.E. Yñiguez, R.G. Salas, and H.B. Bayhon. 1976. Principal River Basins of the Philippines. Report No. 4, National Water Resources Council, Philippines, 82 pp.

Arnone, R.A., A.M. Wood, and R.W. Gould Jr. 2004. The evolution of optical water mass classification. Oceanography 17(2):14–15. [pdf]

Barber, R.T., and F.P. Chavez. 1983. Biological consequences of El Niño. Science 222:1,203–1,210. [CrossRef]

Behrenfeld, M.J., R.T. O’Malley, D.A. Siegel, C.R. McClain, J.L. Sarmiento, G.C. Feldman, A.J. Milligan, P.G. Falkowski, R.M. Letelier, and E.S. Boss. 2006. Climate-driven trends in contemporary ocean productivity. Nature 444:752–755. [CrossRef]

Chu, P.C., Q. Liu, Y. Kia, and C. Fan. 2002. Evidence of a barrier layer in the Sulu and Celebes Seas. Journal of Physical Oceanography 32:3,299–3,309. [CrossRef]

Coble P., C. Hu, R.W. Gould Jr., G. Chang, and A.M. Wood. 2004. Colored dissolved organic matter in the coastal ocean: An optical tool for coastal zone environmental assessment and management. Oceanography 17(2):50–59. [pdf]

Corredor, J.E., J.M. Morell, J.M. López, J.E. Capella, and R.A. Armstrong. 2004. Cyclonic eddy entrains Orinoco River plume. Eos, Transactions, American Geophysical Union 85:197–208. [CrossRef]

Du, Y., D. Wang, P. Shi, P. Guo, and J. Chen. 2004. Barrier layer in the South China Sea and its relationship to the sea surface fluxes. Chinese Journal of Atmospheric Sciences 28:101–111.

Falkowski, P.G., D. Ziemann, Z. Kolber, and P.K. Bienfang. 1991. Role of eddy pumping in enhancing primary production in the ocean. Nature 352:55–58. [CrossRef]

Garcia, C.A.E., and V.M.T. Garcia. 2008. Variability of chlorophyll-a from ocean color images in the La Plata continental shelf region. Continental Shelf Research 28:1,568–1,578. [CrossRef]

Gregg, W.W., and M.E. Conkright. 2002. Decadal changes in global ocean chlorophyll. Geophysical Research Letters 29:1,730–1,734. [CrossRef]

Gordon, A.L., J. Sprintall, and A. Ffield. 2011. Regional oceanography of the Philippine Archipelago. Oceanography 24(1):14–27. [CrossRef]

Hu, C., E.T. Montgomery, R.W. Schmitt, and F.E. Muller-Karger. 2004. The dispersal of the Amazon and Orinoco River plumes in the tropical Atlantic and Caribbean Sea: Observation from space and S-PALACE floats. Deep-Sea Research Part II 51:1,151–1,171. [CrossRef]

Hurlburt, H.E., E.J. Metzger, J. Sprintall, S.N. Riedlinger, R.A. Arnone, T. Shinoda, and X. Xu. 2011. Circulation in the Philippine Archipelago simulated by 1/12° and 1/25° global HYCOM and EAS NCOM. Oceanography 24(1):28–47. [CrossRef]

Juneng, L., and F.T. Tangang. 2005. Evolution of ENSO-related rainfall anomalies in Southeast Asia region and its relationship with the atmosphere-ocean variations in Indo-Pacific sector. Climate Dynamics 25:337–350. [CrossRef]

Lukas, R., and E. Lindstrom. 1991. The mixed layer of the western equatorial Pacific Ocean. Journal of Geophysical Research 96:3,343–3,357. [CrossRef]

Lyon, B., H. Cristi, E.R. Verceles, F.D. Hilario, and R. Abastillas. 2006. Seasonal reversal of the ENSO rainfall signal in the Philippines. Geophysical Research Letters 33, L24710. [CrossRef]

Martinez, E., D. Antoine, F. D’Ortenzio, and B. Gentili. 2009. Climate-driven basin-scale decadal oscillations of oceanic phytoplankton. Science 326:1,253–1,256. [CrossRef]

McGillicuddy, D.J. Jr., A.R. Robinson, D.A. Siegel, H.W. Jannasch, R. Johnson, T.D. Dickey, J. McNeil, A.F. Michaels, and A.H. Knap. 1998. Influence of mesoscale eddies on new production in the Sargasso Sea. Nature 394:263–266. [CrossRef]

McGillicuddy, D.J. Jr., L.A. Anderson, N.R. Bates, T. Bibby, K.O. Buesseler, C.A. Carlson, C.S. Davis, C. Ewart, P.G. Falkowski, S.A. Goldthwait, and others. 2007. Eddy/wind interactions stimulate extraordinary mid-ocean plankton blooms. Science 316:1,021–1,026. [CrossRef]

Morel, A., and B. Gentili. 2009. A simple band ratio technique to quantify the colored dissolved and detrital organic material from ocean color remotely sensed data. Remote Sensing of Environment 113:998–1,011. [CrossRef]

O’Reilly, J.E., S. Maritorena, B.G. Mitchell, D.A. Siegel, K.L. Carder, S.A. Garver, M. Kahru, and C. McClain. 1998. Ocean color chlorophyll algorithms for SeaWiFS. Journal of Geophysical Research 103:24,937–24,954. [CrossRef]

Pan, A., X. Wan, J. Xu, X. Guo, and L. Li. 2006. Barrier layer in the northeastern South China Sea and its formation mechanism. Chinese Science Bulletin 51:472–479. [CrossRef]

Qu, T., and G. Meyers. 2005. Seasonal variation of barrier layer in the southeastern tropical Indian Ocean. Journal of Geophysical Research 110, C11003. [CrossRef]

Qu, T., Y. Du, J. Strachan, G. Meyers, and J. Slingo. 2005. Sea surface temperature and its variability in the Indonesian region. Oceanography 18(4):50–61. [pdf]

Sprintall, J., and M. Tomczak. 1992. Evidence of the barrier layer in the surface layer of the tropics. Journal of Geophysical Research 97:7,305–7,316. [CrossRef]

Smith, W.H.F., and D.T. Sandwell. 1997. Global seafloor topography from satellite altimetry and ship depth soundings. Science 277:1,957–1,962. [CrossRef]

Stewart, R.H. 2005. Introduction to Physical Oceanography. Available online at http://oceanworld.tamu.edu/resources/ocng_textbook/contents.html (accessed August 15, 2010).

Wu, M.C., and J.C.L. Chan. 2005. Observational relationships between summer and winter monsoons over East Asia. International Journal of Climatology 25:437–451. [CrossRef]

Wyrtki, K. 1961. Physical Oceanography of the Southeast Asian Waters. University of California, NAGA Report, No. 2, 195 pp.

Zeng, L., Y. Du, S.P. Xie, and D. Wang. 2009. Barrier layer in the South China Sea during summer 2000. Dynamics of Atmosphere and Oceans 47:38–54. [CrossRef]

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