Spatial distribution of phytoplankton along the Sunda Islands: The monsoon anomaly in 1998

Asanuma, I., K. Matsumoto, H. Okano, T. Kawano, N. Hendiatri, and S.I. Sachoemar (2003): Spatial distribution of phytoplankton along the Sunda Islands: The monsoon anomaly in 1998. J. Geophys. Res., 108 (C6), 3202, doi:10.1029/1999JC000139.

Abstract

Recent ocean color and microwave observations are used to assess the spatial distribution of phytoplankton blooming relative to monsoons along the Sunda Islands. In 1997 and 1999, during the northwest monsoon the eastward South Java Current (SJC) along the Sunda Islands restrained the flows from the straits along the Sunda Islands and ceased blooming. During the southeast monsoon the westward South Equatorial Current (SEC) and the southeasterly wind generated cyclonic eddies along the Sunda Islands. The blooming was observed over those cyclonic eddies, where nutrients were entrained to the surface. In 1998, through the northwest to the southeast monsoon the eastward currents were flowing away from the coast. During the southeast monsoon the SEC was not observed. Through 1998, cyclonic eddies were observed along the Sunda Islands in consequence of these anomalies. The distribution of currents is defined for the monsoon anomaly in 1998. (1) The eastward SJC flowed away from the coast in the northwest monsoon. (2) No westward SEC was observed in the southeast monsoon. (3) The eastward SJC restrained the flow from the straits in the southeast monsoon. (4) Chlorophyll a ∼1 mg m−3 were observed along the Sunda Islands through the year. This monsoon anomaly is hypothesized as a result of anomalies in the distribution of pressure systems between the Pacific and the Indian Ocean following to the El Niño.

Keywords:

  • phytoplankton;
  • chlorophyll;
  • ocean color;
  • remote sensing;
  • Indonesia;
  • through flow

Upwelling along the coasts of Java and Sumatra and its relation to ENSO

R. Dwi Susanto,Arnold L. Gordon,Quanan Zheng,2001. Upwelling along the coasts of Java and Sumatra and its relation to ENSO. Geophysical Research Letters, Volume 28, Issue 8, pages 1599–1602, 15 April 2001.

Abstract

Upwelling along the Java-Sumatra Indian Ocean coasts is a response to regional winds associated with the monsoon climate. The upwelling center with low sea surface temperature migrates westward and toward the equator during the southeast monsoon (June to October). The migration path depends on the seasonal evolution of alongshore winds and latitudinal changes in the Coriolis parameter. Upwelling is eventually terminated due to the reversal of winds associated with the onset of the northwest monsoon and impingement of Indian Ocean equatorial Kelvin waves. Significant interannual variability of the Java-Sumatra upwelling is linked to ENSO through the Indonesian throughflow (ITF) and by anomalous easterly wind. During El Niño episodes, the Java-Sumatra upwelling extends in both time (into November) and space (closer to the equator). During El Nino (La Niña), the ITF carries colder (warmer) water shallowing (deepening) thermocline depth and enhancing (reducing) upwelling strength.

Keywords:

  • Information Related to Geographic Region: Indian Ocean
  • Oceanography: General: Equatorial oceanography
  • Oceanography: General: Upwelling and convergences
  • Oceanography: Physical: El Nino

Upwelling variability along the southern coast of Bali and in Nusa Tenggara waters

Nining Sari Ningsih,Noviani Rakhmaputeri,Agung B. Harto, 2013. Upwelling variability along the southern coast of Bali and in Nusa Tenggara waters. Ocean Science Journal, Volume 48, Issue 1, pp 49-57. DOI 10.1007/s12601-013-0004-3.

Abstract

Spatial and temporal variation of upwelling along the southern coast of Bali and in the Nusa Tenggara waters — Indonesia was studied by using satellite image data of sea surface temperatures and chlorophyll-a from September 1997 to December 2008. This study clearly reveals annual upwelling in the regions from June to October, associated with the southeast monsoon cycle, with the sea surface temperature (chlorophyll-a concentration) being colder (higher) than that during the northwest monsoon. In addition, this study also shows that the upwelling strength is controlled remotely by ENSO and IOD climate phenomena. During El Niño/positive IOD (La Niña/negative IOD) periods, the Bali — Nusa Tenggara upwelling strength increases (decreases).

Keywords:

  • upwelling
  • monsoon
  • ENSO
  • IOD
  • Bali-Nusa Tenggara

Ocean color variability in the Indonesian Seas during the SeaWiFS era

Susanto, R. D., T. S. Moore II, and J. Marra (2006), Ocean color variability in the Indonesian Seas during the SeaWiFS era, Geochem. Geophys. Geosyst., 7, Q05021, doi:10.1029/2005GC001009.

Abstract:

More than 6 years of satellite-derived ocean color (SeaWiFS) and 7 years of sea surface temperature (AVHRR) and sea surface wind (ERS1/2, NSCAT, and QuikSCAT) are investigated for the Indonesian Seas. Harmonic analysis and monthly means in ocean color indicate that during the southeast Asia-Australia monsoon southeasterly wind from Australia generates upwelling and brings cooler and nutrient-rich water near the surface, enhancing productivity and increasing ocean color in the Banda Sea and the southern coasts of Jawa (Java)-Sumatra. Conditions are reversed during the northwest monsoon. The northwest wind induces downwelling and produces a weaker biological response in terms of ocean color. Anomalous winds associated with the 1997–1998 El Niño/La Niña events coinciding with the Indian Ocean Dipole (IOD) produced significant departures from the 6-year monthly mean in both magnitude and timing of the seasonal response to the southeast monsoon. Ocean color intensified in the upwelling region along the southern coast of Jawa-Sumatra, and the area of increased amplitude extended westward and prolonged the southeast monsoon period. In addition, localized minimum values of ocean color are observed along the exit pathways of the Indonesian Throughflow.

Keywords:

  • Indonesian Seas;
  • ENSO;
  • monsoon;
  • upwelling;
  • ocean color;
  • remote sensing

Investigation of different coastal processes in Indonesian waters using SeaWiFS data

Nani Hendiartia, Herbert Siegelb, Thomas Ohdeb

Deep Sea Research Part II: Topical Studies in Oceanography, Volume 51, Issues 1–3, January–February 2004, Pages 85–97

http://dx.doi.org/10.1016/j.dsr2.2003.10.003

Abstract:

SeaWiFS data were applied to investigate coastal processes in Indonesian waters around the most populated island of Java. Coastal processes due to wind forcing were studied the first time using SeaWiFS-derived chlorophyll and TSM concentrations in combination with AVHRR-derived SST in the period from September 1997 to December 2001. Upwelling events were studied along the southern coast of Java during the southeast monsoon (June to September). Satellite-derived chlorophyll concentrations higher than View the MathML source and sea-surface temperatures lower than 28°C are indications of upwelling. Upwelling events influence the distribution and growth of phytoplankton and provide by that good feeding condition for zooplankton, larvae, juvenile and adult of pelagic fish.

Coastal discharge into the western Java Sea contains organic and inorganic materials originating from different sources. Diffuse impacts, particularly from fish farms and aquaculture, as well as coastal erosion influence large coastal areas during the rainy season (December to March), and to a lesser extent during the dry season. Strong Citarum river discharge was observed during the transition phase from the rainy to the dry season (March and April), when the maximum amount of transported material reaches the sea. The river plume is evident from chlorophyll concentrations higher than View the MathML source, and suspended particulate matter concentrations of more than View the MathML source. The Sunda Strait is seasonally influenced by water transport from the Java Sea and from the Indian Ocean. The satellite data show that water transport from the Java Sea occurs during the pre-dominantly easterly winds period (June to September). This is characterized by warm water (SST higher than 29.5°C) and chlorophyll concentrations higher than View the MathML source. This water transport influences the fish abundance in the Sunda Strait. High fish catches coincide with the presence of Java Sea water, while the surface currents lead to the migration of pelagic fish. Conversely, during the dominant westerly winds period, oceanic waters from the Indian Ocean with low chlorophyll concentrations influence the Sunda Strait water.