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

Red Tide Blooms Observed by GOCI

This past summer, the fishing industry in South Korea was severely damaged by large scale red tide Cochlodinium blooms that formed along the entire south and east coasts of Korea. The Korea Ocean Satellite Center (KOSC) of KIOST (Korea Institute of Ocean Science and Technology) continuously monitored and analysed satellite images from GOCI (Geostationary Ocean Color Imager) to determine the rates of transport and diffusion of the bloom. The analysis results were sent to government agencies and related organizations in an effort to mitigate the damage from the red tide bloom.

GOCI red-tide
Image from red tide analyses by GOCI at 12:16:43 KST on
13 August 2013.

This year, the red tide patches had low radiance values in the short wavelengths (i.e. GOCI Bands 1, 2, and 3, for the 400 – 500 nm range), and high radiance values at 680 nm due to the increased fluorescence and backscatter. For this reason, red tide patches can be detected using these spectral features. Small scale red tide blooms were first discovered on 13 July 2013 in the South Sea area and they gradually moved into the East Sea of Korea and expanded further north (up to about 39 °N) and then to the open sea near the East Sea of Korea. According to in situ data, the density of Cochlodinium reached ~7,000 cells per ml in the high concentration areas of the red tide blooms.

Source: IOCCG, http://www.ioccg.org/news/Nov2013/news.html