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

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.

 

Three-dimensional observations from MODIS and CALIPSO for ocean responses to cyclone Nargis in the Gulf of Martaban

Shi, W., and M. Wang (2008), Three-dimensional observations from MODIS and CALIPSO for ocean responses to cyclone Nargis in the Gulf of Martaban, Geophys. Res. Lett., 35, L21603, doi:10.1029/2008GL035279.

Abstract:

Satellites measurements from the Moderate Resolution Imaging Spectroradiometer (MODIS) on Aqua and the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) are used to study physical, optical, and biological changes in the Gulf of Martaban following the passage of cyclone Nargis during early May of 2008. The shortwave infrared (SWIR) atmospheric correction algorithm has been used to derive ocean optical and biological properties from MODIS. Following the passage of cyclone Nargis, a significant increase of surface sediment concentration is observed with considerably enhanced normalized water-leaving radiance at the red and near-infrared (NIR) wavelengths in the Gulf of Martaban and along the mouths of the Ayeyarwady River. It is estimated that, before and after cyclone Nargis, the average total suspended matter (TSM) in the Gulf of Martaban increased from 24 mg/l to 31 mg/l, while the TSM value nearly tripled from 12 mg/l to 34 mg/l along the mouths of the Ayeyarwady River. The CALIPSO measurements also show that, before cyclone Nargis, the sediment concentration in the region increases with depth in the water column, while after cyclone Nargis the sediment vertical profile becomes relatively uniform in the upper 50 m depth due to wind-driven vertical mixing and entrainment.

Keywords:

  • cyclone Nargis;
  • remote sensing;
  • MODIS and CALIPSO

Upwelling induced by meso-scale cyclonic eddies in the Andaman Sea

Buranapratheprat, Anukul,Laongmanee, Penchan,Sukramongkol, Natinee,Prommas, Ritthirong,Promjunda, Sayan,Yanagi, Tetsuo, 2010. Upwelling induced by meso-scale cyclonic eddies in the Andaman Sea. Coastal marine science. Vol. 34, No. 1, 2010, pp. 68-73

http://hdl.handle.net/2261/51653

Abstract:

The results from a survey on oceanographic phenomena and fishery resources in the Andaman Sea, under the Ecosystem-Based Fishery Management in the Bay of Bengal Project, initiated by members of BIMSTEC (the Bay of Bengal Initiative for Multi-Sectoral Technical and Economic cooperation), revealed the evidence of upwelling. It was observed from shallow pycnocline and high salinity near sea surface. The relationship between surface chlorophyll-a (Chl-a) and upwelling was prominent that Chl-a tended to be high in upwelling areas. Satellite altimetry and the surface geostropic current captured during the same period of the field survey, suggest that upwelling is induced by cyclonic eddies. This phenomenon could be observed on satellite Chl-a image over the Andaman Sea. Further investigations are required to assess their role in oceanographic processes, especially primary productivity, in the Andaman Sea.

Keywords:

  • cyclonic eddy
  • upwelling
  • altimetry
  • geostrophic current
  • the Andaman Sea
  • nutrient
  • chlorophyll

Abnormal upwelling and chlorophyll-a concentration off South Vietnam in summer 2007

Liu, X., J. Wang, X. Cheng, and Y. Du (2012), Abnormal upwelling and chlorophyll-a concentration off South Vietnam in summer 2007, J. Geophys. Res., 117, C07021, doi:10.1029/2012JC008052.

Abstract

The present study investigates a strong upwelling and concurrent phytoplankton bloom off the South Vietnam coast in August 2007. Analysis of the alongshore wind, offshore Ekman transport, wind stress curl and other parameters indicates the southwesterly summer monsoon plays an important role in this peculiar case. The change of monsoonal wind involves variations of atmospheric circulation on multiple time scales. On the interannual time scale, a positive Indian Ocean Dipole (IOD) in 2007 accompanying with a La Niña event acts to enhance the southwesterly monsoon over the South China Sea (SCS). The enhanced southwesterly wind is regarded as a major factor in promoting the upwelling and the phytoplankton bloom off the South Vietnam coast. On the intraseasonal time scale, variations of the sea surface temperature (SST) and sea surface wind at 30-60 day periods reveal that the SST cooling develops with the evolution of the southwesterly wind anomalies with nearly one week delay, implying the great significance of the Madden-Julian Oscillation (MJO). Moreover, a tropical storm formed in the western SCS in early August reinforces the westerly wind and SST cooling. Among multiple factors on different time scales, the MJO event is considered as the major cause, since it induces the maximum velocity (4 m/s) of the southwesterly wind anomalies. As a result, the high Chlorophyll-a concentration (>0.56 mg/m3) and low SST center (<27 {degree sign}C) develops in the region off the South Vietnam coast and advects to the central SCS, riding on the northern rim of the southern anticyclonic gyre.

Keywords:

  • Chlorophyll-a concentration
  • El Niño
  • Indian Ocean dipole
  • Madden-Julian Oscillation
  • South Vietnam coast
  • upwelling

Remote sensing oceanography of a harmful algal bloom (HAB) off the coast of southeastern Vietnam

DanLing TANG, H Kawamura, Hai Doan-Nhu, W Takahashi , 2004. Remote sensing oceanography of a harmful algal bloom (HAB) off the coast of southeastern Vietnam. J. of Geophysical Research (Ocean).Vol 109, doi:10.1029/2003JC002045, 2004.

Abstract

Harmful algal blooms (HABs) in the southeastern Vietnamese coastal waters have caused large economic losses in aquacultured and wild fisheries in recent years; however, there have been few oceanographic studies on these HAB events. The present study reports an extensive HAB off southeastern Vietnamese waters during late June to July 2002 with in situ observations and analyzes the oceanographic conditions using satellite remote sensing data. The HAB had high chlorophyll a (Chl a) concentrations (up to 4.5 mg m−3) occurring ∼200 km off the coast and ∼200 km northeast of the Mekong River mouth for a period of ∼6 weeks. The bloom was dominated by the harmful algae haptophyte Phaeocystis cf. globosa and caused a very significant mortality of aquacultured fish and other marine life. In the same period, sea surface temperature (SST) imagery showed a cold water plume extending from the coast to the open sea, and QuikScat data showed strong southwesterly winds blowing parallel to the coastline. This study indicated that the HAB was induced and supported by offshore upwelling that brings nutrients from the deep ocean to the surface and from coastal water to offshore water and that the upwelling was driven by strong wind through Ekman transport when winds were parallel to the coastline. This study demonstrated the possibility of utilizing a combination of satellite data of Chl a, SST, and wind velocity together with coastal bathymetric information and in situ observations to give a better understanding of the biological oceanography of HABs.

Keywords:

  • harmful algal bloom (HAB);
  • satellite remote sensing;
  • upwelling;
  • SeaWiFS;
  • chlorophyll a;
  • AVHRR SST;
  • South China Sea