The circulation in the source area of the South Equatorial Current in the eastern Indian Ocean

1996 ◽  
Vol 101 (C5) ◽  
pp. 12483-12488 ◽  
Author(s):  
Detlef Quadfasel ◽  
Andrea Frische ◽  
George Cresswell
Keyword(s):  
Indian Ocean ◽  
Source Area ◽  
Eastern Indian Ocean ◽  
The South ◽  
South Equatorial Current ◽  
Equatorial Current

scholarly journals Current and sea level control the demise of shallow carbonate production on a tropical bank (Saya de Malha Bank, Indian Ocean)

Geology ◽  
2021 ◽  
Author(s):  
Christian Betzler ◽  
Sebastian Lindhorst ◽  
Thomas Lüdmann ◽  
John J. Reijmer ◽  
Juan-Carlos Braga ◽  
...  
Keyword(s):  
Indian Ocean ◽  
Sea Level ◽  
Coral Growth ◽  
Carbonate Platforms ◽  
The South ◽  
South Equatorial Current ◽  
Carbonate Production ◽  
Equatorial Current ◽  
Saya De Malha Bank ◽  
And Sea Level

Carbonate platforms are built mainly by corals living in shallow light-saturated tropical waters. The Saya de Malha Bank (Indian Ocean), one of the world’s largest carbonate platforms, lies in the path of the South Equatorial Current. Its reefs do not reach sea level, and all carbonate production is mesophotic to oligophotic. New geological and oceanographic data unravel the evolution and environment of the bank, elucidating the factors determining this exceptional state. There are no nutrient-related limitations for coral growth. A switch from a rimmed atoll to a current-exposed system with only mesophotic coral growth is proposed to have followed the South Equatorial Current development during the late Neogene. Combined current activity and sea-level fluctuations are likely controlling factors of modern platform configuration.

Epipelagic mesozooplankton dynamics around the Mascarene Plateau and Basin, Southwestern Indian Ocean

2005 ◽  
Vol 363 (1826) ◽  
pp. 191-202 ◽  
Author(s):  
Christopher P. Gallienne ◽  
Denise Smythe-Wright
Keyword(s):  
Indian Ocean ◽  
Western Indian Ocean ◽  
Environmental Data ◽  
The South ◽  
South Equatorial Current ◽  
Northern Edge ◽  
Biochemical Measurements ◽  
Equatorial Current ◽  
Sampling Programme ◽  
Large Research

It has been suggested that the obstruction of the South Equatorial Current by the Mascarene Plateau might cause upwelling, nutrient enrichment and enhanced chlorophyll and secondary production levels downstream. A study conducted in April and May 2001 showed variability in biomass and community structure which appeared to support this hypothesis but, in the absence of supporting physical and biochemical measurements, we were unable to confirm it. In June and July 2002 the sampling was repeated with the supporting environmental measurements available from a large research vessel. In this paper we present the results from this sampling programme, compare them with the 2001 results, and examine both datasets in the light of physical and other environmental data gathered during the 2002 programme in order to evaluate the evidence for significant upwelling around the Mascarene Plateau. The evidence is inconclusive: the 2002 dataset shows only a little evidence of topographic upwelling. However, the mesozooplankton and other physical and biochemical data from the 2002 sampling programme indicate support for the theory of an open–ocean upwelling between 5 and 10○ S across the central and western Indian Ocean from 50 to 90° E, due to Ekman divergence along the northern edge of the South Equatorial Current. It is possible that these two separate sources of upwelling may coexist and combine at times, producing the very high levels of biomass found during 2001.

scholarly journals Molecular and spatial distributions of dicarboxylic acids, oxocarboxylic acids, and <i>α</i>-dicarbonyls in marine aerosols from the South China Sea to the eastern Indian Ocean

2020 ◽  
Vol 20 (11) ◽  
pp. 6841-6860 ◽  
Author(s):  
Jing Yang ◽  
Wanyu Zhao ◽  
Lianfang Wei ◽  
Qiang Zhang ◽  
Yue Zhao ◽  
...  
Keyword(s):  
Sri Lanka ◽  
Indian Ocean ◽  
South China Sea ◽  
South China ◽  
The South China Sea ◽  
Photochemical Oxidation ◽  
Eastern Indian Ocean ◽  
The South ◽  
China Sea ◽  
Mass Ratios

Abstract. Marine aerosol samples collected from the South China Sea (SCS) to the eastern Indian Ocean (EIO) during a cruise from 10 March to 26 April 2015 were studied for diacids and related compounds. In view of air mass backward trajectories, source regions, and geographical features, the cruise area was categorized into the South China Sea (SCS), the eastern Indian Ocean off the coast of western Indonesia (EIO-WI), the EIO off the coast of Sri Lanka (EIO-SL), Malacca, and the Sri Lanka docking point (SLDP). Total concentrations of diacids, oxoacids, and α-dicarbonyls were high at the SLDP, followed by the SCS and Malacca, and they were the low in the EIO-WI. In this study, oxalic acid (C2) was the dominant diacid during the cruise, followed by malonic acid (C3) in the SCS, EIO-WI, EIO-SL, and Malacca, and succinic acid (C4) was relatively more abundant than C3 diacid at the SLDP. Except for SLDP, C3∕C4 mass ratios were always greater than 1, and no significant difference was observed during the cruise. The C2∕C4 and C2∕total diacid ratios also showed similar trends. The average mass ratios of adipic acid (C6) to azelaic acid (C9) were less than unity except for in the EIO-WI; the mass ratios of phthalic acid (Ph) to azelaic acid (C9) were less than 2 except for in the SCS. The concentrations of diacids were higher when the air masses originated from terrestrial regions than when they originated from remote oceanic regions. Based on the molecular distributions of organic acids, the mass ratios, and the linear correlations of selected compounds in each area, we found that the oxidation of biogenic volatile organic compounds (BVOCs) released from the ocean surface and subsequent in situ photochemical oxidation was the main contributor to diacids, oxocarboxylic acids, and α-dicarbonyls from the SCS to the EIO. In addition, the continental outflow, which is enriched in anthropogenic VOCs and their aged products, influenced the organic aerosol loading, particularly over the SCS. Emissions from Sri Lanka terrestrial vegetation as well as fossil fuel combustion and subsequent photochemical oxidation also played a prominent role in controlling the organic aerosol loading and the molecular distribution of diacids and related compounds at the SLDP.

scholarly journals Seasonal Variation of the Pacific South Equatorial Current Bifurcation

2015 ◽  
Vol 45 (6) ◽  
pp. 1757-1770 ◽  
Author(s):  
Zhaohui Chen ◽  
Lixin Wu
Keyword(s):  
Wave Propagation ◽  
Seasonal Variation ◽  
Rossby Wave ◽  
Wind Forcing ◽  
The South ◽  
Wind Stress Curl ◽  
South Equatorial Current ◽  
Wave Dynamics ◽  
Equatorial Current ◽  
Rossby Wave Propagation

AbstractThe seasonal variation of the South Equatorial Current (SEC) bifurcation off the Australian coast in the South Pacific (SP) is investigated with observations and a nonlinear, reduced-gravity, primitive equation model of the upper ocean. The mean SEC bifurcation latitude (SBL) integrated over the upper thermocline is around 17.5°S, almost 2° south of the position predicted by Sverdrup theory. For its seasonal variation, the SBL reaches its southernmost position in June/July and its northernmost position in November/December. The south–north migration of 2.7° is twice as large as its counterpart in the North Pacific. It is found that the large seasonal amplitude of the SBL results from the combined effect of Low-Lat-SP and Non-Low-Lat-SP processes. The Low-Lat-SP process (referred to as the Rossby wave dynamics forced by the wind stress curl over the low-latitude SP) accounts for almost ⅔ of the SBL seasonal variability, and the Non-Low-Lat-SP processes account for ⅓. Both of these processes are responsible for its south–north migration but in different ways. The Low-Lat-SP wind forcing determines the offshore upper-layer thickness (ULT) via Rossby wave propagation, while the Non-Low-Lat-SP wind forcing determines the alongshore ULT via coastal Kelvin wave propagation. A simple bifurcation model is proposed under the framework of linear Rossby wave dynamics. It is found that the seasonal bifurcation latitude is predominantly determined by the spatial pattern of the wind and baroclinic Rossby wave propagation. This model explains the roles of local/remote wind forcing and baroclinic adjustment in the south–north migration and peak seasons of the bifurcation latitude.

Sign in / Sign up

Export Citation Format

Share Document