East Australian current adjacent to the Great Barrier Reef

1987 ◽  
Vol 38 (6) ◽  
pp. 671 ◽  
Author(s):  
JA Church
Keyword(s):  
Great Barrier Reef ◽  
Bifurcation Point ◽  
Monsoon Season ◽  
Surface Flow ◽  
Barrier Reef ◽  
Surface Shear ◽  
Near Surface ◽  
Indonesian Archipelago ◽  
The Pacific ◽  
The Indian Ocean

Hydrographic data from a series of cruises during 1980-1981 are used to determine the circulation in the western Coral Sea region immediately adjacent to the Great Barrier Reef. The data show flow westward towards the Great Barrier Reef, bifurcating just north of 18�S. During the monsoon season (December to February), the bifurcation point moves north to at least 14�s. The geostrophic westward flow has a subsurface maximum at a depth of about 150 m. South of the bifurcation point, the flow is south-eastward on the upper continental slope and north-eastward offshore. North of the bifurcation point, the surface flow and transport (relative to 900 dbar) are northward. However, there is sometimes a south-eastwards near-surface shear. Near the bifurcation point, the surface currents are weak and variable. All of these features of the surface flow are reflected in the paths followed by satellite-tracked drifters. Although the drifters were fixed infrequently, the drifter data indicate the possible presence of small cyclonic eddies in the region of the bifurcation. All of the satellite-tracked drifters went aground in the Great Barrier Reef within 30 days of entering the region offshore from the Reef. The data are consistent with recent models of the wind-driven circulation in the South Pacific that propose that the westward flow bifurcates at about 20�S., with 17 x 106 m3 s-1 flowing through the Indonesian Archipelago from the Pacific Ocean to the Indian Ocean.

scholarly journals Coral Luminescence Identifies the Pacific Decadal Oscillation as a Primary Driver of River Runoff Variability Impacting the Southern Great Barrier Reef

PLoS ONE ◽  
2014 ◽  
Vol 9 (1) ◽  
pp. e84305 ◽  
Author(s):  
Alberto Rodriguez-Ramirez ◽  
Craig A. Grove ◽  
Jens Zinke ◽  
John M. Pandolfi ◽  
Jian-xin Zhao
Keyword(s):  
Great Barrier Reef ◽  
Pacific Decadal Oscillation ◽  
River Runoff ◽  
Barrier Reef ◽  
The Pacific ◽  
Primary Driver ◽  
Runoff Variability

scholarly journals On the Indonesian throughflow in the OCCAM 1/4 degree ocean model

2007 ◽  
Vol 4 (2) ◽  
pp. 325-370 ◽  
Author(s):  
U. W. Humphries ◽  
D. J. Webb
Keyword(s):  
Indian Ocean ◽  
Ocean Model ◽  
Global Ocean ◽  
Indonesian Throughflow ◽  
Island Rule ◽  
Near Surface ◽  
The North ◽  
The Pacific ◽  
The Indian Ocean ◽  
Pass Through

Abstract. The Indonesian Throughflow is analysed in two runs of the OCCAM 1/4 degree global ocean model, one using monthly climatological winds and one using ECMWF analysed six-hourly winds for the period 1993 to 1998. The long-term model throughflow agrees with observations and the value predicted by Godfrey's Island Rule. The Island Rule has some skill in predicting the annual signal each year but is poor at predicting year to year and shorter term variations in the total flow especially in El Nino years. The spectra of transports in individual passages show significant differences between those connecting the region to the Pacific Ocean and those connecting with the Indian Ocean. This implies that different sets of waves are involved in the two regions. Vertical profiles of transport are in reasonable agreement with observations but the model overestimates the near surface transport through the Lombok Strait and the dense overflow from the Pacific through the Lifamatola Strait into the deep Banda Sea. In both cases the crude representation of the passages by the model appears responsible. In the north the model shows, as expected, that the largest transport is via the Makassar Strait. However this is less than expected and instead there is significant flow via the Halmahera Sea. If Godfrey's Island Rule is correct and the throughflow is forced by the northward flow between Australia and South America, then the Halmahers Sea route should be important. It is the most southerly route around New Guinea to the Indian Ocean and there is no apparent reason why the flow should go further north in order to pass through the Makassar Strait. The model result thus raises the question of why in reality the Makassar Strait route appears to dominate the throughflow.

scholarly journals Bomb 14C in the Indian Ocean Measured by Accelerator Mass Spectrometry: Oceanographic Implications

Radiocarbon ◽  
1989 ◽  
Vol 31 (03) ◽  
pp. 510-522 ◽  
Author(s):  
Edouard Bard ◽  
Maurice Arnold ◽  
J R Toggweiler ◽  
Pierre Maurice ◽  
Jean-Claude Duplessy
Keyword(s):  
Mass Spectrometry ◽  
Indian Ocean ◽  
General Circulation ◽  
Circulation Model ◽  
Equatorial Indian Ocean ◽  
Equatorial Zone ◽  
Mode Water ◽  
Indonesian Archipelago ◽  
The Pacific ◽  
The Indian Ocean

AMS 14C measurements on samples collected in the tropical-equatorial Indian Ocean during the INDIGO program (leg II, 1986) are presented and compared with β-counting results obtained under both INDIGO program and GEOSECS expedition in the Indian Ocean (1978). The most significant observation is a doubling of the bomb-14C inventory and mean penetration depth in the equatorial zone. Based on hydrologic considerations, two hypotheses can be proposed: 1) direct influx of Pacific mid-latitude waters through the Indonesian archipelago and 2) advection and/or mixing with Mode Water from the southern gyre of the Indian Ocean. Results obtained with a general circulation model of the ocean suggest that the influx from the Pacific is important in the upper 300m and that below 500m the bomb-14C budget is dominated by Mode Water advection.

scholarly journals On the Indonesian Throughflow in the OCCAM 1/4 degree ocean model

Ocean Science ◽  
2008 ◽  
Vol 4 (3) ◽  
pp. 183-198 ◽  
Author(s):  
U. W. Humphries ◽  
D. J. Webb
Keyword(s):  
Indian Ocean ◽  
Ocean Model ◽  
Global Ocean ◽  
Indonesian Throughflow ◽  
Island Rule ◽  
Near Surface ◽  
The North ◽  
The Pacific ◽  
The Indian Ocean ◽  
Pass Through

Abstract. The Indonesian Throughflow is analysed in two runs of the OCCAM 1/4 degree global ocean model, one using monthly climatological winds and one using ECMWF analysed six-hourly winds for the period 1993 to 1998. The long-term model throughflow agrees with observations and the value predicted by Godfrey's Island Rule. The Island Rule has some skill in predicting the annual signal each year but is poor at predicting year to year and shorter term variations in the total flow, especially in El Niño years. The spectra of transports in individual passages show significant differences between those connecting the region to the Pacific Ocean and those connecting with the Indian Ocean. On investigation we found that changes in the northern transports were strongly correlated with changes in the position of currents in the Celebes Sea and off Halmahera. Vertical profiles of transport are in reasonable agreement with observations but the model overestimates the near surface transport through the Lombok Strait and the dense overflow from the Pacific through the Lifamatola Strait into the deep Banda Sea. In both cases the crude representation of the passages by the model appears responsible. In the north the model shows, as expected, that the largest transport is via the Makassar Strait. However this is less than expected and instead there is significant flow via the Halmahera Sea. If Godfrey's Island Rule is correct and the throughflow is forced by the northward flow between Australia and South America, then the Halmahers Sea route should be important. It is the most southerly route around New Guinea to the Indian Ocean and there is no apparent reason why the flow should go further north in order to pass through the Makassar Strait. The model result thus raises the question of why in reality the Makassar Strait route appears to dominate the throughflow.

scholarly journals Navigating the Great Barrier Reef: The Inner and Outer Routes, 1815-1860

2021 ◽  
Vol 33 (1) ◽  
pp. 37-53
Author(s):  
Kenneth Morgan
Keyword(s):  
Great Barrier Reef ◽  
East Coast ◽  
Barrier Reef ◽  
Open Sea ◽  
The Pacific ◽  
Eastern Edge

This article examines naval surveying voyages undertaken between 1815 and 1860 by Phillip Parker King, Francis Price Blackwood, Owen Stanley and Henry Mangles Denham to discuss the improvements to the navigation of the Inner and Outer shipping routes along the Great Barrier Reef. The Inner Route lay between Australia’s east coast and the western edge of the reefs while the Outer Route was situated in open sea beyond the eastern edge of the reefs. These were some of the most dangerous waters for ships in the Pacific off Australia’s east coast. The article analyses the improvements to both routes resulting from the surveying of the naval commanders referred to above; it explains why the choice between the Inner and Outer routes was difficult to make; and it shows that the Outer Route was increasingly favoured by merchant vessels.

First record of the genus Umimayanthus from Palau and Micronesia

2015 ◽  
Vol 8 ◽  
Author(s):  
Javier Montenegro ◽  
Julien Lorion ◽  
James Davis Reimer
Keyword(s):  
Molecular Markers ◽  
Great Barrier Reef ◽  
Red Sea ◽  
Pacific Islands ◽  
New Caledonia ◽  
Morphological Characteristics ◽  
First Record ◽  
Barrier Reef ◽  
The Pacific ◽  
The Family

Until recently, the only sponge-associated genera in the order Zoantharia wereParazoanthus(family Parazoanthidae),EpizoanthusandThoracactis(family Epizoanthidae), both within the suborder Macrocnemina. The taxonomy of the genusParazoanthus,as originally described, has been undergoing revision since 2010, with several species, genera and even families described. In 2015, multiple molecular markers were used in combination with morphological characteristics to erect the genusUmimayanthusinside the family Parazoanthidae. It included three species described from southern Japan, with other records for some of the species from the Great Barrier Reef, New Caledonia and the Red Sea. However, little is known of its distribution in the Pacific Islands. Here we report on the finding ofUmimayanthusspecimens in Palau, Micronesia, representing the first records for this region. A total of 32 specimens ofUmimayanthuswere collected from seven different locations; eight of the specimens were identified asUmimayanthus chanpuru,while the remaining 24 colonies were only identified to genus level.

scholarly journals Near-Surface Shear Flow in the Tropical Pacific Cold Tongue Front*

2009 ◽  
Vol 39 (5) ◽  
pp. 1200-1215 ◽  
Author(s):  
Meghan F. Cronin ◽  
William S. Kessler
Keyword(s):  
Turbulent Viscosity ◽  
Instability Wave ◽  
Surface Currents ◽  
Cold Tongue ◽  
Surface Shear ◽  
Near Surface ◽  
The Pacific ◽  
Geostrophic Shear ◽  
Moored Current Meters ◽  
The Tropical Pacific

Abstract Near-surface shear in the Pacific cold tongue front at 2°N, 140°W was measured using a set of five moored current meters between 5 and 25 m for nine months during 2004–05. Mean near-surface currents were strongly westward and only weakly northward (∼3 cm s−1). Mean near-surface shear was primarily westward and, thus, oriented to the left of the southeasterly trades. When the southwestward geostrophic shear was subtracted from the observed shear, the residual ageostrophic currents relative to 25 m were northward and had an Ekman-like spiral, in qualitative agreement with an Ekman model modified for regions with a vertically uniform front. According to this “frontal Ekman” model, the ageostrophic Ekman spiral is forced by the portion of the wind stress that is not balanced by the surface geostrophic shear. Analysis of a composite tropical instability wave (TIW) confirms that ageostrophic shear is minimized when winds blow along the front, and strengthens when winds blow oblique to the front. Furthermore, the magnitude of the near-surface shear, both in the TIW and diurnal composites, was sensitive to near-surface stratification and mixing. A diurnal jet was observed that was on average 12 cm s−1 stronger at 5 m than at 25 m, even though daytime stratification was weak. The resulting Richardson number indicates that turbulent viscosity is larger at night than daytime and decreases with depth. A “generalized Ekman” model is also developed that assumes that viscosity becomes zero below a defined frictional layer. The generalized model reproduces many of the features of the observed mean shear and is valid both in frontal regions and at the equator.

Multitestis Manter 1931 (Digenea: Lepocreadiidae) in ephippid and chaetodontid fishes (Perciformes) in the south-western Pacific Ocean and the Indian Ocean off Western Australia

Zootaxa ◽  
2010 ◽  
Vol 2427 (1) ◽  
pp. 36 ◽  
Author(s):  
RODNEY A. BRAY ◽  
THOMAS H. CRIBB ◽  
JEAN-LOU JUSTINE
Keyword(s):  
Indian Ocean ◽  
Great Barrier Reef ◽  
Western Australia ◽  
Body Shape ◽  
New Caledonia ◽  
Western Pacific Ocean ◽  
Barrier Reef ◽  
Lizard Island ◽  
The Indian Ocean ◽  
Oval Body

Five species of the genus Multitestis are described, figured or discussed: Multitestis pyriformis from Platax orbicularis off Lizard Island, northern Great Barrier Reef, Australia and Platax teira off New Caledonia; Multitestis coradioni n. sp. (syn. Multitestis pyriformis Machida, 1963 of Bray et al. (1994)) from Coradion chrysozonus off Heron Island, which differs from M. pyriformis in its oval body-shape, the more posteriorly situated testicular fields and larger eggs, Multitestis elongatus from Platax pinnatus off Lizard Island, Multitestis magnacetabulum from P. teira off Heron Island, southern Great Barrier Reef, Australia, and New Caledonia, Multitestis paramagnacetabulum n. sp. from P. orbicularis off Ningaloo Reef, Western Australia, which differs from M. magnacetabulum in the more posteriorly situated testicular fields.

Spatial and temporal patterns of near-surface chlorophyll a in the Great Barrier Reef lagoon

2007 ◽  
Vol 58 (4) ◽  
pp. 342 ◽  
Author(s):  
J. Brodie ◽  
G. De'ath ◽  
M. Devlin ◽  
M. Furnas ◽  
M. Wright
Keyword(s):  
Great Barrier Reef ◽  
Chlorophyll A ◽  
Agricultural Development ◽  
Monitoring Program ◽  
Barrier Reef ◽  
Spatial And Temporal Patterns ◽  
Wet Season ◽  
Near Surface ◽  
Nutrient Delivery ◽  
Inshore Waters

Surface chlorophyll a concentrations in the Great Barrier Reef (GBR) lagoon were monitored at individual stations for periods of 6 to 12 years. The monitoring program was established to detect spatial and temporal changes in water quality resulting from increased loads of nutrients exported from the catchments adjoining the GBR. Sampling occurred monthly at up to 86 sites that were located in transects across the width of the continental shelf. In the central and southern GBR (16–21°S), there was a persistent cross-shelf chlorophyll a gradient, with higher concentrations near the coast. No cross-shelf gradient was observed in the far northern GBR (12–15°S). Mean chlorophyll a concentrations in the far northern GBR (0.23 µg L–1) were less than half those in the south and central GBR (0.54 µg L–1). Chlorophyll a varied seasonally within regions, with mean summer-wet season (December–April) concentrations ~50% greater than those in the winter-dry season (May–November). Sub-annual, inter-annual and event-related variations in chlorophyll a concentrations were observed in several zones. Multi-year patterns in concentrations suggest that relatively short (5–8 years) time series may give spurious estimates of secular trends. Higher chlorophyll a concentrations in inshore waters south of 16°S were most likely related to the levels of river nutrient delivery associated with agricultural development on adjacent catchments.

scholarly journals Atmospheric pollutant outflow from southern Asia: a review

2010 ◽  
Vol 10 (4) ◽  
pp. 9463-9646 ◽  
Author(s):  
M. G. Lawrence ◽  
J. Lelieveld
Keyword(s):  
Indian Ocean ◽  
Scale Effects ◽  
Lower Troposphere ◽  
Surface Flow ◽  
Long Distance ◽  
Atmospheric Pollutant ◽  
Near Surface ◽  
Air Masses ◽  
Southern Asia ◽  
The Indian Ocean

Abstract. Southern Asia is one of the most heavily populated regions of the world. Biofuel and biomass burning play a disproportionately large role in the emissions of most key pollutant gases and aerosols there, in contrast to much of the rest of the Northern Hemisphere, where fossil fuel burning and industrial processes tend to dominate. This results in polluted air masses which are enriched in carbon-containing aerosols, carbon monoxide, and hydrocarbons. The outflow and long-distance transport of these polluted air masses is characterized by three distinct seasonal circulation patterns: the winter monsoon, the summer monsoon, and the monsoon transition periods. During winter, the near-surface flow is mostly northeasterly, and the regional pollution forms a thick haze layer in the lower troposphere which spreads out over millions of square km between southern Asia and the Intertropical Convergence Zone (ITCZ), located several degrees south of the equator over the Indian Ocean during this period. During summer, the heavy monsoon rains effectively remove soluble gases and aerosols. Less soluble species, on the other hand, are lifted to the upper troposphere in deep convective clouds, and are then transported away from the region by strong upper tropospheric winds, particularly towards northern Africa and the Mediterranean in the tropical easterly jet. Part of the pollution can reach the tropical tropopause layer, the gateway to the stratosphere. During the monsoon transition periods, the flow across the Indian Ocean is primarily zonal with the trade winds, and strong pollution plumes originating from both southeastern Asia and from Africa spread across the central Indian Ocean. This paper provides a review of the current state of knowledge based on the many observational and modeling studies over the last decades that have examined the southern Asian atmospheric pollutant outflow and its large scale effects.

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