Effects of wind and tide on upper-layer currents at Davies Reef, Great Barrier Reef, during MECOR (July-August 1984)

1986 ◽  
Vol 37 (5) ◽  
pp. 545 ◽  
Author(s):  
GL Pickard
Keyword(s):  
Great Barrier Reef ◽  
Reef Flat ◽  
Clear Correlation ◽  
Barrier Reef ◽  
The South ◽  
North West ◽  
The North ◽  
Transit Times ◽  
Strong Winds

At Davies Reef, flow over the east reef flat was unidirectional downwind at 10-20 cm s-1 with strong winds and smaller tides but was semi-diurnal tidal reversing at 5-15 cm s-1 with lighter winds and higher tides. The flood direction was to the south-east out of the lagoon and the ebb into the lagoon. Wave overtopping was estimated to contribute at least 40% of the flow over the reef flat-the first estimate of this component of flow over reef flats. Transit times over the reef flat were 30-170 min and flushing times for the east lagoon were estimated as ½ -1 day for strong winds to the north-west but 2-4 days for lighter winds. In the east lagoon, the upper-layer currents were semi-diurnal tidal reversing all the time at speeds up to 20 cm s-1, with longer-term net flow downwind at about 2 cm s-1 with strong winds but upwind at 0.2 cm s-1 with light winds. In the east passage, the strongly tidal currents (up to 60 cm s-1.) had a long-term net flow to the south at about 2 cm s-1 without any clear correlation with the wind.

Physical properties of the Great Barrier reef Lagoon waters near Townsville. II. Seasonal variations

1981 ◽  
Vol 32 (3) ◽  
pp. 321 ◽  
Author(s):  
E Wolanski ◽  
M Jones ◽  
WT Williams
Keyword(s):  
Physical Properties ◽  
Great Barrier Reef ◽  
Seasonal Variations ◽  
High Salinity ◽  
Dry Season ◽  
Barrier Reef ◽  
Reef Lagoon ◽  
The North ◽  
Strong Winds ◽  
Calm Weather

The distribution of salinity, temperature, suspended particles, light transmissivity, chlorophyll a and phaeopigments across the Great Barrier Reef lagoon offshore Townsville, was measured from 9 January 1979 to 23 January 1980 at approximately weekly intervals. Previous observations at Low Isles. 400 km to the north, on seasonal variations of temperature and salinity were generally applicable here. A shallow summer thermocline was frequently observed in offshore waters, in the dry season and in calm weather. As a result of evaporation from the lagoon and adjoining mangrove swamps during the dry season, an inverse estuarine circulation can exist when high salinity, sediment-rich, nearshore waters sink below the less saline offshore waters. Only nearshore were bottom sediments strongly entrained in the water column during strong winds, principally in winter.

Pattern of outbreaks of crown-of-thorns starfish (Acanthaster planci L. ) along the Great Barrier Reef since 1966

1992 ◽  
Vol 43 (3) ◽  
pp. 555 ◽  
Author(s):  
PJ Moran ◽  
G De'ath ◽  
VJ Baker ◽  
DK Bass ◽  
CA Christie ◽  
...  
Keyword(s):  
Great Barrier Reef ◽  
Initial Rate ◽  
The Other ◽  
Barrier Reef ◽  
Acanthaster Planci ◽  
The South ◽  
The North ◽  
Rate Of Movement

Two series of outbreaks of the crown-of-thorns starfish, Acanthaster planci (L.), have been recorded on the Great Barrier Reef since the early 1960s. Data from scientific surveys and reliable unpublished observations were analysed statistically to quantify the pattern of movement of these outbreaks. Data on outbreak populations were obtained from 84 and 97 reefs for the periods 1966-74 and 1979-91, respectively. Outbreaks during the former period were found to occur further south with time, their rate of movement increasing from 49 km year-1 in 1966 to almost 81 km year-1 by 1974. Two sets of outbreaks were identified during the 1979-91 period, one occurring to the north, and the other to the south, of latitude 16�s. The 'southern drift' in outbreaks was found to be the more dominant of the two, 'travelling faster' for a greater period. Its initial rate of movement was estimated at 77 km year-1 compared with 57 km year -1 for the 'northern drift'. The latter travelled 150 km before it stopped in 1984. In contrast, the 'southern drift' had travelled a distance of 560 km by 1991, although it had also become almost stationary by then. Outbreaks that moved south during 1979-91 followed a path similar to those that occurred in the 1966-74 period. This similarity in the outbreak paths was particularly evident during the first 6 years of each period. In all, 35 reefs were recorded as experiencing both outbreaks, the average time between each being 14.68 years. The origin of the northern and southern patterns in the 1979-91 period was found to coincide, suggesting that the likely epicentre for primary outbreaks is close to latitude 16�s.

The tidal and longer-period circulation of Capricornia, Southern Great Barrier Reef

1987 ◽  
Vol 38 (4) ◽  
pp. 461 ◽  
Author(s):  
DA Griffin ◽  
JH Middleton ◽  
L Bode
Keyword(s):  
Continental Shelf ◽  
Great Barrier Reef ◽  
Tidal Flow ◽  
Barrier Reef ◽  
Mean Flow ◽  
Data Set ◽  
Study Region ◽  
North West ◽  
The North ◽  
Hourly Data

Between June and December 1983, nine current meters and three water level recorders were deployed on the continental shelf and slope of the Capricornia Section of the Great Barrier Reef between Fraser Island (25�s.) and the mouth of the Capricorn Channel (23�s.) on the east coast of Australia. Tidal analyses of the hourly data set reveal an amplification of the semi-diurnal tides as they propagate north- westward into the Capricorn Channel. The results of a numerical model of tidal flow show excellent agreement with observations. The daily averaged (non-tidal) currents are highly variable and produce complex circulation patterns, but with a mean flow generally alongshore to the north-west. Comparisons with previous drifter studies and satellite-tracked buoy data suggest that the south-eastward flowing East Australian Current drives a large clockwise eddy, in the lee of the Swain Reefs, located east of the study region. It is postulated that this eddy, in addition to the generally north-westward wind stress, contributes to the north-westward flow within the study region. Temperatures recorded by the deployed instruments and temperature profiles from conductivity-temperature-depth casts confirm that tidal and longer period variablity contribute to upwelling onto the continental shelf.

Review of Australian species of Plectranthias Bleeker and Selenanthias Tanaka (Teleostei: Serranidae: Anthiadinae), with descriptions of four new species

Zootaxa ◽  
2021 ◽  
Vol 4918 (1) ◽  
pp. 1-116
Author(s):  
ANTHONY C. GILL ◽  
JOHN J. POGONOSKI ◽  
GLENN I. MOORE ◽  
JEFFREY W. JOHNSON
Keyword(s):  
Great Barrier Reef ◽  
Reef Coral ◽  
Barrier Reef ◽  
North West ◽  
The North ◽  
Christmas Island ◽  
Lord Howe Island ◽  
Coral Sea ◽  
Tasman Sea ◽  
Arafura Sea

Australian species of the anthiadine genera Plectranthias and Selenanthias are reviewed. Twenty-two species of Plectranthias and two species of Selenanthias are recorded from Australian waters: Plectranthias sp. 1 from a seamount north of Middleton Reef and Norfolk Ridge, Tasman Sea; P. alleni Randall from off southwest Western Australia; P. azumanus (Jordan & Richardson) from off southwest Western Australia; P. bennetti Allen & Walsh from Holmes Reef, Coral Sea; P. cruentus Gill & Roberts from Lord Howe Island, and possibly off Stradbroke Island, Queensland; P. ferrugineus n. sp. from the North West Shelf and Arafura Sea; P. fourmanoiri Randall from Christmas Island and Holmes Reef, Coral Sea; P. grahami n. sp. from off central New South Wales, Tasman Sea; P. inermis Randall from Christmas Island; P. japonicus (Steindachner) from the Arafura Sea and North West Shelf; P. kamii Randall from the Coral Sea, Lord Howe Island and Christmas Island; P. lasti Randall & Hoese from the North West Shelf and off Marion Reef, Queensland; P. longimanus (Weber) from the Timor Sea, Great Barrier Reef, Coral Sea and southern Queensland; P. maculicauda (Regan) from southeastern Australia; P. mcgroutheri n. sp. from the North West Shelf; P. megalophthalmus Fourmanoir & Randall from northeast of the Whitsunday Islands, Queensland; P. melanesius Randall from southeastern Queensland and a seamount north of Middleton Reef; P. moretonensis n. sp. from off Stradbroke Island, Queensland; P. nanus Randall from the Cocos (Keeling) Islands, Christmas Island, Great Barrier Reef and Coral Sea; P. retrofasciatus Fourmanoir & Randall from the Great Barrier Reef; P. robertsi Randall & Hoese from off Queensland, Coral Sea; P. winniensis (Tyler) from the Great Barrier Reef and Coral Sea; Selenanthias analis Tanaka from the North West Shelf and Arafura Sea; and S. barroi (Fourmanoir) from west of Lihou Reef, Coral Sea. Five of the species represent new records for Australia: P. azumanus, P. kamii, P. megalophthalmus, P. melanesius and S. barroi. Previous records of P. megalophthalmus from the North West Shelf are based on misidentified specimens of P. lasti. Records of P. wheeleri from the North West Shelf are based on specimens here identified as P. mcgroutheri n. sp. A record of P. yamakawai Yoshino from Christmas Island is based on a misidentified specimen of P. kamii. Plectranthias retrofasciatus was previously recorded from the Great Barrier Reef as P. pallidus Randall & Hoese, here shown to be a junior synonym of P. retrofasciatus. Video-based records of P. kelloggi from the Great Barrier Reef appear to be based on P. retrofasciatus. Identification keys, diagnoses, character summaries, photographs and Australian distribution information are presented for all species. Full descriptions are provided for the new species and for those newly recorded from Australia. 

Long-term Cyclic Variations of Prominences, Green and Red Coronae over Solar Cycles

2000 ◽  
Vol 179 ◽  
pp. 201-204
Author(s):  
Vojtech Rušin ◽  
Milan Minarovjech ◽  
Milan Rybanský
Keyword(s):  
Emission Lines ◽  
High Latitudes ◽  
Green Line ◽  
Solar Cycles ◽  
The South ◽  
Coronal Emission ◽  
Local Maxima ◽  
The North ◽  
Cyclic Variations

AbstractLong-term cyclic variations in the distribution of prominences and intensities of green (530.3 nm) and red (637.4 nm) coronal emission lines over solar cycles 18–23 are presented. Polar prominence branches will reach the poles at different epochs in cycle 23: the north branch at the beginning in 2002 and the south branch a year later (2003), respectively. The local maxima of intensities in the green line show both poleward- and equatorward-migrating branches. The poleward branches will reach the poles around cycle maxima like prominences, while the equatorward branches show a duration of 18 years and will end in cycle minima (2007). The red corona shows mostly equatorward branches. The possibility that these branches begin to develop at high latitudes in the preceding cycles cannot be excluded.

CURRENT STATE AND DEVELOPMENT PERSPECTIVES OF THE CASPIAN SPRAT FISHERIES

2018 ◽  
pp. 69-75
Author(s):  
Tatiana Vasilievna Pomogaeva ◽  
Aliya Ahmetovna Aseinova ◽  
Yuriy Aleksandrovich Paritskiy ◽  
Vjacheslav Petrovich Razinkov
Keyword(s):  
Food Item ◽  
Growth Potential ◽  
North West ◽  
Marine Fishery ◽  
The North ◽  
Current State ◽  
West Part ◽  
Eggs And Larvae ◽  
Intensive Growth

The article presents annual statistical data of the Caspian Research Institute of Fishery. There has been kept track of the long term dynamics of the stocks of three species of Caspian sprat (anchovy, big-eyed kilka, sprat) and investigated a process of substituting a food item of sprats Eurytemora grimmi to a small-celled copepod species Acartia tonsa Dana. According to the research results, there has been determined growth potential of stocks of each species. Ctenophoran-Mnemiopsis has an adverse effect on sprat population by eating fish eggs and larvae. Ctenophoram - Mnemiopsis is a nutritional competitor to the full-grown fishes. The article gives recommendations on reclamation of stocks of the most perspective species - common sprat, whose biological characteristics helped not to suffer during Ctenophoram outburst and to increase its population during change of the main food item. Hydroacoustic survey data prove the intensive growth of common sprat biomass in the north-west part of the Middle Caspian. According to the results of the research it may be concluded that to realize the volumes of recommended sprat catch it is necessary to organize the marine fishery of common sprat at the Russian Middle Caspian shelf.

Depositional Environment Drive as Overpressure Generation: Study Case in “Gap” Field, North West Java Basin

2020 ◽  
Author(s):  
A., C. Prasetyo
Keyword(s):  
Clay Mineral ◽  
Depositional Environment ◽  
Mineral Content ◽  
Hydrocarbon Generation ◽  
Well Test ◽  
Burial History ◽  
The South ◽  
North West ◽  
The North ◽  
Geological Processes

Overpressure existence represents a geological hazard; therefore, an accurate pore pressure prediction is critical for well planning and drilling procedures, etc. Overpressure is a geological phenomenon usually generated by two mechanisms, loading (disequilibrium compaction) and unloading mechanisms (diagenesis and hydrocarbon generation) and they are all geological processes. This research was conducted based on analytical and descriptive methods integrated with well data including wireline log, laboratory test and well test data. This research was conducted based on quantitative estimate of pore pressures using the Eaton Method. The stages are determining shale intervals with GR logs, calculating vertical stress/overburden stress values, determining normal compaction trends, making cross plots of sonic logs against density logs, calculating geothermal gradients, analyzing hydrocarbon maturity, and calculating sedimentation rates with burial history. The research conducted an analysis method on the distribution of clay mineral composition to determine depositional environment and its relationship to overpressure. The wells include GAP-01, GAP-02, GAP-03, and GAP-04 which has an overpressure zone range at depth 8501-10988 ft. The pressure value within the 4 wells has a range between 4358-7451 Psi. Overpressure mechanism in the GAP field is caused by non-loading mechanism (clay mineral diagenesis and hydrocarbon maturation). Overpressure distribution is controlled by its stratigraphy. Therefore, it is possible overpressure is spread quite broadly, especially in the low morphology of the “GAP” Field. This relates to the delta depositional environment with thick shale. Based on clay minerals distribution, the northern part (GAP 02 & 03) has more clay mineral content compared to the south and this can be interpreted increasingly towards sea (low energy regime) and facies turned into pro-delta. Overpressure might be found shallower in the north than the south due to higher clay mineral content present to the north.

Water quality in the inshore Great Barrier Reef lagoon: Implications for long-term monitoring and management

2012 ◽  
Vol 65 (4-9) ◽  
pp. 249-260 ◽  
Author(s):  
Britta Schaffelke ◽  
John Carleton ◽  
Michele Skuza ◽  
Irena Zagorskis ◽  
Miles J. Furnas
Keyword(s):  
Water Quality ◽  
Great Barrier Reef ◽  
Barrier Reef ◽  
Reef Lagoon ◽  
Long Term Monitoring ◽  
Term Monitoring ◽  
Inshore Great Barrier Reef

A gold diadem from Aegina

1987 ◽  
Vol 107 ◽  
pp. 182-182
Author(s):  
Reynold Higgins
Keyword(s):  
Bronze Age ◽  
British Museum ◽  
The South ◽  
North West ◽  
The North ◽  
The Dead ◽  
Middle Helladic ◽  
Dead Man ◽  
The Bronze Age ◽  
Grave Goods

A recent discovery on the island of Aegina by Professor H. Walter (University of Salzburg) throws a new light on the origins of the so-called Aegina Treasure in the British Museum.In 1982 the Austrians were excavating the Bronze Age settlement on Cape Kolonna, to the north-west of Aegina town. Immediately to the east of the ruined Temple of Apollo, and close to the South Gate of the prehistoric Lower Town, they found an unrobbed shaft grave containing the burial of a warrior. The gravegoods (now exhibited in the splendid new Museum on the Kolonna site) included a bronze sword with a gold and ivory hilt, three bronze daggers, one with gold fittings, a bronze spear-head, arrowheads of obsidian, boar's tusks from a helmet, and fragments of a gold diadem (plate Va). The grave also contained Middle Minoan, Middle Cycladic, and Middle Helladic (Mattpainted) pottery. The pottery and the location of the grave in association with the ‘Ninth City’ combine to give a date for the burial of about 1700 BC; and the richness of the grave-goods would suggest that the dead man was a king.

Water circulation around Britomart Reef, Great Barrier Reef, during July 1979

1980 ◽  
Vol 31 (4) ◽  
pp. 415 ◽  
Author(s):  
E Wolanski ◽  
M Jones
Keyword(s):  
Great Barrier Reef ◽  
Sea Level ◽  
Central Region ◽  
Reef Flat ◽  
Water Circulation ◽  
Barrier Reef ◽  
Trade Winds ◽  
Sea Breezes ◽  
Coral Sea ◽  
Sea Level Oscillations

Weather and currents at eight sites were measured and drogue trajectories obtained in July 1979 at Britomart Reef, a middle reef located at 18�16'S.,146� 38'E. in the central region of the Great Barrier Reef province. The longest current records (3 weeks) were obtained at two sites in passes between the Coral Sea and the Great Barrier Reef Lagoon where westerly currents modulated by tides were observed. Analysis of residuals also showed the importance of wind-driven secondary circulation. Non-tidal sea-level oscillations were very small. Shorter current records (1-10 days) at six sites in the lagoon and on the reef flat showed a predominant northerly flow, also modulated by tides and wind. A residual anticlockwise water circulation existed in the lagoon where flushing was controlled more by winds than by tides. The rise in sea level over the reef flat as a result of waves breaking was negligible. Temperature differences between air and water accounted for the cooling of the water column during the expedition. Constant south-east trade winds were experienced at the reef, while on land the wind was weaker. more variable, and often dominated by land-sea breezes.

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