The formation and evolution of East Australian current warm-core eddies

Nilsson, C. S.; Cresswell, GR

doi:10.1016/0079-6611(80)90008-7

Cited by 179 publications

(139 citation statements)

References 15 publications

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“…Eddy separation, coalescence, and dissipation events such as these are similar to those observed in other years with satellite imagery, satellite-tracked drifters, and shipboard observations [Nilsson and Cresswell, 1981;Cresswell and Legeckis, 1986]. With the Pathfinder data we have processed, it is possible to view this mesoscale variability continuously over a period of 8 years, without the confounding effect of clouds in the images.…”

Section: Validation Of the Estimates Against In Situ Datamentioning

confidence: 69%

Optimal averaging of NOAA/NASA Pathfinder satellite sea surface temperature data

Walker¹,

Wilkin²

1998

J. Geophys. Res.

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Abstract. Statistical interpolation is applied to 8 years of cloud-interrupted satellite radiometer data to produce estimates of sea surface temperature (SST) at 10-day intervals in the Indo-Australian region. The data are 9-km resolution daily "best SST" values calculated globally by the NOAA/NASA Pathfinder project reanalysis of advanced very high resolution radiometer (AVHRR) data. The optimal averaging technique determines an unbiased estimate of the signal that has the minimum mean square variance from the data, within the limits of the expected measurement error. Previous studies have shown that the method is superior to other linear averaging techniques, especially that of simple composite averaging. The method is applied in the time domain only, preserving the 9-km spatial resolution of the data. The signal and noise covariances were evaluated from the data. This was done with care so that accurate estimates of the error bounds that bracket the optimally averaged values might be obtained. These error bounds were then verified against in situ data. A Markov function, (1 + r/a) exp (-r/a), where r is the time lag and a is a characteristic timescale, was fitted to the data and used for the signal correlation function. This was selected after evaluation of functional forms proposed in other studies. The effect on the analysis of geographical variation in the correlation function was considered. The computational demand of the repeated matrix operations in optimal interpolation was reduced by using a limited duration data window. The complete analysis procedure for the 8-year data set, comprising over 106 time series, was tractable on a modern workstation. The result is a set of SST maps for 1987-1994 at an interval of 10 days and a spatial resolution of 9 km. The analyses are suitable for applications such as high-resolution ocean and atmosphere modeling where the timescales and space scales of interest are comparable to the analysis (i.e., of the order of 10 days, 9 km) and for which the presence of gaps due to clouds is problematic. Some features of Indo-Australian regional mesoscale circulation that the analysis highlights are examined, including examples of detailed mesoscale SST evolution and interannual variability. IntroductionRemotely sensed sea surface temperature (SST) data from the radiometers on board NOAA meteorological satellites are used widely in studies of the ocean. Clouds obscure radiometer SST observations, and this is problematic for applications where an uninterrupted high-resolution SST data set is required. Cloud detection algorithms help minimize data loss, but the gaps created by cloud cover often must be filled by time and space averaging or interpolation. This paper describes the application of a statistical interpolation/averaging method to produce uninterrupted SST maps with a spatial resolution of 9 km and temporal separation of 10 days. The results are suitable as boundary conditions for high-resolution regional models of the ocean and atmosphere, and they also directly chart ...

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Section: Validation Of the Estimates Against In Situ Datamentioning

confidence: 69%

Optimal averaging of NOAA/NASA Pathfinder satellite sea surface temperature data

Walker¹,

Wilkin²

1998

J. Geophys. Res.

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“…1). The shelf off Sydney is 40 km wide, and the shelf break occurs at a depth of approximately 200 m. The dominant current in this region is the southward flowing East Australian Current (EAC) and associated eddies (Nilsson & Cresswell 1981). Local wind stress and the passage of coastally trapped waves result in regular reversals of the shelf and slope flow.…”

Section: Methodsmentioning

confidence: 99%

Displacement of diverse ichthyoplankton assemblages by a coastal upwelling event on the Sydney shelf

Smith¹,

Suthers²

1999

Mar. Ecol. Prog. Ser.

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The influences of upwelling-favourable winds and thermocline displacement on the distribution of temperate/tropical lchthyoplankton assemblages were determined from vertically stratified plankton hauls across the Sydney shelf, southeastern Australia. Five stations were sampled along a shore-normal transect off Sydney. Australia, on 3 or 4 consecutive nights during January and April 1994. High taxonomic diversity (111 ichthyoplankton families) was attributed to the convergence of temperate and tropical waters in this region. Total larval abundance was higher in January than in April, reflecting the spawning times of many coastal taxa. In both months, hlghest larval density and taxononlic diversity were associated with the interface between the mixed layer and the thermocline. In April, a period of upwelling-favourable winds resulted in the offshore displacement of the nearshore mixed layer, as well as numerous shelf-spawned larvae (e.g. Centroberyx affinis, Chromis hypsilepsis, Arnpis trutta) from the nearshore region, and coincided with the injection of deeply distributed mesopelagic larvae into the nearshore zone (e g Scopelosaurus sp., Melamphaes sp.). Shelf-spawned larvae were d~splaced to the outer shelf, where they were still associated with the mixed layer/thermocline interface. Dynamic ichthyoplankton distributions are interpretable, at least at a scale of weeks, by considering larvae as tracers of the local hydrography.

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“…The coast of NSW is home to a western boundary current, the East Australian Current (EAC), that flows southwards to c. 32-36°S, then veers eastwards and either flows toward New Zealand or splits into anticyclonic eddies that flow at variable speeds southwards (Hamon 1965;Nilsson & Cresswell 1981;Cresswell & Legeckis 1986). It is possible that larvae spawned off the north coast of NSW are transported from the spawning area by the EAC to more southern areas, such as off Sydney and Ulladulla, where the width of the continental shelf is narrower and the current not as strong as further north.…”

Section: Length Compositionmentioning

confidence: 99%

Distribution and abundance of recruits of the eastern rock lobster (Jasus verreauxi) along the coast of New South Wales, Australia

Montgomery

Craig²

2005

New Zealand Journal of Marine and Freshwater Research

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In the mid 1990s, the New South Wales government introduced management measures to increase the size of the population of the eastern rock (spiny) lobster, Jasus verreauxi. A fully orthogonal sampling design was begun in July 1995 to test, amongst others, the hypothesis that the relative abundance of recruits (stages of peuruli to early juveniles combined) to the eastern rock lobster population will change over space and time. In the design for the full sampling strategy were the factors of Year (eight levels) and Location (four levels). Three replicate collectors at each of three sites at each location were sampled during the first quarter of each lunar month between August and January between 1995-96 and 2002-03 (inclusive). Recruits occurred on collectors between September and January each year. Results of the two-factor ANOVA showed a significant interaction between Year and Location, meaning that differences in mean relative abundance of recruits between years will depend upon the location. Comparison of means (SNK test) show that in each year the relative abundance of recruits was greatest at the southern locations, but no pattern in mean relative abundance between years for each location was apparent. Management measures introduced in the mid 1990s to increase population size have not to date resulted in increasing levels of recruitment. Considering this, levels of recruitment to the population appear to be influenced most by variation in environmental factors rather than levels of egg production from the stock.

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The formation and evolution of East Australian current warm-core eddies

Cited by 179 publications

References 15 publications

Optimal averaging of NOAA/NASA Pathfinder satellite sea surface temperature data

Optimal averaging of NOAA/NASA Pathfinder satellite sea surface temperature data

Displacement of diverse ichthyoplankton assemblages by a coastal upwelling event on the Sydney shelf

Distribution and abundance of recruits of the eastern rock lobster (Jasus verreauxi) along the coast of New South Wales, Australia

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