Variability in sea surface temperature around New Zealand from AVHRR images

Chiswell, Stephen M.

doi:10.1080/00288330.1994.9516606

Cited by 81 publications

(71 citation statements)

References 11 publications

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“…This flow gives rise to the EAUC north-east of North Cape, and from there it flows south-east along the east coast of North Island to East Cape (Heath 1985;Ridgway & Greig 1986;Stanton et al 1997). Consequently, SSTs during autumn, winter, and early spring are generally 1 °C warmer off the north-east North Island than at the corresponding latitude on the west coast (Chiswell 1994). Iwasaki (1970) found that whale shark sightings in the western north Pacific Ocean tended to be associated with the path of the Kuroshio Current, and were most common at SSTs between c. 21 and 25°C.…”

Section: Resultsmentioning

confidence: 99%

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Distribution, seasonality, lengths, and feeding behaviour of whale sharks(Rhincodon typus)observed in New Zealand waters

Duffy¹

2002

New Zealand Journal of Marine and Freshwater Research

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Data from 36 whale shark (Rhincodon typus Smith, 1828) sightings off north-east North Island, New Zealand are summarised. Sightings were concentrated over the outer shelf and shelf break in areas influenced by the East Auckland Current at sea surface temperatures (SST) of 21-24°C. Sightings occurred from late spring to early autumn (November-April) but were most frequent in midsummer (February) when upwelling along the north-east shelf is weakest. The data indicate whale sharks occur off north-east New Zealand most summers, including those when SST is colder than usual. A cluster of sightings and three observations of whale sharks feeding on schools of anchovy (Engraulis australis) near Whale Island, Bay of Plenty, suggest whale sharks may aggregate seasonally in this area. Estimated total lengths (TL) of 26 whale sharks ranged from 3.5 to 15 m, with 73% between 6 and 9 m TL.

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Section: Resultsmentioning

confidence: 99%

“…Iwasaki (1970) found that whale shark sightings in the western north Pacific Ocean tended to be associated with the path of the Kuroshio Current, and were most common at SSTs between c. 21 and 25°C. In the New Zealand region, mean summer SST generally ranges from 20 to 23°C north of 38°S (Chiswell 1994;Anon. 2000Anon.…”

Section: Resultsmentioning

confidence: 99%

Distribution, seasonality, lengths, and feeding behaviour of whale sharks(Rhincodon typus)observed in New Zealand waters

Duffy¹

2002

New Zealand Journal of Marine and Freshwater Research

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“…Similarly, salinity drops by lpsu. Immediately to the east of New Zealand, the Chatham Rise, which rises to a depth of 400 m, appears to constrain the latitudinal movement of the STF, although satellite thermal images show the surface front is highly variable in strength with meanders and eddies forming on many different scales (Chiswell 1994b).…”

Section: M99004 Received 26 January 1999; Accepted 12 July 2000mentioning

confidence: 99%

Eddy energetics in the subtropical front over the Chatham Rise, New Zealand

Chiswell¹

2001

New Zealand Journal of Marine and Freshwater Research

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The Chatham Rise, which rises to a depth of 400 m immediately to the east of New Zealand, appears to constrain the latitudinal movement of the Subtropical Front (STF). Data from current meters moored over the Chatham Rise are used to estimate the spatial variation of mean and turbulent kinetic energies and Reynolds stresses in and around the STF. Mean currents over 8 months are to the east, and are stronger south of the rise. Mean speeds at 250 m south of the rise are as high as 15 cm s -1 compared to 4.5 cm s -1 north of the rise. In contrast, the eddy kinetic energy is higher to the north at 8.2 J m -3 compared to 3.3 J m -3 to the south. Short-term current meter moorings over the crest of the rise show no coherence over length scales of 15 km for periods less than 10 days. At 250 m depth, Reynolds stresses are positive north of the rise, and negative south of it, suggesting an export of momentum away from the STF.

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“…An automatic front-enhancement algorithm can prove valuable in the objective assessment of the so-called 'tuna-front' association. Various edge-detection techniques are described in the literature, involving isotherm-contouring, empirical orthogonal functions (Chiswell 1994), surfacefitting (Shaw & Vennell 2000), convolution with kernels (Simpson 1990, Canny 1986, and specifically designed algorithms (Cayula & Cornillon 1995). Systematic analysis of AVHRR images has resulted in databases of ocean fronts (Ullman & Cornillon 1999) and improved knowledge of frontal dynamics (Miller 2000).…”

Section: Seawifs Data L1-l2 Processingmentioning

confidence: 99%

Association between bluefin tuna schools and oceanic features in the western Mediterranean

Royer¹,

Fromentin²,

Gaspar³

2004

Mar. Ecol. Prog. Ser.

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We present an analysis of the distribution of bluefin tuna Thunnus thynnus schools spotted during aerial surveys in the Gulf of Lions, in relation to oceanographic features. Bio-optical and thermal properties of the sea surface derived from high-resolution sensors (AVHRR and SeaWiFS) were studied on a daily basis, and an edge-detection technique was applied to detect frontal zones. Geostatistics and point-process analyses were used to evaluate the role of the environment in structuring the spatial pattern of bluefin tuna (BFT). The distribution of schools spotted was strongly nonstationary both in space and time; this is believed to be an effect of the survey design (transect sampling) and the influence of transient oceanographic structures (surface fronts and eddies). The empirical variograms indicated a spatial range of the BFT schools at around 40 km, with substantial daily variability. Ripley's K statistic, as well as autocorrelation plots, revealed that the fish schools were clustered over a wider range of scales (from 10 to 80 km), indicating more spatial structure than would be expected from a random process. Finally, BFT school distributions appeared well determined by the oceanic features, except at very small scales (<10 km), where over-aggregation occurred, and at the largest scales of our study (> 40 km), where over-spreading was detected. Dynamical ecological processes, such as foraging, are likely to induce this complex spatial pattern. Possible reasons for the association of tuna with fronts are presented.

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Variability in sea surface temperature around New Zealand from AVHRR images

Cited by 81 publications

References 11 publications

Distribution, seasonality, lengths, and feeding behaviour of whale sharks(Rhincodon typus)observed in New Zealand waters

Distribution, seasonality, lengths, and feeding behaviour of whale sharks(Rhincodon typus)observed in New Zealand waters

Eddy energetics in the subtropical front over the Chatham Rise, New Zealand

Association between bluefin tuna schools and oceanic features in the western Mediterranean

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