ALBERT

Description: Markedly different cooling histories for the hanging- and footwall of theVari detachment on Syros and Tinos islands, Greece, are revealed by zircon and apatite fission-track data. The Vari/Akrotiri unit in the hangingwall cooled slowly at rates of 5–15 ◦CMyr−1 since Late Cretaceous times. Samples from the Cycladic blueschist unit in the footwall of the detachment on Tinos Island have a mean zircon fission-track age of 10.0±1.0 Ma, which together with a published mean apatite fission-track age of 9.4±0.5 Ma indicates rapid cooling at rates of at least ∼60 ◦CMyr−1. We derive a minimum slip rate of ∼6.5 kmMyr−1 and a displacement of 〉∼20 km and propose that the development of the detachment in the thermally softened magmatic arc aided fast displacement. Intra-arc extension accomplished the final ∼6–9 km of exhumation of the Cycladic blueschists from ∼60 km depth. The fast-slipping intra-arc detachments did not cause much exhumation, but were important for regionalscale extension and the formation of the Aegean Sea.

Description: Spirula spirula has stimulated considerable interest since it was first discovered. It is a member of one of the two genera of sepioids to frequent oceanic water (the other being Heteroteuthis); it has a unique spiral shell which acts as a buoyancy mechanism and can withstand considerable pressure (Denton, Gilpin-Brown & Howarth, 1967); and, until the capture by the Danish Oceanographical expeditions it was considered very rare, only 12 specimens having been captured. The Dana expeditions caught 193 individuals from 1909 to 1931 and these were described by Kerr (1931) and Bruun (1943,1955). Most of these were caught in the waters around the Canary Islands of the North Atlantic. Bruun (1943) arranged the specimens according to month and size and claimed that two size groups could be distinguished. The specimens were taken over a wide geographical area, in several years and during the months of February (1 specimen), March (40), April (3), May (8), June (1), August (1) and October (23). His conclusion concerning growth depends entirely upon his decision to split the March sample into two year-groups; those above 1.9 cm in ventral mantle length he put in a separate year-class to those below 1.9 cm in ventral mantle length. This division was arbitrary and, one suspects, based on a belief that a one-year life-span was likely. Clearly the growth of Spirula requires further study based on a larger collection and the present paper is an attempt to fulfil this need.

Description: A new species of terebellid polychaete, Lanice arakani sp. nov., is described from two specimens collected in deep water at seamounts of the west Pacific by the submersible `JAGO', and comparisons are made with the established species of the genus. Special reference is given to the morphology of the worm's sediment tube and in situ observations.

Description: The application of plagioclase geothermometry to plagioclase-bearing volcanic ash layers and to the glassy margins of pillow basalts from the fast-spreading East Pacific rise, the moderately spreading Gorda and Juan de Fuca ridges, and the slow-spreading mid-Atlantic ridge has shown that magma temperatures, as well as average An contents of plagioclases, are negatively correlated with spreading rates. A detailed investigation of the major element chemistry of volcanic glasses from each of these areas suggests that the observed consistent element-element covariances among individual populations of samples have been caused by fractional crystallization of the magmas. The regularity of chemical variation and the similarity of magma temperatures within each population of samples suggest that magmas ascending from beneath each ridge have had similar evolutionary histories. Vector analysis of the chemical data of all samples of volcanic glasses indicate that each population of samples from each of the spreading centers is chemically distinct, even though all samples have been subjected to similar amounts of fractional crystallization. The compositional distinctiveness of each population of oceanic tholeiites probably reflects differences in the depths at which the magmas were generated. Calculated magma temperatures and geothermal gradients calculated from published heat flow measurements can be used to estimate depths of magma generation of about 16 km beneath the East Pacific rise and about 23 km beneath the mid-Atlantic ridge.

Description: The distinguishing features of the common squid of British waters, Loligo forbesi, are summarized, and contrasted with those of L. vulgaris. The life-cycle and growth of L. forbesi are described, based on samples from trawl catches off Plymouth. This species seems to be an annual - young squid first appear in the trawl in late May, when their length is about 10 or 11 cm. Subsequent growth is rapid, and the males reach 30 cm and the females 25 cm by November. Spawning takes place mainly in December-January, but may continue into the spring. Neither sex survives beyond a single spawning season. Hatching of the spawn probably takes 30–40 days, and if the young squid taken in the trawl in late May hatched in the early part of the same year, a growth rate of about 25 mm/month would be required. Known growth rates for other species of Loligo are about 20 mm/month, so that indicated for L. forbesi does not seem to be impossibly high. The life-cycle is summarized in Fig. 8. There is also a summer spawning population, which grows to a rather smaller size at maturity, and which also seems to be annual. During the summer L. forbesi ranges throughout the English Channel and southern North Sea, particularly in inshore areas. In October the squid migrate farther offshore and tend to occupy the western part of the Channel. Values for total weight of squid/2 h trawl are given, on a monthly basis, for 1966–9. The largest quantities are usually taken in October and November, the highest single figure being 30.54 kg/2 h trawl, in November 1967.

Description: Twenty-four out of 240 fishes caught by bottom lines at 366–3333 m had something in their stomachs. Stomach contents included parts of cephalopods, fish, cetaceans and bottom-living invertebrates, thin rubber sheet and terrestrial mammal bones. The material provides evidence that four species of cephalopod are at least partially demersal and suggests a means by which the tapeworm Phyllobothrium could pass from its secondary to its primary host. During the five biological cruises of R.R.S. ‘Discovery’ between 1967 and 1971 a total of 31 bottom lines with 1483 hooks were fished in depths of water between 366 and 3333 m. The stomachs of the 240 fish caught were examined and 216 (90%) proved to be empty. The high incidence of empty stomachs is thought to be due to frequent loss of food during the ascent from great depths and accounts for our poor knowledge of the feeding habits of demersal fish living at depths exceeding 400 m. The present collection of food from 25 stomachs (24 from ‘Discovery’ collections and one from a fish caught by Mr G. R. Forster from R. V. ‘Sarsia’) of fish belonging to 11 species (Table 1) probably gives little indication of the usual diet of the fish concerned, but its nature prompts some useful speculation and the rarity of such observations justifies placing them on record (Bigelow & Schroeder, 1948; Marshall, 1954). All the fish were caught on lines which lay on the bottom for several hours and it is our firm belief that they were hooked while on or very near the bottom.

Description: The decadal-scale variability in the tropical Pacific has been analyzed herein by means of observations and numerical model simulations. The two leading modes of the sea surface temperature (SST) variability in the central western Pacific are a decadal mode with a period of about 10 yr and the ENSO mode with a dominant period of about 4 yr. The SST anomaly pattern of the decadal mode is ENSO like. The decadal mode, however, explains most variance in the western equatorial Pacific and off the equator. A simulation with an ocean general circulation model (OGCM) forced by reanalysis data is used to explore the origin of the decadal mode. It is found that the variability of the shallow subtropical–tropical overturning cells is an important factor in driving the decadal mode. This is supported by results from a multicentury integration with a coupled ocean–atmosphere general circulation model (CGCM) that realistically simulates tropical Pacific decadal variability. Finally, the sensitivity of the shallow subtropical–tropical overturning cells to greenhouse warming is discussed by analyzing the results of a scenario integration with the same CGCM.

Description: Oceanic ecosystems altered by interdecadal climate variability may provide a feedback to the physical climate by phytoplankton affecting heat fluxes into the upper ocean and dimethylsulfide fluxes into the atmosphere

Description: The current system east of the Grand Banks was intensely observed by World Ocean Circulation Experiment (WOCE) array ACM-6 during 1993–95 with eight moorings, reaching about 500 km out from the shelf edge and covering the water column from about 400-m depth to the bottom. More recently, a reduced array by the Institut für Meerskunde (IfM) at Kiel, Germany, of four moorings was deployed during 1999–2001, focusing on the deep-water flow near the western continental slope. Both sets of moored time series, each about 22 months long, are combined here for a mean current boundary section, and both arrays are analyzed for the variability of currents and transports. A mean hydrographic section is derived from seven ship surveys and is used for geostrophic upper-layer extrapolation and isopycnal subdivision of the mean transports into deep-water classes. The offshore part of the combined section is dominated by the deep-reaching North Atlantic Current (NAC) with currents still at 10 cm s−1 near the bottom and a total northward transport of about 140 Sv (Sv ≡ 106 m3 s−1), with the details depending on the method of surface extrapolation used. The mean flow along the western boundary was southward with the section-mean North Atlantic Deep Water outflow determined to be 12 Sv below the σθ = 27.74 kg m−3 isopycnal. However, east of the deep western boundary current (DWBC), the deep NAC carries a transport of 51 Sv northward below σθ = 27.74 kg m−3, resulting in a large net northward flow in the western part of the basin. From watermass signatures it is concluded that the deep NAC is not a direct recirculation of DWBC water masses. Transport time series for the DWBC variability are derived for both arrays. The variance is concentrated in the period range from 2 weeks to 2 months, but there are also variations at interannual and longer periods, with much of the DWBC variability being related to fluctuations and meandering of the NAC. A significant annual cycle is not recognizable in the combined current and transport time series of both arrays. The moored array results are compared with other evidence on deep outflow and recirculation, including recent models of different types and complexity.

Description: This study investigates and accounts for the influence of various ice cloud parameters on the retrieval of the surface solar radiation budget (SSRB) from reflected flux at the top of the atmosphere (TOA). The optical properties of ice clouds depend on ice crystal shape, size distribution, water content, and the vertical profiles of geometric and microphysical structure. As a result, the relationship between the SSRB and TOA-reflected flux for an ice cloud atmosphere is more complex and differs from that for water cloud and cloudless atmospheres. The sensitivities of the relationship between the SSRB and TOA-reflected flux are examined with respect to various ice cloud parameters. Uncertainties in the retrieval of the SSRB due to inadequate knowledge of various ice cloud parameters are evaluated thoroughly. The uncertainty study is concerned with both pure ice clouds and multiphase clouds (ice cloud above water cloud). According to the magnitudes of errors in the SSRB retrieval caused by different input variables, parameterized correction terms were introduced. If the input variables are known accurately, errors in the retrieval of the SSRB under a wide range of ice cloud conditions are expected to diminish substantially, to less than 10 W m−2 for 91% of the simulated ice cloud cases. In comparison, the same accuracy may be attained for only 19% of the retrievals for the same ice cloud cases using the retrieval algorithm designed for non-ice-cloud conditions.