Updating an earlier account by Dickson et al., (1990), this paper reviews the initial development phase of North Atlantic Deep Water (NADW) production from the points where the dense inflows from Nordic seas cross the Greenland-Scotland Ridge to the point off south Greenland where the buildup of new production appears almost complete. In particular, three long-term current meter arrays totaling 91 instruments and set at • 160 km intervals south from the Denmark Strait sill are used to validate earlier short-term arrays by others and, in combination with these earlier arrays, to describe the downstream evolution of mean speed, depth and entrainment, the variability of the overflow current in space and time, and the likely contribution of the other three main constituents of NADW production at densities greater than tr0 = 27.8. From the points of overflow (5.6 Sv) the transport within this range increases by entrainment and confluence with other contributory streams to around 13.3 Sv at Cape Farewell. While recirculating elements prevent us from determining the net southgoing transport, a NADW transport of this order appears consistent with recent estimates of net abyssal flow passing south through the North and South Atlantic. Antarctica during austral winter [Warren, 1981] but principally formed (-80%) in the Weddell Sea [Foldvik and Gammelsrod, 1988]. On the millennial timescales which describe the glacial/ postglacial signal the teaC13 record in benthic forams from Southern Ocean sediments is interpreted as showing radical and rapid change in the production and flux of NADW in the abyssal circulation [Charles and Fairbanks, 1992]. Our knowledge of its present-day production, however, remains poor. This paper is intended to update an earlier report by Dickson et al. [1990] by describing the renewal, variability (where known), and pathways of the four main constituents of NADW through the northern North Atlantic. The primary aim, however, is to provide a more detailed description than currently exists for the Denmark Strait Overflow component using a large body of new and direct observational evidence. As Broecker and Peng [1982, p. 317] point out, a more realistic quantitative representation of the ventilation of the deep sea "remains one of the major unsolved problems in oceanography." The most famous papers of a series describing schemes for deep ventilation and exchange in the northern gyre are those by Worthington [1970, 1976] and McCartney and Talley [1984]. Although these schemes (Figures la-lc) derive more or less the same value for the transport of the Deep Western Boundary Current (DWBC) where it passes south through 50øN (10 Sv in both of Worthington's [1970, 1976] schemes and 11.1 Sv in one case described by McCartney and Talley [1984]; 1 Sv = 106 m 3 s-l), these numbers are in fact based on completely different sets of assumptions, suggesting that the available range of conjecture is too wide to be useful. For example, although Worthington's [1970, 1976] schemes both imply a 10 Sv DWBC passing throug...

In this paper we analyse the spatial footprint and temporal clustering of extreme sea level and skew surge events around the UK coast over the last 100 years (1915–2014). The vast majority of the extreme sea level events are generated by moderate, rather than extreme skew surges, combined with spring astronomical high tides. We distinguish four broad categories of spatial footprints of events and the distinct storm tracks that generated them. There have been rare events when extreme levels have occurred along two unconnected coastal regions during the same storm. The events that occur in closest succession (<4 days) typically impact different stretches of coastline. The spring/neap tidal cycle prevents successive extreme sea level events from happening within 4–8 days. Finally, the 2013/14 season was highly unusual in the context of the last 100 years from an extreme sea level perspective.

Since the early surveys carried out by the Eastern Tropical Pacific (EASTROPIC) and Scripps Tuna Oceanographic Research (STOR) projects in the tropical Pacific off Mexico, the northerly winds which blow over the Gulf of Tehuantepec were described as an important factor controlling the dynamics of this coastal ocean. In January–February 1989 an international team carried out the experiment Tehuano, designed to study the response of the gulf to these wind pulses. The complete evolution of the coastal ocean after an event of moderate intensity was observed. The forcing is characterized by a mostly symmetric, fanshaped, offshore wind jet, which in turn produces a remarkably asymmetric upper ocean response. While analytical results based on Ekman theory forced by a symmetric offshore wind predict the formation of a symmetric dipolar circulation, the observed flow consists mainly of a large (200 km in diameter) anticyclonic warm‐core eddy in the western gulf, with only a weak cyclonic counterpart in the eastern gulf. Intense surface cooling under the wind jet is caused by entrainment of subsurface water into the upper layer. The thermocline in the west deepens with the development of the eddy, which is formed initially by the advection of warm surface waters from west of the gulf. East of the axis of the wind, the mixed layer deepens due to wind‐induced entrainment, while, at the same time, shoaling and compression of the deeper isotherms by curl‐induced upwelling (Ekman pumping) strengthen the thermocline.

The mechanisms controlling the temperature and salinity structure of shallow continental shelf seas have been understood for over thirty years, yet knowledge of what drives their large‐scale circulation has remained relatively unknown. Here we describe a decade long programme of measurements, using satellite‐tracked drifting buoys on the northwest European shelf, to draw attention to a striking picture of highly organised thermohaline circulation consisting of narrow, near surface, fast flowing jets. These are ubiquitous above sharp horizontal gradients in bottom temperatures and/or salinities. The circulation phenomena we describe are likely to be prevalent on all similar, wide, tidally energetic continental shelves including those off north‐eastern China, Argentina and parts of the Arctic. The robust, repeatable observation of the key role of jets above bottom fronts results in a fundamental reassessment of how we view the dynamics of shelf seas.

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