In recent years, mass loss from the Antarctic Ice Sheet has contributed nearly 0.5 mm yr–1 to global mean sea level rise, about one-sixth of the current rate (Church et al., 2011). Around half of that contribution has come from accelerated draining of outlet glaciers into the southeast Amundsen Sea (Rignot et al., 2008), where the flow speed of Pine Island Glacier (PIG; Figure 1) in particular has increased by over 70%, to around 4 km yr–1, since the first observations in the early 1970s (Rignot, 2008; Joughin et al., 2010). The accelerations have been accompanied by rapid thinning of the glaciers extending inland from the floating ice shelves that form the glacier termini (Shepherd et al., 2002, 2004). One implication of these observed patterns of change is that the mass loss has probably been driven by changes in the rate of submarine melting of the floating ice shelves. The ubiquitous presence of warm Circumpolar Deep Water (CDW) on the Amundsen Sea continental shelf, at temperatures 3–4°C above the pressure freezing point, was first revealed during a 1994 cruise of RVIB Nathaniel B Palmer (Jacobs et al., 1996). Repeat observations at the Pine Island Ice Front made from the Palmer in 2009 showed that submarine melting of PIG had increased by 50% over the intervening 15 years despite a modest rise in the temperature of CDW of only about 0.1°C (Jacobs et al., 2011). While ice front observations were able to document those changes, the reason for the dramatic increase in submarine melting would have remained speculative while the ocean cavity beneath the approximately 65 x 35 km, fast-flowing, central part of the ice shelf remained a black box.

The cavities beneath Antarctic ice shelves are among the least studied regions of the World Ocean, yet they are sites of globally important water mass transformations. Here we report results from a mission beneath Fimbul Ice Shelf of an autonomous underwater vehicle. The data reveal a spatially complex oceanographic environment, an ice base with widely varying roughness, and a cavity periodically exposed to water with a temperature significantly above the surface freezing point. The results of this, the briefest of glimpses of conditions in this extraordinary environment, are already reforming our view of the topographic and oceanographic conditions beneath ice shelves, holding out great promises for future missions from similar platforms.

The autonomous underwater vehicle (AUV) Autosub II is presently engaged on a three-year science programme to carry out surveys under Arctic and Antarctic floating ice shelves and sea ice. This under ice mode of operation necessitates a review of how the vehicle control and navigation operate to account for ice cover, inaccessibility during the mission and get home strategies in the event of sub system failure. The paper reports on lessons learnt during an Antarctic campaign in 2001, subsequent development work and proving trials in waters off the UK.

The authors describe how the use of manganese alkaline batteries for the Autosub science programme has enabled the project to progress swiftly from being a technological demonstrator to providing new ways of gathering environmental data not possible by other methods. Throughout the programme, all areas of the battery system have undergone development. that is: specification, design and manufacture of the pack; inspection and testing; packaging, storage and physical handling; electrical and thermal insulation; estimates of remaining endurance; and disposal of depleted packs.

Here we present the results of a Large Eddy Simulation of a non-buoyant jet issuing from a circular orifice in a wall, and developing in neutral surroundings. The effects of the subgrid scales on the large eddies have been modelled with the dynamic large eddy simulation model applied to the fully 3D domain in spherical coordinates. The simulation captures the unsteady motions of the largescales within the jet as well as the laminar motions in the entrainment region surrounding the jet. The computed time-averaged statistics (mean velocity, concentration, and turbulence parameters) compare well with laboratory data without invoking an empirical entrainment coefficient as employed by line integral models. The use of the large eddy simulation technique allows examination of unsteady and inhomogeneous features such as the evolution of eddies and the details of the entrainment process.

AUTOSUB‐2, an autonomous underwater vehicle (AUV) developed by the Southampton Oceanography Centre, was used for high resolution hydrographic surveys in the Sicily Strait. A combination of “seasoar” type profiling and terrain following missions were undertaken and velocity and hydrographic measurements taken from AUTOSUB‐2 were compared with concurrent shipboard hydrographic and velocity profiles. Even though shipboard stations were separated by just 5 to 8 km along the mission path, data from the AUV showed small scale variability that was missed by the shipboard sampling. In this paper we present the example of an intense jet, with maximum speed greater than 0.50 m s−1, less than 4 km wide.

As pointed out by Rodi standard integral solutions for jets and plumes developed for discharge into infinite, quiescent ambient are difficult to extend to complex situations, particularly in the presence of boundaries such as the sea floor or ocean surface. In such cases the assumption of similarity breaks down and it is impossible to find a suitable entrainment coefficient. The models are also incapable of describing any but the most slowly varying unsteady motions. There is therefore a need for full time-dependent modeling of the flow field for which there are three main approaches: (1) Reynolds averaged numerical simulation (RANS), (2) large eddy simulation (LES), and (3) direct numerical simulation (DNS). Rodi applied RANS modeling to both jets and plumes with considerable success, the test being a match with experimental data for time-averaged velocity and temperature profiles as well as turbulent kinetic energy and rms axial turbulent velocity fluctuations. This model still relies on empirical constants, some eleven in the case of the buoyant jet, and so would not be applicable to a partly laminar plume, may have limited use in the presence of boundaries, and would also be unsuitable if one is after details of the unsteady component of the flow (the turbulent eddies). At the other end of the scale DNS modeling includes all motions down to the viscous scales. Boersma et al. have built such a model for the non-buoyant case which also compares well with measured data for mean and turbulent velocity components. The model demonstrates its versatility by application to a laminar flow case. As its name implies, DNS directly models the Navier-Stokes equations without recourse to subgrid modeling so for flows with a broad spectrum of motions (high Re) the cost can be prohibitive - the number of required grid points scaling with Re(exp 9/4) and the number of time steps with Re(exp 3/4). The middle road is provided by LES whereby the Navier-Stokes equations are formally filtered with the filter chosen to only exclude the smallest turbulent motions. If successful, LES should provide much of the detail available to DNS but at more bearable cost. Fatica et al. in comparing LES with DNS for a low Reynolds number jet showed that the LES could simulate the temporally evolving behavior including growth of the jet thickness. It is the intention of this report to explore the application of an LES model to jets and plumes. As always, before tackling complex situations, the model must be tested for the simplest of cases and so we address only two, a non-buoyant axisymmetric jet issuing steadily from an orifice into a semi-infinite stationary environment and a buoyant jet in the same environment. The work is a continuation of Basu and Mansour.

Abstract Autonomous Underwater Vehicles (AUVs) are becoming accepted data-gathering tools within the marine science community in Europe, the US and elsewhere. Technology can now provide vehicles with a useful range and depth envelope. For example, the Southampton Oceanography Centre's Autosub-1 vehicle has already covered 263 km in a single oceanographic survey mission, reaching depths of 500 m off Bermuda in September 1998. The challenge now is to 'free the technology from the research community. Potential direct and indirect benefits from the offshore energy industry's use of AUVs have been quantified. For one company, the benefits of using survey class AUVs has been estimated at $60m over 5 years. The economics become more attractive as the industry moves to deeper water. While today's AUVs of long endurance are limited in depth, developments on the horizon in composite materials and high capacity, lightweight secondary batteries will enable 1000 km range, eight-day endurance and at least 1600 m diving depth to be in active service within the next two years. This paper will review the oceanographic survey achievements of the Autosub AUV over its 216 missions (to December 1999), working in UK, US and Bermudan waters. Moving to the future, the paper will illustrate how such an AUV could be used in the offshore industry for survey, monitoring and emergency response. Finally, we will describe the present Autosub development programme, scheduled to deliver an operational 1000 km, 1600 m vehicle by mid 2000. Introduction The Autosub AUV was conceived as a survey vehicle to complement research ship programs by the provision of a cost effective tool to collect water column and seafloor information. Included within the design brief was the aim to address the widest possible scientific community hence allowing varied missions and payloads. This requirement ensured that flexibility was fundamental to the technology design. Hence for Autosub-1 there was no fixed sensor suite, the vehicle sub-systems were modular and thus offered a simple upgrade path as new technologies became available. One other by-product which is envisaged but not yet proven is the opportunity to change the vehicle characteristics i.e. size and shape, without a major re-design program. (Fig 1) The first vehicle, Autosub -1 was constructed in 8 months, being completed in May 1996. The short production cycle was only possible because of the extensive development programme which had been underway for the previous 5 years. The first phase saw Autosub-1 progress from its first 'in water' missions in Empress Dock, Southampton, (June 1996) to completion of the acceptance trials in just under one year (April 1997) Oban 97 The Autosub performance and acceptance trial criteria have been described by Millard et al (1), the main objectives were:Profiling autonomously from close to the surface to near the seabed in at least 100m of water;Mission lengths of at least 6 hours, with satellite fixes updating the dead reckoning(DR) vehicle navigation; andCollection of meaningful scientific data.

Autonomous Underwater Vehicles (AUVs) are no longer engineering curiosities, They have been under development since the 1970s but the last three years, in particular, have seen significant advances towards their use in operational missions, The state of the art for European and North American vehicles is summarised and the opportunities for future scientific missions are explored, The UK Natural Environment Research Council (NERC) AUTOSUB project epitomises the progress made in AUV technology, and recent field trials in coastal waters are described. Having proved its ability to gather scientific data autonomously, the vehicle is about to enter the next phase of performing operational scientific missions supported by appropriate technological upgrades.

In this paper we describe some of the desirable characteristics of an autonomous underwater vehicle capable of undertaking environmental surveys in the ocean. Several of these characteristics are incorporated in the 7 m long Autosub-1 vehicle which has completed over 120 missions to date in UK and US waters. We review some of the key technological innovations used within Autosub-1 and describe some results from a 110 km survey off the coast of Florida in December 1997. While the survey demonstrated many of the advantages of using an AUV for environmental monitoring the paper concludes with a discussion of technical and procedural areas that still require attention before the use of AUVs can be considered routine.

To the Editor.— In a recent editorial (235:2224, 1976), current knowledge of the restless legs syndrome is summarized. I wish to report briefly a case in which the arms were involved in this bizarre condition. Report of a Case.— A 23-year-old man had become a paraplegic from an injury to the spinal cord when struck by a falling tree about six months before the onset of symptoms. Though paralysis was complete below the fourth thoracic vertebra, there was persistent paresthesia in his legs. The patient was in a hospital undergoing rehabilitation when the gradual onset of an urge to move the arms in an aimless manner was noted only at night. This urge did not occur with any degree of regularity, nor did it relate to the type or intensity of physical activity or fatigue. It did not relate to any emotional state of depression or anxiety. The movements were not

A rare case of isolated idiopathic right ventricular endocardial calcification with outflow tract obstruction, organized pulmonary emboli, and subsequent right heart failure is presented. Diagnostic features, possible etiologies, investigation and treatment are outlined. This case is believed to be the first of its kind reported in North America. A rare case of isolated idiopathic right ventricular endocardial calcification with outflow tract obstruction, organized pulmonary emboli, and subsequent right heart failure is presented. Diagnostic features, possible etiologies, investigation and treatment are outlined. This case is believed to be the first of its kind reported in North America.