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Expendable bathythermographs (XBT) to profile upper-ocean temperatures from vessels in motion have been in use for some 50 years now. Developed originally for navy use, they were soon adapted by oceanographers to map out upper-ocean thermal structure and its space–-time variability from both research vessels and merchant marine vessels in regular traffic. These activities continue today. This paper describes a new technology—the Autonomous Expendable Instrument System (AXIS)—that has been developed to provide the capability to deploy XBT probes on a predefined schedule, or adaptively in response to specific events without the presence of an observer on board. AXIS is a completely self-contained system that can hold up to 12 expendable probes [XBTs, XCTDs, expendable sound velocimeter (XSV)] in any combination. A single-board Linux computer keeps track of what probes are available, takes commands from ashore via Iridium satellite on what deployment schedule to follow, and records and forwards the probe data immediately with a time stamp and the GPS position. This paper provides a brief overview of its operation, capabilities, and some examples of how it is improving coverage along two lines in the Atlantic. 

Using vessel-mounted acoustic Doppler current profiler data from four different routes between Scotland, Iceland and Greenland, we map out the mean flow of water in the top 400 m of the northeastern North Atlantic. The poleward transport east of the Reykjanes Ridge (RR) decreases from 8.5 to 10 Sv (1 Sverdrup 106 m3 s1) at 59.58N to 618N to 6 Sv crossing the IcelandFaroesScotland Ridge. The two longest 1200 km transport integrals have 1.40.94 Sv uncertainty, respectively. The overall decrease in transport can in large measure be accounted for by a 1.5 Sv flow across the RR into the Irminger Sea north of 59.58N and by a 0.5 Sv overflow of dense water along the IcelandFaroes Ridge. A remaining 0.5 Sv flux divergence is at the edge of detectability, but if real could be accounted for through wintertime convection to 400 m and densification of upper ocean water. The topography of the Iceland Basin and the banks west of Scotland play a fundamental role in controlling flow pathways towards and past Iceland, the Faroes and Scotland. Most water flows north unimpeded through the Iceland Basin, some in the centre of the basin along the Maury Channel, and some along Hatton Bank, turning east along the northern slopes of George Bligh Bank, Lousy Bank and Bill Bailey’s Bank, whereupon the flow splits with 3 Sv turning northwest towards the IcelandFaroes Ridge and the remainder continuing east towards and north of the Wyville-Thomson Ridge (WTR) to the Scotland slope thereby increasing the Slope Current transport from 1.5 Sv south of the WTR to 3.5 Sv in the FaroesShetland Channel