The Monterey Bay Aquarium Research Institute (MBARI) has developed an autonomous seafloor mapping capability for high resolution mapping of the deep ocean seafloor. The D. Allan B. is a 0.53 m diameter, Dorado class autonomous underwater vehicle equipped with a 200 kHz multibeam sonar, 110 kHz and 410 kHz sidescan sonars, and a 2-16 kHz subbottom profiler. All components of the vehicle are rated to 6,000 m depth. Using precise navigation and attitude data from a laser-ring-gyro-based inertial navigation system integrated with a Doppler velocity log sonar, the D. Allan B. can image the deep-ocean seafloor and shallow subsurface structure with much greater resolution than is possible with sonars operated from surface vessels. Typical survey operations use a vehicle speed of 1.5 m per second (3 knots) and an altitude of 40 m to 100 m. The D. Allan B. has now been operated in a variety of settings, including submarine canyons (Monterey Canyon, Barkley Canyon), submarine fan systems (Redondo Channel, Lucia Chica, San Clemente), seamounts (Axial Seamount), methane hydrate outcrops and gas seeps (Santa Monica Basin, Barkley Canyon), and cable route surveys across continental margin slopes (Monterey Bay). The bathymetry surveys achieve a vertical precision of 0.1 m; surveys from a 50 m altitude achieve 1 m lateral resolution and surveys from up to 100 m altitudes achieve lateral resolutions less than 2 m. The subbottom profile data provides resolution of ~0.1 m with penetrations up to 50 m in soft sediments. These survey data are sufficient in quality and resolution to use in conjunction with visual observations and sampling for mapping benthic habitats in the deep ocean.

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[1] We show that ocean acidification from fossil fuel CO 2 invasion and reduced ventilation will result in significant decreases in ocean sound absorption for frequencies lower than about 10 kHz. This effect is due to known pHdependent chemical relaxations in the B(OH) 3 /B(OH) 4 À and HCO 3 À /CO 3 2À systems. The scale of surface ocean pH change today from the +105 ppmv change in atmospheric CO 2 is about À0.12 pH units, resulting in frequency dependant decreases in sound absorption (a = dB/km) exceeding 12%. Under reasonable projections of future fossil fuel CO 2 emissions and other sources a pH change of 0.3 units or more can be anticipated by mid-century, resulting in a decrease in a by almost 40%. Ambient noise levels in the ocean within the auditory range critical for environmental, military, and economic interests are set to increase significantly due to the combined effects of decreased absorption and increasing sources from mankind's activities. Citation: Hester, K. C., E. T. Peltzer, W.J. Kirkwood, and P. G. Brewer (2008), Unanticipated consequences of ocean acidification: A noisier ocean at lower pH, Geophys. Res. Lett., 35, L19601,

Whitt et al. Future of Autonomous Ocean Observations reductions. Cost reductions could enable order-of-magnitude increases in platform operations and increase sampling resolution for a given level of investment. Energy harvesting technologies should be integral to the system design, for sensors, platforms, vehicles, and docking stations. Connections are needed between the marine energy and ocean observing communities to coordinate among funding sources, researchers, and end users. Regional teams should work with global organizations such as IOC/GOOS in governance development. International networks such as emerging glider operations (EGO) should also provide a forum for addressing governance. Networks of multiple vehicles can improve operational efficiencies and transform operational patterns. There is a need to develop operational architectures at regional and global scales to provide a backbone for active networking of autonomous platforms.

FIG. 1. The antFOCE experiment was deployed in 14m of water under sea ice at Casey Station, in East Antarctica. Mixing ducts 40m long were required to allow pH to equilibrate following the addition of CO 2 enriched seawater into the flow-through system.