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We present the design and preliminary results from ocean deployments of Zooglider, a new autonomous zooplankton-sensing glider. Zooglider is a modified Spray glider that includes a low-power camera (Zoocam) with telecentric lens and a custom dual frequency Zonar (200 and 1000 kHz). The Zoocam quantifies zooplankton and marine snow as they flow through a defined volume inside a sampling tunnel. Images are acquired on average every 5 cm from a maximum operating depth of ~ 400 m to the sea surface. Biofouling is mitigated using a dual approach: an ultraviolet light-emitting diode and a mechanical wiper. The Zonar permits differentiation of large and small acoustic backscatterers in larger volumes than can be sampled optically. Other sensors include a pumped conductivity, temperature, and depth unit and chlorophyll a fluorometer. Zooglider enables fully autonomous in situ measurements of mesozooplankton distributions, together with the three-dimensional orientation of organisms and marine snow in relation to other biotic and physical properties of the ocean water column. It is well suited to resolve thin layers and microscale ocean patchiness. Battery capacity supports 50 d of operations. Zooglider includes two-way communications via Iridium, permitting near-real–time transmission of data from each dive profile, as well as interactive instrument control from remote locations for adaptive sampling.

The 2009-2010 El Niño marked the first occurrence of this climate phenomenon since the initiation of sustained autonomous glider surveillance in the California Current System (CCS). Spray glider observations reveal the subsurface effects of El Nio in the CCS with spatial and temporal resolutions that could not have been obtained practically with any other observational method. Glider observations show that upper ocean waters in the CCS were unusually warm and isopycnals were abnormally deep during the El Nio event, but indicate no anomalous water masses in the region. Observed oceanic anomalies in the CCS are nearly in phase with an equatorial El Nio index and local anomalies of atmospheric forcing. These observations point toward an atmospheric teleconnection as an important mechanism for the 2009-2010 El Nio's remote effect on the midlatitude CCS. Copyright 2011 by the American Geophysical Union.

Since 2005, Spray underwater gliders have been used to sample sections across the southern California Current System (CCS). Properties measured are depth-averaged velocity and profiles of temperature, salinity, Acoustic Doppler Profiler shear, chlorophyll a fluorescence, and 750-kHz acoustic backscatter. Although slow and carrying a relatively small sensor suite, gliders observed multiple 350-700-km sections that reveal details of known elements of the CCS circulation like the California Current and Undercurrent as well as a previously undescribed undercurrent 100-200 km offshore. The long time series with high spatial resolution disclose the close link between fronts in physical and biological variables, both the main pycnocline front and secondary weaker but sharp fronts farther offshore. These fronts appear to organize chlorophyll and acoustic backscatter fields, particularly during spring. Much of the patchiness of chlorophyll is associated with vertical displacements of fields that are much smoother within potential density surfaces. The horizontal structure of both chlorophyll and spice (the dynamically passive variable formed from temperature and salinity) appear to be formed by mesoscale stirring. © 2008, by the American Society of Limnology and Oceanography, Inc.

As part of the World Ocean Circulation Experiment, 306 autonomous floats were deployed in the tropical and South Pacific Ocean and 228 were deployed in the Indian Ocean to observe the basinwide circulation near 900-m depth. Mean velocities, seasonal variability, and lateral eddy diffusivity from the resultant 2583 float-years of data are presented. Area averages, local function fits, and a novel application of objective mapping are used to estimate the mean circulation. Patterns of mean circulation resemble those at the surface in both basins. Well-developed subtropical gyres, twice as strong in the Indian Ocean as in the Pacific, feed western boundary currents. Tropical gyres are separated by eastward flow along the equator in both hemispheres of both basins, although the Indian subcontinent splits the north Indian tropical gyre. The Antarctic Circumpolar Current (ACC) and west wind drifts are prominent in both basins, generally tending slightly southward but deviating to the north behind the Del Cano, Kerguelen, and Campbell Plateaus and, of course, South America. Remarkably, the eastern boundaries of the southern subtropical gyres in all three basins apparently occur in the ocean interior, away from land. The Indian Ocean's subtropical gyre, and perhaps part of the South Atlantic's, reaches east to a retroflection just upstream of the Campbell Plateau south of New Zealand. Seasonal variability at 900 m is focused around the equator with weaker variability found near certain bathymetric features. There is a remarkable agreement between the observed seasonable variability and that predicted by the Jet Propulsion Laboratory (JPL)-Estimating the Circulation and Climate of the Ocean (ECCO) data-assimilating numerical model. Aside from seasonal effects, eddy variability is greatest along the equator, in tropical and subtropical western basins, and along the ACC. Integrals of velocity across regional passages (Tasman Sea, Mozambique Channel) provide useful reference for hydrographic analyses of transport. Across whole ocean basins, however, the uncertainty associated with the appropriate continuity relation for horizontal flow (e.g., geostrophy vs nondivergence) is comparable to the mean flow.

The multi-year mean, mid-depth circulation of the subpolar North Atlantic Ocean from direct velocity measurements obtained over a 7.5-year period by 211 neutrally-buoyant, profiling, subsurface floats is estimated. A statistical analysis of these velocity data is presented and features of the circulation from 400-1500m dept as measured by the floats is described.

Autonomous floats profiling in high-nitrate low-silicate waters of the Southern Ocean observed carbon biomass variability and carbon exported to depths of 100 m during the 2002 Southern Ocean Iron Experiment (SOFeX) to detect the effects of iron fertilization of surface water there. Control and 'in-patch' measurements documented a greater than fourfold enhancement of carbon biomass in the iron-amended waters. Carbon export through 100 m increased two- to sixfold as the patch subducted below a front. The molar ratio of iron added to carbon exported ranged between [10.sup.4] and [10.sup.5]. The biomass buildup and export were much higher than expected for iron-amended low-silicate waters., The Southern Ocean plays a critical role in the global carbon cycle and in the regulation of levels of atmospheric C[O.sub.2] (1-3), yet the biological and physical processes that sequester [...]

The analysis of interdecadal physical and biological variability is made challenging by the relative shortness of available time series. It is showed that a composite analysis of climatic records recently used to identify regime shifts which is likely to find them in Gaussian, red noise with stationary statistics.

Two autonomous robotic profiling floats deployed in the subarctic North Pacific on 10 April 2001 provided direct records of carbon biomass variability from surface to 1000 meters below surface at daily and diurnal time scales. Eight months of real-time data documented the marine biological response to natural events, including hydrographic changes, multiple storms, and the April 2001 dust event. High-frequency observations of upper ocean particulate organic carbon variability show a near doubling of biomass in the mixed layer over a 2-week period after the passage of a cloud of Gobi desert dust. The temporal evolution of particulate organic carbon enhancement and an increase in chlorophyll use efficiency after the dust storm suggest a biotic response to a natural iron fertilization by the dust., Marine phytoplankton biomass is replaced, on average, once every 1 to 2 weeks (1-3). Carbon products of photosynthesis (4), i.e., particulate organic carbon (POC), particulate inorganic carbon (PIC), and dissolved [...]

Author(s): Kara L. Lavender (corresponding author) [1]; Russ E. Davis [1]; W. Brechner Owens [2] The Labrador Sea is one of the sites where convection exports surface water to the [...]

Estimates of time-averaged velocity in the North Atlantic Ocean are presented using wind, hydrographic, and bottom-topography data. Hyperbolic dynamics are reviewed with emphasis on determining a numerical model. Results are compared with those obtained using other methods. Values for time-averaged velocity are affected by errors in density and variations in the free mode.

A composite analysis is examined of time series that proposed to identify regime shifts and using time series with stationery statistics and plausible frequency content, it demonstrated that the composite analysis had an uncomfortably high rate of false positives. It did not conclude whether or not true regimes exist, or physical and biological process is coupled.