The Kuroshio Extension System Study (KESS) aimed to quantify processes governing the variability of and the interaction between the Kuroshio Extension and the recirculation gyre. To meet this goal, a suite of instrumentation, including 43 inverted echo sounders equipped with bottom pressure gauges and current meters [current and pressure recording inverted echo sounders (CPIES)], was deployed. The array was centered on the first quasi-stationary meander crest and trough east of Japan, which is also the region of highest eddy kinetic energy. KESS was the first experiment to deploy a large quantity of these new CPIES instruments, and it was unique in that the instruments were deployed in water depths (5300-6400 m) close to their limit of operation. A comprehensive narrative of the methodology to produce mesoscale-resolving fourdimensional circulation fields of temperature, specific volume anomaly, and velocity from the KESS CPIES array is provided. In addition, an improved technique for removing pressure drift is introduced. Methodology and error estimates were verified with several independent datasets. Temperature error was lowest on the equatorward side of the Kuroshio Extension core and decreased with depth (1.58C at 300 m, 0.38C at 600 m, and ,0.18C below 1200 m). Velocity errors were highest in regions of strong eddy kinetic energy, within and south of the jet core. Near the surface, the error in geostrophic velocity between adjacent CPIES was typically 10 cm s 21 , decreasing downward to 6 cm s 21 at 500-m depth and 5 cm s 21 below 800 m. The rms differences from pointwise current measurements are nearly twice as large as the geostrophic errors, because the pointwise velocities include submesoscale and ageostrophic contributions.

[1] The 4-year, calibrated SeaWiFS data set provides a means to determine seasonal and other sources of phytoplankton variability on global scales, which is an important component of the total variability associated with ocean biological and biogeochemical processes. We used empirical orthogonal function (EOF) analysis on a 4-year time series of global SeaWiFS chlorophyll a measurements to quantify the major seasonal (as well as the late El Niño and La Niña phase of the 1997-1998 ENSO) signals in phytoplankton biomass between 50°S and 50°N, and then a second analysis to quantify summer patterns at higher latitudes. Our results help place regional satellite chlorophyll variability within a global perspective. Among the effects we resolved are a 6-month phase shift in maximum chlorophyll a concentrations between subtropical (winter peaks) and subpolar (spring-summer peaks) waters, greater seasonal range at high latitudes in the Atlantic compared to the Pacific, an interesting phasing between spring and fall biomass peaks at high latitudes in both hemispheres, and the effects of the 1998 portion of the 1997-1998 ENSO cycle in the tropics. Our EOF results show that dominant seasonal and ENSO effects are captured in the first six of a possible 184 modes, which explain 67% of the total temporal variability associated with the global mean phytoplankton chlorophyll pattern in our smoothed data set. The results also show that the time (seasonal)/space (zonal) patterns between the ocean basins and between the hemispheres are similar, albeit with some key differences. Finally, the dominant global patterns are consistent with the results of ocean models of seasonal dynamics based on seasonal changes to the heating and cooling (stratification/destratification) cycles of the upper ocean.

The Mediterranean Sea produces a salty, dense outflow that is strongly modified by entrainment as it first begins to descend the continental slope in the eastern Gulf of Cadiz. The current accelerates to 1.3 meters per second, which raises the internal Froude number above 1, and is intensely turbulent through its full thickness. The outflow loses about half of its density anomaly and roughly doubles its volume transport as it entrains less saline North Atlantic Central water. Within 100 kilometers downstream, the current is turned by the Coriolis force until it flows nearly parallel to topography in a damped geostrophic balance. The mixed Mediterranean outflow continues westward, slowly descending the continental slope until it becomes neutrally buoyant in the thermocline where it becomes an important water mass.

The formation of three Loop Current Eddies, Ekman, Franklin, and Hadal, of the Loop Current. Where strong, the horizontal down-gradient eddy heat flux (baroclinic conversion rate) nearly balances the vertical down-gradient eddy heat flux indicating that eddies extract available potential energy from the mean field and convert eddy potential energy to eddy kinetic energy.

Shipboard data from cruises in the 1982 time series on a single Gulf Stream warm‐core ring are composited in a cylindrical coordinate system following the motion of the ring. Measurements of 10°C isotherm depth are used with a two‐layer model of the ring's structure to compute gradient current, kinetic energy, available potential energy (APE), and potential vorticity in the ring, The momentumrelated quantities are compared with surface‐derived velocity measurements by using an acoustic Doppler log (APOC; Joyce and Kennelly, this issue). The volume of waters carried with the ring are also computed on the basis of thermal data. The changes in these quantities as the ring evolves are discussed. The evolution of the ring can be divided into two periods. The first, from April to late June, while the ring is isolated from strong interactions with the Gulf Stream, is associated with slow changes in ring properties. During this period, the ring loses APE at a rate of 94×106 W (94 MW). Kinetic energy is constant within the measurement errors. Ring volume for waters warmer than 10°C decreases at 0.04×106 m3 s−1 (0.04 Sv). A shift in ring volume out to larger radius is observed. After this interval the ring is involved in several interactions with the Gulf Stream and topography. Ring energy is lost at rates exceeding 900 MW. The ring volume is diminished at 1.4 Sv during the July period. Within the measurement errors, however, the potential vorticity at the center of the ring is conserved from April through August, implying nearly inviscid dynamics.