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- Author or Editor: Klaus Wyrtki x
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Abstract
Mean sections based on data from a discrete one-year period during the Hawaii-to-Tahiti Shuttle Experiment are used to describe and analyse the equatorial current system, its water masses and the transverse circulation in the central Pacific Ocean. Computations of mean geostrophic transports for the individual currents identify the south equatorial current as the strongest flow, transporting 55 × 106 m3 s−1. Information derived from the water mass and nutrient distributions is used to develop a consistent picture of the transverse circulation and of the role of the different divergences and convergences.
Abstract
Mean sections based on data from a discrete one-year period during the Hawaii-to-Tahiti Shuttle Experiment are used to describe and analyse the equatorial current system, its water masses and the transverse circulation in the central Pacific Ocean. Computations of mean geostrophic transports for the individual currents identify the south equatorial current as the strongest flow, transporting 55 × 106 m3 s−1. Information derived from the water mass and nutrient distributions is used to develop a consistent picture of the transverse circulation and of the role of the different divergences and convergences.
Abstract
Routinely taken oceanographic data from 55 temperature sections across the North Pacific Current along 158°W between Hawaii and Alaska are used to determine the accuracy of heat storage computations. Errors caused by the use of different instruments and their calibration are as large as those caused by environmental variability on short time and space scales and amount to ∼18×107 J m−2, which is about 15% of the mean annual cycle in observed heat storage. Anomalies of heat storage and month-to-month changes of heat storage cannot be determined with any confidence, but over a complete heating or cooling season the observed changes in heat storage are systematically larger than the heat gain or loss during that season by about 50%, indicating a regular contribution by horizontal advection.
Abstract
Routinely taken oceanographic data from 55 temperature sections across the North Pacific Current along 158°W between Hawaii and Alaska are used to determine the accuracy of heat storage computations. Errors caused by the use of different instruments and their calibration are as large as those caused by environmental variability on short time and space scales and amount to ∼18×107 J m−2, which is about 15% of the mean annual cycle in observed heat storage. Anomalies of heat storage and month-to-month changes of heat storage cannot be determined with any confidence, but over a complete heating or cooling season the observed changes in heat storage are systematically larger than the heat gain or loss during that season by about 50%, indicating a regular contribution by horizontal advection.
Abstract
Observations made during the Hawaii to Tahiti Shuttle Experiment allow the study of the time and space scales of equatorial upwelling. Individual upwelling events can be identified. Each is caused by a burst in the trade winds lasting from 10 to 20 days. Sea level drops, surface temperature decreases, and near-surface isotherms rise by several tens of meters. The vertical velocity of upwelling is at least 3 m per day. Five such upwelling events were observed during the 18-month experiment.
Abstract
Observations made during the Hawaii to Tahiti Shuttle Experiment allow the study of the time and space scales of equatorial upwelling. Individual upwelling events can be identified. Each is caused by a burst in the trade winds lasting from 10 to 20 days. Sea level drops, surface temperature decreases, and near-surface isotherms rise by several tens of meters. The vertical velocity of upwelling is at least 3 m per day. Five such upwelling events were observed during the 18-month experiment.
Abstract
Sea level variability at Tahiti is analyzed from daily to interannual time scales and compared with that at neighboring island stations. Tahiti lies close to an amphidromic point with respect to the major semidiurnal tides; it is rarely affected by strong atmospheric disturbances, and the standard deviations of daily and monthly mean sea level are the lowest for nearby stations with a representative record length. Low-frequency variability of sea level is smallest when compared with nearby stations; only the 1982–83 El Niño event is clearly apparent in the data. Tahiti displays the lowest variability of sea level on all time scales considered, which makes it an ideal location for the calibration of satellite altimeter measurements.
Abstract
Sea level variability at Tahiti is analyzed from daily to interannual time scales and compared with that at neighboring island stations. Tahiti lies close to an amphidromic point with respect to the major semidiurnal tides; it is rarely affected by strong atmospheric disturbances, and the standard deviations of daily and monthly mean sea level are the lowest for nearby stations with a representative record length. Low-frequency variability of sea level is smallest when compared with nearby stations; only the 1982–83 El Niño event is clearly apparent in the data. Tahiti displays the lowest variability of sea level on all time scales considered, which makes it an ideal location for the calibration of satellite altimeter measurements.
Abstract
The resultant flow calculated from 42 current meter measurements near the Hawaiian Islands for different periods of from two to six weeks between October 1964 and May 1969 indicate nearshore anticyclonic circulation around the Islands. Two possible mechanisms generating this flow are considered: steady currents induced by oscillations around the Islands and the cyclonic shear imposed on the local trade winds by the Islands.
Abstract
The resultant flow calculated from 42 current meter measurements near the Hawaiian Islands for different periods of from two to six weeks between October 1964 and May 1969 indicate nearshore anticyclonic circulation around the Islands. Two possible mechanisms generating this flow are considered: steady currents induced by oscillations around the Islands and the cyclonic shear imposed on the local trade winds by the Islands.
Abstract
Correlations of monthly mean sea level variations along the Pacific Ocean margin are used to define length scales. In the northeast quadrant a minimum length scale at about 38°N separates two distinct regimes of longer length scale. This transition corresponds to a change from a regime north of 38° that is dominated by local atmospheric forcing to a regime south of 38° that is dominated by remote forcing. In the northwest quadrant a transition occurs near 35°N near the point of the separation of the Kuroshio. A transition at about 30°S in the southwest quadrant is associated with the southernmost extent of the Great Barrier Reef off the coast of Australia. In the southeast quadrant, a transition is observed at 18°S that may be due to a sharp change in the direction of the South American coastline. In general. tropical length scale values of 800 to 3100 km are separated from midlatitude values of 700 to 1300 km by a narrow region in which length scales are as short as 250 km. These results suggest the need for latitude-dependent criteria for the spacing of tide gauges in a global oceanographic sea level system.
Abstract
Correlations of monthly mean sea level variations along the Pacific Ocean margin are used to define length scales. In the northeast quadrant a minimum length scale at about 38°N separates two distinct regimes of longer length scale. This transition corresponds to a change from a regime north of 38° that is dominated by local atmospheric forcing to a regime south of 38° that is dominated by remote forcing. In the northwest quadrant a transition occurs near 35°N near the point of the separation of the Kuroshio. A transition at about 30°S in the southwest quadrant is associated with the southernmost extent of the Great Barrier Reef off the coast of Australia. In the southeast quadrant, a transition is observed at 18°S that may be due to a sharp change in the direction of the South American coastline. In general. tropical length scale values of 800 to 3100 km are separated from midlatitude values of 700 to 1300 km by a narrow region in which length scales are as short as 250 km. These results suggest the need for latitude-dependent criteria for the spacing of tide gauges in a global oceanographic sea level system.
