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- Author or Editor: Walter Düing x
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Abstract
A large number of vertical profiles of horizontal current were observed during the last two years in the Florida Straits. For a two-week set of observations, it is found that westward meandering of the Florida Current is accompanied by a reduction of the overall volume transport through the Straits of Florida, deep southward flow, and a deepening of the midstream isothermal field. The meandering motion for the observed case is interpreted as a predominantly barotropic wave with a time scale of several days.
Abstract
A large number of vertical profiles of horizontal current were observed during the last two years in the Florida Straits. For a two-week set of observations, it is found that westward meandering of the Florida Current is accompanied by a reduction of the overall volume transport through the Straits of Florida, deep southward flow, and a deepening of the midstream isothermal field. The meandering motion for the observed case is interpreted as a predominantly barotropic wave with a time scale of several days.
Abstract
To assess the importance of possible feedbacks between ocean and atmosphere in the Arabian Sea, we computed a preliminary heat budget for the upper ocean layer. The observed total heat loss during the Southwest Monsoon between April and August is essentially balanced by three phenomena: positive heat gain from the atmosphere, negative northward heat flux across the equator, and heat loss due to upwelling along the coasts of East Africa and Arabia. Upwelling constitutes the dominant factor and the question is discussed as to which processes replenish the cold upwelled water on a seasonal time scale.
The average annual heating rate above and beyond seasonal fluctuations is found to be 24 W m−2. This net heat input must be compensated by ocean currents. The manner in which the ocean accomplishes this remains to be clarified.
Abstract
To assess the importance of possible feedbacks between ocean and atmosphere in the Arabian Sea, we computed a preliminary heat budget for the upper ocean layer. The observed total heat loss during the Southwest Monsoon between April and August is essentially balanced by three phenomena: positive heat gain from the atmosphere, negative northward heat flux across the equator, and heat loss due to upwelling along the coasts of East Africa and Arabia. Upwelling constitutes the dominant factor and the question is discussed as to which processes replenish the cold upwelled water on a seasonal time scale.
The average annual heating rate above and beyond seasonal fluctuations is found to be 24 W m−2. This net heat input must be compensated by ocean currents. The manner in which the ocean accomplishes this remains to be clarified.
Abstract
The vertical displacements associated with oscillations near the local inertial frequency f, in a stratified ocean, are found to be significant, even very close to f. For a frequency, ω=(1+ε)f, the ratio of rms vertical velocity to horizontal velocity is O(ε1/2). Observations near Hawaii, made with a recently developed pycnocline follower, show inertial oscillation events similar to those found by Webster in current meter records, and discussed theoretically by Crepon and by Pollard.
Abstract
The vertical displacements associated with oscillations near the local inertial frequency f, in a stratified ocean, are found to be significant, even very close to f. For a frequency, ω=(1+ε)f, the ratio of rms vertical velocity to horizontal velocity is O(ε1/2). Observations near Hawaii, made with a recently developed pycnocline follower, show inertial oscillation events similar to those found by Webster in current meter records, and discussed theoretically by Crepon and by Pollard.
Abstract
Temperature and current records were obtained from four subsurface moorings deployed in the source region of the Somali Current from mid-January to mid-July 1976.
The first part of the records from January until early April showed that the array straddled the convergence zone of the northward-flowing East African Coast Current and the southward-flowing Somali Current. During this time, except for the southernmost location off Mombasa, the mean flow at all locations was weak and variable. The predominant variability had a time-scale of 4–5 days.
Around 20 April the wind shifted to the southeast and three days later the flow in the upper 80 m turned northward and intensified. Development of strong northward flows below the thermocline took several more weeks. The observations imply that a switching mechanism took place at that time. The initially eastward-flowing Equatorial Counter Current is shifted rapidly 45° to the left to run northward along the coast. This mechanism may, in part, be responsible for the impulsive beginning of the Somali Current during the early stages of the monsoon onset south of the equator.
Abstract
Temperature and current records were obtained from four subsurface moorings deployed in the source region of the Somali Current from mid-January to mid-July 1976.
The first part of the records from January until early April showed that the array straddled the convergence zone of the northward-flowing East African Coast Current and the southward-flowing Somali Current. During this time, except for the southernmost location off Mombasa, the mean flow at all locations was weak and variable. The predominant variability had a time-scale of 4–5 days.
Around 20 April the wind shifted to the southeast and three days later the flow in the upper 80 m turned northward and intensified. Development of strong northward flows below the thermocline took several more weeks. The observations imply that a switching mechanism took place at that time. The initially eastward-flowing Equatorial Counter Current is shifted rapidly 45° to the left to run northward along the coast. This mechanism may, in part, be responsible for the impulsive beginning of the Somali Current during the early stages of the monsoon onset south of the equator.
Abstract
A 50-day time series was obtained from a current meter mooring in the Florida Current off Miami. The results agree with earlier observations regarding the significance of several-day oscillations in the Gulf Stream. The energy spectrum of the V component shows a pronounced peak at periods of 5–6 days with an amplitude of about 20 cm sec−1. Quantitatively the results are reminiscent of barotropic shelf waves, although definite conclusions about the occurrence of such waves require additional observations.
Analysis of tidal fluctuations shows that 25% of the variance in the V component and 6% of the variance in the U component can be accounted for by the four major constituents, M2, S2, K1 and O1. The largest constituent in the V component is the O1 tide, whereas the K1 tide dominates in the U component. The results are in good agreement with earlier observations from the sea surface, indicating that the vertical structure of the tides is predominantly barotropic.
Abstract
A 50-day time series was obtained from a current meter mooring in the Florida Current off Miami. The results agree with earlier observations regarding the significance of several-day oscillations in the Gulf Stream. The energy spectrum of the V component shows a pronounced peak at periods of 5–6 days with an amplitude of about 20 cm sec−1. Quantitatively the results are reminiscent of barotropic shelf waves, although definite conclusions about the occurrence of such waves require additional observations.
Analysis of tidal fluctuations shows that 25% of the variance in the V component and 6% of the variance in the U component can be accounted for by the four major constituents, M2, S2, K1 and O1. The largest constituent in the V component is the O1 tide, whereas the K1 tide dominates in the U component. The results are in good agreement with earlier observations from the sea surface, indicating that the vertical structure of the tides is predominantly barotropic.
Abstract
Current measurements from three stations along the east coast of Florida at about 300 m water depth with a maximum longshore separation of 180 km were used to analyze for the presence of propagating waves.
The analysis was done by solving the inverse problem of determining the most likely wave parameters from 36 independent auto spectra and cross spectra from four current meters. For the 10–13 day band a significant fit of the data by a wave cross-spectral function was found. The wavelength is 170 km and the phase propagation 17 cm s−1 toward the south. The current fluctuations are elliptically polarized with anti-cyclonic rotation and with an axis ratio of 0.30. The mean current amplitude is 14.3 cm s−1. A marginally significant fit with similar wave parameters resulted for the 7–10 day band. The results suggest that these waves are continental shelf waves, probably generated by atmospheric cold front passages.
Abstract
Current measurements from three stations along the east coast of Florida at about 300 m water depth with a maximum longshore separation of 180 km were used to analyze for the presence of propagating waves.
The analysis was done by solving the inverse problem of determining the most likely wave parameters from 36 independent auto spectra and cross spectra from four current meters. For the 10–13 day band a significant fit of the data by a wave cross-spectral function was found. The wavelength is 170 km and the phase propagation 17 cm s−1 toward the south. The current fluctuations are elliptically polarized with anti-cyclonic rotation and with an axis ratio of 0.30. The mean current amplitude is 14.3 cm s−1. A marginally significant fit with similar wave parameters resulted for the 7–10 day band. The results suggest that these waves are continental shelf waves, probably generated by atmospheric cold front passages.
