36 4
C'ARI. 11. (illlSON ET AL..
55 cniZlsec at 120 m on 2'27. I: seemed to decrease with depth on 2,127 by
about a factor of 10 from 29 to 120 m. 1 was twice as large at 23 m on 2/28
than at 120 m on 2/27. Low values of c2 were found at 29 and 2 3 m on 2/27
arid 2!28, but are probably low due to reduced frequency response of hot
film probes fouled by plankton. Generally. the data seem reasonably consistent with what could be expecttd in the upper layer of the ocean. Again.
however. noise levels were sufficiently high that strip chart records did not
give a satisfactory definition of continuous or patchy turbulence.
3.2. Oconostol~i.-- Mi.wd L q w r
The same "fish" used in the C'romwell current measurements Wits towed
in November 1972 from the Scripps' ship Oconostotn at several depths from
20 to SO m in the mixed layer and thermocline a few miles off San Diego. As
indicated above, the velocity and temperature elcctronics had been completely redesigned and packaged in a pressure case attached to the fish. and
the .various signals were sensed, amplified, prewhitened, isolated, and transmitted up the four-conductor armored cable to the tape recorder in the ship
laboratory.
A strip chart of temperature, velocity, and their derivatives is shown in
Fig.6, along with the corresponding XBT temperature versus depth profile.
The instruments were towed at a depth of 18.3 m at 130 cm/sec with the ship
moving with the waves. The XRT temperature profile shows T = 16.90 &
0.05 c' to about 25 m. so the data correspond to a horizontal sample threcquarters of the way down in a well-mixed surface layer. From the upper
trace of Fig. 6 it can be seen that the temperattire derivative signal 0' was not
continuous but occurred in bursts which are closely correlated with the
periodic variations in the hot film anemometer output shown in the bottom
trace. A similar correlation exists for the velocity derivative signal c;'
although the latter is more noisy and is contaminated by plankton "hits."
Periodic variations in the velocity past the fish may be induced through thc
cable by the ship or may exist in the water, but in both cases should be in
phaw with the surface waves. The magnitude of the variations o f
10 2 0 cmbec is consistent with the expected amplitude of the wave orbital
velocity at the depth of towing and the period of 5.- 10 sec is consistent with
the observed period of the surface waves, rather than half the period which
would he expected if the periodicity was due to heaving of the ship. Horizontal velocity variations of the ship due to the waves ate generally rather
poorly transmitted to towed bodies, but in any event should be in phase with
the package motions since the wire angles were less than 5". Therefore it
seems reasonable to assume that most of the motion indicated by the lower
trace in Fig. 6 is in phase with the surface waves and probably due to thc
orbital velocity rather than ship motion.
C'ARI. 11. (illlSON ET AL..
55 cniZlsec at 120 m on 2'27. I: seemed to decrease with depth on 2,127 by
about a factor of 10 from 29 to 120 m. 1 was twice as large at 23 m on 2/28
than at 120 m on 2/27. Low values of c2 were found at 29 and 2 3 m on 2/27
arid 2!28, but are probably low due to reduced frequency response of hot
film probes fouled by plankton. Generally. the data seem reasonably consistent with what could be expecttd in the upper layer of the ocean. Again.
however. noise levels were sufficiently high that strip chart records did not
give a satisfactory definition of continuous or patchy turbulence.
3.2. Oconostol~i.-- Mi.wd L q w r
The same "fish" used in the C'romwell current measurements Wits towed
in November 1972 from the Scripps' ship Oconostotn at several depths from
20 to SO m in the mixed layer and thermocline a few miles off San Diego. As
indicated above, the velocity and temperature elcctronics had been completely redesigned and packaged in a pressure case attached to the fish. and
the .various signals were sensed, amplified, prewhitened, isolated, and transmitted up the four-conductor armored cable to the tape recorder in the ship
laboratory.
A strip chart of temperature, velocity, and their derivatives is shown in
Fig.6, along with the corresponding XBT temperature versus depth profile.
The instruments were towed at a depth of 18.3 m at 130 cm/sec with the ship
moving with the waves. The XRT temperature profile shows T = 16.90 &
0.05 c' to about 25 m. so the data correspond to a horizontal sample threcquarters of the way down in a well-mixed surface layer. From the upper
trace of Fig. 6 it can be seen that the temperattire derivative signal 0' was not
continuous but occurred in bursts which are closely correlated with the
periodic variations in the hot film anemometer output shown in the bottom
trace. A similar correlation exists for the velocity derivative signal c;'
although the latter is more noisy and is contaminated by plankton "hits."
Periodic variations in the velocity past the fish may be induced through thc
cable by the ship or may exist in the water, but in both cases should be in
phaw with the surface waves. The magnitude of the variations o f
10 2 0 cmbec is consistent with the expected amplitude of the wave orbital
velocity at the depth of towing and the period of 5.- 10 sec is consistent with
the observed period of the surface waves, rather than half the period which
would he expected if the periodicity was due to heaving of the ship. Horizontal velocity variations of the ship due to the waves ate generally rather
poorly transmitted to towed bodies, but in any event should be in phase with
the package motions since the wire angles were less than 5". Therefore it
seems reasonable to assume that most of the motion indicated by the lower
trace in Fig. 6 is in phase with the surface waves and probably due to thc
orbital velocity rather than ship motion.