Abstract. An electrochemical based, all solid-state, calibration-free pH sensor is presented. The sensor is targeted for monitoring the pH of ocean and estuarine environments covering a salinity range from 10–35 ppt without the need for additional salinity measurements. The sensor performance is demonstrated in both laboratory and field conditions. The field tests were conducted in an estuarine environment close to Oban in Scotland where the sensor was deployed for a period of three days. The sensor was validated against a sampled solution and tested alongside a glass pH sensor. The data highlighted the efficiency of the sensor to monitor the tidal variations of pH in the estuarine environment.
Long-term current measurements at depths of 50 and 100m obtained with Richardson current meters at two deep-water moorings south of Bermuda are reported. The records are dominated by anticyclonic rotations which appear and degenerate, possibly in response to the passage of storms. Spectral analysis of the records indicates that this motion has a period of 24 hours at a depth of 50 m, and 25•3 hours at a depth of 100m. No explanation is given to account for this difference in period over a 50-m separation. Both records indicate the existence of semidiurnal tidal motion. The long-term motions at both depths indicate a systematic change in the net direction of flow over a three-month period. COLLECTION OF MEASUREMENTS IN THE autumn of 1962, six deep-sea buoy stations equipped with recording current meters, were established along the 65th meridian, south of Bermuda. Mooring failure resulted in the loss of most of this equipment, but three instruments were subsequently recovered. The records obtained are reported. The moorings and instrumentation were identical to the system described by RICHARDSON (1963) , except that 16m oft inch chain was used immediately below the buoy bridle to reduce surges on the cable due to buoy motion. Each current meter was set to record for 1 minute at 20 minute intervals. Reading of the films was done by eye; signals too weak to be resolved by the electronic method together with blurred rotor counts at the higher current speeds made attempts at automatic read-out unsatisfactory. Subsequent changes in current meter design and in read-out technique appear to have solved these problems. WEBSTER (l963) analyzed the energy distribution of rotor counts from similar records, but dismissed the directional values because of the wide scatter in vane readings. Similar directional scatter was encountered in the records reported here, particularly at current speeds below 15 em/sec. In an effort to obviate this difficulty, it was arbitrarily decided to read the directional record once only during each recording interval at the least ambiguous point of the record , this being the spot where both compass and vane appeared to have least motion. It is not possible to assess the consequences of this decision. Such an assessment would require multiple readings, all equally unambiguous during each recording interval over an extended period; the present records do not offer an opportunity for such an analysis because of vane fluttering. The bulk of the data obtained came from two instruments set at depths of 50 and 100m on Stn. 101 at 28° 07'N, 65° 02'W, some 250 miles south of Bermuda *Contribution No. 1513 from the Woods Hole O~eanographic Institution .
A transponding drift buoy has been developed to aid in the study of the horizontal motions of surface waters. Experiments to study the non-tidal drift off Martha's Vineyard, Mass., in June 1956, off Yarmouth, N.S., in October and November 1956, in Grand Manan Channel in October 1956, and off Saint John, N.B., in December 1956, are described and discussed.
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