Long-Term, Deep-Ocean Moorings Of Current Measuring Arrays

ABSTRACT The Research and Development Department of the Naval Oceanographic Office has developed considerable capability in deep ocean mooring technology. This capability was employed in the Barbados Oceanographic and Meteorological Experiment (BOMEX) to establish a series of long-term, deep-ocean moorings containing current sensors. In support of Project BOMEX, NAVOCEANO has completed the implantation and recovery of six deep-ocean current measuring arrays. These arrays were positioned along a 740 kilometer (400 nautical mile) diagonal, from 12 °23' north to 17 °36' north, extending through the BOMEX area centered at 15 ° north and 56 °30' west. The entire operation was conducted from aboard the USCGC LAUREL with the implantation phase commencing on 18 April 1969 and the recovery phase terminating 6 August 1969. Taut-line arrays were utilized with self-contained Richardson type current meters vertically positioned at 80, 150, 300, 850, 1500, 2000, 3000, 4000, and 5000 meters depending on water depth at each array site. A total of 28 current meters were recovered and contain current data collected at 30 minute intervals over a continuous period of 86 to 104 days. This paper presents a description of equipment, hardware, implanting, and recovery techniques; and a brief summary of some of the results. INTRODUCTION The Barbados Oceanographic and Meteorological Experiment (BOMEX) was a large-scale air-sea interaction field experiment and was conducted in the vicinity of the Island of Barbados in late spring and early summer 1969. In addition to the extensive scientific investigations of the interaction between the air and the sea, studies of tropical circulation, radiation balance, ocean circulation, and internal waves were carried out through the joint effort of Federal agencies, universities, and private laboratories and corporations. The Naval Oceanographic Office (NAVOCEANO) in the past five years has developed the capability to monitor the deep-ocean environment with self-contained buoyed systems. This in-house developed capability was employed to establish a series of taut-line, deep-ocean moorings in the BOMEX area. This line of moorings will provide data to examine the spectral density of horizontal motions as a function of latitude and depth. In support of this study, NAVOCEANO implanted seven deep-ocean current measuring arrays during the periods 18 through 23 April 1969 and 1 through 6 May 1969 from aboard the USCGC LAUREL (Seagoing Buoy Tender). As shown in Figure 1, six of these arrays were positioned along a 740 kilometer (400 nautical mile) diagonal, through the-center of the BOMEX area, from 12 °23' north and 58 °23' west to 17 °36' north and 54 °34' west. Array "G" was positioned approximately 130 kilometers (75 nautical miles) to the southeast of the line of arrays. The recovery phase of the operation was conducted during the period 31 July through 6 August 1969 from aboard the LAUREL. - This study involved the most extensive buoy operation undertaken by NAVOCEANO. The success of the buoy recovery operations were directly dependent on the performance of the recently acquired acoustic command release-pinger system.