2.0 Description of cruises


2.0 Description of cruises

Description of cruises In this section, we briefly describe the cruises operations. The scientific personnel who participated are listed in Table 2.1.

Table 2.1

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2.1 EQ-1

Fig. 1 shows the cruise track indicating the positions of hydrographic, XBT and mooring stations. Webster and Lukas (1992) describe the ATLAS mooring and the PROTEUS current meter mooring. The R/V Moana Wave departed Guam on April 17, 1992. The cruise included a northward transect along 143°E, a southward transect along 147°E, and an equatorial transect from 150°E to 170°E. The ship headed initially to 5°N, 133°E, as the initial plan was to locate the ATLAS moorings along 133°E. During this transit, the decision was made to shift the site for the ATLAS mooring from 2°N, 133°E to 2°N, 137°E in order to have acceptable bottom topography for the deployment. The long time series hydrographic section (Qiu and Joyce, 1992) along the 137°E meridian was also an important factor in the final choice. The ship then changed course, and arrived at 5°N 137°E on April 20. A bathymetric survey was made for a future ATLAS mooring deployment at 5°N, 137°E, and the deployment of an ATLAS mooring was made at 2°N, 137°E. CTD casts were completed at 2°N and 5°N along 137°E.

After completing all operations along 137°E, the ship steamed to the coast of Papua New Guinea at 143°E. It headed northward along 143°E to occupy a line of CTD stations which ended at 5°N. CTD casts were taken every-half degree of latitude between the coast of Papua New Guinea and 5°N. The deployment of an ATLAS mooring was made at 0°, 143°E.

The ship then steamed to 5°N, 147°E. Mooring operations along 147°E included a recovery of an ATLAS mooring at 5°N and deployments of 2 ATLAS moorings (5°N and 2°N). CTD stations were occupied every one-half degree of latitude between 5°N and 2°S.

After all operations along 147°E were completed, the ship transited to 0°, 150°E to occupy CTD stations along the equator, with one degree spacing between 150°E and 170°E. Mooring operations along the equator included deployments of ATLAS moorings (154°E, 160.5°E and 170°E) and the recovery and deployment of the current meter mooring at 0°, 156°E. After the last deployment at 0°, 170°E, the ship transited to Majuro arriving on May 14.

For the entire period of the cruise, a shipboard ADCP was operated. A thermosalinograph collected near-surface data throughout the cruise. High resolution meteorological data were acquired from sensors on a meteorological tower installed on the foredeck of R/V Moana Wave. These meteorological data are not covered in this report. Meteorological observations were also made every 4 hours by the ship's officers on the bridge and every 6 hours by the science group. XBTs were launched at various locations during the cruise (Fig. 1).

Figure 1.

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2.2 EQ-2

The R/V Moana Wave departed Guam on March 3, 1993. The cruise track is shown in Fig. 2. The cruise included an equatorial transect from 154°E to 170°E, and a northward transect along 165°E.

After completing a CTD test cast at 11°51'N, 145°42'E, the ship transited to the first mooring station at 0°, 154°E. Mooring operations along the equator included recoveries and deployments of 3 ATLAS moorings (154°E, 160.5°E and 170°E), two PROTEUS mooring recoveries (156°E and 165°E) and one PROTEUS mooring deployment (156°E). CTD stations were occupied every degree of longitude between 143°E and 170°E along the equator.

After all operations along the equator were completed, the ship steamed to 8°S, 165°E. CTD casts were taken at every degree of latitude between 8°S and 5°N. Mooring operations along 165°E included the recovery of one ATLAS mooring at 2°S, deployments of 2 ATLAS moorings (5°S and 2°S) and one PROTEUS mooring deployment at the equator.

After the CTD cast at 5°N, 165°E was completed, the ship transited to Kwajalein for loading of additional mooring equipment, arriving on March 28. The ship departed Kwajalein on March 28 for the recovery and deployment of an ATLAS mooring at 8°N, 165°E. After completing the mooring operations and the CTD cast at 8°N, 165°E, the ship steamed to Pohnpei, arriving on March 31.

A shipboard ADCP was run throughout the cruise. Operations also included bow-mounted sensor sampling, thermosalinograph sampling and meteorological observations. Temperature, conductivity and velocity fluctuations near the surface were measured by the bow-mounted sensors. Details of the bow-mounted sensor measurements are described in a separate data report (Soloviev et al., 1995)

Figure 2.

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2.3 EQ-3

The EQ-3 cruise consisted of two legs. The cruise track, with positions of hydrographic and mooring stations, is shown in Fig. 3.

Leg 1

The R/V Moana Wave departed Pohnpei on April 11, 1994. Recoveries of moorings were made at 8°N, 2°S, and 8°S along 165°E, and at 0°, 160.5°E. Deployments of ATLAS moorings were made at 8°N, 2°S; 5°S and 8S° along 165°E. CTD casts were taken every degree of latitude between 8°N and 2°S, with half-degree spacing between 2°N and 2°S. CTD casts were also completed at 5°S, 6.5°S, and 8°S along 165°E, and at the 0°, 160.5°E mooring recovery site. In addition to this mooring work, an adrift ATLAS buoy was recovered on the transit from 8°S, 165°E to 0°, 160.5°E. The ship arrived at Pohnpei on April 25.

Leg 2

The ship departed Pohnpei on April 26. Leg 2 included a southward transect along 156°E, an equatorial transect from 154°E to 143°E, and a short northward transect along 137°E before arrival at Guam. Mooring operations along 156°E included the recovery of the bottom portions of two moorings where the surface buoys had broken free (2°N and 2°S), one subsurface ADCP mooring recovery at the equator, one surface mooring recovery at the equator, one PROTEUS mooring deployment at the equator and 2 ATLAS mooring deployments (2°N and 2°S). CTD stations were occupied at every degree of latitude between 5°N and 2°S along 156°E.

After completing all operations along 156°E on April 30, the ship transited to 0°, 154E°. CTD stations were occupied at every two degrees of longitude along the equator between 156°E and 143°E. After a recovery operation of the ATLAS mooring at 0°, 143°E was completed, the ship steamed to 2°N, 137°E. An ATLAS mooring was recovered and deployed at 2°N, 137°E. After the deployment of another ATLAS mooring at 5°N, 137°E, the ship began to transit to Guam and arrived on May 11.

A shipboard ADCP was operated throughout the cruise. Underway operations also included bow-mounted sensor sampling, thermosalinograph sampling, and meteorological observations. Vertical profiles of temperature, salinity, and velocity fluctuations measured by the Russian free rising profiler were made when time permitted. Details of these and the bow-mounted sensor measurements are described in a separate data report (Soloviev et al., 1995).

Figure 3.

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