RR10106 Cruise Plan ITOP Mooring Recovery and PhilSea10 Seaglider Operation (R/V Revelle November 6-26, 2010)

Transcription

1 RR10106 Cruise Plan ITOP Mooring Recovery and PhilSea10 Seaglider Operation (R/V Revelle November 6-26, 2010) Chief Scientist: Ren-Chieh Lien, Applied Physics Lab, University of Washington Co-Chief Scientist: Lora van Uffelen, University of Hawaii I. Objectives 1. Recovery of ITOP Moorings The first objective of this cruise is to recover the surface and subsurface moorings in the western Pacific Ocean as a part of ITOP (Impact of Typhoon on the Western Pacific Ocean) DRI program. These moorings were deployed in March and August of During this cruise, we will recover four ATLAS surface moorings and three subsurface moorings. We will also make CTD casts at the mooring sites and collect underway hydrography and meteorology data using on shipboard instruments. If there is cold wake generated by recent typhoons, we will perform the cold wake study. Also, we will help recover ITOP oceanic assets, if they are within the range and time permitted. 2. PhilSea10 - Seaglider Deployment and Operations The second objective of this cruise is to deploy four Seagliders in the Philippine Sea to serve as mobile tomography receivers as part of the ONR Ocean Acoustics sponsored PhilSea10 experiment. The data obtained by the gliders listening to six moored tomography sources, installed by Peter Worcester in April 2010, will be used to improve the tomographic resolution of the reconstructed sound speed (temperature) fields in the experiment domain. The gliders will be deployed during November 2010 and recovered in April 2011 during Peter Worcester s mooring recovery cruise. II. Shipboard Equipment Major shipboard equipment requirement is listed as follows. Steady Internet connection for Seaglider piloting, gliders and floats recovery (We hope the pedestal problem on the Hiseasnet can be fixed before the cruise) Standard equipment for mooring deployment and recovery, e.g. TSE winch, tugger, capstan, Multibeam and Knudsen for bathymetry survey 1

2 Shipboard ADCP (75 khz and 150kHz) Revelle deep sonar HDSS (50 khz and 140 khz) Met sensors Intake sea surface temperature and conductivity Shipboard CTD Marine radar repeater (with digital recording as discussed in the pre-cruise meeting) GPS position and heading Small boat operation III. Scientific Activity 1. ATLAS Surface and ADCP Subsurface Moorings recovery We will recover four ATLAS surface moorings and three ADCP subsurface moorings. Each mooring recovery will take about 4-6 hrs. We also plan to conduct CTD casts before each mooring recovery. The planned cruise route is shown in Fgure 1. Positions of moorings are listed in Table 1. The schematic drawing of surface and subsurface moorings are shown in Figure 2. Distances between way points are given in Table 2. The ATLAS surface mooring is equipped with 14 underwater temperature sensors, meteorological suite, meteorology data Iridium transmitter, and Self-Contained Iridium Transmitter (SIT) (Fig. 2a). The subsurface ADCP mooring is equipped with one 75-kHz Long Ranger ADCP in a 45 syntactic-float housing. SA4 is equipped with one 300-kHz ADCP in the top 45 syntactic-float housing. There are 7 temperature/conductivity sensors mounted on the top 500-m jacketed wire (Fig. 2b) and 5 temperature loggers on the lower Kevlar line between 500 and 1500-m depth. The buoyancy of the moorings is provided by two 45" syntactic-foam floats. The top syntactic-foam float is about m below the sea surface. The Kevlar line has a breaking strength of 5,500 lb, extra caution needed during the recovery. Several technicians from Taiwan Ocean Research Institute (TORI) and mooring engineers from NCOR will work with Revelle's resident technicians for the mooring recovery operation. 2

3 Figure 1. The tentative cruise route (blue lines), the positions of moorings (A1, A2, A3, A4, SA1, SA2, and SA4) and the PhilSea10 domain (T1~6, DVLA). Seagliders are planned to be deployed at the DVLA site. EEZ boundaries are shown by green lines. ATLAS Surface Mooring Recovery Procedure Estimated operation time: 4-6 hr each Search surface buoy with marine radar and marine light on the buoy. Steam closer to buoy and send release code to the acoustic release. Recover the buoy by A-frame, and disconnect the mooring line from the bridle below the buoy. Transfer load, run the jacketed wire (approx. 500m) through the winch, and stop and detach temperature loggers from the mooring line. 3

4 Run the nylon rope through capstan and relay it into the foldable wire basket. Each basket can hold three sections of 500-m nylon rope (approx. 1500m). Recover the glass floats and acoustic releases. Subsurface Mooring Recovery Procedure Estimated operation time: 4-6 hr each Ping acoustic releases with commander and verify the mooring location. Steam closer to buoy and send release code to the acoustic release. Recover the top 45" float by A-frame, and disconnect the mooring line below the float. Transfer load, run the jacketed wire (approx. 500m) through the winch, and stop and detach temperature loggers from the mooring line. Recover the bottom 45" float by A-frame, and disconnect the Kevlar line below the float. Continue run the Kevlar line through the winch and recover sensors. Recover the glass floats and acoustic releases. We plan to recover A4 and SA4 moorings first, conduct the PhilSea10 Seaglider operation, and then recover the rest the moorings. We also plan to recover other ITOP assets, including Craig Lee s gliders, and EM-APEX and Lagrangian floats if they are within the range for recovery. Table 1. ITOP mooring locations Site Lon Lat Lon Lat Type A E N E N Surface A E N ' E ' N Surface A E N E N Surface A E N ' E ' N Surface SA E N E N Subsurface SA E N E N Subsurface SA E N E N Subsurface 4

5 Table 2. Distance between waypoints. waypoint Distance (nm) Kaohsiung - A4 230 A4 - DVLA 130 DVLA - A1 110 A1 - A3 124 A3 - A2 205 A2 - Keelung 269 a b Figure 2. Schematic diagrams of ITOP ATLAS surface mooring and subsurface ADCP/TC 5

6 mooring. 2. PhilSea10 Seaglider Deployment and Operations Glider Deployment Plan The gliders will be deployed in international waters at the DVLA site (Distributed Vertical Line Array; see Table 3 for all site names and coordinates and Figure 3 for a map). Gliders will be loaded on the ship 4 November in the main lab; 8 benches are required near the aft starboard door. When onboard, they will be tested, requiring some clear deck/rail area on the aft starboard quarter (to accommodate 50 ft cable runs from the gliders to the lab). During the cruise our party will require clear Internet access for glider piloting purposes. Deployment of the gliders will be done either directly off the ship using a sling around the rudder, or from a small boat if conditions permit. If a recovery is necessary, the same applies. Four days of ship time are available for glider work. The deployment of gliders will be the first operation of the cruise. If all goes well, all four gliders will be deployed over 1-2 days. If there are problems, fewer will be deployed on the first attempt; for planning purposes, we will plan to spend 36 hours on site (two days and a night). Subsequent visit(s) to the DVLA site will be made in between mooring recoveries. If necessary, gliders can be deployed instead at T6 (second choice) or at another mooring site. Personnel include Jennie Mowatt, glider technician, and Lora van Uffelen (Scientist). 6

7 Figure 3. Baseline Plan A glider operations during PhilSea10. The six transceiver moorings are labeled T1-T6; the distributed vertical line array mooring is labeled DVLA. The orange lines are glider paths. The A1-A3 sites are ITOP mooring locations. EEZ boundaries are shown by thin yellow lines. In the baseline Plan A, gliders will operate within the shaded region, the PhilSea10 experiment domain. Table 3. PhilSea10 site coordinates (tomography moorings T1-T6, DVLA; Glider waypoints T1p-Tp) Site Lat deg N Lon deg E Lat deg Lat min Lon deg Lon min T T T T T T DVLA T1p T4p

8 T5p Tp Glider Operation Plan The glider operation plan has two parts: (1) a baseline plan in which the gliders sample over the entire PhilSea10 experiment domain, including within the EEZs of Japan and the Philippines, and (2) a plan with sampling in only international waters. (At the time of this writing, the Marine Science Research Authorization (MSR) for Japan is in hand and we are awaiting the one from the Philippines.) Plan A Baseline Glider operations in the full PhilSea10 domain for the baseline plan are shown in Figures 3 and 4. Glider paths are indicated by orange lines. All four gliders will be deployed at the DVLA. At the DVLA site they will cross-calibrate sensors (e.g., temperature and salinity) against each other and against the sensors on the DVLA mooring. If all gliders cannot be deployed at DVLA, then they can be deployed at T6. After four days at the DVLA they all fly to the central mooring T6, then out on radials to T1-T5, respectively. They then fly clockwise around the pentagon on straight-line segments between moorings. At each mooring site, the gliders will loiter for a day repeating the cross-calibration operation. As the time for the glider recovery approaches, during the April 2011 mooring recovery cruise, the gliders will be pre-positioned at appropriate transceiver mooring sites to facilitate their recovery. Given a nominal 20 km/day glider speed, they will be able to go about 3000 km in the 150 days, or 1.4 times around the pentagon (i.e., the glider going first to T1 will end at T3). 8

9 Figure 4. As Figure 1 but zoomed in. DVLA, T2, T3, and T6 are in international waters; T1 is in Japan waters; and T4 and T5 are in Philippine waters. Plan B Operations in International Waters In this plan, gliders would operate only in international waters, Figures 5 and 6 below, but would otherwise follow the same general sequence of events as for Plan A. All gliders would be deployed at DVLA, fly to T6, then out along radials to the perimeter of the reduced domain, and then fly around the perimeter between the waypoints indicated in the figures and Table 3. As in Plan A, they would be picked up during the April 2011 mooring recovery cruise. 9

10 Figure 5. Plan B glider operations during PhilSea10 in international waters. The six transceiver moorings are labeled T1-T6. New waypoints T1p, T4p, T5p and Tp are defined here. The distributed vertical line array mooring is labeled DVLA. The orange lines are glider paths. The A1-A3 sites are ITOP mooring locations. EEZ boundaries are shown by thin yellow lines. In Plan B, gliders will operate within the shaded region, the portion of the PhilSea10 experiment domain in international waters. 10

11 Figure 6. As Figure 3 but zoomed in. DVLA, T2, T3, and T6 are in international waters; T1 is in Japan waters; and T4 and T5 are in Philippine waters. T1p, Tp, T4p and T5p are waypoints. 11

12 IV. Cruise Schedule The tentative cruise schedule is shown below assuming we return to the port of Keelung on Nov. 26. For logistic reasons, we prefer to return to the port of Kaohsiung on Nov. 24, instead of the port of Keelung on Nov. 26. The time estimate for the mooring recovery in this tentative scheudle inlcudes weather days and CTD casts. The actual operation time can be shortened in good sea state. If we complete the mission earlier, we will return to the port of Kaohsiung on Nov :00 LT. V. Other Scientific Activity: If there are cold wakes generated by typhoons during this cruise, we will perform cold wake study. The exact schedule for the cold wake study will depend on the circumstances, e.g., the distance from the mooring and Seaglider sites. 12

13 Many oceanic assets will be deployed in the western Pacific for the ITOP study in mid October. Some of these assets will be recovered before RR1015. We will help recover the rest of assets as best as we can. Some Seagliders have been deployed for ITOP cold wake study. We plan to recover these Seagliders, if time is permitted. 13