2.1:  Description  of  Project  

Overview  The US Office of Naval Research sponsored Internal Waves in Straits Experiment (IWISE) will utilize the R/V Revelle during the 70-day window from 5-June 2011 to 13 August 2011. IWISE is focused on the internal wave response in sea straits to tidal forcing. Luzon Strait has been selected as the focus area because of the large tidal currents in the area, which generate large amplitude internal waves. These internal waves, with ranges up to 150m are a prominent feature of the South China Sea and readily visible in remote sensing images. The waves have been intensively studied in recent years, especially to the west of the strait where their amplitude and nonlinear behavior is greatly modified due to effects wave steepening and the decreasing water depth. Of particular interest in this project is measurement of the internal waves over a several month period to see how modulation of the Kuroshio affects the generation. During August 2010, a pilot phase of the IWISE experiment was conducted during a 30-day expedition on the R/V Revelle. The 2011 field program is the primary IWISE field season, and the study will involve a number of different instrument systems, as described below. To facilitate the deployment of these systems, the research program is divided into 4 cruise legs, as listed here. Dates include days in port for mobilization and demobilization. IWISE schedule for R/V Revelle

1. 5 Jun – 14 Jun Mooring deployment and sea glider deployment work, Chief Scientist: M. Alford

2. 15 Jun – 6 July Lowered acoustic Doppler and microstructure profiling work, Chief Scientist: L. St. Laurent

3. 7 Jul – 21 Jul Underway CTD profiling and wire-walker surveys, Chief Scientist: R. Pinkel

4. 22 Jul – 13 Aug Towed CTD chain survey, recovery of moored assets, Chief Scientist. R.-C. Lien

A description of each cruise leg is described below.

IWISE  Mooring  Deployments  

Area  of  operation  The area of operation is Luzon Strait, south of Taiwan and north of the Philippines. A total of 7 full-depth and 6 partial-depth moorings will be deployed (Figure 1). In addition,

10 inverted Pressure Inverted Echo Sounders (PIES) will be deployed on the bottom (Figure 2). All of these assets involve an anchor, an acoustic release system, and a sub-surface float. The full-depth moorings will utilize a RD Instrument Acoustic Doppler Current Profilers (ACDPs) and Seabird MicroCat Conductivity-Temperature-Depth (CTD) sensors. Two of the full-depth moorings will also include McLane Moored Profilers (MMPs) (Figure 3). The partial depth moorings will utilize thermistor sensors in a 500-m segment above the bottom only. PIES sensors are a signal sensor package near the bottom.

Figure 1. Internal tide energy flux vectors in the Luzon Passage from a numerical simulation. The energy conversion rate is also shown in color shading, with hot colors representing the most intense regions of internal wave generation. The locations of 7 full-depth moorings are shown; those with MMPs are shown in red. The 6 partial-depth moorings will be located along-side the full-depth moorings in the Luzon Passage. A single full-depth mooring will also be deployed at 117.8E, 20.4N.

Spray  glider  deployments  

Two  Spray  gliders  will  be  deployed  in  Luzon  Passage.    These  gliders  will  each  run  for  a  2-­‐3  month  mission  in  the  Passage  region.  

Figure 2. Bathymetry map of the Luzon Passage region (depth in meters given by color bar). Proposed locations for PIES are shown (triangles). Satellite altimetry tracks are super-imposed on the map.

Recovery of mooring assets and Spray gliders The recovery of mooring and PIES hardware will be done by the Revelle during the final leg of the study. Assistance in recovering some mooring and PIES hardware may be provided by a Taiwan Research Vessel.

Figure 3. Full-depth mooring diagram, including a McLane Moored Profiler unit.

IWISE  survey  legs  

All  IWISE  cruise  legs  will  require  the  ship’s  CTD  (SBE911+),  Hydrographic  Doppler  Sonar  System  (HDSS),  and  multi-­‐beam  system  to  be  operational.  Two  RDI  Workhorse  ADCPs  will  be  mounted  on  the  CTD  rosette  to  be  used  as  a  Lowered  ADCP  system  (LADCP).  The  CTD/LADCP  system  is  used  at  station  locations,  including  all  those  where  a  mooring  or  PIES  deployment  is  planned.    The  HDSS  and  multibeam  systems  are  generally  run  continuously,  during  stations  and  transects.  

The  3  legs  following  in  the  mooring  deployment  leg  will  each  employ  specialized  profiling  instrumentation  from  the  Revelle.    The  instruments  are  either  used  in  station  keeping  format,  or  towed  transects.    The  focus  of  IWISE  is  the  area  in  the  Luzon  Passage  proper:  between  [120E,  122E].    However,  some  survey  activities  may  be  conducted  further  west,  to  the  limit  set  by  the  western-­‐most  mooring  at  117.8E.  The  exact  cruise  track  of  each  leg  will  be  determined  subject  to  conditions  judged  closer  to  the  actual  study  dates.    

Specialized  equipment  to  be  deployed  and  used  from  the  ship  during  surveys  • Revelle’s CTD system.

• Revelle’s Hydrographic Doppler Survey System (HDSS). • Revelle’s multi-beam system. • Lowered ADCP system. • Two Spray gliders. • Microstructure profiler systems (Rockland Scientific VMP-2000 andVMP-5500). • Fast towed underway-CTD. • Towed CTD-chain. • Seasoar.

Personnel roster, by institution Here we list PI’s and primary personnel. Some personnel will join multiple legs. Additional technicians and student participants are expected. A more complete listing of personnel for each leg, with passport information, will be provided before the start of the program.

• Matthew Alford (APL/UW, principle Investigator, Chief Scientist for leg 1) • Ren-Chieh Lien (APL/UW, principle Investigator, Chief Scientist for leg 4) • Brian Chinn (APL/UW) • Andrew Cookson (APL/UW) • John Mickett (APL/UW) • Andy Pickering (APL/UW) • Luc Rainville (APL/UW, principal investigator) • Yiing Jang Yang (CAN, lead IWISE scientist from Taiwan) • Jonathan Nash (OSU, principal investigator) • Ke Hsien Fu (NSYSU) • Taylor Hughen (SIO/UCSD) • Shaun Johnston (SIO/UCSD, principal investigator) • Jennifer Mackinnon (SIO/UCSD, principal investigator) • Rob Pinkel (SIO/UCSD, principal investigator, Chief Scientist for leg 3) • Harper Simmons (UAF, principal investigator) • Gerry Chaplin (URI) • Jody Klymak (U. Victoria, principal investigator) • Ken Decoteau (WHOI) • Steve Lambert (WHOI) • Louis St. Laurent (WHOI, principal investigator, Chief Scientist for leg 2) • Emily Shroyer (WHOI) • Oliver Sun (WHOI)

2.2  Relevant  previous  or  future  research  cruises   5 August – 5 September 2010, R/V Revelle (Chief Scientist: Matthew Alford) IWISE-pilot program.

3.3  Particulars  of  methods  and  scientific  instruments   Here we provide details on some of the less common instrument systems. None of these instruments will ‘dig at’ (i.e. collect samples from) the sea bed or the continental shelves.

Spray  gliders  Spray gliders are small, reusable, long-range autonomous underwater vehicles designed to glide from the ocean surface to as deep as 1000 m and back while collecting profiles of temperature, salinity, dissolved oxygen concentration, and optical properties. Gliders steer through the water by controlling attitude (pitch and roll) and can thus navigate between waypoints to execute survey patterns; or they hold station while profiling and collect Eulerian time series as a ‘virtual mooring’. Mission durations depend largely on ambient stratification and profile depth, but for this application should be approximately 2 months. Gliders are commanded remotely and report their measurements via Iridium satellite telephone at the conclusion of each dive. The vehicles also archive all data to onboard storage for delayed mode transmission or post-recovery interrogation. They use GPS navigation at the sea surface to dead reckon toward commanded target locations. Navigation and knowledge of vehicle buoyancy and pitch angle allows estimation of depth-averaged current and suitably energetic vertical velocity fluctuations. Sensor suites include pressure, temperature, conductivity, Doppler sonar, dissolved oxygen, chlorophyll fluorometer, and optical backscatter. Gliders have been deployed and recovered from a wide range of platforms including small rubber boats, chartered fishing vessels and large research ships. Because the vehicles are relatively small and light, special handling gear is not required and field teams typically consist of one or, at most, two individuals. Size: length: 2 m, max.diameter: 0.3 m Weight: 52 kg Materials: aluminum, fiberglass, carbon fiber Note: 2 Spray gliders will be used in the study http://spray.ucsd.edu/pub/rel/info/spray_description.php

Spray glider

McLane  Moored  Profiler  (MMPs)  

Size: height: 1.31 m, length: 0.51 m, width: 0.33 m Weight: 71 kg in air, 64 kg in water. Materials: polyethylene (plastic shell), titanium pressure case Serial numbers: 101, 102 Note: Instrument is deployed on a mooring, profiles up and down the mooring line measuring water properties (i.e. stays at a fixed location but goes up and down), and is recovered at the end of the cruise. http://www.mclanelabs.com/mmp.html

Acoustic  Doppler  Current  Profilers  (ADCPs)  • Workhorse 300 kHz ADCP (3 units)

Size: diameter: 0.23 m, height: 0.2 m Weight: 7.6 kg in air, 3.0 kg in water. Materials: stainless steel Serial numbers: 8065, 8122, 7966 Note: Instrument is deployed on a mooring (fixed location) and is recovered at the end of the cruise. http://www.adcp.com/monitor.aspx • Workhorse 300 kHz ADCP (2 units)

Size: diameter: 0.55 m, height: 0.92 m Weight: 86 kg in air, 56 kg in water. Materials: stainless steel Note: Instrument is deployed on a mooring (fixed location) and is recovered at the end of the cruise. http://www.adcp.com/longranger.aspx

CTD  chain   The CTD chain is a 1000-m long array of temperature and conductivity sensor elements. Sensor nodes are every 5 m. The chain has a anchored foot, and a buoyant tow fish at its top. The system can be towed at 10 knots. Probe size: length: 1000 m, diameter: 0.1 m Probe weight: 500 kg. Materials: Kevlar coated cable. Note: Winch is mounted on the ship. The vehicle is towed from a steel faired cable at speeds of 9 to 12 knots. Maximum depth of the package is 1000 m. http://staff.washington.edu/aganse/philsea09pix/ctdchain.html

 SeaSoar   A modified Chelsea Technologies Group Seasoar system is operated by the R/V Revelle. This system is a towed flight platform, with wings and a tail to control its vertical position during descent and ascent. The system is equipped with a CTD package. Probe size: length: 2 m, width: 1 m, height 1 m Probe weight: 200 kg.

Materials: aluminum and steel enclosure. Note: Winch is mounted on the ship. The vehicle is towed from a steel faired cable at speeds of 9 to 12 knots. Maximum depth of the package is 500 m. http://www.chelsea.co.uk/Vehicles%20SeaSoar.htm

Wire-­‐walking  profiling  drifter   The wire-walker is a profiling CTD system that traverses up and down a drifting line. The line is secured by a surface float and a drifting anchor. Probe size: length: 2 m, diameter: 0.2 m. Probe weight: 20 kg. Materials: aluminum pressure case. Note: profiling unit rides on a steel cable of 500 m length.

Fast  underway  CTD  The fast uCTD is a T-S probe tethered to a conducting caple. The probe can be dropped from a ship moving as fast as 20 knots. The probe free-falls, collecting a profile of temperature and salinity (maximum depth depends on ship speed). At the end of it’s profile, the probe is reeled back in using a fast winch. Probe size: length: 2 m, diameter: 0.2 m. Probe weight: 100 kg. Materials: aluminum pressure case. Note: Winch is mounted on the ship. The probe is dropped in the water, sink to ~2000 m depth, and is recovered.

Rockland  Scientific  VMP-­‐2000  and  VMP-­‐5500  Microstructure  Profilers  The VMP microstructure profilers are free-falling instrument systems. The profilers carry Seabird CTD sensors, as well as specialized sensors for measuring turbulent microstructure. The microstructure sensors include FP07 fast-response thermistors and SPM-38 shear probes. The VMP-2000 and VMP-5500 are similar instruments. The primary difference is that the VMP-2000 is a tethered profiler, connected to the ship via a Kevlar coated conducting cable, while the VMP-5500 is an autonomous profiler. The VMP-2000 profiler is run from a shipboard winch. The VMP-5500 uses a programmed release to jettison iron ballast weights. Probe size: length: 2 m, diameter: 0.2 m. Probe weight: 100 kg (VMP-2000) and 200 kg (VMP-5500). Materials: aluminum pressure case, stainless steel hardware, Kevlar cable for tether. Note: The winch for the VMP-2000 is mounted on the ship. The probe is suspended from a tether, dropped in the water, sinks to ~1500 m depth, and is pulled back aboard. http://rocklandscientific.com/VMP5500/tabid/77/Default.aspx

VMP-2000 (left) and VMP-5500 (right)

Pressure  Recording  Inverted  Echosounder  Each PIES is a battery powered instrument that transmits a short acoustic pulse up towards the ocean surface every 6 seconds, and then listens for the echo. The acoustic travel time provides information on the temperature structure and allows the waves to be detected. Detailed information about the instruments is provided in the paper: Qiang Li, David M. Farmer, Timothy F. Duda, Steve Ramp, 2008, Acoustical Measurement of Nonlinear Internal Waves using the Inverted Echo Sounder, J Atmos. Oceanic Technol. 26:2228-2242. The following paper describes the kind of data that the PIES instruments to be used in this project produces, and the way in which it can be interpreted: Farmer, David, Li Qiang, Jae-Hun Park, 2009, Internal Wave Observations in the South China Sea: The Role of Rotation and Non-Linearity, Atmosphere-Ocean, 47 (4): 267-280.

A Pressure Inverted Echo Sounder (PIES). The instrument sits on the sea floor and sends an acoustic pulse toward the surface, measuring travel time of the reflecion.

Pressure Sensor Manufacturer: Paroscientific, Inc. Doppler Current Sensor Manufacturer: Aanderaa Data Instruments Persistor CF1 Computer Module Manufacturer: Peripheral Issues, Inc. Lithium Battery Manufacturer: Tadiran Batteries http://www.po.gso.uri.edu/dynamics/IES/IESManual6_2.pdf

Revelle  Hydrographic  Doppler  Sonar  System  The R/V Revelle is equipped with a Hydrographic Doppler Sonar (HDS) System which provides estimates of:  

• Absolute ocean velocity • Ocean shear • Acoustic scattering intensity • Scattering intensity gradient (plankton layering)

The system consists of two 4-beam Doppler sonars and assorted support sensors:

• The “Deep Sonar” operates at 44 kHz and can profileto depths in excess of 1 km in favorable conditions. Depth resolution is 12 m.

• The “High Resolution Sonar” operates in a band near 140 kHz, profiling with 4m resolution to depth of 150-350m, depending on weatherand bio-scattering conditions. Individual sonar returns (echos) are recorded at 2s intervals.

Both sonars are configured in the conventional 4-beam Janus geometry. In plan, the beams are oriented 45° relative to the fore/aft axis of the ship’s hull. The depression angle of each beam relative to horizontal is 60°.   The HDSS sonars transmit through a protective polyethelene “window” mounted flush with the ships’s hull. They are similar in principle to the commercial instruments found on many research vessels. The HDSS sonar beam patterns are significantly narrower than those of most commercial systems.   Each sonar transmits a coded acoustic pulse at 2-s intervals. The sound scatters from plankton drifting in the water column. From the Doppler shift of the return echo, the relative speed between the ship and the water can be inferred. GPS, along with a variety of other support sensors, is used to infer the absolute ocean velocity.    This equipment is permanently mounted on the R/V Roger Revelle. More information can be found at: http://opg1.ucsd.edu/HDSS/RevMan7July2009sm.pdf

4  Details  of  installations  and  equipment  (dates  of  laying,  servicing,  recovery;  exact  locations  and  depth)   Moorings will be deployed at: M01 117.80E 20.40N (tentatively planned for deployment/recovery by Taiwan vessel) M02 120.75E 20.50N M03 120.75E 20.25N M04 121.25E 20.50N M05 121.25E 20.25N M06 121.50E 20.50N M07 121.50E 20.25N PIES will be deployed at: P01 118.72E 21.39N P02 118.77E 20.71N P03 118.81E 20.02N P04 119.33E 22.00N P05 119.83E 21.33N P06 119.83E 20.66N P07 119.83E 20.00N P08 120.87E 21.00N P09 121.25E 21.17N P10 121.25E 20.77N P11 121.25E 20.37N P12 121.30E 20.00N P13 122.27E 21.48N P14 122.50E 20.50N All other operations (ship survey work, gliders, etc) will be confined to the region inside [118.7E, 122.5E], [19.75N, 22.25N] excluding territorial waters and disputed regions.

5.1  Indicate  geographical  areas  in  which  the  project  is  to  be  conducted  (with  reference  in  latitude  and  longitude)   All operations (e.g. mooring, surveys, gliders, etc) will be confined to the region inside [117.8E, 122.6E], [19.75N, 22.25N] excluding territorial waters and disputed regions.

 

5.2  Attach  chart(s)  at  an  appropriate  scale  (1  page,  high-­‐resolution)   showing   the  geographical  areas  of  the   intended   work   and,   as   far   as   practicable,   the  positions  of   intended  stations,  the  tracks  of  survey  lines,   and   the   locations   of   installations   and  equipment.  

Figure showing the proposed network of moorings (circles) and bottom deployed PIES (triangles). The western-most mooring at (20.4N, 117.8E) is tentatively planned for tending by a Taiwan research vessel. The IWISE R/V Revelle activities will be contained in the boxed region. The limits of the survey region are [118.7E, 122.5E], [19.75N, 22.25N]. Depths are indicated by the color bar.