Description of the WHOTS-18 Mooring Cruises
Contents
2. Description of the WHOTS-18 Mooring Cruises¶
2.1. WHOTS-18 Cruise: WHOTS-18 Mooring Deployment¶
The Woods Hole Oceanographic Institution Upper Ocean Processes Group (WHOI/UOP) , with the UH group’s assistance, conducted the 18 deployment of the WHOTS mooring on board the Oscar Elton Settle during the WHOTS-18 cruise between July 22 and July 27, 2022. The WHOTS-18 mooring was deployed at Station 52 on July 24, 2022, 02:17 UTC at 22 40.002’N, 157 56.793’W, and the WHOTS-17 mooring were recovered on July 25, 2022. The scientific personnel that participated during the cruise are listed in Table 2.1.
Name |
Title or Function |
Affiliation |
|---|---|---|
Plueddeman, Albert |
Chief Scientist |
WHOI |
Graham, Raymond |
Research Associate |
WHOI |
Llanos, Nico |
Senior Engineering Assistant |
WHOI |
Fitzgerald, Dan |
Marine Electronics Technician |
UH |
Harris, James |
Student Assistant |
UH |
Maloney, Kelsey |
Scientific Research Volunteer |
UH |
Howins, Noah |
Undergraduate Volunteer |
UH |
Penunuri, Alexander |
Graduate Student |
CU |
Conner, Kyle |
Graduate Student |
UH |
Rohrer, Tully |
Research Associate |
UH |
The UH group conducted shipboard oceanographic observations during the cruise. A complete description of these operations can be found in [Santiago-Mandujano et al., 2022].
A Sea-Bird CTD (conductivity, temperature, and depth) system was used measure T, S, and O2 profiles during CTD casts. The time, location, and maximum CTD pressure for each profile are listed in Table 2.2. Nine CTD casts were conducted during the WHOTS-18 cruise. CTD profile data were collected at Station 50 (near the WHOTS-17 buoy) and Station 52 (near the WHOTS-18 buoy). A test cast was conducted at Station 20 offshore of Makaha, HI, to an approximate depth of 1501 m to test three acoustic releases ( two to be used in the WHOTS-18 mooring and one backup) were attached to the rosette frame for function testing. Four CTD yo-yo casts were conducted to obtain profiles for comparison with subsurface instruments on the WHOTS-18 mooring after deployment, and four yo-yo casts were performed for comparison with the WHOTS-17 mooring before recovery. The yo-yo casts were started about 0.25 nm from the buoys with varying drift during each cast, and consisted of 5 up-down cycles between near the surface and 203 to 210 m. The first set of T, C and O2 sensors displayed bad data during various casts, apparently due to problems with the cable termination, but the second sensors set displayed good data.
Between 3 and 4 water samples were taken from all casts, except from Station 52 casts 2, 3 and 4, in which the pylon failed to communicate with the CTD. These samples were analyzed for salinity at UH and used to calibrate the CTD conductivity sensors.
Station/cast |
Date |
In-water Time |
Location |
Maximum pressure (dbar) |
|---|---|---|---|---|
20/1 |
7/23/2022 |
04:30 |
21°28.286´N, 158°21.342´W |
1501 |
50/1 |
7/24/2022 |
16:04 |
22°46.021´N, 157°56.186´W |
208 |
50/2 |
7/24/2022 |
20:14 |
22°46.224´N, 157°56.091´W |
208 |
50/3 |
7/24/2022 |
23:57 |
22°46.006´N, 157°56.014´W |
204 |
50/4 |
7/25/2022 |
04:06 |
22°46.068´N, 157°56.001´W |
210 |
52/1 |
7/26/2022 |
16:13 |
22°39.682´N, 157°59.152´W |
203 |
52/2 |
7/26/2022 |
20:06 |
22°39.836´N, 157°59.066´W |
203 |
52/3 |
7/27/2022 |
00:10 |
22°40.087´N, 157°59.123´W |
206 |
52/4 |
7/27/2022 |
04:13 |
22°40.192´N, 157°59.041´W |
203 |
Also, continuous ADCP and near-surface thermosalinograph data were obtained while underway.
The R/V Oscar Elton Settle was equipped with a TRDI Ocean Surveyor 75 kHz ADCP, set to function in broadband and narrowband configurations. The configuration information is shown in Table 2.3. The ADCP used input from a SAMOS gyrometer and Furuno GP 150, a GPS receiver, to establish the ship’s heading and attitude.
Parameters |
OS75BB |
OS75NB |
|---|---|---|
Sample interval (s) |
300 |
300 |
Number of bins |
80 |
55 |
Bin Length (m) |
8 |
16 |
Transducer depth (m) |
5 |
5 |
Blanking length (m) |
8 |
8 |
Near-surface temperature and salinity data during the WHOTS-18 cruise were acquired from the thermosalinograph (TSG) system installed on the NOAA Ship Oscar Sette. The sensors were sampling water from the continuous seawater system running through the ship, and were comprised of one thermosalinograph model SBE-21 (SN 3168) and a micro-thermosalinograph 17 model SBE-45 (SN 0290), both with (internal) temperature and conductivity sensors located in the ship’s chemistry lab, about 70 m from the hull intake; and an SBE-38 (SN266) external temperature sensor located at the entrance of the water intake. All instruments recorded data every second. The water intake is located at the bow of the ship, forward from the starboard side bow thruster at a depth of 3m. The system has a flow meter in the chemistry lab, showing a flow rate of about 1.1 liter/minute during the cruise. Only the SBE-45 has a debubbler. Salinity water samples were taken every 8 hours from the exhaust in the Chemistry lab using 0.25 litter glass bottles, measured in the UH lab and used to correct for any drift in the thermosalinograph conductivities.
2.2. WHOTS-19 Cruise: WHOTS-18 Mooring Recovery¶
The WHOI/UOP Group conducted the mooring turnaround operations during the WHOTS-19 cruise between June 15, and June 22, 2023. The WHOTS-19 mooring was deployed at Station 50 on June 17, 2023, 02:59 UTC at 22 46.002’N, 157 53.768’W, and the WHOTS-18 mooring was recovered on June 19, 2023, 17:49 UTC. The scientific personnel that participated during the cruise are listed in Table 2.4.
Name |
Title or function |
Affiliation |
|---|---|---|
Plueddeman, Albert |
Chief Scientist |
WHOI |
Bigorre, Sebastian |
Research Specialist |
WHOI |
Graham, Raymond |
Senior Engineering Assistant |
WHOI |
Llanos, Eduardo |
Senior Engineering Assistant |
WHOI |
Santiago-Mandujano, Fernando |
Research Associate |
UH |
Fitzgerald, Dan |
Marine Electronics Technician |
UH |
Rohrer, Tully |
Research Associate |
UH |
Maloney, Kelsey |
Scientific Research Volunteer |
UH |
Adkison, Camille |
Graduate Student |
UH |
Dale, Elizabeth |
Technician |
WHOI |
The UH group conducted the shipboard oceanographic observations during the cruise. A complete description of these operations is available in the WHOTS-19 cruise report [Santiago-Mandujano et al., 2024]
A Sea-Bird CTD system was used to measure T, S, and O2 profiles during CTD casts. The time, location, and maximum CTD pressure for each profile are listed in Table 2.5.
Five CTD casts were conducted during the WHOTS-19 cruise from June 16 through June 19. CTD profile data were collected at Station 20 (in transit to the WHOTS mooring) and Station 52 (near the WHOTS-18 buoy). The cast at Station 20 was ~1500 m deep, and three acoustic releases (two to be used in the WHOTS-19 mooring and one backup) were attached to the rosette frame for function testing. Four CTD yo-yo casts were conducted to obtain profiles for comparison with subsurface instruments from WHOTS-18 mooring before recovery. The yo-yo casts started at about 0.25 nm from the buoys with varying drifts during each cast, and they consisted of 5 updown cycles near the surface and 200 to 215 m. CTD modulo errors started appearing during casts 3 and 4, indicating problems in communication between the CTD and the deck box. The number of modulo errors considerably increased at the start of casts conducted near the WHOTS-19 mooring, and those casts were aborted. The errors persisted after re-terminating the CTD wire connection and even after replacing the CTD with our spare CTD. We suspect the problem was in the CTD wire or the slip-rings. We were not able to conduct CTD casts near the WHOTS-19 mooring because of this problem.
Between 2 and 4 water samples were taken from all casts. These samples were analyzed for salinity at UH and used to calibrate the CTD conductivity sensors.
Station/cast |
Date |
In-water Time |
Location |
Maximum pressure (dbar) |
|---|---|---|---|---|
20/1 |
6/16/2023 |
07:01 |
21°28.052´N, 158°21.087´W |
1489 |
52/1 |
6/18/2023 |
16:05 |
22°40.680´N, 157°58.892´W |
215 |
52/2 |
6/18/2023 |
20:02 |
22°40.888´N, 157°58.803´W |
203 |
52/3 |
6/19/2023 |
00:05 |
22°40.707´N, 157°58.954´W |
202 |
52/4 |
6/19/2023 |
05:22 |
22°41.226´N, 157°58.574´W |
200 |
Also, continuous ADCP and near-surface thermosalinograph data were obtained while underway.
The NOAA Ship Oscar Sette was equipped with a TRDI Ocean Surveyor 75 kHz ADCP, set to function in broadband and narrowband configurations. The configuration information is shown in Table 2.6. The ADCP used input from a SAMOS gyrometer and Furuno GP 170, a GPS receiver, to establish the ship’s heading and attitude.
Parameters |
OS75BB |
OS75NB |
|---|---|---|
Sample interval (s) |
300 |
300 |
Number of bins |
80 |
55 |
Bin Length (m) |
8 |
16 |
Transducer depth (m) |
5 |
5 |
Blanking length (m) |
8 |
8 |
Near-surface temperature and salinity data during the WHOTS-19 cruise were acquired from the thermosalinograph (TSG) system installed on the NOAA Ship Oscar Sette. The sensors were sampling water from the continuous seawater system running through the ship, and were comprised of one thermosalinograph model SBE-21 (SN 3168) and a micro-thermosalinograph model SBE-45 (SN 0290), both with (internal) temperature and conductivity sensors located in the ship’s chemistry lab, about 70 m from the hull intake; and an SBE-38 (SN 212) external temperature sensor located at the entrance of the water intake. All instruments recorded data every 17 second. The water intake is located at the ship’s bow, forward from the starboard side bow thruster at a depth of 3 m. The system has a flow meter in the chemistry lab, showing a flow rate of about 1.1 liter/minute during the cruise. Only the SBE-45 has a debubbler. Salinity water samples were taken every 8 hours from the exhaust in the Chemistry lab using 0.25 litter glass bottles, measured in the UH lab and used to correct for any drift in the thermosalinograph conductivities.