Description of the WHOTS-16 Mooring Cruises
Contents
2. Description of the WHOTS-16 Mooring Cruises¶
2.1. WHOTS-16 Cruise: WHOTS-16 Mooring Deployment¶
The Woods Hole Oceanographic Institution Upper Ocean Processes Group (WHOI/UOP) , with the UH group’s assistance, conducted the sixteenth deployment of the WHOTS mooring onboard the NOAA Oscar Sette during the WHOTS-16 cruise between October 4 and October 12, 2019. The WHOTS-16 mooring was deployed at Station 52 on October 6, 2019, 02:12 UTC at 22°40.096 ‘N, 157°56.788 ‘W, and the WHOTS-15 mooring were recovered on October 8, 2019. The scientific personnel that participated during the cruise are listed in Table 2.1.
Name |
Title or function |
Affiliation |
|---|---|---|
Plueddeman, Albert |
Chief Scientist |
WHOI |
Pietro, Ben |
Senior Engineering Assistant |
WHOI |
Graham, Raymond |
Research Associate |
WHOI |
Maloney, Kelsey |
Student Assistant |
UH |
Fitzgerald, Dan |
Marine Electronics Technician |
UH |
Rohrer, Tully |
Research Associate |
UH |
Santiago-Mandujano, Fernando |
Research Associate |
UH |
Tabata, Ryan |
Research Oceanography Specialist |
UH |
Howins, Noah |
Undergraduate Volunteer |
UH |
Pezoa, Sergio |
Scientist |
ESRL |
Gonzales, Sean |
Undergraduate Volunteer |
HPU |
The UH group conducted the shipboard oceanographic observations during the cruise. A complete description of these operations is available in the [Santiago-Mandujano et al., 2021]
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. Eleven CTD casts were conducted during the WHOTS-16 cruise. CTD profile data were collected at Station 50 (near the WHOTS-15 buoy) and Station 52 (near the WHOTS-16 buoy). A test cast was conducted at Station 20 (21°28.164´N, 158°21.552´W) offshore of Makaha, HI, to an approximate depth of 1500 m to test three acoustic releases ( two to be used in the WHOTS-16 mooring and one backup) were attached to the rosette frame for function testing. Five CTD yo-yo casts were conducted to obtain profiles for comparison with subsurface instruments on the WHOTS-16 mooring after deployment, and five yo-yo casts were performed for comparison with the WHOTS-15 mooring before recovery. These casts were started less than 0.25 nm from the buoys with varying drift during each cast and consisted of 5 up-down cycles between near the surface and 218 dbar.
Water samples were taken from all casts; 3 to 4 samples for each of them. These samples were to be 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 |
10/05/2019 |
01:51 |
21°28.164´N, 158°21.552´W |
1502 |
52/1 |
10/10/2019 |
16:38 |
22°40.391´N, 157°58.744´W |
215 |
52/2 |
10/10/2019 |
19:55 |
22°40.551´N, 157°58.679´W |
211 |
52/3 |
10/10/2019 |
23:58 |
22°40.790´N, 157°58.635´W |
211 |
52/4 |
10/11/2019 |
04:05 |
22°41.023´N, 157°58.256´W |
211 |
52/5 |
10/11/2019 |
07:55 |
22°40.551´N, 157°58.323´W |
209 |
50/1 |
10/06/2019 |
16:10 |
22°45.101`N, 157°55.049´W |
213 |
50/2 |
10/06/2019 |
20:03 |
22°44.962´N, 157°54.839´W |
211 |
50/3 |
10/07/2019 |
00:04 |
22°45.136´N, 157°55.144´W |
218 |
50/4 |
10/07/2019 |
04:08 |
22°45.209´N, 157°55.006´W |
211 |
50/5 |
10/07/2019 |
07:56 |
22°44.787´N, 157°55.066´W |
210 |
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 2.3. 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-16 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. They comprised 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 266) external temperature sensor located at the entrance of the water intake. All instruments recorded data every 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 liters/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-liter glass bottles, to be measured in the UH lab to correct any drift in the thermosalinograph conductivities.
Both thermosalinographs exhibited a number of conductivity and temperature glitches due to air going into the plumbing. The system had to be secured the last day of the cruise due to the bad weather because the system kept shutting down due to air going into the plumbing causing the pumps to stop working. The temperature differences between the internal SBE-45 and SBE-21 were between 0.2 and 0.4°C and the conductivity differences 17 were nearly 0.05 S/m resulting in a salinity difference of about 0.28 g/kg. Sensor SBE-21 seems too large as compared to surface salinity from CTD casts conducted during the cruise. A diurnal cycle is apparent in the temperature and conductivity.
2.2. WHOTS-17 Cruise: WHOTS-16 Mooring Recovery¶
The WHOI/UOP Group conducted the mooring turnaround operations during the WHOTS-17 cruise between August 24, and September 1, 2021. The WHOTS-17 mooring was deployed at Station 50 on August 26, 2021, 03:13 UTC at 22°46.042 ‘N, 157°53.795 ‘W, and the WHOTS-16 mooring was recovered on August 28, 2021, 17:52 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 |
Hasbrouck, Emerson |
Senior Engineering Assistant |
WHOI |
Fitzgerald, Dan |
Marine Electronics Technician |
UH |
Santiago-Mandujano, Fernando |
Research Associate |
UH |
Jackson, Caroline |
Graduate Student |
UH |
Maloney, Kelsey |
Student Assistant |
UH |
Harris, James |
Student Assistant |
HPU |
The UH group conducted the shipboard oceanographic observations during the cruise. A complete description of these operations is available in the WHOTS-17 cruise report [Santiago-Mandujano et al., 2022]
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. Ten CTD casts were conducted during the WHOTS-17 cruise, from August 24 through September 1, 2021. CTD profile data were collected at Station 20 (in transit to the WHOTS mooring), Station 50 (near the WHOTS-17 buoy), Station 52 (near the WHOTS-16 buoy), and at Station 2 at the ALOHA site. The cast at Station 20 was 1508 m deep, and three acoustic releases (two to be used in the WHOTS-17 mooring and one backup) were attached to the rosette frame for function testing. Five CTD yo-yo casts and one near-bottom CTD cast were conducted to obtain profiles for comparison with subsurface instruments on the WHOTS-17 mooring after deployment, and two yo-yo casts were conducted for comparison with the WHOTS-16 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 202 m. One additional near-bottom CTD cast was conducted at Station ALOHA.
Water samples were taken from all casts; 3 to 4 samples for each of them. These samples were to be analyzed for salinity at UH and used to calibrate the CTD conductivity sensors.
Station/cast |
Date |
In-water Time |
Location |
Maximum pressure (dbar) |
|---|---|---|---|---|
2/1 |
8/31/2021 |
18:29 |
22°45.12´N, 157°59.98´W |
4796 |
20/1 |
8/24/2021 |
23:03 |
21°28.03´N, 158°20.83´W |
1508 |
50/1 |
8/29/2021 |
15:59 |
22°45.73´N, 157°55.25´W |
202 |
50/2 |
8/29/2021 |
21:55 |
22°46.17´N, 157°54.85´W |
202 |
50/3 |
8/29/2021 |
23:52 |
22°46.19´N, 157°54.72´W |
204 |
50/4 |
8/30/2021 |
04:02 |
22°45.89´N, 157°54.65´W |
202 |
50/5 |
8/30/2021 |
07:57 |
22°44.79´N, 157°54.53´W |
202 |
50/6 |
9/1/2021 |
01:36 |
22°44.28´N, 157°54.14´W |
4754 |
52/1 |
8/27/2021 |
19:58 |
22°40.69´N, 157°58.38´W |
202 |
52/2 |
8/28/2021 |
04:00 |
22°40.67´N, 157°58.73´W |
202 |
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-17 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. They 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 266) external temperature sensor located at the entrance of the water intake. All instruments recorded data every 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 liters/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-liter glass bottles, to be measured in the UH lab to correct any drift in the thermosalinograph conductivities.