Description of the WHOTS-17 Mooring Cruises
Contents
2. Description of the WHOTS-17 Mooring Cruises¶
2.1. WHOTS-17 Cruise: WHOTS-17 Mooring Deployment¶
The Woods Hole Oceanographic Institution Upper Ocean Processes Group (WHOI/UOP) , with assistance from the UH group, successfully carried out the 17th deployment of the WHOTS mooring during the WHOTS-17 cruise. This operation took place on board the Oscar Elton Settle between August 24 and September 1, 2021. The WHOTS-17 mooring was deployed at Station 50 on August 26, 2021, at 03:13 UTC, at 22°46.042’N, 157°53.795’W. Additionally, the WHOTS-16 mooring was recovered on August 28, 2021.
The scientific personnel that participated during the cruise are listed in Table 2.1.
Name |
Title or function |
Affiliation |
|---|---|---|
Plueddeman, Albert |
Chief Scientist |
WHOI |
Hasbrouck, Emerson |
Senior Engineering Assistant II |
WHOI |
Fitzgerald, Dan |
Marine Electronics Technician |
UH |
Santiago-Mandujano, Fernando |
Research Associate |
UH |
Maloney, Kelsey |
Student Assistant |
UH |
Harris, James |
Student Assistant |
UH |
Jackson, Caroline |
Student Assistant |
UH |
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., 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. Ten CTD casts were conducted during the WHOTS-17 cruise, from August 24 through September 1. 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 to 204 m. One additional near-bottom CTD cast was conducted at Station ALOHA. The CTD had modulo errors during some of the casts, displaying some glitches.
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 |
4:02 |
22° 45.89´ N, 157° 54.65´ W |
202 |
50 / 5 |
8/30/2021 |
7:57 |
22° 44.79´ N, 157° 54.53´ W |
202 |
50 / 6 |
9/1/2021 |
1:36 |
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 |
4:00 |
22° 40.67´ N, 157° 58.73´ W |
202 |
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 utilized primary heading measurements from a SAMOS gyrometer, with additional heading corrections obtained from Trimble ABX-Two gyrocompass. GPS positions were derived from Furuno GP-170 GNSS (Global Navigation Satellite System).
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, 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 266) external temperature sensor located at the entrance of the water intake. All instruments recorded data every second. The water intake was located at the bow of the ship, forward from the starboard side bow thruster at a depth of 3 m. The system had a flow meter in the chemistry lab, showing a flow rate of about 1.1 liter/minute during the cruise. Only the SBE-45 had a debubbler. Salinity water samples were taken every 8 hours from the exhaust in the Chemistry lab using 0.25 litter glass bottles, to be measured in the UH lab to correct for any drift in the thermosalinograph conductivities.
Both thermosalinographs exhibited a number of conductivity and temperature glitches due to air going into the plumbing. In addition, the system had a drainage problem according to the ship’s technician. The data between August 26 at 13:30 and 27 at 07:00 are particularly bad because it was during transit back to Oahu to disembark a crew member with medical problems, and the flow through the system was stopped during that time. The temperature differences between the internal SBE-45 and SBE-21 were between -0.5 and 0.5°, and the conductivity differences were ±0.007 S/m resulting in a salinity difference of about ±0.05 g/kg. These conductivities were calibrated against the bottle samples collected during the cruise, and the bad data was be flagged. A diurnal cycle was apparent in the temperature and conductivity.
2.2. WHOTS-18 Cruise: WHOTS-17 Mooring Recovery¶
The WHOI/UOP Group conducted the mooring turnaround operations during the WHOTS-18 cruise between July 23, 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 was recovered on July 25, 2022, 18:03 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 |
Graham, Raymond |
Senior Engineering Assistant II |
WHOI |
Llanos, Nico |
Senior Engineering Assistant I |
WHOI |
Fitzgerald, Dan |
Marine Electronics Technician |
UH |
Harris, James |
Student Assistant |
UH |
Maloney, Kelsey |
Visiting Researcher Program Coordinator |
UH/HIMB |
Howins, Noah |
Undergraduate Volunteer |
UH |
Penunuri, Alexander |
Graduate Student |
University of Colorado Boulder |
Conner, Kyle |
Graduate Student |
UH |
Rohrer, Tully |
Research Associate |
UH |
The UH group conducted the shipboard oceanographic observations during the cruise. A complete description of these operations is available in the WHOTS-18 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. Nine CTD casts were conducted during the WHOTS-18 cruise from July 23 through July 27. CTD profile data were collected at Station 20 (in transit to the WHOTS mooring), Station 50 (near the WHOTS-17 buoy), and Station 52 (near the WHOTS-18 buoy). The cast at Station 20 was 1501 m deep, and 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 conducted 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 sensor 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 to be analyzed for salinity at UH and used to calibrate the CTD conductivity sensors. Station numbers were assigned following the convention used during HOT cruises.
Station/cast |
Date |
In-water Time |
Location |
Maximum pressure (dbar) |
|---|---|---|---|---|
20/1 |
7/23/22 |
04:30 |
21° 28.286´ N, 158° 21.342´ W |
1501 |
50 / 1 |
7/24/22 |
16:04 |
22° 46.021´ N, 157° 56.186´ W |
208 |
50 / 2 |
7/24/22 |
20:14 |
22° 46.224´ N, 157° 56.091´ W |
208 |
50 / 3 |
7/24/22 |
23:57 |
22° 46.606´ N, 157° 56.014´ W |
204 |
50 / 4 |
7/25/22 |
04:06 |
22° 46.068 ´ N, 157° 56.001´W |
210 |
52 / 1 |
7/26/22 |
16:13 |
22° 39.682´ N, 157° 59.152´ W |
203 |
52 / 2 |
7/26/22 |
20:06 |
22° 39.836´ N, 157° 59.066´ W |
203 |
52 / 3 |
7/27/22 |
00:10 |
22° 40.087´ N, 157° 59.123´ W |
206 |
52 / 4 |
7/27/22 |
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 2.6. The ADCP utilized primary heading measurements from a SAMOS gyrometer, with additional heading corrections obtained from Trimble ABX-Two gyrocompass. GPS positions were derived from Furuno GP-170 GNSS (Global Navigation Satellite System).
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 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 was located at the bow of the ship, forward from the starboard side bow thruster at a depth of 3 m. The system had a flow meter in the chemistry lab, showing a flow rate of about 1.1 liter/minute during the cruise. Only the SBE-45 had a debubbler. Salinity water samples were taken every 8 hours from the exhaust in the Chemistry lab using 0.25 litter glass bottles, to be measured in the UH lab to correct for any drift in the thermosalinograph conductivities.