Contents

Description of WHOTS-19 Mooring

3. Description of WHOTS-19 Mooring

The WHOTS-19 mooring was deployed on June 17, 2023, from the NOAA Ship Oscar Elton Sette and recovered on June 6, 2024. The mooring consisted of a surface buoy equipped with two complete sets of Air–Sea Interaction Meteorological (ASIMET) sensors and a suite of subsurface oceanographic instruments mounted along the bridle and mooring line down to 155 m, with additional sensors near the bottom. For a detailed technical description of the mooring design, see [Santiago-Mandujano et al., 2024, Santiago-Mandujano et al., 2024].

The WHOTS-19 mooring was designed to collect high-quality time series of surface meteorology and upper-ocean temperature, salinity, and biogeochemical variables in support of long-term air-sea flux studies at Station ALOHA.

3.1. Surface Components

The buoy included the following instrumentation mounted on a blue hull with a white tower and yellow deck (Table 3.1):

Table 3.1 Surface meteorological instrumentation on the WHOTS-19 buoy, organized by system side (port = System 1, starboard = System 2). All sensors were mounted on the buoy tower. Heights are reported relative to the buoy deck.

Instrument Type

IDs / Details

Data Loggers

9 (System 1, port side); ID 42 (System 2, starboard side)

Relative Humidity and Air Temperature (HRH) Sensors

269 and 247, mounted at 231 cm

Barometric Pressure Recorders (BPR)

210 and 206, mounted at 242 cm

Wind Sensors (RM Young)

225 and 701, mounted at 264 cm

Precipitation Sensors (PRC)

235 (System 1 – top broken before recovery); ID 506, both mounted at 256 cm

Longwave Radiation Sensors (LWR)

214 and 219, mounted at 281 cm

Shortwave Radiation Sensors (SWR)

233 and 373, mounted at 281 cm

Sea Surface Temperature (SST)

1727 and 5996, mounted at –155 cm

Iridium Satellite Systems

IMEIs: 300234063855630, 300234063160290

GPS – Melo

IMEI: 300034013707580

GPS – Rover

1034 and 724; IMEIs: 300434064530400, 300434063547190

Other Sensors

Vaisala WXT (ID 204, 264 cm); Airmar (ID 6079L253, 273 cm, hanging); HC2A (ID WI9, 232 cm); SBE39AT (ID 719, 228 cm)

3.2. Subsurface Instrumentation

Subsurface instruments were mounted along the bridle and at a fixed depth on the mooring line, as follows (Table 3.2):

Table 3.2 Additional shared surface instrumentation on the WHOTS-19 buoy, including GPS units, Iridium satellite modems, and auxiliary sensors.

Instrument Type

ID

Depth

Notes

MAPCO₂ System

26

155

With equilibration tube

CTD (SBE16)

6832

155

Oxygen Sensor

1381

155

Fluorometer

2597

155

Includes bio-wiper

pH Sensor (SAMI)

P246

155

Span Gas Canister

JB03812

—

For sensor calibration

Xeos Kilo Transmitter

1494

—

IMEI: 300234062727610

Five internally logging Sea-Bird SBE-56 temperature sensors were bolted to the buoy hull’s underside, measuring sea surface temperature and salinity. The SBE-56s measured SST once every 60 sec between 80-110 cm below the surface. Two SBE-37 MicroCATs were at 1.55m measuring at every 300s (See Table 3.3).

Table 3.3 WHOTS-19 MicroCAT and SBE-56 Temperature Sensor Information.

Instrument

SN

Depth (m)

Sample Interval (sec)

SBE-56

6410

0.8

60

SBE-56

6239

0.8

60

SBE-56

6412

1.0

60

SBE-56

6983

1.1

60

SBE-56

7211

0.8

60

SBE-37

1727

1.55

300

SBE-37

5996

1.55

300

Instrumentation provided by UH for the WHOTS-19 mooring included 18 Sea-Bird SBE-37 MicroCATs, of which 9 were pressure-equipped. Two of them were installed approximately 39 m above the anchor. All MicroCATs measured temperature and conductivity and were deployed with antifoulant capsules to minimize biofouling. In addition, UH deployed two upward-looking RDI Workhorse Acoustic Doppler Current Profilers (ADCPs) operating at 300 kHz and 600 kHz, respectively. WHOI contributed two Vector Measuring Current Meters (VMCMs), an Acoustic Receiver, and all required deep mooring hardware. The ADCPs were mounted at nominal depths of 47.5 m and 125 m, and the VMCMs were positioned at 10 m and 30 m.

The Table 3.4 table provides detailed metadata for the WHOTS-19 subsurface instrumentation, including nominal depths, serial numbers, sample intervals, and event times. To verify the performance of internal clocks, a cold-water spike was applied to all UH MicroCATs before deployment by placing an ice pack against each temperature sensor (Table 3.4) and again after recovery (Table 3.5). For the ADCPs, a 20-second manual transducer rub was performed to generate a recognizable signal spike (Table 3.6, Table 3.7).

Table 3.4 WHOTS-19 mooring subsurface instrument deployment. Times are UTC (MM/DD/YY hh:mm). Columns: SN = Serial Number, Inst = Instrument, Z = Depth (m), P SN = Pressure Sensor Serial Number, Δt = Sample Interval (s), CS = Cold Spike.

SN

Inst

Z

P

Δt

Start

CS Beg

CS End

In

3382

MC

7

N/A

180

06/13/23 23:59

06/16 00:00

06/16 00:30

06/16 21:00

0035

VMCM

10

N/A

60

06/08/23 00:21

06/16 20:23*

N/A

06/16 20:28

6892

MC

15

2651234

75

06/13/23 23:59

06/16 00:00

06/16 00:30

06/16 20:25

4663

MC

25

N/A

180

06/13/23 23:59

“

“

06/16 20:19

112497

AR

25

N/A

N/A

06/12/23 19:00

N/A

N/A

06/16 20:19

0058

VMCM

30

N/A

60

06/08/23 00:21

06/16 20:13*

N/A

06/16 20:16

3633

MC

35

N/A

180

06/13/23 23:59

“

“

06/16 20:12

3381

MC

40

N/A

180

06/13/23 23:59

“

“

06/16 20:09

3668

MC

45

5579

180

06/16/23 00:01

06/16 01:40

06/16 02:05

06/16 20:06

13917

ADCP

47.5

N/A

600

06/15/23 23:59

Table 3.6

Table 3.6

06/16 21:23

3619

MC

50

N/A

180

06/13/23 23:59

“

“

06/16 21:24

3620

MC

55

N/A

180

06/13/23 23:59

“

“

06/16 21:27

3621

MC

65

N/A

180

06/13/23 23:59

“

“

06/16 21:29

9988

MC

75

N/A

180

06/13/23 23:59

“

“

06/16 21:31

4699

MC

85

10209

240

06/13/23 23:59

“

“

06/16 21:32

3791

MC

95

N/A

180

06/16/23 02:00

06/16 02:06

06/16 02:30

06/16 21:34

2769

MC

105

12364705

240

06/13/23 23:59

“

“

06/16 21:36

25352

MC-N

120

5983494

240

06/13/23 23:59

“

“

06/16 21:47

7637

ADCP

125

N/A

300

06/15/23 23:59

Table 3.6

Table 3.6

06/16 21:47

25444

MC-N

135

12152941

240

06/13/23 23:59

“

“

06/16 21:49

4701

MC

155

10211

240

06/13/23 23:59

“

“

06/16 21:51

11381

MC

+39 m

2146836

300

06/16/23 00:01

“

“

06/17 00:02

11380

MC

+39 m

2146835

300

06/16/23 00:01

“

“

06/17 00:02
Table 3.5 WHOTS-19 mooring recovery summary for C-T (Conductivity-Temperature) and ADCP (Acoustic Doppler Current Profiler) instruments. All times in UTC (MM/DD/YY hh:mm:ss). SN = Serial Number, Tlg = Logging, Spk = Spike, Q = Quality.

Z (m)

SN

T out

Spk

End Spk

Tlg Stop

N Samples

Q

7

3382

06/07/24 01:46:00

06/07/24 05:56:00

06/07/24 06:26:00

06/11/24 00:13:21

174243

Good

15

6892

06/07/24 01:54:00

06/07/24 05:56:00

06/07/24 06:26:00

06/14/24 14:38:03

414947

Good

25

4663

06/07/24 01:57:00

06/07/24 05:56:00

06/07/24 06:26:00

06/08/24 03:38:40

172873

Good

35

3633

06/07/24 00:41:00

06/07/24 05:56:00

06/07/24 06:26:00

06/07/24 19:31:30

172710

Good

40

3381

06/07/24 00:37:00

06/07/24 05:56:00

06/07/24 06:26:00

06/08/24 03:19:15

172866

Good

45

3668

06/07/24 00:33:00

06/07/24 05:56:00

06/07/24 06:26:00

06/08/24 03:07:45

171871

Good

47.5

ADCP 13917

06/07/24 00:29:00

06/07/24 05:56:00

06/07/24 06:26:00

N/A

40846

Stopped 3/25/24

50

3619

06/07/24 00:28:00

06/07/24 05:56:00

06/07/24 06:26:00

06/11/24 00:19:06

174245

Good

55

3620

06/07/24 00:27:00

06/07/24 05:56:00

06/07/24 06:26:00

06/11/24 00:01:23

174240

Good

65

3621

06/07/24 00:25:00

06/07/24 05:56:00

06/07/24 06:26:00

06/10/24 23:56:24

174238

Good

75

9988

06/07/24 00:25:00

06/07/24 05:56:00

06/07/24 06:26:00

06/07/24 20:19:00

172725

Good

85

4699

06/07/24 00:24:00

06/07/24 05:56:00

06/07/24 06:26:00

06/10/24 23:52:11

130678

Good

95

3791

06/07/24 00:24:00

06/07/24 05:56:00

06/07/24 06:26:00

06/07/24 04:30:20

171890

Good

105

2769

06/07/24 00:23:00

06/07/24 05:56:00

06/07/24 06:26:00

06/08/24 03:28:10

129653

Did not record P/C

120

25352

06/07/24 00:21:00

06/07/24 05:56:00

06/07/24 06:26:00

06/08/24 00:27:30

129607

Good

125

ADCP 7637

06/07/24 00:17:00

06/07/24 05:56:00

06/07/24 06:26:00

06/07/24 19:07:00

51522

Good

135

25444

06/07/24 00:16:00

06/07/24 05:56:00

06/07/24 06:26:00

06/07/24 22:42:30

129581

Good

155

4701

06/07/24 00:14:00

06/07/24 05:56:00

06/07/24 06:26:00

06/07/24 22:06:10

129571

Good

38 mab

11380

06/06/24 19:50:00

06/07/24 19:52:00

06/07/24 20:10:00

06/08/24 00:27:06

103093

Good

38 mab

11381

06/06/24 19:50:00

06/07/24 19:52:00

06/07/24 20:10:00

06/08/24 00:27:19

103093

Good
Table 3.6 WHOTS-19 mooring ADCP deployment and configuration information. All times are in UTC (MM/DD/YY hh:mm:ss).

Parameter

ADCP S/N 13917

ADCP S/N 7637

Frequency (kHz)

600

300

Number of Depth Cells

25

30

Depth Cell Size (m)

2 m

4 m

Pings per Ensemble

80

40

Time per Ensemble (min)

10 min

10 min

Time per Ping (sec)

2 sec

4 sec

Time of First Ping

06/15/2023, 23:59:00

06/15/2023, 23:59:00

Transducer 1 Spike Time

06/16/2023, 05:40:00

06/16/2023, 05:40:00

Transducer 2 Spike Time

06/16/2023, 05:40:15

06/16/2023, 05:40:15

Transducer 3 Spike Time

06/16/2023, 05:40:30

06/16/2023, 05:40:30

Transducer 4 Spike Time

06/16/2023, 05:40:45

06/16/2023, 05:40:45

Ice Spike Time Begin

06/16/2023, 00:00:00

06/16/2023, 00:00:00

Ice Spike Time End

06/16/2023, 00:30:00

06/16/2023, 00:30:00

Time in Water

06/16/2023, 21:23:00

06/16/2023, 21:47:00

Depth (m)

47.5 m

125 m
Table 3.7 WHOTS-19 mooring ADCP recovery information. All times are in UTC (MM/DD/YY, hh:mm:ss).

Parameter

ADCP S/N 13917

ADCP S/N 7637

Frequency (kHz)

600

300

Number of Depth Cells

25

30

Depth Cell Size (m)

2 m

4 m

Pings per Ensemble

80

40

Time per Ensemble (min)

10 min

10 min

Time per Ping (sec)

2 sec

4 sec

Time of Last Ping

06/07/24, 05:40:00

06/07/24, 05:40:00

Transducer 1 Spike Time

06/07/24, 07:32:00

06/07/24, 07:21:00

Transducer 2 Spike Time

06/07/24, 07:32:15

06/07/24, 07:21:15

Transducer 3 Spike Time

06/07/24, 07:32:30

06/07/24, 07:21:30

Transducer 4 Spike Time

06/07/24, 07:32:45

06/07/24, 07:21:45

Ice Spike Start Time

06/07/24, 05:56:00

06/07/24, 05:56:00

Ice Spike End Time

06/07/24, 06:26:00

06/07/24, 06:26:00

Time in the Water

06/16/23, 21:47:00

06/16/23, 21:47:00

Time out of Water

06/07/24, 00:29:00

06/07/24, 00:17:00

Depth (m)

47.5 m

125 m

The 300 kHz ADCP at 125 m (SN 7637) operated flawlessly for the entire deployment and was still recording on recovery. In contrast, the 600 kHz ADCP at 47.5 m (SN 13917) stopped logging on 25 March 2024. Data collected are good, aside from near-surface side-lobe interference.

The RDI 300 kHz Workhorse Sentinel ADCP, SN 7637, was installed at 125 m with its transducers facing upward and an external battery pack. It pinged every 4 s for 160 s once every 10 min—a burst regime selected to reduce aliasing from large-swell orbital motions. Bin size was 4 m. In total, 51 522 ensembles were logged, beginning 06/15/2023 23:59:00 and ending 06/07/2024 18:48:59 (see Table 3.6, Table 3.7, and WHOTS-19 300 kHz - Serial 7367). This instrument also measured temperature.

The RDI 600 kHz Workhorse Sentinel ADCP, SN 13917, was installed at 47.5 m with transducers facing upward and an external battery pack. It pinged every 2 s for 160 s once every 10 min, with a 2 m bin size. The instrument logged 40 846 ensembles between 06/15/2023 23:59:00 and 03/25/2024 15:38:59 (see Table 3.6, Table 3.7, and WHOTS-19 600 kHz - Serial 13917). Upon recovery it was silent. Diagnostic checks suggest a Y-cable fault: the internal battery was fully depleted, whereas both external packs were only partially discharged—an imbalance not expected under normal operation. Data collected before shutdown are high-quality, apart from near-surface side-lobe interference. This instrument also measured temperature.

Two VMCMs (SN 0035 at 10 m and SN 0058 at 30 m) were configured by the WHOI/UOP group to sample every minute; both also recorded temperature.

Recovery details for the C-T instruments appear in Table 3.5. All WHOTS-19 instruments were retrieved. Biofouling was common—severe near the surface and detectable, though minor, down to the 125 m ADCP.

Post-recovery inspection found every MicroCAT intact with its antifoulant capsule. High-quality records were obtained from all units except those flagged in Table 3.5 (see MicroCAT Data Processing Procedures, MicroCAT Data). One exception is SN 2769, which failed to log pressure and conductivity, although no external damage to the sensor or its conductivity cell was observed.

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