Mooring Service Cruise (MSC) 2022

The main objective of the cruise was to retrieve and deploy ocean moorings in the north-western Barents Sea and on the continental slope north of Kvitøya for the Nansen Legacy and A-TWAIN projects. A secondary objective was to perform hydrographic surveys in regions of Atlantic Water inflow and other regions of interest. In addition, the cruise aided other research groups by deployment and recovery of minor equipment at sites along the cruise trajectory. 
In general, mooring operations were conducted during day hours, while nights were used to collect CTD data along various transects. Mooring work was completed quickly, efficiently, and ahead of schedule. This left ample time for additional pre-planned hydrographic surveys after the mooring work was complete. 
The cruise departed from Longyearbyen in the afternoon on 02.10.2022. An IMR ARGO float was deployed north of Spitsbergen the day after. On the following day, the ship operated for three days in the area around the A-TWAIN mooring array on the continental slope north of Kvitøya. Here, four moorings were recovered, and four were deployed, and hydrographic transects (CTDs) were conducted across the Atlantic Water inflow current and across northern Kvitøya Trough. 
After transiting south from the A-TWAIN area on the evening of 06.10.2022, another transect was conducted at night across the southern outlet of Kvitøya Trough. Mooring work began the following morning at the Nansen Legacy M1 location in the north-western Barents Sea. Two moorings were recovered and redeployed. Afterwards, a cross-slope transect was conducted intersecting the M1 mooring location. In the following days, consecutive transects were conducted into the through extending from M1 to Hartogbukta, along the Storisstraumen glacier front, from Storisstraumen southeast across the ocean basin, and along the bathymetric saddle west of Kong Karls Land. 
During the transit back north and west, an additional brief transect was conducted outward from Wahlenbergfjorden into the Hinlopen Trough, to obtain data from a fjord with tidewater glaciers that are likely not influenced by Atlantic Water. On 10.10.2022 an NPI radio transmitter was retrieved from the island of Moffen by small boat. The ship then transited back to Longyearbyen, arriving in port on the evening of 11.10.2022. 
Overall, the cruise was highly successful. All planned operations were completed in good time, allowing room for extensive hydrographic surveying as well as two minor deployment and recovery operations for other research groups. The success was in part due to fair weather during the first five days of the cruise and completely sea ice-free seas throughout. This allowed mooring work to take place in favourable conditions in an area where operations are often hampered by wind, swell, and sea ice. However, we would also like to highlight the competence and professionalism of the crew of the Kronprins Haakon as a key factor in the success of the cruise. Cooperation and communication with crewmembers on deck and on the bridge were excellent throughout. In addition, the cruise participants efficiently completed all the planned objectives despite the small size of the team (7 team members).

In general, mooring operations were conducted during day hours, while nights were used to collect CTD data along various transects.Mooring work was completed quickly, efficiently, and ahead of schedule.This left ample time for additional pre-planned hydrographic surveys after the mooring work was complete.
The cruise departed from Longyearbyen in the afternoon on 02.10.2022.An IMR ARGO float was deployed north of Spitsbergen the day after.On the following day, the ship operated for three days in the area around the A-TWAIN mooring array on the continental slope north of Kvitøya.Here, four moorings were recovered, and four were deployed, and hydrographic transects (CTDs) were conducted across the Atlantic Water inflow current and across northern Kvitøya Trough.
After transiting south from the A-TWAIN area on the evening of 06.10.2022, another transect was conducted at night across the southern outlet of Kvitøya Trough.Mooring work began the following morning at the Nansen Legacy M1 location in the north-western Barents Sea.Two moorings were recovered and redeployed.Afterwards, a cross-slope transect was conducted intersecting the M1 mooring location.In the following days, consecutive transects were conducted into the through extending from M1 to Hartogbukta, along the Storisstraumen glacier front, from Storisstraumen southeast across the ocean basin, and along the bathymetric saddle west of Kong Karls Land.
During the transit back north and west, an additional brief transect was conducted outward from Wahlenbergfjorden into the Hinlopen Trough, to obtain data from a fjord with tidewater glaciers that are likely not influenced by Atlantic Water.On 10.10.2022 an NPI radio transmitter was retrieved from the island of Moffen by small boat.The ship then transited back to Longyearbyen, arriving in port on the evening of 11.10.2022.
Overall, the cruise was highly successful.All planned operations were completed in good time, allowing room for extensive hydrographic surveying as well as two minor deployment and recovery operations for other research groups.The success was in part due to fair weather during the first five days of the cruise and completely sea ice-free seas throughout.This allowed mooring work to take place in favourable conditions in an area where operations are often hampered by wind, swell, and sea ice.However, we would also like to highlight the competence and professionalism of the crew of the Kronprins Haakon as a key factor in the success of the cruise.Cooperation and communication with crewmembers on deck and on the bridge were excellent throughout.In addition, the cruise participants efficiently completed all the planned objectives despite the small size of the team (7 team members).

Study area and conditions during the cruise
The cruise began and ended in port in Longyearbyen, Svalbard.The cruise trajectory (Figure 1) went west and north of Spitsbergen to the A-TWAIN array on the continental slope of the Nansen Basin.From there, it followed a clockwise trajectory around Nordaustlandet, with mooring work in the northwestern Barents Sea as well as hydrographic transects along the way.The return journey from the northern Barents Sea went through Hinlopen Strait before transiting back to port north and west of Spitsbergen.
Ocean and ice temperatures were both relatively high for the season during the cruise (Figure 3).Ocean temperatures measured at the water intake were around 2-3 C during most of the work, with slightly higher temperatures in the northwestern Barents Sea than in the A-TWAIN area (Figure 4).Air temperatures were above freezing except in a few instances north of Svalbard.Winds were occasionally strong, in particular during the passage of a pressure system starting around 07.10, but did not significantly impede operations.

Activity reports 2.1. Mooring operations
Two moorings were recovered and redeployed for the Nansen Legacy project.The NPI mooring M1-4 was recovered and its replacement M1-5 was deployed at the same site.The IMR mooring M1-Bioac-2 was similarly replaced by M1-Bioac-3.Four moorings were recovered and four deployed for the Fram Centre A-TWAIN/SIOS-Infranor.The two NPI moorings AT800 and AT200 were both recovered and redeployed.The NPI bottom mooring lander AT500 was recovered but not redeployed.The IMR mooring AT800-BioAC was recovered.The IMR moorings AT800-BioAC-300 and AT800-BioAC-600 were deployed.
An upward looking Nortek Signature250 ADCP recovered from AT800-7 had an incomplete data record, and there were issues communicating with the instrument.This instrument was therefore not redeployed on the replacement mooring AT800-8.Otherwise, all moorings were equipped according to plan.
Moorings were deployed anchor first.Both deployment and recovery were done over the starboard side of the ship.The ship's small boat was used to recover the AT500 bottom lander mooring.
An overview of recovered and deployed moorings is found in Table 1 and Table 2. Mooring diagrams showing the nominal depths and serial numbers of instruments on all recovered moorings are found in Appendices Appendix F and Appendix G.

Note about the AT800-8 mooring
The top of this mooring was too shallow when deployment was nearly complete, presumably due to wrong length Kevlar lines.Instruments attached to top 150 m were taken off, the line length was adjusted, and the top 150 m was again lowered and instruments attached.Instruments above the middle buoy were measured from the top buoy, and are assumed to be correctly positioned relative to each other.Instruments below the middle buoy were positioned relative to the anchor, and are also assumed to be positioned correctly relative to other instruments in this range.However, there is some uncertainty in the positions of the top instruments relative to the bottom ones.This should be possible to resolve from the pressure records from RBR Concertos when they are recovered.

Shipboard CTDs
A total of 77 shipboard profiles were conducted during the cruise (Appendix B).The main steel cable usually used on the rosette was not available, and the main CTD rosette could therefore only be deployed with a more sensitive neutrally buoyant kevlar cable.As a result, the main CTD rosette could only be deployed through the ship's moon pool, resulting in meaningful profiles only below the depth of the ship's hull.The CTD was also only lowered at a speed of 0.7 m/s due to the use of the Kevlar cable.
Profiles from the CTD transmissometer exhibited frequent drops to zero within otherwise sensible data.This indicates an issue with the electronic transmission rather than with the instrument itself.The connector cables were gone over, but the issue seems to have persisted throughout the cruise.The remaining data from this instrument appears to be of good quality.Before scientific use of the data, bin average profiles should be recalculated from the full-resolution data after bad scans have been removed.
The CTD was controlled by IMR instrument engineers using SBE Seasave software.GPS data from the ship's navigation system were logged with every scan.CTD unit on the rosette was a SBE911plus.Serial numbers and calibration dates of individual sensors/components are shown in Table 3: The CTD feed also contains measurements from a SPAR sensor (Biospherical/Licor) mounted on the ship (20568, calibrated 27-Nov-2017).Data from this instrument were not assessed during the cruise, but were reported as being unstable or absent.
Two 300 kHz RDI ADCPs were mounted on the rosette in Lowered ADCP (LADCP) mode, one looking up and one looking down.The two instruments sampled coherently in master/slave mode.LADCP data were downloaded between casts.
At each cast, the CTD rosette was lowered to 20 m.After the instrument feeds stabilised, the rosette was raised to 10 m before being lowered to the desired depth (~10 m above bottom with the exception casts #222 and #241).The CTD was lowered at 0.5 m/s above 100 m depth, and at 0.7 m/s below.Water samples for salinity calibration were taken from maximum depth by instrument engineers at each cast, to be sent to IMR for salinity calibration corrections for postprocessing of the CTD profiles.Water samples for nutrients were taken on 4 stations (Section 2.3, Appendices Appendix B and Appendix C).
On stations #222 and #276 -#297, a small, internally recording CTD unit was used to supplement the main rosette with data from the upper 20 m.The unit measured temperature, salinity and pressure, and was lowered to >40 m depth before the cast with the main rosette.The unit (SAIV MINI STD/CTD, S/N 882) was most recently calibrated on 04.07.2010, so great care should be taken when interpreting profiles from this sensor.

CTD transects
In addition to CTD stations taken for mooring calibrations, hydrographic surveys were performed along set transects (Figure 6: Locations of hydrographic transects around Nordaustlandet (left) and near the continental slope (right).Transects indicated in orange, with CTD stations shown as yellow dots and ship track shown as gray line.).The CTD stations associated with each transect are shown in Table 4.

Nutrient sampling
At total of 40 nutrient water samples for were collected at four stations: at AT800, AT200, M1, and in front of the Storisstraumen glacier terminus.Samples were collected in accordance with the Nansen Legacy Sampling Protocols v10 and using Falcon 50 ml tubes.Water was collected from CTD bottles set to close at fixed depths, as well as 10 m above bottom.In addition, one sample per station was collected from the ship intake.
The water samples will be analysed for nitrate + nitrite (NO3+NO2), phosphate (PO4) and silicate (SiO 4 ).A detailed overview of the nutrient samples can be found in Appendix C.

Underway thermosalinograph and PCO2
Measurements from the seawater intake at 4 m depth were collected throughout the cruise since no sea ice was encountered.Close to the water intake, a SBE38 temperature sensor recorded the temperature in order to obtain temperature measurements before the water is heated up as it travels along the piping.In the Clean Seawater Lab, a SBE21 SeaCAT thermosalinograph monitored temperature, salinity, and fluorescence (WET Labs WET star fluorometer).
Instrumentation for measurements of CO2, pCO2, (General Oceanics), dissolved oxygen (DO) (Aanderaa sensor), salinity, temperature, CDOM and chlorophyll-a fluorescence was also active during the cruise.These records were not examined specifically but are reported to have functioned well during the cruise.

Shipboard ADCP
A 150 kHz vessel-mounted ADCPs measured continuously from shortly after leaving port until the end of the cruise.A 38kHz ADCP was used during parts of the cruise where the ship operated in water deeper than 4-500 m.Data acquisition was done using VMDas.Both ADCPs sampled in broadband mode, favouring resolution over range, and both were mounted in the hull (the drop keel mounted instruments were not used).The following, standard configurations were used throughout the cruise: 150kHz ADCP: CR1 CB611 WP00001 NP00000 WN070 WS0400 WF0600 CX 1,0 BP000 BX08000 ND111100000 TP000100 TE00000200 EZ1020001 EX00000

Weather station
Continuous measurements of air temperature, humidity, wind speed/direction, air pressure, humidity, dew point, seawater temperature at 8.5 m, and solar radiation were collected by a Vaisala AWS430 weather station on the ship.

07.10.2022
Finished KVS transect and arrived at M1 site in the morning.Pre-recovery CTD with nutrient sampling at M1 at 05:55.Easterly wind picking up but manageable working conditions.Pinged M1-BioAc-2 and released at 06:42.Foggy and poor visibility but found the mooring float after a short time.On deck 07:05.Moving on to M1-4 site, pinged and released M1-4 at 07:16.Some difficulty connecting to the mooring due to swell.Entire M1-4 mooring on deck 08:10.Pause on site to prepare for deployment of the two remaining moorings.Collected one CTD to examine any changes in the mixed layer during wind forcing.
Steamed north to conduct a cross-slope transect at M1 (M1T).Transect included a postdeployment CTD at the M1 site (CTD #249).Finished last station shortly after midnight UTC.

08.10.2022
Continued doing CTD westward from M1, both along (HBA) and across (HBC) the trench connecting the M1 area and Hartogbukta.SAIV CTD used in the surface waters from HBA-4 onward.Finished the HB transects and arrived at the first station of the Storisstraumen transect (SS) close to Storisstraumen glacier front in Hartogbukta.First station SS-1 at 11:57, also took nutrient samples.Very poor visibility, but calving front is visible in front of the ship.Clear delineation into surface plume water visible both as a color change (blue->brown), on the ice radar (as a line feature at the edge of the surface plume waters) and in the thermosalinograph (as a >2 C drop in temperature and >1 g/kg drop in salinity).Conducted CTD within plume.Due to shoaling waters and unknown bathymetry, the ship went away from the glacier front on the way to the next station.Using Kartverket bathymetry (available slightly further south) and going back toward the glacier front to collect a new CTD, this time in an indent of the Storisstraumen front near the middle of the terminus (station SS-2).Brown, fresh waters were also observed here and on the two subsequent CTDs taken along the glacier front.
Moved on to a new CTD transect (SSO) extending outward from SS-2, across the basin toward Svenskøya.First station 19:59.

09.10.2022
Finished the SSO transect around 03:30, went on to a new transect (SAD) westward across the saddle toward to Olga Basin.Finished after 11:00 and steamed north into Hinlopen Strait.
At this point, we were considering whether it was feasible to pick up radiosondes on Lågøya and Moffen for NPI colleagues working on walrus tracking.Given a weather forecast of strong NE winds in the morning and a ~4 h transect time between the two locations, we decided not to go to Lågøya, but instead to arrive at Moffen around noon and assess the conditions, resulting in some extra time being available during transit.

Figure 1 :
Figure 1: Map of cruise track with stations and operations.

Figure 2&2 :
Figure 2&2: Zoomed in maps of the A-TWAIN (left) and M1 (right) areas.

Figure 4 :
Figure 4: Near-surface salinity (left) and temperature (right) along the cruise track.Data from thermosalinograph, water intake at 4 m depth.

Figure 6 :
Figure 6: Locations of hydrographic transects around Nordaustlandet (left) and near the continental slope (right).Transects indicated in orange, with CTD stations shown as yellow dots and ship track shown as gray line.

Table 1 :
Overview of moorings recovered during the MSC2022 cruise.Date/time in UTC.BGC: Biogeochemical, OA: Ocean Acoustics.Exact positions and depths taken from deployment during the MSC2021 cruise report.The #CTD column shows the CTD station number of profiles collected at the mooring site before recovery.

Table 2 :
Overview of moorings deployed during the MSC2022 cruise.Date/time in UTC.The #CTD column shows the CTD station number of profiles collected at the mooring site after deployment.*206 m on echo sounder, estimated 203 m on the aft deck where the mooring was deployed.

Table 3 :
Overview of sensors on the CTD rosette.

Table 4 :
CTD transects showing dates and associated CTD numbers.Note that some stations fall along multiple transects (addtional stations from other transects are indicated in parentheses).