US GO-SHIP is part of the international GO-SHIP network of sustained hydrographic sections, supporting physical oceanography, the carbon cycle, and marine biogeochemistry and ecosystems. The US program is sponsored by US CLIVAR and OCB. Funded by the National Science Foundation and NOAA.

News

Arctic Geotraces 2015 Weekly Science Report from Jim Swift, CTD/hydrographic Scientist, Week 8 Oct 5, 2015

USCGC Healy Cruise HLY-1502

US Arctic Geotraces

Weekly CTD/Hydrographic Team Report 08

from Jim Swift, UCSD/SIO, CTD/hydro team scientific leader at sea

Sunday, 04 October 2015, 7:30 pm, local date and time (0330 05 October UTC)

73°N, 158.8°W (on the Beaufort slope)

air -4 degC / 25 degF

water -0.5 degC / 31 degF

wind 1-2 knots from ENE

on station 060 (a Geotraces ‘slope’ station)

Note: This is a hydrography-oriented report from Jim Swift, who is working with the SIO Oceanographic Data Facility (ODF) CTD/hydrographic team on the US Geotraces Arctic Ocean expedition led by Dr. David Kadko, FIU, chief scientist. This is not a report from Dr. Kadko or the other science teams.

Dear Colleagues,

This week started out rough for the expedition’s science programs, with Geotraces hit especially hard. Reversing the order of the cruise plan worked out well for most of the cruise, enabling excellent Arctic Ocean spatial coverage for example. But one of the acknowledged risks was the degree to which fall storms would undermine the ability to carry out the final stations when the ship was in open water late in the season, just as we are now. Although we arrived in the southern Canada Basin with equipment working well, and what seemed to be a fine amount of time to do the scheduled work (I am not privy to the cruise time line, however), a series of low pressure systems has disrupted station work and led to damage to two of the three oceanographic cables used this cruise: the trawl wire experienced damage some hundreds of meters above the termination and the Vectran synthetic cable required for the trace metal rosette program had to be inspected for possible damage about 1000 meters above the termination. Both of the cables are used over the stern A-frame and both were involved in very high wire angle situations during casts the same day of worsening weather during the past week. No equipment was lost. The trawl wire was quickly put back into service, and the Vectran cable issue also was not a special problem, but the core issue remains that stormy weather makes for rough conditions, affecting most severely our science operations over the stern. We lost several days of stern operations due to weather, and this has put a dent in plans for the final thrust of the science program, which focuses on examining the basin-to-slope-to-shelf transition in the Southern Canada Basin. By the time of next week’s report all this will have been settled one way or the other.

One other cable problem, not associated with bad weather, occurred a few hours ago: We lower the big 36x10-liter ODF rosette to within 10 meters of the bottom, take our first water sample, then haul it up and stop to take other water samples at other levels. When it came time to haul up from near the bottom, the winch went down instead of up and quickly lowered the rosette onto the bottom. No damage was done to the rosette, but when tension is taken off the CTD cable like that, the cable kinks due to accumulated torque, so after the rosette was back on deck we had to cut off the kinked part and make a new termination. As a result all three of our oceanographic cables have had new terminations since my previous report.

Although we are now in good weather, storms continue to haunt us with the next one due some time Monday. If it is bad enough and lasts long enough, that might be the end of science operations on the Canada Basin section because at some point we must begin heading for Dutch Harbor.

Fair weather windows can be short, making science planning less orderly than the norm preferred by the Coast Guard, which prefers a firm plan for the next 24 hours at 6:30 pm each day. There is also the matter that bathymetric charts for this region are inaccurate whereas we need to stop and do stations at scientifically-chosen isobaths, rather than assign in advance firm positions as favored by the Coast Guard. The Coast Guard has patiently worked this out with us, and now we are working well together on this.

Meanwhile, the CTD/hydrographic measurements and data processing for both Geotraces and repeat hydrography continue to go very well when we are able to work. Deck operations are smooth and quick, the CTD works well in the just- below-freezing (as opposed to deeper cold) weather of the past, and all hydro team lab systems continue excellent performance. The CFC and ocean carbon teams have been able to do full profiles, generating a treasure of data for repeat hydrography.

Here in the Canada Basin we have replicated a significant portion of the section done from the Swedish icebreaker Oden in 2005. Temperature comparisons show that the mid-depth layers have warmed since 2005 and that the upper layer has greatly freshened. These results are overall similar to the 2015-minus-1994 Makarov Basin differences reported earlier this cruise, demonstrating the widespread nature of these Arctic Ocean changes.

I mentioned in last week’s report that we were going to be looking for intermediate depth waters from the Chukchi Borderlands / Northwind Ridge boundary spreading into the Canada Basin interior. This week we did see boundary-like waters along our transect, in the same latitude range where they have been observed previously. There are also clear indications that the shallower halocline silicate maximum layer is being swept into the Canada Basin from that same Chukchi Borderland / Northwind Ridge area.

One way or the other our science work ends in a few days. We are tired, but not tired out. We are certainly not hungry, not with the excellent food the galley continues to provide. We enjoy working with our Coast Guard comrades, who treat us very well indeed. But we are all - Coast Guard and science teams alike - ready to finish up and head for port.

Saving a nice moment for last: We had a clear night with an aurora! Cory Mendenhall, the ship’s public affairs officer, captured a wonderful photo (attached) from the Healy’s helicopter pad, looking forward towards the hangar, with the ship’s red night lights glowing and the moon illuminating the sky beyond, auroral drapery shifting, changing, beautiful.

I will send a final report in one week.

Jim Swift

Research Oceanographer

UCSD Scripps Institution of Oceanography

Read More

Arctic Geotraces 2015 Letter from Jim Swift, CTD/hydrographic Scientist, 9 Oct 5, 2015

HLY1502 letter 09 from Jim Swift

Sunday, 04 October 2015, 7:30 pm, local date and time (0330 05 October UTC)

73°N, 158.8°W (on the Beaufort slope)

air -4 degC / 25 degF

water -0.5 degC / 31 degF

wind 1-2 knots from ENE

on station 060 (a Geotraces ‘slope’ station)

Dear Family, Friends, and Colleagues,

This week started out rough for the expedition’s science programs, with Geotraces hit especially hard. Reversing the order of the cruise plan worked out well for most of the cruise, enabling excellent Arctic Ocean spatial coverage, for example. But one of the acknowledged risks was the degree to which fall storms would undermine the ability to carry out the final stations when the ship was in open water late in the season, just as we are now. Although we arrived in the southern Canada Basin with equipment working well, and what seemed to be a fine amount of time to do the scheduled work (I am not privy to the cruise time line, however), a series of low pressure systems (fall storms) has disrupted station work and led to damage to two of the three oceanographic cables used on this cruise: the trawl wire experienced damage some hundreds of meters above the termination and the Vectran synthetic cable, required for the trace metal rosette program, had to be inspected for possible damage about 1000 meters above the termination. Both of the damaged cables are used over the stern A-frame and both were involved in very high wire angle situations during casts the same day of worsening weather during the past week. No equipment was lost. The trawl wire was quickly put back into service, and the Vectran cable issue also was not a special problem, but the core issue remains that stormy weather makes for rough conditions, affecting most severely our science operations over the stern. We lost several days of stern operations due to weather, and this has put a dent in plans for the final thrust of the science program, which focuses on examining the basin-to-slope- to-shelf transition in the Southern Canada Basin. By the time of next week’s letter all this will have been settled one way or the other.

One other cable problem, not associated with bad weather, occurred a few hours ago: We lower the big 36x10-liter ODF rosette to within 10 meters of the bottom, take our first water sample (by closing it via remote control from our CTD computer), then haul the rosette up and stop to take other water samples at other levels. When it came time to haul up from near the bottom, the winch went down instead of up and quickly lowered the rosette onto the bottom. No damage was done to the rosette, but when tension is taken off the CTD cable like that, the cable kinks due to accumulated torque, so after the rosette was back on deck we had to cut off the kinked part and make a new termination. As a result all three of our oceanographic cables have had new terminations since I last wrote.

Although we are now in good weather, storms continue to haunt us with the next one due some time Monday. If it is bad enough and lasts long enough, that might be the end of science operations on the Canada Basin section because at some point we must begin heading for Dutch Harbor.

Meanwhile, the CTD/hydrographic measurements and data processing for both Geotraces and repeat hydrography continue to go very well when we are able to work. Deck operations are smooth and quick, the CTD works well in the just- below-freezing (as opposed to deeper cold) weather of the past, and all hydro team lab systems continue excellent performance. The CFC and ocean carbon teams have been able to do full profiles, generating a treasure of data for repeat hydrography. Here in the Canada Basin we have replicated a significant portion of the section done from the Swedish icebreaker Oden in 2005. Temperature comparisons show that the mid-depth layers have warmed since 2005 and that the upper layer has greatly freshened. These results are overall similar to the 2015-minus-1994 Makarov Basin differences reported earlier this cruise, demonstrating the widespread nature of these Arctic Ocean changes.

The fair weather windows can be short, making science planning less orderly than the norm preferred by the Coast Guard, which prefers a firm plan for the next 24 hours at 6:30 pm each day. (This is understandable seeing that they must orchestrate functions for a large crew.) There is also the matter that bathymetric charts for this region are inaccurate whereas we need to stop and do stations at scientifically-chosen isobaths, rather than assign in advance firm positions as favored by the Coast Guard. The Coast Guard has patiently worked this out with us, and now we are working well together on this.

Because we are now in open water and the air is usually sub-freezing, we see a moderate amount of sea ice formation, mostly grease ice but sometimes forming into small pancakes. The pancakes do not interfere significantly with the operation of the Healy’s rapid-launch small boat, which Geotraces uses for near surface trace metal sampling away from the influence of the ship (see photo taken by Chris Marsay, Skidaway Institute of Oceanography).

One way or the other our science work ends in a few days. We are tired, but not tired out. We are certainly not hungry, not with the excellent food the galley continues to provide. We enjoy working with our Coast Guard comrades, who treat us very well indeed. But we are all - Coast Guard and science teams alike - ready to finish up and head for port.

Saving a nice moment for last: We had a clear night with an aurora! Cory Mendenhall, the ship’s public affairs officer, captured a wonderful photo from the Healy’s helicopter pad, looking forward towards the hangar, with the ship’s red night lights glowing and the moon illuminating the sky beyond, auroral drapery shifting, changing, beautiful.

One way or the other our science work ends soon. I will send a final letter in one week.

Jim Swift

Research Oceanographer

UCSD Scripps Institution of Oceanography

Read More

Arctic Geotraces 2015 Weekly Science Report from Jim Swift, CTD/hydrographic Scientist, Week 7 Sep 29, 2015

USCGC Healy Cruise HLY-1502

US Arctic Geotraces

Weekly CTD/Hydrographic Team Report 07

from Jim Swift, UCSD/SIO, CTD/hydro team scientific leader at sea

Sunday, 27 September 2015, 1:30 pm, local date and time (2130 27 September UTC)

77°27’N, 147°54’°W (over the Canada Basin)

air -2 degC / 28 degF

water -1.2 degC / 30 degF

wind 4 knots from WNW

on station 052 (a Geotraces ‘full’ station)

Note: This is a hydrography-oriented report from Jim Swift, who is working with the SIO Oceanographic Data Facility (ODF) CTD/hydrographic team on the US Geotraces Arctic Ocean expedition led by Dr. David Kadko, FIU, chief scientist. This is not a report from Dr. Kadko or the other science teams.

Dear Colleagues,

We experienced a Big Change on Friday: We left the Arctic ice pack. There are some ice bits around, and we are not far south of a few belts of broken up new ice, but we have left the pack behind. Another big change is that our internet access returned yesterday evening when we arrived at this station.

During the past several days the weather warmed to only a few degrees under freezing, which is easier to contend with. We have had a fair bit of snow, but the ship puts out enough heat that the decks are less icy now. It’s a noticeable change. The ship can now transit day or night, and the work goes on. We also have full darkness every night, and we are keeping our hopes up for a clear night with an auroral display. (At Sunday brunch today a couple of the grad students said they could see shifting illumination - presumably an aurora - behind the clouds last night.)

We are greatly pleased that the engineers repaired the second evaporator, so everyone has now caught up on laundry, are we’re back to regular dishes and silverware in the mess.

The work carried out by the CTD/hydrographic team is going quite well. Although steady vigilance on equipment, procedures, and data is always beneficial, few problems have been popping up. The lack of problems is partly attributable to the warmer weather we have experienced much of the past week. Those few degrees make quite a difference to sensors that are at risk in past weeks’ deeper cold but are fine at -2°C.

Healy’s track is now (and next week) over the deep, flat abyssal plain of the Canada Basin. During pre-cruise planning I had asked that this part of our transect from the Pole to Alaska be moved east a bit to help assure a ‘miss’ of boundary currents associated with a major feature in the bathymetry west of us called the Chukchi Borderlands and Northwind Ridge. The point was that there are indications from past data that boundary waters spread from there into the Canada Basin, and so I wanted to be sure that any ‘boundary water’ we saw was truly in the basin and not just an artifact of our coming close to the boundary itself. Preliminary data indicate this is all working out as planned, i.e. that we are seeing the boundary-separated waters well away from the boundary itself. We even saw temperature-salinity intrusion features and a small decrease in light transmission at the appropriate level at a propitiously-located Repeat Hydrography station, signs of boundary water intruding into our basin-interior location.

Observing and enjoying sea ice is one of the highlights of working in the polar regions. Thus when I realized that we would be leaving the ice - perhaps for good for me - I spent a bit more time up on the bridge. I sent a selection of ice photos in my weekly outreach report. For this science report I will include a few favorites. (The small file size versions that fit into email may not do the scenes justice, but it’s the best I can do for now.)

On a cold, windy day, new ice crystals form off the edge of solid ice and as they are blown away from the ice edge they form into windrows generated by Langmuir circulation (photo by Bill Schmoker, Polar Trec):

If the wind is still, a thin sheet of ice forms, and then when that sheet is disturbed from the edge (say by the pressure wave ahead of the ship), it will fracture in right-angle patterns - a wonderful macroscopic effect of a microscopic aspect of ice crystals - called finger rafting (my photo):

Finger-rafting occurs on a wide variety of spatial scales. On this trip I saw some unusually large scale rafting - football field size (note the right angled ‘fingers’ in this photo I took):

All is well.

Jim Swift

Research Oceanographer

UCSD Scripps Institution of Oceanography

Read More

Arctic Geotraces 2015 Letter from Jim Swift, CTD/hydrographic Scientist, 8 Sep 28, 2015

HLY1502 letter 08 from Jim Swift

Sunday, 27 September 2015, 1:30 pm, local date and time (2130 27 September UTC)

77°27’N, 147°54’°W (over the Canada Basin)

air -2 degC / 28 degF

water -1.2 degC / 30 degF

wind 4 knots from WNW

on station 052 (a Geotraces ‘full’ station)

Dear Family, Friends, and Colleagues,

We experienced a Big Change on Friday: We left the Arctic ice pack. There are some ice bits around, and we are not far south of a few belts of broken up new ice, but we have left the pack behind. Another big change is that our internet access returned yesterday evening when we arrived at this station. Most of us have taken a start at examining our shore email - that part of the outside world making its return to our lives byte by byte, plus we can now send and receive somewhat larger emails (such as this one).

During the past several days the weather warmed to the upper 20s (in Fahrenheit degrees), which is easier to contend with. We had a fair bit of snow, but the ship puts out enough heat that the decks are less icy now. It’s a noticeable change. The ship can now transit day or night, and the work goes on (and on). We also have full darkness every night, and we are keeping our hopes up for a clear night with an auroral display. (At Sunday brunch today a couple of the grad students said they could see shifting illumination - presumably an aurora - behind the clouds last night.)

We are greatly pleased that the engineers repaired the second evaporator, so everyone has now caught up on laundry, are we’re back to regular dishes and silverware in the mess.

The work carried out by the CTD/hydrographic team is going quite well. Although steady vigilance on equipment, procedures, and data is always beneficial, few problems have been popping up. The lack of problems is partly attributable to the warmer weather we have experienced much of the past week. Those few degrees make quite a difference to sensors that are at risk in past weeks’ deeper cold but are fine at -2°C (28°F; i.e. temperatures near the seawater freezing point).

Healy’s track is now (and next week) over the deep, flat abyssal plain of the Canada Basin. During pre-cruise planning I had asked that this part of our transect from the Pole to Alaska be moved east a bit to help assure a ‘miss’ of boundary currents associated with a major feature in the bathymetry west of us called the Chukchi Borderlands and Northwind Ridge. The point was that there are indications from past data that boundary waters spread from there into the Canada Basin, and so I wanted to be sure that any ‘boundary water’ we saw was truly in the basin and not just an artifact of our coming close to the boundary itself. Preliminary data indicate this is all working out as planned, i.e. that we are seeing the boundary-separated waters well away from the boundary itself.

Observing and enjoying sea ice is one of the highlights of working in the polar regions. Thus when I realized that we would be leaving the ice - perhaps for good for me - I spent a bit more time up on the bridge. We do not see icebergs (glacial ice) here; the ice here is formed over the open ocean, shelf seas, and near river mouths. In fact, new sea ice has been forming the past few weeks as winter nears. To provide an idea of what I’ve seen this trip, I have included some ice photos. (The small file size versions that fit into email may not do the scenes justice, but it’s the best I can do for now.)

On a cold, windy day, new ice crystals form off the edge of solid ice and as they are blown away from the ice edge they form into windrows caused by a phenomenon called Langmuir circulation (photo by Bill Schmoker, Polar Trec):

If the wind is still, a thin sheet of ice forms, and then when that sheet is disturbed from the edge (say by the pressure wave ahead of the ship), it will fracture in right-angle patterns - a wonderful macroscopic effect of a microscopic aspect of ice crystals - called finger rafting (my photo):