SBI Mooring Cruise 2003

USCGC HEALY

September - October 2003, Barrow - Nome, Alaska





FIELD REPORTS

September 10, 2003
September 14, 2003
September 18, 2003
September 25, 2003
October 12, 2003
October 19, 2003


September 10, 2003 - Chief Scientist Report

Dear All,

Well, here we are poised in Barrow to join the ship.  The science party arrived yesterday - the first load in a gap in the snow storm, the second in clearer weather.  Today we feel the bite in the air, but the sun has been seen and the seas are coming down. Since I arrived on Sunday we have had wild, stormy weather. With the land being mostly a coarse-grained black sand, the waves crashing onto the beach look particularly menacing. Especially so as they wash away the road in front of you! We are staying a couple of miles out of town at NARL.  The road in hugs the shore and everyday there are diggers pushing the natural sand into piles to hold back the waves.  For the last few days, they've lost - we drive the inland road instead, longer and "washboarded" - a vocative expression if you remember scrubbing clothes on boards by hand.  I spent most of Monday and Tuesday telling school kids about physical oceanography, making them use their "human salinometer" to taste the difference between Pacific and Atlantic waters, and playing demonstration games with some salt solutions, a glass jar and food colourings.

Today was final pre-cruise planning .. and tomorrow should (we hope) whisk the 20 science party and the 3000lbs of freight off to the Healy.  So, with any luck, the next should be from sea!  Flying up was like travelling 6 months in a day - from the summer of Seattle, to the Fall of Fairbanks, to the barren winter of Barrow.  Enjoy the summer for us, and we'll hope for a more wintery than stormy autumn for the start of the trip.

Best wishes,
Rebecca

September 14, 2003 - Chief Scientist Report

Dear All,

Greetings from the Healy, somewhere off Hanna Shoal! We're all aboard, 3 days now and already things are slipping into a routine.  Despite a large storm pounding the beaches off Barrow so hard it washed away the road early in the week, the weather calmed down enough for the helicopter transfers of all personnel and equipment (3000lbs science gear, 6000lbs stores) on the 11th.  We sailed into calming seas, ADCPed the night away running across-canyon sections of Barrow Canyon and successfully recovered the Barrow Canyon mooring on the afternoon of Friday 12th.  Saturday saw more ADCP sections whilst the CTD and chemists completed their set-ups and by Saturday night we were running the first CTD casts in a 17-station section (2nm separation) across the southern end of Barrow Canyon.  This morning completed the CTD section, and as I type we are steaming north towards the Chukchi Slope moorings, ETA Monday morning.

All well, 
Rebecca


September 18, 2003 - Chief Scientist Report - running south along the Chukchi Slope line

Dear All,

Time flies, and we are making good progress.  Monday morning saw us at the mooring site CS1, with some ice, but good open water.  Though the mooring was in position and both releases perky, once released the mooring failed to come up.  Time, thus, to dig out the dragging gear, and some hours later, on the first drag, the mooring came to the surface.  The drag had caught the mooring and given it a sufficient shake to free it from whatever was hanging it up, since it surfaced normally and was on board by late evening.  We can only speculate on improbable theories.  It is a reminder that these things can take time.  Post recovery, we ran northwest CTDing down across the slope, to catch the core of Herald Valley outflow, ADCPed back and fro across it, returning to the second mooring recovery yesterday.  This went smoothly, both recovery and the redeployment of both the Chukchi Slope moorings, and by evening we were running north again to start our main line south through the mooring positions, CTD, ADCP water sampling and the occasional VPR cast .. which is where you currently find us.  Ice has been light light light, nothing to hinder our progress so far.  Two pairs of polar bears and the remains of their hunt (Walrus?) indicate we are in the nutrient rich waters of the Pacific.  One swimming polar bear today makes you ask the eternal question of how did it get there?  The ship's ADCP is tracking well, the Seabeam also.  We'll finish this line, then head to the Central Channel mooring.  Weatherwise, fog seems our biggest hazard, a small penance given what's happening on the east coast!

All well,
Rebecca

September 25, 2003 - Chief Scientist Report - working the Beaufort line

Dear All,

Thursday 25th Sept and all well.  You find us working the Beaufort line and having covered a lot of ground since last week.  Last week we were up by the Chukchi Slope moorings in light, mostly negligible ice, and CTDing (and VPRing) south through the mooring line.  We extended that section southeast to Hanna Shoal and back south towards the Alaskan Coast, giving us a quasi-synoptic slice through the central Chukchi Sea.  We are still finding pockets of winter water, and comparison with the Palmer data of a few months ago gives interesting progression of features. 

On reaching the coast, we deadheaded to our fourth mooring recovery, the UAF mooring in the Central Channel, another trouble free recovery and redeployment.  Whilst in the area we took the opportunity to assist Chinese colleagues who deployed a surface mooring some months ago but, due to a large storm, were unable to recover it before heading south.  We circled the site in Force 5-6 seas, visual contact being our only hope for recovery, since the mooring carried no acoustic mechanism.  The large red top float and radar reflector was not to be found, presumably torn off by the storm.  The amazingly sharp eyes of the US Coastguard did however locate the second float, the only remaining surface expression, a small, (14inch diameter) white sphere, hidden in a sea of white-caps!  From there, the recovery went well, thanks to the dedicated boat and deck crews, and the instruments and the data are safely aboard, enroute back to the Chinese.

Mooring work in the Chukchi completed, we ran another closely spaced hydrographic section (CTD and VPR) through the Central Channel mooring, to the coast, and headed northeast to the Beaufort Slope line.  We have been here two days, and so far have been remarkably lucky with weather.  We recover moorings in the day and work net-tows and CTD casts (predominantly the calibration casts for mooring instruments to be redeployed) in the night.  So far, six moorings are safely recovered.  We aim to try for the remaining three tomorrow.

We have been working mostly in calm seas, no ice, little wind, few waves, northern lights on the clear nights and occasional sun and snow flurries in the day.  It's not really very Arctic, but if it gives fair weather for the mooring work, that's fine too.

Rebecca


October 12, 2003 - Chief Scientist Report

Dear All,

Sunday 12th October and all well.  Many miles under the keel since the last report.

We are now back in the Chukchi having completed the Beaufort Slope work we were engaged in when I last wrote.  The remaining Beaufort mooring recoveries went smoothly.  Bob has a terrific haul of data, with all his crawlers (the instruments that twice daily climb the length of his moorings recording T, S and velocity) working extremely well.  

The WHOI team worked hard to get all the instrumentation turned around for redeployment.  In the meantime we ran and reran the CTD section across the Beaufort slope, with accompanying ADCP lines and CTD sections offset to the east and to the west.  The collection, (some 7 full or partialCTD lines and 18 ADCP transects) gives a marvelous picture of the evolution of the boundary current system under sustained easterly (i.e. upwelling favorable) winds.  The variability in the Pacific waters is remarkable and uniquely documented by these surveys, which were frequently run at night to allow for mooring deployments in the daylight hours.  We completed the deployments by last Sunday and started into the final, high resolution CTD line with chemistry and VPR casts, when the largest storm yet hit us.  Forty to fifty knot winds and Force 7+ seas left us able only to ride it out.  The Healy is a remarkably stable platform, so you needn't feel too sorry for us - just frustrating not to able to CTD the line.  After two days of sitting it out, the seas calmed down enough to recommence the section, and by Thursday afternoon we were headed back again to east of Barrow.  

You now find us working north again with another major section across the Chukchi slope, along the line occupied twice by the Healy last year and once by the Palmer this last summer.  We find trapped waters over Hanna Shoal and are expecting the boundary current of the Pacific waters any cast now.  We've had rough seas again, forcing a retermination of the CTD wire, but are back to a steady CTD routine for these last few days - we'll turn for Nome at the end of the week.  We've sighted a few whales, another swimming polar bear, but really remarkably little - though the fog does little for the sightings and the northern lights, stars and sun are things of the past.  Still, as long as the winds and seas stay down, that's the main thing.  

All the best,

Rebecca

October 19, 2003 - Chief Scientist Report

Dear All,


Nome, sweet Nome, that's where you find us.  All packed, disembarked and headed for home.  The final week passed swiftly. We completed another two sections across the Chukchi Slope, and finding a variety of warm and cold cores of water, most likely eddies, ran a quick XBT survey to try and capture the eddy inventory of the slope region.  A final southward leg brought us back up into Hanna Shoal with our enddate coming fast and the weather worsening.  Still, the line was completed, and after concluding a few stations into the peculiar regime west of Hanna Shoal, we quit CTDing and hotfooted for Nome.  The time of year necessitates leaving time for 10 knot transit in fog.  However, good visibility and a 25 knot tail wind sped us to Nome at almost 18 knots(!!), allowing us to take advantage of a good weather window on the 18th Oct and get everyone and everything ashore before the weather broke.

The total work accomplished reflects strongly the admirable stamina of the team, the ice-free waters we encountered and the comparatively mild weather. We completed 13 mooring recoveries, and 15 mooring deployments, 321 CTD casts, including 953 salinity samples, 948 nutrient samples, 842 oxygen samples, 548 chlorophyll samples, 34 VPR casts, 11 net tows, 63 XBTs, 70 Sonobuoys drops  (passive listening for whales), and 35 days of ADCP and Seabeam data.  These are all just statistics - sciencewise, in both water mass properties and water velocity, we have a substantial areal and temporal survey of the Beaufort Slope current, the shelf-slope transition over the Chukchi Shelf and Chukchi Sea itself. Together with the mooring data and the Palmer survey of early in the year, this substantial data set will go a long way to identify and quantify the many processes in this highly variable shelf-slope system.

It has been a successful, hard-working cruise.  Our thanks go to all the crew of the Healy, especially the MSTs, whose tireless support and professionalism allow us not only to bring home this marvelous data set, but also to have had an enjoyable time collecting it!

Thanks to everyone for a great cruise,

Rebecca

 

For use of any of these figures, please contact
Rebecca Woodgate (woodgate@apl.washington.edu)





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© Polar Science Center, University of Washington, 2003


We gratefully acknowledge financial support for this work from  Office of Naval Research (ONR) High Latitude Dynamics Program and the National Science Foundation (NSF) Office of Polar Programs.

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