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.
HLY1502 letter 01 from Jim Swift
Sunday, 09 August 2015, 1:30 pm, local date and time (2130 UTC)
53.6°N, 166.5°W (Dutch Harbor, AK)
air 11.3 degC / 52 degF
water 13.5 degC / 56 degF
wind 12 knots from SW
leaving port, heading north to the Arctic Ocean
Dear Family, Friends, and Colleagues,
A half hour ago, the US Coast Guard science icebreaker Healy left the Aleutian Islands port of Dutch Harbor, Alaska, bound for the Arctic Ocean. 51 members of the science team, approximately 90 Coast Guard officers and crew, and shore support personnel worked diligently the past four days to ready the laboratories, deck work areas, science holds, and other areas for a long- planned NSF-funded (principally) 65-day voyage to study the geochemistry of the Arctic Ocean, not to mention filling huge stores of fuel and topping off tanks holding approximately one million gallons of fuel.
Wikipedia notes that Dutch Harbor was “one of the few sites, besides the attack on Pearl Harbor in Hawaii, in American territory to be bombed by the Japanese during World War II”. There are ruin-like remains all around from the war-era military facilities which involved over 20,000 personnel. Today the town is one of the top US commercial fishing ports; that and related support activities now dominate the town. It is also the closest US port to Bering Strait and the western Arctic Ocean, which is why we staged our expedition from here.
We enjoyed some of Dutch Harbor’s finest summer weather - easy winds, warm sun, and temperatures in the upper 50s. The treeless hills and lower slopes of the volcanic mountains were lush green with myriad low plants and wildflowers, humpback whales were breeching in the bay, and there were bald eagles overhead. What a great place for a walk after working in the labs! Dutch Harbor also offers a few restaurants and watering holes where science teams and off-watch crew congregated.
Well, that is literally behind us now, as we head north. There is a well- planned sequence of events to prepare the equipment for science use. For example, while docked at the pier we did in-water tests of one of the water sampling devices - the one not used for geochemistry - and this evening we will be soaking the main “clean-sample” geochemistry equipment to help purge the devices from minute traces of possible contaminants.
The part of the program I lead has to do with measuring and interpreting the distributions of the same seawater characteristics I and my colleagues have measured on most of my cruises over the years: the temperature, salinity, dissolved oxygen, and “nutrients” (nitrate, nitrite, phosphate, and silicate) in the water column from the surface to a little above the ocean bottom. And also similar to those other cruises, my colleagues on “hydrography” program will be determining the concentrations of ocean carbon parameters, CFCs (“freons”), and oxygen isotopes. Our team did similar work along part of the intended 2015 track in 1994 and another part in 2005, so we hope to be able to compare our measurements with the earlier ones. This is known by oceanographers as “repeat hydrography”, which is how the geochemists who lead this expedition refer to our work.
They, the geochemists, will meanwhile be determining the concentrations of various trace elements in seawater - “trace elements” because they are present in truly minute concentrations. Why? Because the ones they chose to measure are especially useful at illuminating the processes that interconnect the oceans, atmosphere, sea floor, continental shelves, rivers, ice, and so forth. The concept of “salinity” is based on the fact that to significant extent, the ratio of the various dissolved ions in ocean water (from sodium, calcium, potassium, sulfur, etc.) is nearly constant, no matter the location or the total concentration of all the salts. In other words, relatively fresh (lower salinity) water from the North Atlantic will have about the same ratio of sodium to calcium to potassium to sulfur ions as would a sample of salty (higher salinity) water from the subtropical Pacific Ocean. But there are variations, and they are important in telling us how the oceans work. In the case of this cruise, the geochemists are taking advantage of decades of earlier work to carry out a tightly focused exploration of the variations of a good number of the trace elements.
Hence this is the “US Geotraces Arctic Ocean cruise”, on which the hydrographic measurements provide crucial oceanographic context for interpretation of the geochemistry, as well a rare opportunity to address changes in the Arctic Ocean hydrography over the past 10 and 20 years.
We boarded yesterday and so have had enjoyed our first night’s sleep and first meals on board. We have been warmly welcomed and greatly assisted by the Coast Guard captain, officers, and crew, with whom we will spend the next two months. We are comfortable and ready to work. All is well.
Jim Swift
Research Oceanographer
UCSD Scripps Institution of Oceanography
Read MoreDaily pictures from the aloft conning tower
Cruise Blog: Bill Schmoker, US Arctic GEOTRACES
Arctic Andy and the 2015 U.S. Arctic Ocean Section
Dr. Katlin Bowman: Hg in the sea
Dr. Peter Morton: U.S. Geotraces Arctic 2015
Cruise Blog: Bill Schmoker, US Arctic GEOTRACES
Alison Agather: Alison’s Arctic Adventure
Read MoreFollow the participants of P16N as they do science in the Central and Northern Pacific.
Read MoreFollow the participants of P16N as they do science in the Central and Northern Pacific.
Read MoreLynne Talley (SIO) and Brendan Carter (Princeton)
The CLIVAR/GO-SHIP P16S cruise passed north of 50°S at the start of this week, sailed on past 40°S, and we are now working towards the mid 30°s. The weather improved dramatically just past 50°S and gave us a long stretch of much-needed routine work. Because of major weather delays in the previous weeks, we increased our station spacing to 40 nm, and are now working at a steady pace of 2 to 3 stations per day. We are mostly able to sample while underway, and stations are being occupied at a good pace. An extratropical storm yesterday pushed us back into memories of last week’s poor weather, and necessitated sampling on station.
The switch to the backup CTD wire at the end of week 4 was completely successful after a days’ very hard work on the part of the ETs and MTs who got the setup rigged and the winch in top working order. The switch to outside coincided with conditions that make sampling more comfortable every day.
Milestones this week: We completed 18 morestations, moving clearly into the subtropical gyre and our deepest stations, in the Southwest Pacific Basin. We completed all of the biogeochemical float deployments. All 12 floats are reporting and the data are being posted. We continue to make nearly real-time comparisons with the shipboard lab analyses. We also completed the last of our 30 surface drifter deployments and are receiving data from those that were deployed.
Some fun around the last couple of floats when we were cleared to have “float signings” (left). An Easter wombat visited the Palmer on Sunday leaving 68 tiny origami candy boxes hidden all over the labs.
Some science highlights: excellent quality data from all groups! Compared with 2005, oxygen continues to increase in the ventilated subtropical thermocline. The pioneering nitrous oxide is looking great. Speculations rife about the energetic subthermocline eddy or internal wave at a station outside the ACC’s eddy field with westward flow > 30 cm/sec at 1200-1800m, and 300 m isopycnal deflections.
Read MoreLynne Talley (SIO) and Brendan Carter (Princeton)
In our fourth week at sea, we completed 16 stations, deployed 3 additional biogeochemical Argo-equivalent floats, and 18 surface drifters for the NOAA Global Surface Velocity Program. All of our biogeochemical floats have thus far reported their first profiles, and the earliest floats have successfully completed their first 10 day cycles. We have been able to send our coincident lab analyses back to the float PIs for comparison with the float results, which are giving good profile shapes but with offsets, confirming the usefulness of chemistry at the time of biogeochemical float deployments.
Our station completion rate continued at the slow rate of the previous week, again due to weather restrictions as we continued to battle the broad wind tunnel centered at 60S and extending over our full station track to 55S, just beyond the top of the Pacific-Antarctic Ridge and in the center of the Antarctic Circumpolar Current. Beyond this point, the weather began to clear and we began more routine operations at a rate of about 3 stations per day.
Our station 29 was directly north of the Subantarctic Front based on the high surface velocities registered by the shipboard ADCP, and the abrupt change to subantarctic type waters. Water samplers appreciated the vanishing of negative temperature waters.
As we proceeded northward across the ridge, at the first station deeper than 4100 m, we uncovered multiple breaks in the outer layer of the CTD wire. The breaks looked to be worse farther down in the spool. We continued safely sampling to 4100 m for the next 8 stations over the next two days while considering options for sampling to the > 5000 m depths that are arriving at 49S. After determining that the spare wire appears to be in good shape, the viable option was to transfer operations from the Baltic room to the main deck even though the sheave is not the best for this wire. With excellent weather today, the transfer was accomplished successfully (picture). Because the deck has been nearly continuously awash for most of the cruise, the water sampling will likely not be done underway, which will add approximately 60 hours of station time to the cruise. This and the time required for the transfer of operations means cancelling a large number of stations, and will be accommodated by increasing the station spacing, potentially from the stipulated ½ degree to 1 degree.
As said last week, on the positive side, it is a pleasure to work with this team of professionals and dedicated students, each contributing their thorough expertise and the ability to adapt to circumstances.
Read MoreLynne Talley (SIO) and Brendan Carter (Princeton)
Our third week at sea of hydrography, float and surface drifter deployments, and bio-topical measurements began smoothly, with 10 stations, and 2 floats deployed in the relatively calm Ross Sea. By mid-week, we were sitting in a very wide tunnel of sustained westerly winds with gusts to more than 45 knots and very high seas centered at 60°S, right over our station plan. Most of the rest of the week was consumed with frequent consultations with Captain Souza, working with the Spawar and OTSR weather forecasters, who proved to be quite accurate. Because of the persistently bad conditions, we decided to sail northward out of the weather, from 62°S to 58°S. We then proceeded back to the south, making stations every 1 degree latitude, following the forecast of a developing lull between two low pressure systems, and were able to return to 61°S. Given the total cruise time, we then had to turn back northward, and began filling in our ½ degree stations. We had to abandon 2 stations and will be sampling for the next few days at station separations dictated by weather. Overall for the week we completed 15 stations, and deployed 3 floats and 4 surface drifters.
On the positive front, the data collection and quality are excellent, and the entire team from science to ASC to ECO dealt well with the protracted poor weather. The floats that we’ve deployed are returning their first profiles, and our first float has just reported its second profile. The two floats with the cutting edge pH sensors are reporting good pH profiles. Our first surface drifters for NOAA’s Global Velocity Program were deployed at 60°S. The NASA team been able to complete bio-optical profiling each day when we have been able to work, and their work was featured on the NASA outreach website, Image of the Day for April 5 (Cruising for Ocean Data) http://earthobservatory.nasa.gov/IOTD/
An initial science result: The Ross Sea bottom waters continue to warm, with a monotonic increase over the 4 WOCE/CLIVAR surveys thus far: 1992, 2005, 2011, and now 2014. The bottom 1000 m thick layer is nearly adiabatic (well mixed with lower temperature variance than the abyssal thermocline above it), and can be easily compared from one survey to the next. Additionally, we note that the entire deep temperature structure has shifted from cooler to warmer, and hence it appears that the warming of the bottom layer is partly a function of warming of the abyssal layer, from 2500 to 4500 m.
Read MoreLynne Talley (SIO) and Brendan Carter (Princeton)
During our second week on the Nathaniel B. Palmer, we completed an 11-‐day transit from Hobart, Tasmania to the southernmost station of our GO-‐SHIP hydrographic section, at 67°S, 150°W. We are arriving on station 5 to commence that section today, which will go northward with stations every 30 nm (55 km) to 15°S.
During the second half of our transit, beginning south of New Zealand, we deployed 4 biogeochemical profiling floats, spaced roughly 1 days’ steam apart. Each float has a CTD (temperature/salinity), and sensors for oxygen, nitrate and fluorescence/backscatter. At each float location we made a CTD/36-‐place rosette/LADCP/transmissometer/fluorometer station to depth, and a profile of Inherent optical properties (IOP) to 200 m (nicknamed the “NASA Cage”). Three of the four CTD stations were to the ocean bottom. The first was at the location of a station on WOCE/GO-‐SHIP P14S, south of Chatham Rise, so it will be possible to not only use our water sample data (nutrients, oxygen, pH, alkalinity, HPLC pigments) to calibrate the float profile, but also to compare our water properties with those collected in 1996 in WOCE and in 2012 in GO-‐SHIP. Station and float deployment 2 was on the northern flank of the Pacific-‐Antarctic Ridge and that profile was also taken to the ocean bottom, given the minimal additional time required and the nearly unmeasured hydrographic nature of this region.
Station and float deployment 3, located south of the Pacific-‐Antarctic Ridge and within the Ross Sea gyre south of the Antarctic Circumpolar Current, were shifted farther east along the transit than originally planned because of sustained high winds and seas. During a break in the weather, the station was occupied to the minimum necessary depth of 2000 m, a bio-‐optics cast was carried out, and the third float was deployed. As a result of the weather and constant waves on the main deck, which has often been secured, the DIC analysis group moved operations from their van into the main lab.
Station and float deployment 4 were then also shifted eastward to lie between station 3 and the anchor station for the P16S repeat at 67°S, 150°W. Weather and seas calmed considerably prior to Station 4, and we began seeing tabular icebergs and smaller floating ice. The mid-‐day conditions were sufficiently calm that the NASA bio-‐optics group deployed their apparent optical properties (AOP) profiler (nicknamed the “Javelin” by popular acclaim), the farthest south such profile at the time. The subsequent “Javelin” profile at Station 5 broke that record, as it was slightly farther south at our southernmost station overall.
During the long transit we have been collecting underway data: ADCP velocities to 1200 m, surface water properties with sampling every four hours, meteorology, and bathymetry.
PI Ken Johnson sent us early data returned by float 7557, which we have compared to data from the CTD deployment and the shipboard measurements of water from the rosette on station 2. The float data captured the features we observed in the oxygen and nitrate profiles well, though with a distinct offset in both quantities. This comparison underscores the potential for these floats to autonomously measure biogeochemical properties in the ocean, as well as the need for floats to be cross-‐calibrated upon deployment on cruises like this one.
We are now more than ready to start our 4 station per day regimen after many long days of no stations or at most one station a day, which always seemed to fall on the noon-‐mid watch. Labs are more than ready, watchstanders ready, crew ready. We’ve enjoyed the comforts of the 03 conference room, with airport connections to computers and comfie chairs, daily science presentations and discussion, excellent and varied food, the start of a 2-‐team gym competition, various card tournaments, daily NY Times crossword puzzles printed large for team use, lots of movies and books, and fun spotting icebergs and building a (tiny) snowman on the bow. The ship’s crew and USAP ASC team are excellent; we are in great hands for the intense part of our work, which started today.
Read MoreLynne Talley (SIO) and Brendan Carter (Princeton)
On 20 March, 2014, we sailed from Hobart, Tasmania on the U.S. Antarctic Program’s Nathaniel B. Palmer, passing under the Tasman Bridge and on out to sea. We are underway to our first bio-Argo float deployment far south of New Zealand, which is on the way to GO-SHIP section P16S, commencing at 67°S, 150°W. The transit to the first float deployment is taking about 6 days. By the end of the cruise in Tahiti on May 5 we will have deployed 12 profiling biogeochemical floats, 30 surface drifters, made daily biogeochemical observations for NASA ocean color satellite cal/val, and completed more than 105 stations with physical and chemical measurements from surface to bottom. We are sampling or deploying instruments for approximately 18 different principal investigators, from NSF funding, NOAA and NASA. Our science party of 29 includes 9 grad students from all over the U.S. and the world.
The 12 floats that we will be deploying will be part of the global Argo float array, profiling every 10 days to 2000 m depth. They include the first set of fully-equipped Southern Ocean biogeochemical profiling floats, measuring oxygen, nitrate, fluorescence and backscatter, and―the newest addition―pH sensors, with the southernmost group having the capability to sense and avoid coming up to the sea surface under sea ice. We hope that these will be the “tip of the iceberg” for the growing Southern Ocean Observing System. The goal is to observe the Southern Ocean’s important uptake of excess CO2 from the atmosphere, and directly observe its acidification resulting from global change.
The stations that we will occupy along 150°W are repeats of two earlier transects. This set of stations was occupied in 1991 as part of that decades’ global observing program WOCE, and then again in 2005 as part of the international repeat hydrography program, now called GO-SHIP, which criss- crosses all of the oceans. We are analyzing about 19 different properties in the water collected from the rosette water sampler, and collecting vertical profiles of conductivity, temperature, oxygen (2 sensors), and pressure (on the CTD), velocity from a Lowered Acoustic Doppler Current Profiler (LADCP), transmittance, fluorescence, and temperature microstructure from a new program (“chi-pod”) for U.S. GO-SHIP. The goal is to observe changes over the decades in the ocean’s heat, salt, nutrient, oxygen, and carbon content. In this part of the world ocean, many of the changes observed thus far have been linked to global change.
We’re currently steaming southeast just along the Australian/New Zealand EEZ boundary. We passed north of Macquarie Island earlier today, getting a push from the northernmost branch of the Antarctic Circumpolar Current, which roughly parallels the Campbell Plateau. Underway measurements commenced close to Hobart: velocity profiling with the ship’s two ADCP systems; meteorological and bathymetric measurements; surface seawater sampling for temperature, salinity, pCO2; and continuous surface sampling of optical properties (backscatter, chlorophyll, CDOM fluorometry).
We estimate that we’ll be in position for the first station/float deployment ―on a P14S waypoint measured in 2012 by a Japanese research expedition, and in 1996 as part of WOCE―in the afternoon on the 26th of March local time.
In between logistical meetings, we’ve been having daily science meetings. We’ve had four people give science talks already, and have a rough plan for 8 more talks, 2 software tutorials, and a host of ‘lab visits’ between our various analysts in the days to come.
Some analysts have already begun their watch schedules to deal with the underway sampling. The rest of us are looking forward to losing ourselves in the blur of deploying a rosette package every few hours, though having time for daily science meetings has been a luxury indeed.
Read MoreLearn more about what’s happening on the P16S Cruise! Below are the blogs that scientists on the ship are updating, more blogs will be added soon.
Chief Scientist’s Weekly Reports - Dr. Lynne Talley
Co-Chief Scientist’s Blog - Dr. Brendan Carter
NASA Ocean Ecology Laboratory - Aimee Neeley (Editor)
Veronica Tamsitt - Graduate student
Andrew Barna - Emails from Andrew Barna
Read More