NOAA Teacher at Sea Dave Grant Aboard NOAA Ship Ronald H. Brown February 15 – March 5, 2012
Mission: Western Boundary Time Series Geographical Area: Sub-Tropical Atlantic, off the Coast of the Bahamas Date: February 13, 2012
Weather Data from the Bridge
Position: 26.30N Latitude – 71. 55W Longitude
Windspeed: 15 knots
Wind Direction: South (bearing 189 deg)
Air Temperature: 23.2 C / 74 F
Atm Pressure: 1013.9 mb
Water Depth: 17433 feet
Cloud Cover: 30%
Cloud Type: Cumulus
Personal Log
After an uneventful flight from New Jersey and an eventful trip from the airport at Charleston and through security at the naval base (Taxi drivers don’t like to have their vehicles inspected…), I am setting up my bunk on the Brown. There is a skeleton crew since I have arrived early and everyone else is expected to report tomorrow. Crates of equipment are still being loaded, so it is advisable to stay off the outside decks, and after a quick orientation by every ship’s most important crew member (the chef), I will have the evening free to find my way around the ship and explore the dock.
First order of business: Pick up bedding from the laundry down below.
Next: PB&J sandwich (Since the galley doesn’t open until tomorrow).
Finally: Grab the camera to catch the sunset and an amazing assortment of cloud types.
South Carolina’s estuaries are noted for their fine “muff” mud and oyster banks and the tideline at the docks is covered with a dense ring of oysters. Besides filtering great quantities of water and improving its quality, oyster “reefs” provide a secure habitat for a myriad of marinelife, and food for many creatures. (As a frustrated oyster farmer in South Jersey once remarked: “There ain’t much that lives in the ocean that doesn’t like to eat oysters!”)
Oyster Chain
Comorant
Grebe
The prettiest bird around is the red-breasted merganser, another diving fish eater. Hunters nicknamed mergansers “saw-bills” since their bills have tooth-like notches for snaring fishes. The word merganser comes via Latin mergere meaning “diver” and “to plunge.” Curiously, one of my favorite students always mixes up the word and somehow it comes out as Madagascar (!).
(Images on the Ron Brown by Dave Grant)
The most secretive and uncommon bird around the piers is the pied-billed grebe. It also dives for its dinner, but on the bottom. When frightened (or pestered by a photographer trying to get close in the fading light) it discreetly sinks straight down and disappears like a submarine. Locally, this trick earned the grebe the nickname water witch, and by Louisiana sportsmen Sac de plomb (bag-of-lead).
Grackle
By far the noisiest birds around and the only ones onboard, are boat-tailed grackles. The iridescent, purple-black males are hard to ignore when gathering for the night on our upper rigging. A common bird of Southeastern marshes; since the 1960’s boat-tails have been expanding their range north along the Eastern seaboard beyond Delaware Bay, and now breed all along the New Jersey coast. (A normal extension of their population, or perhaps a response to warming climate? Time will tell.)
Just before dark a peregrine falcon surprised me as it glided past the ship – undeniably the most exciting sighting of the day and a great way to end it.
“Oh end this day,
show me the ocean. When shall I see the sea. May this day set me in emotion I ought to be on my way”
(James Taylor)
NOAA Teacher at Sea Dave Grant Aboard NOAA Ship Ronald H. Brown February 15 – March 5, 2012
Mission: Western Boundary Time Series Geographical Area: Sub-Tropical Atlantic, off the Coast of the Bahamas Date: February 15, 2012
Weather Data from the Bridge
Position: Windspeed: 15 knots
Wind Direction: South/Southeast
Air Temperature: 23.9 deg C/75 deg F
Water Temperature: 24.5 deg C/76 deg F
Atm Pressure: 1016.23 mb
Water Depth: 4625 meters/15,174 feet
Cloud Cover: less than 20%
Cloud Type: Cumulus
Personal Log
Crew and scientists are reporting for duty and everyone is to be onboard by sunset for a scheduled departure tomorrow morning. There are many boxes of equipment to unload and sampling devices to assemble, so everyone is busy, even during meal times.
Tall ships had miles of rope and lines for handling enormous amounts of sail.
The Brown is also carrying miles of line and cable too, but not for sailing. This is coiled neatly on reels and will be used to anchor moorings of monitoring equipment that will record water temperatures and salinities for an entire year until they are recovered on the next cruise. These moorings are anchored with ship recycled chain and old railroad wheels and their long lines of sensors rising to the surface from 5,000 meters form the electronic “picket fence” spaced between Florida and Africa across the 26.5 degree North Latitude line we are sailing.
On our last night ashore we went downtown to enjoy dinner at one of the many nice restaurants in the historic district. It was a good time to update each other on different projects and make any last minute purchases. Everyone is anxious to get started. As captains like to say:
“Ships and sailors rot at port.”
(Horatio Nelson)
Day 3 We are leaving the dock on schedule and heading down river.
Old sailors’ superstitions say that a small bird or bee landing on the deck of a departing vessel foretells good luck on a voyage, and a tangled anchor line forecasts bad luck. Glancing around, I observe our noisy grackles preparing to depart neighboring ships at dock – so I hope they qualify as small birds. And huddled out of the wind on deck is a crane-fly – not a bee, but a harmless bug that looks like a giant mosquito. Perhaps no guarantee of good luck, but since all our lines and chain are neatly stowed, I am confident that an old “salt” – seeing how ship-shape the Brown is – would concur that we shouldn’t unnecessarily envision any bad luck on our cruise.
CraneflyDolphin "X"
Sailing down river we receive a great treat and are guided to the sea by small groups of dolphins surfing underwater in our bow wave. These are Tursiops – the bottle-nosed, the most common and well-known members of the dolphin family Delphinidae. Tursiops is Latin for “dolphin-like.” Their comradeship is another reassuring sign of good luck to suspicious sailors. It is a remarkable spectacle and entertainment to everyone, even the veteran crew members, who, like the ancient mariners, have reported it many times. Although they seem to be taking turns at the lead, one dolphin that keeps resurfacing has a small cross-shaped scar on the port side (Left) of the blowhole; proving that at least one member of the pod has kept pace with us for the entire time.
Ship mates. (Images on the Ron Brown by Dave Grant)
Curiously, they know to abandon us near the river mouth to join other “bow riders” that have caught the wave of a freighter that is entering the river and heading upstream. Noteworthy is the bulbous bow protruding in front of the freighter. Reminiscent of the bottle nose of a dolphin, the bulb modifies the way the water flows around the ship’s hull, reducing drag – which increases speed, range, fuel efficiency and stability – things dolphins were rewarded with through evolution. And what a show the dolphins make riding the steeper bow wave! Actually launching out of the vertical face of it like surfers.
Bow rider!
Passing historic Ft. Sumter we receive an impromptu lecture by some of the crew on Charleston’s rich history from the days of Blackbeard the pirate, up through the Civil War. There is an interesting mix of people on board, from several countries and with extraordinary backgrounds. There is also a great assortment of vessels using the bay – freighters, tankers, tugs, patrol boats, cranes, sailboats and a huge bright cruise ship. I am reminded of Walt Whitman’s Song for All Seas, All Ships:
Of ships sailing the seas, each with its special flag or ship-signal, Of unnamed heroes in the ships – of waves spreading and spreading As far as the eye can reach, Of dashing spray, and the winds piping and blowing, And out of these a chant for the sailors of all nations…
I note a transition here from the river to bay ecosystems reflected in the birdlife observed. Grebes and mergansers are replaced by pelicans and gulls.
The bay mouth is protected from wave action by low rip-rap jetties, and outside of them in a more oceanic environment are loons, scoters, and our first real seabirds – northern gannets. Loons spend the summer and nest on pristine northern lakes like those in New Hampshire (Reminding me of the movie On Golden Pond) but migrate out to saltwater to winter in ice-free coastal areas.
Scoters (Melanitta) are stocky, dark sea ducks that winter over hard bottoms like the harbor entrance, where they can dive down and scrape mussels and other invertebrates from the rocks and gravel.
Gannets are cousins of the pelicans but much more streamlined. They too dive for food but from much greater heights, sometimes over 100’. They also plunge below the surface like javelins to snare fishes. They are wide-ranging visitors along the East and Gulf coasts, wintering at sea, and returning to isolated cliff nesting colonies known as a “gannetry” in Maritime Canada
The ship was cheered, the harbor cleared, Merrily did we drop, Below the kirk, below the hill, Below the lighthouse top.
(Coleridge) Sullivan Island lighthouse
Latitude: 32.75794 Longitude: -79.84326
The odd triangular shaped tower of Sullivan Island lighthouse originally had installed the second brightest light in the Western Hemisphere. (Said to be so powerful that keepers needed to wear asbestos welding gear when servicing the light)
At 163 feet, its unusual flash pattern is tricky to catch on camera, but it is our last visual link to the mainland, and it will be the only land feature we will see until we are off the lighthouse at Abaco, Bahamas, after ten days at sea. A lighthouse keeper at the lens room, watching us sail away, could calculate at what distance (in miles) we will disappear over the horizon with a simple navigator’s formula:
The square root of 1.5 times your Elevation above se level. Try it out: √1.5E’ = _____ Miles
NOAA Teacher at Sea Dave Grant Aboard NOAA Ship Ronald H. Brown February 15 – March 5, 2012
Mission: Western Boundary Time Series Geographical Area: Sub-Tropical Atlantic, off the Coast of the Bahamas Date: February 17, 2012
Weather Data from the Bridge
Position: Windspeed: 15 knots
Wind Direction: South/Southeast
Air Temperature: 23.9 deg C/75 deg F
Water Temperature: 24.5 deg C/76 deg F
Atm Pressure: 1016.23 mb
Water Depth: 4625 meters/15,174 feet
Cloud Cover: less than 20%
Cloud Type: Cumulus
Science/Technology Log
Sailors used to describe their trips as short-haul or coastal, or “long seas” which also was described as going “Blue Water”
We are off to a great start after passing the harbor lighthouse and breakwater, and the seas are calm and winds gentle. The Low Country and barrier islands of South Carolina disappear quickly over the horizon, and the most striking change for me is the color of the water. As we have transited from the sediment rich waters upriver, to the estuary, and out to the ocean, its color has gone from grayish, to green to blue.
Bay/Estuary water in Charleston
Gulf Stream water
As a rapid indicator of what’s going on within it biologically, oceanographers use the color of the water. To quantify their observations for other scientist to compare results, a white secchi disc is lowered just below the surface and the observer compares the ocean’s color with tinted water in a series of small vials – the Forel-Ule Scale. (Francois Forel was an oceanographer and his end of the scale is the bluest; and Willi Ule was a limnologist and his end of the scale is darker, reflecting the fresh waters he studied.) The 21 colors run the gambit of colors found in natural waters and modified by the plankton community and range from brownish-to-green-to-blue. This gives you a quick measure of productivity of the waters and the types of phytoplankton predominating. For example: Diatom blooms are brownish and Dinoflagellate blooms form the notorious red tides. Clear, less productive waters look blue, and we are sailing into waters that are a deeper blue with every league we sail.
I lack a secchi disk and we can’t stop the ship to lower one anyway, so I am using instead a scupper on the side as a photographic frame to document this well-studied and interesting phenomenon.
“Being on a boat that’s moving through the water, it’s so clear. Everything falls into place in terms of what’s important, and what’s not.”
(James Taylor)
Before departing on the trip I came across Richard Pough’s bird map of the Atlantic. On it he divides the ocean into 10-degree quadrants and indicates the average water temperature and number of birds he sighted daily. The good news is we are heading southeast into warmer waters. The bad news is, he does not indicate a very productive hunting ground for bird watching. For example, Cape Hatteras, NC, where the Gulf Stream skirts North Carolina, shows 40 birds. Off the highly productive sub-polar regions like Iceland where there are great breeding colonies of seabirds like gannets, he indicates scores of birds. Regardless, I am hopeful we will find some true seabirds to photograph on our voyage; and perhaps have some migrating songbirds drop in for a rest.
Gulf Stream sunset
Today, as our colleague Wes Struble discusses on his blog, we retrieved our first samples with the CTD rosette. Water is retrieved from predetermined levels between the surface and 4,500 meters sealed in bottles for salinity and dissolved oxygen analysis. These two physical features, along with temperature, are the benchmarks physical oceanographers rely upon to track the ocean circulation.
For an understanding of this process and an overview of the project, I met with Molly Baringer in her office – a large bench that the ship’s carpenter built on deck. It seats three and is similar to a lifeguard stand, so it can give a view of the water and fit over the [dis]array of equipment constantly being shifted around the fantail by various scientists and deck hands. With the calm seas and sunny weather, it is the perfect spot on the ship to sit with a laptop to outline daily assignments for all of us, review the mass of data streaming in, and relax to watch the sunset.
“When I am playful, I use the meridians of longitude and parallels of latitude for a seine,
and drag the Atlantic Ocean for whales!”
Mark Twain
Scientists and crew prepare to retrieve a mooring before the next big wave!
Chief scientist Dr. Baringer is a physical oceanographer and so is interested less in the creatures moving around in the ocean and more about the water currents that are moving them around, and particularly the vast amount of heat that is transferred from the Equator to the Polar Regions by “rivers in the sea” like the Gulf Stream.
Currents and storms in our atmosphere produce our daily weather patterns, which of course change seasonally too. Ocean currents work on a much longer time scale and the text book example of the turnover time of warm water moving Pole-ward, cooling and returning to the Tropics as “centuries.” This timeframe infers that dramatic fluctuations in climate do not occur.
However, by analyzing ice cores from Greenland, scientists recently have detected evidence of abrupt changes in climate – particularly a significant cooling event 8,200 years ago – that could be associated with vacillations in the Gulf Stream. Although lacking a blackboard at her impromptu lecture hall on deck, a patient Dr. Baringer was artful in walking me through a semester of climatology and modeling to highlight the implications of an oscillating Gulf Stream and its deepwater return waters – the Deep Western Boundary Current.
Surface water is driven from the southern latitudes towards the Poles along the western side of the Atlantic, constantly deflected in a clockwise pattern by the Earth’s rotation. Bathing Iceland with warm and saltier water and keeping it unusually mild for its sub-polar latitude, the Gulf Stream divides here with some water flowing into the Arctic Sea and the rest swirling down the Eastern Atlantic moderating the climate in Great Britain, France and Portugal. (This explains the presence of a rugged little palm tree that I once saw growing in a Scottish garden.)
Perturbations in the northward flow of heat by meanderings of the Gulf Stream or the smothering of it of it by lighter fresh waters from melting ice in Greenland and Canada appears play a significant role in occasionally upsetting Europe’s relatively mild and stable climate – which is bad enough. What is more alarming is new evidence that these changes don’t necessarily occur gradually over centuries as once assumed, but can take place rapidly, perhaps over decades.
There is more bad news. The surface of the sea is dynamic and even without wind and waves, there are gentle hills and valleys between areas. I remember my surprise when our physical oceanography teacher, Richard Hires, pointed out that because of warmer water and displacement by the Earth’s rotation, Gulf Stream waters are about a meter higher than the surrounding ocean…that to sail East into it from New Jersey, we are actually going uphill. If these giant boundary currents are suppressed in their movements, it will exasperate an ongoing coastal problem as those hills and valleys of water flatten, resulting in rising sea levels and erosion along northern coastlines.
This explains why we are “line sailing” at 26.5 North, sampling water and monitoring sensors arrayed on the parallel of latitude between Africa and the Bahamas. To measure change, it is necessary to have baseline data, and the stretch of the Atlantic is the best place to collect it.
Snap shots of the water column are taken using the CTD apparatus as we sail an East-West transect, but at $30-50,000. Per day for vessel time, this is not practical or affordable. Here is where moorings, data recorders and long-life Lithium batteries come into play. By anchoring a line of sensors in strategic locations and at critical depths to take hourly readings, year-long data sets can be recorded and retrieved periodically. Not only does this save time and money, it is the only way to generate the ocean of data for researchers to analyze and create a model of what is happening over such a vast region – and what may occur in the future.
For more specific details, check out the project overview.
Deep Western Boundary Current Transport Time Series to study:
-the dynamics and variability of ocean currents;
-the redistribution of heat, salt and momentum through the oceans;
-the interactions between oceans, climate, and coastal environments; and
-the influence of climate changes and of the ocean on extreme weather events.
Information at: http://www.aoml.noaa.gov/phod/wbts/ies/index.php
We hear that “The package is on deck” and it is time to collect water samples from the 24 different depths the Niskin bottles were fired (Remotely closed). As any aquarist will assure you, as soon as seawater is contained it begins to change, so we always start with the bottom water and work around to the top water since dissolved oxygen levels can drop with rising temperatures and biological activity from planktonic creatures trapped along with the water samples.
Although as oceanography students we read that most ocean water is quite cold (~3.5C) because only the top 100 meters soaks up the warmth from sunlight, it is still an awakening for me to fill the sample bottles with even colder bottom water. After a half hour of rinsing and filling bottles, my hands are reminded of the times I worked in an ice cream parlor restocking containers from the freezer and filling soft-serve cones. It is a delight to get to the last several bottles of warm (25C) surface water.
Once the DO and salinity bottles are filled, they are removed to the chemistry lab and the Niskins are all mine. By holding a small plankton net under them as they drain excess water, I try my luck at catching whatever has almost settled to the bottom. There is an extra bonus too. A patch of floating Sargassum weed that tangled in the rosette was retrieved by the technician and set aside for me to inspect.
Windrows of Sargassum weed drift past the Ron Brown
Here is what I found under the microscope so far:
From depth:
The bottom water is absolutely clear with no obvious life forms swimming around. However a magnification of 50x’s and the extra zoom of my handy digital camera set-up reveals a number of things of interest I am sorting into AB&C’s: Abiotic: Specks of clear mineral crystals. Are these minute sediments washed from the mainland or nearby Caribbean islands? Or is it possible they are quartz grains carried from much greater distances, like the Saharan dust that satellite images have proven are swept up by desert winds and carried all the way across the Atlantic?
Biotic: Although I can not find anything living, the silica dioxide skeletons (frustules) of at least two species of diatoms are present. These fragile fragments of glass accumulate in deep sediments below highly productive zones in the sea and different species are useful to paleontologists for determining the age of those deposits. On land, fossil diatom deposits are mined for diatomaceous earth – used as an abrasive and cleaner, pool filter material, and even in nanotechnologyresearch applications. There is other detrital material in the samples, but nothing identifiable.
Celestial(?): One tiny round particle caught my attention under the microscope. It looks like the images I’ve seen of microtektites – glassy and metallic meteor particles that have been molded by the heat of entry into the atmosphere. The Draxler brothers, two science students in Massachusetts, collect them and I hope they will confirm my identification when I see them again.
Dust particle (Right) and foraminifera (Center)
From the surface:
The warm, sunlit surface water here is covered with Sargassum weed, a curious algae that sustains an entire ecosystem in the waters mariners named the Sargasso Sea. On board the Brown it is simply called “weed” in part because it can be a minor nuisance when entangled with equipment. The Sargassum’s air bladders that support it at the surface reminded Portuguese sailors of their sargazagrapes and they named the gulfweed after them.
Can you spot the two Sargassum shrimp next to the air bladder?
Floating Sargassum weed harbors a great variety of other creatures including baby sea turtles, crustaceans and especially bryozoan colonies. The film of life encrusting the weed is sometimes called aufwuchs by scientists and is a combined garden and zoo.
A quick rinse in a plastic bag revealed two species of bryozoan and numerous tiny crustaceans. The Phylum Bryozoa is the “moss animals” a puzzling colonial creature to early biologists. Bryozoans are an ancient group with a long fossil record and are used by paleontologists as an “index” species to date sediments.
Byozoan colony
To my delight there were also some foraminifera in the samples. “Forams” as they are called by researchers, are single celled protozoa with calcium carbonate skeletons. They are abundant and widespread in the sea; having had 330 million years to adjust to different habitats – drifting on the surface in the plankton community and on benthic habitats on the bottom.
It is not necessary for you to go to sea with a microscope to find them. I have seen their skeletons imbedded in the exterior walls of government buildings in Washington, DC; and our own lab building at Sandy Hook, NJ has window sills cut from Indiana limestone – formed at the bottom of the warm Mesozoic seas that once covered the Midwest. In the stone, a magnifying glass reveals pin-head sized forams cemented among a sea of Bryozoan fragments. Some living forams from tropical lagoons are large enough to be seen without a magnifier, and are among the largest single-celled creatures on the planet. With a drop of acid (The acid test!) our Geology students confirm that our window sills are indeed made of limestone as the drops fizzing reaction releases carbon dioxide sequestered when the animal shell formed.
Living foraminifera eat algae, bacteria and detritus and are fed upon by fishes, crustaceans and mollusks. Dead forams make contributions to us by carrying the carbon in their skeletons to the bottom where it is sequestered for long geological periods.
Geologists also use different species of forams as “index” species to fix the date of strata in sediment cores and rocks. The appearance and demise of their different fossil assemblages leave a systematic record of stability and change in the environment; and paleoclimatologists use the ratios of Carbon and Oxygen isotopes in their skeletons document past temperature ranges.
Our first plankton samples extracted from the deepest samples retrieved from the Niskin bottles at 4,000 meters (2.5C) did not produce any forams. This may be because in deep, cold water, calcium carbonate is more soluble and the skeletons dissolve. Presumably why we identified only the glassy tests of diatoms.
Foraminifera shell at 100x’s
Tiny Paramecia swarm over the detritus in my slide and taking a closer look at that and the growth associated with the weed I am reminded of Jonathon Swifts jingle:
Big fleas have little fleas Upon their backs to bite ’em And little fleas have lesser fleas And so, ad infinitum
Sunset over the Sargassum Sea
The Chief Scientist:
A day in the life of our chief scientist involves: checking with her staff to evaluate the previous day’s collections, consulting with visiting scientists on their needs and any problems that might arise, checking with the deck hands and technicians about equipment needs and repairs, advising the ship’s officers of any issues, and making certain we are on course and schedule for the next station.
And then rest? Hardly!
Even when off duty there are inquiries to field from staff, scientists and crew; equipment repairs to be made; and software that needs to be tweaked to keep the data flowing.
How does one prepare for a career like this? Physically: the capacity to function on little sleep so you can work 12-hour shifts and be on-call the other twelve. (And there is little escape at mealtimes either, where the conversation never stays far from the progress of the cruise.)Mentally: the capability to multi-task with a variety of very different chores. Emotionally: the flexibility to accommodate people with many different personalities and needs, while staying focused on your own work.
Also, excellent organizational skills, since months of planning and preparation are crucial.
And perhaps most importantly, a sense of humor!
“Lock-and-Load!
Midnight shift.
Chief Scientist Dr. Molly Baringer prepares to fire the XBT
off the stern for an 800 meter profile of temperature and pressure.
NOAA Teacher at Sea
Dave Grant
Onboard NOAA Ship Ronald H. Brown November 6 – December 3, 2008
Mission: VOCALS, an international field experiment designed to better understand the physical and chemical processes of oceanic climate systems Geographical area of cruise: Southeast Pacific Date: November 13, 2008
Gooseneck barnacles and Grapsid crab
Weather Data from the Bridge
Wind: AM Calm; PM 5kts
Seas: 5’
Precipitation: 0.0
Pressure: 1016
Science and Technology Log
Big whirls have little whirls That feed on their velocity, And little whirls have lesser whirls And so on to viscosity. (L.F. Richardson)
This little imitation of Jonathon Swift’s ditty helps illustrate the parallels between the atmosphere and ocean. Just as in the atmosphere, but much slower because of the increased density, turbulence in the water is expressed by meandering currents, and vortices. Good examples of this are observable when an oar is dipped into the water to push a boat, or a spoon is drawn across a bowl of soup. One of the mysteries of the SEP (South East Pacific) region is the presence of large oceanic vortices (Eddies), the mechanisms that generate them, and the length of time they persist as identifiable entities slowly spinning in the surrounding waters.
Dave holding the UTCD
In a number of coastal areas fishermen and oceanographers have discovered that some important fish species can be found associated with these so-called mesoscale water structures, like upwelling areas, meandering currents and eddies. Such links are fairly well known and heavily exploited in the vicinity of the boundary currents off eastern North America (Gulf Stream), California (California Current) and Japan (Kuroshio Current); for tuna, swordfish, sardines and anchovies. The coast of Peru and Chile is swept by the northward flowing Humboldt (Peru-Chile) Current and the area is famous for the upwelling that brings deep, cold, nutrient-rich water to the surface (and every 5-7 years when it doesn’t, El Nino conditions). Exposed to sunlight, phytoplankton utilize the nutrients to form the base of the world’s largest industrial fishery for fish meal and oil. The area also supports a large commercial tuna fishery.
UCTD Data
Poorly understood is the role of eddies that spin off the major current; vortices averaging about 50-Km (30-miles) wide (i.e. mesoscale). These may be either cold or warm water eddies that may last offshore for months, and move as discrete masses to the west. In general these vortices have more energy that the surrounding waters, circulate faster; and are important because they transport heat, masses of water and nutrients to less productive regions towards the mid-ocean. The eddies also transport marine life and the mechanisms for this are also poorly understood, however the outcome is not. Moored buoys out here collect and support masses of fouling organisms like goose-neck barnacles that must be cleaned off periodically, along with other routine maintenance of the batteries and recording instruments. Servicing these buoys is also part of the mission of the Ron Brown.
Chasing “Eddy”
CTD Data
Tracking these “cyclones in the sea” requires interpreting daily satellite images that measure water temperature and by data collected by the UCTD (Underway Conductivity Temperature Depth) probe. This is a torpedo-shaped device cast off the stern of the Brown while we are underway. It rapidly sinks to several hundred meters. Then, like a big, expensive ($15,000.) fishing lure, it is retrieved with an electric motor that winds back over 600 meters of line. The whole process takes about 20-minutes (including the 2minute plunge of the UCTD).
The information acquired is phenomenal, and if collected any other way, would involve stopping the ship and repeatedly lowering Niskin or Nansen bottles; and adding weeks or months to a cruise schedule. Once back onboard the ship, the data is downloaded and plotted to give us a continuous picture of the upper layers of the ocean along our sailing route. All of this hourly data allows the tracing of water currents. The procedure is not without trials and tribulations. Lines can tangle or break, and there is always the possibility that the probe will bump into something – or something will bump into it down in the deep, dark ocean. However, any data retrieved is invaluable to our studies, and each cast produces a wealth of information.
Teeth marks on a UCTD
Personal Log
Today’s weather is fabulous. Most mornings are heavily overcast, but we are still close enough to the coast to enjoy breaks in the clouds. So, everyone is taking their breaks in folding chairs on the foredeck at “Steel Beach” since we are never certain when we’ll again have a sunny moment, or how long it will last.
After lunch there was a bit of excitement; we saw other mariners. In the old days of sailing, ships passing each other at sea would often stop to exchange greetings, information and mail. This practice was known as gamming. We sighted our first ship of the cruise; a cargo carrier heading north and piled high with shipping containers. It was too far off for gamming or even waving (The scientists who are sampling air want to keep their instruments free of exhaust from any nearby sources) so it would have been out of the question anyway. The bridge gave it a wide berth; so wide that even with binoculars I could not be certain of the ship’s flag, name or registry, other than oversize lettering on containers that spelled JUDPER. Presumably it was carrying agricultural goods from southern Chile or manufactured goods and minerals from the central part of the country. Chile is a major exporter of copper; and the smelters, factories and vehicles in this upscale corner of South America (And the sulfur and particulate matter they spew into the sky) are a interesting land signatures for the atmospheric scientists and their delicate instruments. So the only gamming today is in the narrow passageways throughout the Brown. There is no wasted space on a ship, so in many areas there is “barely enough room to swing a cat.” (The cat being the cat-o-nine-tails once used to flog sailors. “The cat is out of the bag” when someone is to be punished.*)
Group watching a ship on the horizon
I am still not certain what the proper ship’s etiquette is in passageways and stairways, but I am quick to relinquish the right-of-way to anyone who is carrying something, looks like they are in a hurry or on a mission, or in uniform (obviously) or kitchen staff in particular. Because the ship is always rocking, I’ve found that I tend to lean against the right wall while moving about. By lightly supporting myself leaning with a hand, elbow or shoulder (depending on the how significant the ship is rolling, pitching or yawing) I slide along the wall, and probably look like a clumsy puppy scampering down the hall, but it works…except for a few bruises here and there. Often I come face-to-face with the same shipmates repetitively during the day. (How many times a day can you say “Hello” to someone?) Everyone is polite and considerate, especially when moving about the ship, and in spite of repeatedly passing the same people many times every day. So generally, since everyone is busy for most of their shift, when meeting in the hallways, you resort to awkward routines like: muttered Hey, Hi, Yo or What’s-up; tipping your hat or a dumb half-salute; or a nod…or if from New England, what is known as the reverse nod.
*Flogging: There was a science to this horrible practice, not only with the number of lashes imposed, but what they were administered with: a colt (a single whip) or a cat (They varied in size from “king size” to “boy’s cats”).
Although the U.S. admirals reported that “it would be utterly impossible to have an efficient Navy without this form of punishment” Congress abolished flogging on July 17, 1862. And the last official British Navy flogging was in 1882 – although the captain’s authority remained on the books until 1949. (To politely paraphrase Winston Churchill, the British Navy was bound together by…*#@#&!, rum and the lash.)
One Final Note
We discovered stowaways onboard…two cattle egrets. Egrets are wading birds that feed in shallow ponds and marshy areas; and the cattle egret regularly feed along roadsides and upland fields where cattle or tractors stir up insects. Even when threatened, they tend to fly only short distances, so it is odd to see them so far from land. However, in the 1950’s a small flock of these African birds crossed the South Atlantic to Brazil and establish a breeding colony. I remember spotting them for the first time on the Mexican border near Yuma in the 1970’s and today they have managed to thrive and spread all the way across the warmer half of North America.
Of ships sailing the seas, each with its special flag or ship-signal, Of unnamed heroes in the ships – of waves spreading and spreading As far as the eye can reach, Of dashing spray, and the winds piping and blowing, And out of these a chant for the sailors of all nations…
(Song for All Seas, All Ships – Walt Whitman)
NOAA Teacher at Sea
Dave Grant
Onboard NOAA Ship Ronald H. Brown November 6 – December 3, 2008
Mission: VOCALS, an international field experiment designed to better understand the physical and chemical processes of oceanic climate systems Geographical area of cruise: Southeast Pacific Date: November 10, 2008
Weather Data from the Bridge
Sunrise: 07:12 Sunset: 20:11
Wind: S-SW 8-10 Kts
Seas: S-SW 8-10’
Precipitation: 0.0
Temperature: 18º-C
Pressure: 1015 Mb
Science and Technology Log
“Send them our latitude and longitude.”
Admiral William Halsey, 1944 (Response to an intercepted Japanese radio message: “Where is the American fleet?)
A Twin Otter plane flying over
Now that we are out of sight of land and the ocean is featureless except for the waves, so pinpoint navigation becomes crucial. Using the most modern navigation tool – GPS (Global Positioning Satellite system) our navigation officer has put us precisely where we need be to await over-flights from aircraft sampling the atmosphere above us. We are not just near our sampling station – not a mile, a minute, a knot, or a league – we are within a hairsbreadth* of it. We will be here for the day taking water and air measurements, while waiting for the only things we’ll see flying over the Pacific besides birds and balloons; our last connection to the land for several weeks.
“Thanks for the memories.”
The CTD Rosette
The ocean water we test has a memory for the weather and climate conditions today and over the last several months and years. The “code” we need to understand these secrets is hidden in the temperature and salinity of the water, and the keys to unlock them are a number of devices that sink, float and drift. Over the next few weeks we will use all these techniques to see what stories the water has to share. My first introduction to this remote sampling and sensing was a long-necked beverage bottle with a weight, retrieval line, and a cork that could be popped with a string. (And of course, duct tape to hold it all together.) Using it in the local pond and discovering that there were indeed differences between the surface and bottom temperatures was enough to pique my curiosity to move on to bigger things in college. This involved more sophisticated devices, typically named after the oceanographers that perfected them: Secchi, Nansen, Eckmann, Peterson and Niskin. All students of science and oceanography should study these pioneers and their struggles and achievements, but perhaps the foremost is Fridtjof Nansen (1861-1930)…arctic explorer, distinguished scientist and Nobel Laureate.
A storm petrel
The Nansen bottle has been a standard water collection device since 1910 and when lowered by a strong line, can be signaled to close with a weighted “messenger” sent down the line to “fire” off a release mechanism that closes off a tube of water from any depth. The only limitation is the length of your line. Then that water can be brought to the surface for analysis of its physical features, nutrients and even contaminants washed into the sea or wafted from land. In 1966 Shale Niskin perfected a version of the bottle that today we will lower with eleven others on a circular frame called a rosette. These Niskin bottles can be signaled automatically to capture water at preprogrammed depths as the CTD device on the bottom of the frame records data. The CTD (Conductivity, Temperature, Depth) is one of today’s most important oceanographic tools. It is mounted on the rosette with the Niskin bottles and records the temperature and salinity of the layers of water, which allows oceanographers to trace the origins of the currents. The Brown has enough cable to lower it to 6,000 meters, but here in the Peru Basin, we are limited to less than 4,000 (Still deep enough to swallow any mountain east of the Mississippi, and most of the ones in the west.)
Data from the CTD cast
The crew does an amazing job holding the Brown on station, and can literally turn on a dime since the ship has fore and aft thrusters. When the seas are high and it is choppy, they maneuver into position by making a slow (right) turn to starboard (Where the rosette is deployed) so it is in the lee of the wind and much calmer. The turning creates a “pond” of flat water that also attracts seabirds, so I try to have my camera ready at all times. The whole process takes several hours and has to be done with great care and constant adjustments from the bridge since anything lowered over the side might become tangled with the rudder or propellers, its own cable, or otherwise be damaged or lost. The water brought up from depth in the Niskin bottle is collected for chemical analysis, salinity, dissolved oxygen and plankton samples. Nutrient bottles are quickly frozen for later analysis in the lab, plankton is preserved for identification under the microscope, and dissolved oxygen must be chemically tested immediately; so there is always a flurry of activity when the CTD finally is retrieved and in deck. Water on the surface is 18º and drops to 5º near the bottom. Salinity ranges between about 35.25 ppt on the surface and as low as 34.5 ppt at depth.
An NSF C-130 sampling information
Personal Log
There has been a good roll to the ship about every 10 seconds since we left port and after a few days your body anticipates it and I only notice the movement when I see water in a basin or the shower floor sloshing with it, or when something that is not secured bangs around. This movement approximates the wave period of the largest swells and they are generated by the constant winds drawn towards the Equator – the Trade Winds which merchant sailing vessels could always rely upon. In 1520, these same winds pushed Magellan northwest after crossing into the waters to our south that he called El Pacifico. When on deck, I have noticed a low and longer period swell from the west, which is a clue that there is some far off storm brewing. Or perhaps, since the Pacific is so wide, that like the light from distant stars, it has gone through its entire existence, dissipated, and its energy is just reaching us now…only a faint remembrance in the sea.
I’ll take note of things over the next few days and look for changes like the Polynesians did when watching for storms. Higher, shorter period swells indicate that the storm is approaching. This gives you time to prepare for the large, short period, wind-driven seas that challenge ships and sailors.
“Look not to leeward for fine weather.” J. Heywood, 1546
This sailor’s expression helps illustrate the fact that because winds are generated by the pressure gradient between high and low air masses, tacking into the wind moves you closer to fairer weather than running with it. (In actuality, the high pressure, and hopefully fair weather, is about 90º to the pressure gradient.) That doesn’t always explain waves however. Wave size is determined by wind speed, duration and fetch (the distance over which the wind blows), and over the broad expanse of the Pacific, there can be many storms and wind patterns creating waves simultaneously.
Before physicists and meteorologists fined-tuned the mathematics, sailors had their own theories about waves. One observation was that the size of seas (waves in a storm) could be estimated by the wind speed…a storm with 60-knot winds might produce 60-foot waves. People tend to overestimate wave size, especially when at sea, and the theoretical height is probably only about 80% of that figure (Still a very sizable and terrifying mass of water if you are in the midst of it!).
“Now would I give a thousand furlongs of sea for an acre of barren ground.” Shakespeare – The Tempest.
Another difficult aspect of wave behavior is estimating the velocity and distance between waves (wave period); and here we turn to the oceanographers and their experimental wave tanks. To try to understand waves at sea, it is much simpler to generate perfect swells in a controlled environment. Although wave behavior in a storm is chaotic and almost impossible to monitor accurately, there is good data on the swells that spread out from the fetch, and for that we turn to the ship’s “Bowditch.” (Nathanial Bowditch’s – American Practical Navigator).
So the 10 second swells rocking the ship are traveling at a speed of about 30-knots, and have a wavelength of over 500-feet; which means, among other things, smooth sailing for the Brown (and most of her passengers). I’ll continue to watch for signs of change and hopefully our fine weather will continue.
