Section K and Coronation Island

Coronation Island and clouds on the morning of 29 April 2017. Many of the wave-like clouds arise from leewaves, also known as mountain waves.

Section K measurements

Saturday, 29 April 2017 from the Scotia Sea, on the north side of the Orkney Passage. 

The air hovers around -10C with 10-20 knot winds. Sun sprinkles through overcast skies. Coronation Island shields us from open ocean swell.  Sei, minke, and gray whales poke around the ship, feeding, investigating, and cruising.

We have been near Coronation Island for the past three days. We completed a CTD section (Section K for “Kurt”) yesterday, then an overnight tow-yo completed this morning covering much of the same region. Today, we recovered Kurt’s mooring deployed on 22 March (see post then).

 

Kurt doing some good-luck yoga prior to recovering his mooring on 29 April 2017. Or, perhaps he is just trying to warm up in the cold air?

After recovering Kurt’s mooring, we started a deep (5400 metres) VMP/CTD station at the northern end of the section. We hope that this station will provide a bound to this very rich section, perhaps offering somewhat quiet data station as a benchmark to compare with the other more dynamically active stations. 

Grant, Andy, Paul, and Steve removing one of the mooring instruments.

After this station, we will move a bit west to tow-yo along two new sections, offered to us by the grace of fair weather and seas. These sections were chosen due to their rather steep bottom topography, thus favoring strong bottom currents and fluid instabilities of interest during this cruise.  We thus hope these tow-yos will continue to reveal elements of the rich dynamical features seen through much of our Orkney Passage cruise. The tow-yos are scheduled for completion Monday morning, 01May. That task will then conclude our roughly seven weeks of science measurements.

We are excited about the measurements.  Indeed, there are various ideas floated concerning how to dynamically interpret what we are seeing. Alas, a compelling science story will likely take months if not years. 

A bird's eye view of the mooring recovery on 29 April.

Atmospheric fluid dynamics around Coronation Island

The mountains, sea, and sky around Coronation Island express elements of fluid dynamics that would touch many a scientist’s heart and head. In one direction, cloud formations manifest leewaves emanating downstream (the ''lee'' side) from the mountains. These waves arise from atmospheric winds passing over the island’s mountains. Mountains lift stratified air through the earth’s gravity field. As the lifted air moves downstream from the mountains, gravity creates a rebound effect that sends waves down then up again.  The trail of waves is visualized by clouds that form when the rising air moves into colder air aloft, in which case water vapor condenses into ice crystals thus forming a cloud. Some clouds appear as dragons with razor sharp claws that scratch at the sky. Others form the wings of a planetary bird holding up the heavens.Still others appear as lens-like flying saucers emanating from the mountain.

On another horizon, overturning clouds break like water waves on the beach.  They reveal roiling Kelvin-Helmholtz billows that arise from stratified shear instability.  I can imagine the cat’s eye features that signal efficient stirring and mixing of air parcels in the fluid layers far above these distant mountains. 

Some other-worldly post-card images from Coronation Island. The top left shows some mountain waves reaching up from the island. The top right reveals more mountain waves reminiscent of flying saucers.  The lower panel shows signs of shear instability, with subsequent pictures (not shown) revealing the unstable waves in the dark clouds moving to the left. Each of these clouds have more technical names. These sorts of cloud views would make nearly anyone want to know more about cloud phenomenology and dynamics. 

Mountain waves (aka topographic leewaves) and Kelvin-Helmholtz billows are fluid dynamical features that also take place within the ocean.  Indeed, some of the measurements may be signals of these processes, or to other related fluid processes.  Whereas atmospheric scientists can readily view the objects of their study, deep sea oceanographers must rely in instruments sent thousands of metres into the abyss.  Interpreting these measurements requires a strong grounding in geophysical fluid mechanics. It also requires an internal visualization and imagination to nurture ideas and understanding. Some ideas are off the mark, but others hit the target, which in turn can lead to further insights and explorations.  

More images from Coronation Island.  The mountain view on the top left was our nearest neighbor, and it sits in the middle of the more panaramic view at the bottom.  The middle left shows Coronation Island as a backdrop to two or three whales cruising by the ship.  The top right is a far distant portion of the island.  I darkened the image by removing most of the light, thus revealing the white caps on a dark sea, the mountains, and the layered clouds.  This portion of the island was often shrouded in mist and fog.  Contemplating its far shores occupied a great deal of my dream time on top of Monkey Island.

Personal reflections on Coronation Island

During the past three days, the morning sun revealed distinct facets of this spectacular primordial place known as Coronation Island. Clouds shroud glacier covered mountains that spill into the sea. Light reveals for a moment the underlying geology, only to be covered minutes later by a thick cloud blown by winds swirling over rocky ridges and glacial crevasses.  Atmospheric molecules scatter short light waves, thus exposing the longer waves that offer stellar sunrises over the island and sea.

Coronation Island juts out of the sea without the hint of a shoreline. Views of the shoreline are hindered by a mirage. The mirage arises from the relatively warm 0C ocean that is cooled by the -10C windy air above.  The heat sucked out of the ocean sends radiant plumes into the atmosphere, just like hot air rising above the desert.  The mirage transforms a rocky shoreline into a vertical cliff.  It is as if this island does not wish to host any people. Instead, it prefers to be seen from afar.

The clouds and mountains seem as if from another planet.  Or perhaps this extra-terrestrial impression is just my mind unaccustomed to extreme juxtapositions of mountain, atmosphere, and ocean.  Indeed, this strangely beautiful and ancient place is foreign to my normal experience. It nonetheless has been deeply compelling and penetrating to my soul.  Sacred and mystical capture the sense that Coronation Island gives as I stare and wander and dream at its distance.

The island is just a few miles away, with a palpable presence as if I am standing on its shore. I float on a ship above its crustal roots living deep beneath the ocean where whales, penguins, and krill move through their flow field. Photos are taken, and more yet again.  Alas, to capture the presence of this place on a digital image is an elusive quest. Its deeper reality is best felt in the bones and heart.

During this cruise, I have stood for hours on the Monkey Island atop the ship’s navigation bridge. I have felt the incessant winds and been mesmerized by never-ending waves.  I have explored multitudes of skyscapes.  I have become tuned to water spouts exhaled from cruising whales and the fleeting glimpses of penguins flying through the waters. Yet perhaps more than any other vista on this trip, Coronation Island has me fixated and astonished. It has me magnetized as the sun rises over the island. Its dynamic vistas are stunning. They bring tears of amazement and gratitude.  Toes and fingers are near frost bite as I am blown open. I must return to the UIC as the next CTD is prepared.  Well, perhaps I will return to work after just a few more moments on Monkey Island. 

There were many colours to be seen. Yet for a number of photos, I found that black and white nicely focused my eye on the many shapes and textures revealed by the sea, land, and sky.

On feasting and fitness

This post is from the Scotia Sea on 26 April 2017

Sunrise on 24 April 2017 from the Orkney Passage region of the Southern Ocean. This beautiful orange sky was a welcome sight after many days of overcast and gray.

Some of us are feeling a bit guilty due to the fair weather these past few days.  Well, in fact we are not feeling that guilty. Perhaps we just anticipate the need for payback. Indeed, we thought payback would start today, with forecasts indicating a major storm to our north.  But the storm appears to be mostly near South America, possibly not extending too far into our path in the Scotia Sea region of the Southern Ocean.  We will likely experience swells starting tomorrow, which can be huge and will disturb sleep and science.  But we are hopeful that the bulk of the storm’s energy will remain elsewhere. 

The sun revealed itself yesterday morning and all day today. The night watch had prime viewing for two spectacular sunrises. Especially after so many weeks of “black and white” scenery in the Southern Ocean, the presence of sun and blue feel like a spring morning after a tough long winter.  Don’t get me wrong, I have been in awe of the winds, waves, and very interesting weather down here.  But a day or two with sunshine go a long way towards getting me through the inevitable next round of winds, waves, and overcast. 

One thing of note about the sky in this part of the world: when the clouds clear, there are no signs of airplane contrails.  Rather, the sky is 100% natural. This sort of free and clear sky is rare on the planet these days.

 

Humpback fluke with the sun shimmering off the water.  Note the drops of water on the fluke.

Another few days of science, then steaming north to Montevideo

We just completed our penultimate scientific measurement, consisting of an extended tow-yo CTD along a section in the Scotia Sea, and a single VMP station to fill in one that we missed earlier due to weather.  The tow-yo CTDs have revealed some intriguing oceanographic features that will undoubtedly occupy brain cells for years to come.

Our final critical task is to recover Kurt’s moorings deployed at the start of the cruise (see post on 22 March).  That work should take about half a day once we get to the location, which is about six hours from here in fair weather.  But as mentioned above, the weather, including the swells, will need to cooperate.  We have a couple extra days buffer, which we may need. On the other hand, if the weather cooperates, we may have time to do a bit more tow-yos after Kurt’s mooring is recovered.

Feasting on the ship

As I mentioned in on the 7 April post, food on the ship has been wonderful. We are incredibly well fed.  The cooks and stewards who take care of us are a regular part of our days, keeping the food coming even when we have odd hours of work and when the ship rocks and rolls during swells and storms.  We are incredibly grateful for their nonstop efforts. 

Those of the crew that keep us fed and sorted. Top left: Chris, the baker, preparing some new bread for the day. Chris baked Sonya's birthday cake, as mentioned on the 16 April post. Top centre: Chief cook Paddy in the ship's kitchen, preparing for the day's meals. Imagine organizing food for an eight week cruise with 54 crew, scientists, and engineers all needing to remain healthy and satisfied. That is Paddy's job in a nutshell. Top right: Jimmy, one of the kitchen staff and ship stewards.Lower left: Roger, who along with the other stewards Winnie and Derek, serves food for the scientists and officers. Lower centre: Winnie, Paddie, and Derek in the officers/scientists mess Lower right: Lloyd, the ship's purser. Lloyd keeps things moving on the ship, making sure all our paperwork is tidy. He keeps track of the many needs of entering and leaving a port and how people come and go from the ship. He is famous (at least in my mind) for saying ''buy one get one'' when I asked about any bargains available in the ship's store.

Fitness on the ship

I mentioned in the 7 April post, Helen Jones, the ship's medical doctor, leads a fitness class each Monday, Wednesday, and Friday.  Her “Circuit” classes have been a great way for some of us to remain healthy and energized in a group setting.  A group meets for the roughly one hour class, with folks coming and going according to schedules.  It has been a great means for me to retain a clean conscious as I feast during meal times.    

 

Helen, Jack, Paul, Carson, Chris, Rob, Eleanor, and Stephen at the end of a fitness class on 26 April.

Andris (chief engineer) and Andy (from WHOI), are our resident strong men. They weight lift next to the Circuit training.

 

Feasting in the ocean 

Inevitably, many of these blog posts mention marine life.  This one is no exception. Today we had perhaps the best whale (and penguin) watching yet during the cruise. No matter how many whales we see, their presence continues to generate enthusiasm and excitement. Today was especially wonderful as the weather was perfect (-9C and sunny) for viewing whales as they swam around the ship and out to the horizon.     

Two humpback whales feeding near the ship on 26 April. As a humpback rises for a breath, it expresses a spray cloud into the air.  It also releases a sound like a deep and pure belch that nearly causes my body to vibrate, especially when it happens right next to the ship.  Their presence is simply amazing to experience. 

The whale watching started when I was head deep into a research paper. I vaguely heard  Eleanor announce that the humpbacks had returned, and I then watched as folks started going outside for close viewing. I played it cool, pretending to have “seen it all” and thus decided to remain in a “seriously” mental state.  About 10 minutes later Christian came back inside, urging me to check out the amazing display of charismatic Southern Ocean megafauna (i.e., whales!).  I finally gave in, thus putting on my coat and grabbing the camera.  

Usually when I go outside for whale watching, the I need to wait a few minutes for the whales to come around to within view. Yet on this occasion, as soon as I walked onto deck I saw about five or six humpback whales nearly within spitting distance from the ship. Among the whales, we also saw heaps of penguins swimming around and diving near the ship. This display of ocean life was something splendid to behold.  

The whales feasted on krill around the ship, doing so for about an hour. After taking heaps of photos, I became a bit frustrated as I too needed to feast as lunch was being served. Yet the whales, for some reason, did not keep to my schedule! 

Southern right whale fluke, sea, and sky in the Scotia Sea on 26 April. A few southern rights came around to feed after the group of humpbacks went elsewhere.

The styrofoam cup experiment & aspects of ocean mass, pressure, and heat

A humpback whale fluke with ''angel slides'' from sun rays poking through the clouds, as seen from the south Scotia Sea region of the Southern Ocean on the JC Ross research ship.

An overcast sky let the sun peak through the clouds for most of the day.  The sea state has been relatively mild this past week, a result of the modest (less than 20knot) winds for most of the time (though it blew above 30knots last night).  We have thus made further progress on oceanographic measurements in the Orkney Passage region of the Southern Ocean.  In particular, the auto-sub Boaty McBoatface completed its final mission, this one for three days in the Orkney Passage.  In addition, we have taken many more CTD and VMP measurements, and we have seen some interesting signals in the high resolution CTD measurements taken from the tow-yos. 

Although we have seen modest winds, we do have signs of the approaching winter, with the air temperature dipping down to -13C yesterday.  With colder temperatures, the humidity (nearly 100% for much of the past week) has reduced to around 70%, thus making the colder air less bone chilling than it would be with the 100% humidity.  Nonetheless, it is still quite cold, particularly for those working outside.

Whales remain frequent companions, with both southern right and humpbacks often following the ship. Humpback whales offer a bit more of a show than southern rights, with humpbacks often found extending their flippers and splashing around. They also generally swim in packs of two or more.  Indeed, on some days with a reasonably clear sky, we can see a horizon full of a number of blow hole vapour trails.  Any kind of whale sighting remains a joy, even after having seen heaps thus far on this cruise.

Two humpback whales (mother and child?) swimming near the ship in the Scotia Sea.

 

The styrofoam cup experiment and the immense pressures of the deep ocean 

Upon roaming through my cabin when first arriving onboard in Chile, I was puzzled why the previous scientist using my cabin left a bag of styrofoam cups in one of the desk drawers.  The ship does not use styrofoam cups, for good reason as they contribute to the exponentially growing problem of plastic pollution in the ocean.  So what are these cups doing here?

My puzzle was resolved when I recalled the experiment (first described to me by Jennifer MacKinnon of Scripps in La Jolla, California) of placing a styrofoam cup on the rosette wheel to illustrate the incredibly large pressures in the deep ocean. I thus brought the bag to the UIC, at which point others on board, particularly the graduate students Jack and Nikki, became excited about performing the experiment as well.

Here is how the experiment works.  Draw some designs or such on the side of a styrofoam cup.  Then place the cup in a sock and tie it to the rosette wheel, letting it travel into the abyss during a CTD cast.  What returns from the CTD cast is a wonderful example of how pressure works to compress objects on all sides.

Styrofoam cup on the right, before going into the deep ocean.  Note my amazing artistic skills (joke!),  meant to show waves, penguins, a sun behind clouds, and single star (seen just the other morning by the night watch!), and some birds. The mug on the left is for size comparison.

Styrofoam cup on the right after going into the deep ocean.  The mug on the left is roughly the same size as the blue mug above (I could not find the blue mug when taking this photo).  Note how the cup deformed nearly uniformly.  To help in this uniform compression, Jack stuffed some paper towels into the cup. 

Jack prompted the experiment yesterday (22 April) when he came on shift at 4pm.  We each drew on our cups with some Sharpees, trying to channel our inner artist.  I then took a photo of the cup to record the "before" state. I gave him one of my socks to tie onto the next CTD cast, which was planned for late night when I was sleeping.

The next morning (today), Nikki gave me the cup after it had gone to near 4000 m depth.  I expected it to be a crumpled ball with little to recognize. What I saw was something far different and much more pleasing.  It was a "mini-me" version of the cup.  Upon reflection, and after being chided by others for my naivety, I understood what had happened.

The cup is a very small object relative to the depth scales over which pressure changes.  So pressure acts on all parts of the cup in roughly the same manner. Hence, one side of a cup wall feels a pressure force just as on the other side.  As a result, pressure forces compress each and every piece of styrofoam in roughly the same proportion, ensuring that the cup does not merely collapse into a crumpled ball.  Instead, pressure compresses the cup into a mini version of its original self by squeezing out the air within the styrofoam pores. Because the styrofoam has a "memory", when returning to the surface it retains its compressed state. I hope to bring this cup home in one piece to show my family and to place on my office desk! 

Eleanor, Alberto, and Kurt during an animated science discussion in the UIC on a recent morning.

 

Some numbers to help understand ocean mass and pressure

The ocean is really massive, which in turn produces huge pressure forces when descending into the abyss. Eleanor, in her post about Boaty’s second mission on 19 April, already mentioned the difficulties of engineering ocean measurement devices to withstand these pressures. The styrofoam cup experiment offers a vivid illustration. It is also useful to consider some numbers to garner a more quantitative understanding of the scales.

Our bodies have adapted to pressure from the weight of the atmosphere.  At sea level, the mass of atmosphere per unit horizontal area is roughly 10^4 kg/m2.  That is, for every square metre of earth surface at sea level, there is about ten thousand kilograms of atmosphere above.  When multiplied by the gravitational acceleration at the earth's surface, that atmospheric mass leads to about 10^5 Newtons per square metre of pressure acting on our bodies.  This pressure is known as ''sea level pressure'' for obvious reasons.  

Our bodies have evolved to withstand atmospheric pressure at sea level as well as in higher elevations (where pressure is less due to the reduced atmospheric mass at higher elevations), maintaining its integrity even as the atmosphere presses on our bodies. However, consider an alien from the moon who visits the earth.  This moon being lives on an object with far less gravitational acceleration than the earth (since the moon is far less massive than the earth), and with nearly zero atmospheric pressure (since the moon has basically no atmosphere).  So this moon being would be compressed in the absence of an "earth suit" to protect against pressures felt at sea level on the earth.

Now what about when we dive into water?  Most people have jumped into a swimming pool deep enough to notice the increased pressure on the ears.  Even more compression is felt when scuba diving down a few tens of metres.  For such dives into a swimming pool or ocean, we can perform an inner ear equilibration to adjust to the increased pressure. Likewise, we can adjust our inner ear when riding in a car that climbs to the top of a mountain, where there is less atmospheric pressure acting on our ears. However, note the huge differences in scales. Namely, we must adjust our inner ear pressure when diving to the bottom of a 10 metre pool, but we have no such need when climbing to the top of a 10 metre tree. The difference is related to the huge difference in density between air and water.

Air density is roughly 1.2 kg/m^3, whereas seawater density is roughly 1030 kg/m^3.  Ever try to lift the water out of your full rain barrel?  This density difference means that upon reaching 10 m into the ocean, we have accumulated a full atmosphere's worth of pressure just from the 10 metres of water over our heads. Hence, at 10 m depth in the ocean, we feel the pressure equal to two full earth atmospheres (one from the atmosphere itself, and the second from the 10 m of seawater).  In turn, at 4000 m in the ocean abyss, there is roughly 400+1 earth atmospheres of pressure.  That pressure produces a huge force on any object at this depth.  

In particular, marine life in the abyss must withstand pressures of the ocean water. Even marine life living in the upper ocean, say just a few tens of metres deep, must adapt a body structure quite distinct from terrestrial beings feeling only a single atmosphere's worth of pressure. In turn, it can be lethal for marine life to rise to the surface ocean too fast, without allowing sufficient time for their body to equilibrate to the lower pressure.

Back deck of the JR Ross on 23 April.  Note the snowman on top of a mooring float on the right.  The blue sky has been quite a treat this day, as well as the very cold yet somewhat drier air.

 

A few facts about ocean heat 

Another facet of seawater concerns its ability to absorb and to store a huge amount of heat.  This property is due to the very large mass of the ocean as well as its large heat capacity. Let’s again consider some numbers. 

The atmosphere is warming through human-induced climate change arising from increases in greenhouse gases that change the earth's radiation balance ("anthropogenic climate change"). Measurements of the planetary heat budget indicate that more than 90% of the extra heat from greenhouse gas pollution (from burning fossil fuels) is absorbed by the ocean.  This ocean warming contributes to sea level rise through thermal expansion (warm water expands) and melting of ice shelves that are exposed to the warmer water. 

Ocean measurements estimate that roughly 2.4 x 10^{23} Joules of heat accumulated in the ocean during the past 40 years.  The surface area of the oceans is roughly 3.6 x 10^{14} m^2.  When dividing the net heat accumulated (2.4 x 10^{23} Joules) by 40 years (time it took to accumulate this heat) and dividing by 3.6 x 10^{14} m^2 (surface area of the ocean), we find an averaged surface heat flux of roughly 0.5 Watts per square meter entering the ocean.  That is, for each square metre of surface ocean, there is, when globally averaged, about one-half a Watt entering that square due to anthropogenic warming.  This heat flux is quite small when compared to, say, the heat flux generated by a 60 Watt light crossing its glass bulb.  But consider this heat flux in comparison to something more planetary in scale, and something far more dramatic.

The amount of energy released from one Hiroshima bomb was roughly 6.3 x 10^{13} Joules. Assume there is one such bomb exploded each second, and distribute the released heat energy over the area of the ocean. Crunching through the numbers reveals that one Hiroshima's worth of energy per second, spread over the ocean surface, corresponds to 0.17 Watts/m^2 heat flux. Hence, the observed ocean warming during the past 40 years, due to increases in greenhouse gas pollution, is equivalent to the amount of heat released by exploding three Hiroshima bombs every second for 40 years.  When measured in this manner, we see that the magnitude of ocean heating is thus very large indeed.

As a means to understand the role of the ocean for the climate system, consider an earth without an ocean. Instead of sequestering 2.4 x 10^{23} Joules of heat in the ocean, we instead let it remain in the atmosphere where it originated.  Given the mass of the atmosphere and its heat capacity, and assuming the added heat is mixed uniformly throughout the atmosphere, the average temperature of the atmosphere would rise about 40 degrees Celsius.  This is an incredibly large increase in atmospheric temperature. The ocean thus performs a huge "climate service" to those of us who live on land. Indeed, one of the biggest questions of climate science is how long the ocean will continue to absorb the extra heat produced by increases in greenhouse gases that alter the earth's energy budget.

The day watch on 23 April: Eleanor Frajka-Williams from Southampton University, Paul Anker from British Antarctic Survey (BAS), Stephen Griffies from NOAA/Geophysical Fluid Dynamics Lab and Princeton University, and Christian Buckingham from BAS. Weeks of close work has made us quite a team indeed!