Sunday, June 28, 2015

In port at last

Entering Strait of Juan de Fuca
Yesterday, at about 10 am, we reached the U.S. Coast Guard dock in Seattle, our final destination. Temperatures were >80ºF (~27ºC) during the day, impressing all our friends from southerly states on the ship. The last 12 hours, cruising through the Strait of Juan de Fuca, past Vancouver Island and the Olympic Peninsula, and into Puget Sound, were also quite impressive. While Seattle is home for some of us, others still have to journey home to states as far away as Florida (NOAA/AOML). So long, CLIVAR/GO-SHIP P16N, Leg 2! Thanks to everyone on land and at sea, including all scientists, officers, and crew on the R/V Brown, who made P16N 2015 a successful and fun cruise.

Final post by Yours Truly, Sabine Mecking

Approaching Port Angeles at ~2am
Continuing into Puget Sound
(Co-)chief scientists and Seattle skyline

Thursday, June 25, 2015

Encircling 'The Blob'

It’s not often that climate phenomena penetrate the realm of popular media. The ‘Polar Vortex’ certainly has, becoming a bugbear for the extreme winters that the American Northeast has experienced in these last couple years. ‘The Blob’ is another such feature that has reached regional notoriety in the Pacific Northwest. It’s been blamed for everything between sending salmon north to Canada to the lack of a ski season in the Cascades. ‘The Blob’ manifests itself as, well, a large blob of water sitting in the Gulf of Alaska that is warmer than usual forced by an unusual high pressure ridge. As can be seen in the figures below, you can see the Blob’s ever-shifting form skirted by our cruise track.

Snapshots of daily sea surface temperature taken from satellite during our cruise. Red colors indicate warmer than averages temperatures. Black line is the cruise track, including the steam to Seattle at the end.
 In addition to the water sampling that we do from the rosette, one of the ship’s sensors collects surface temperature and salinity continuously while underway. Despite the fact that we never crossed the core of the blob, we still saw its influence north of 37ºN with higher-than-average temperatures.

Daily averaged surface temperatures from the ship’s underway sensor. The influence of the Blob can be seen in the top panel as positive temperature anomalies north of 37ºN and in the bottom panel as the difference between the red and black lines (37ºN was crossed on 06/05).

If you’re interested in the origins and effects of the Blob check out the blog posts by UW Atmospheric Scientists Cliff Mass and Dennis Hartmann:

“Did "THE BLOB" cause our warm summer?”

“The tropics as a prime suspect behind the warm-cold split over North America during recent winters”

By Andrew Shao

Tuesday, June 23, 2015

Last day of sampling

Early this morning, we completed our final stations of the section across the northern Alaska Gyre and are done with all CTD casts as well as other over-the-side operations.
Celebrating the recovery of the CTD rosette on the last station of the day shift yesterday 
(station 203 at 18:30).
Total number of stations accomplished on leg 2 is 95 of which 78 were along 152ºW and 17 were on the cross-gyre section. The night shift is slowly adjusting to a normal-life schedule, and everyone is trying to catch up on some sleep. We have a 4-day steam from our last station to Seattle which gives time to pack up and also to get those data reports in!

An underwater crater or not?

Image of multibeam bathymetry in northern Alaska Gyre.

Jump from 6074 to 3472m in just a few seconds.

A couple of days ago, while conducting our cross-gyre section, we were surprised to find a >6000 m crater underneath the ship as seen in the underway multibeam bathymetry display, but not on any chart. Well, after much initial excitement, we have concluded that this must be an artifact of anomalous multibeam behavior induced by a nearby (very steep) seamount. We saw another crater later on and turned back briefly to verify and better map it. Upon return, while steaming at a slower charting speed of 8 knots (rather than >11 as before), we could not find it!! Instead, only a  steep seamount that agreed with the 1 minute Smith&Sandwell topography was present. To all oceanographers: Have you seen this type of multibeam behavior before?

A poem by the chief scientist

Of Molokai the Ctenofore
(a.k.a. Inspired by a Jelly in the Gulf of Alaska)

Of Molokai they sing great songs;
A jelly of renown.
She had translucent pumping veins
And a purple gown.

A Ctenofore, young Michael said,
“Let’s shine a light upon her”
The “oohs” and “aahs” resounded then,
A rainbow cast about her.

Alas, she was from the briny depths.
We knew she could not stay.
So Jessie cast her back again
Into the foggy spray.

Of Molokai they sing great songs;
A jelly of renown.
We think of her of now and then,
In her brilliant purple gown.

By Alison Macdonald

Saturday, June 20, 2015

152ºW section completed

Two days ago, in the early morning hours of June 18, we completed our main cruise objective by finishing the last 152ºW stations on the Alaskan Shelf near Kodiak Island.
Salinity along 2015 152ºW transect: Salty subtropical surface waters (orange, excess evaporation) and fresh subpolar and equatorial surface waters (blue, excess precipitation) are evident as well as the intermediate salinity minima (300-1000m) and a high-salinity subsurface "blob" (150m) within the northequatorial current system at 10ºN.

We continue to be incredibly lucky with the weather as we now head eastward across the northern part of the Alaska Gyre toward Sitka. 17 more stations along this transect, and then we will be portbound to Seattle (and the nearest pub).
North Pacific Ocean at its calmest.
View off the bow.

Thursday, June 18, 2015

UVP photos of the day

I’m not a biologist, or a zoologist. I work with an underwater camera system designed to capture marine particles. Many of those particles happen to be zooplankton, the ocean’s tiny drifting animals. Every day, I’ve been posting some choice snapshots on the door of the CTD computer lab, in the hopes that the other scientists on board can help me identify some of the more mysterious animals.

How does the camera system capture all of these images? With flashing red lights! The Underwater Vision Profiler (UVP) takes pictures of 1-liter parcels of water as it descends toward the seafloor. (In the attached photo, my face is taking up the space that gets photographed by the camera.) The camera itself sits at the bottom of the metal cylinder, and the horizontal red lights are the inward-facing camera “flash.” The camera identifies all of the objects within each picture that are 100 micrometers to several centimeters in size. For scale, that’s anything larger than the width of one human hair and smaller than my face.  As it goes down with the CTD rosette, it can capture up to five 1-liter chunks of water per second, saving thousands of images every single cast.

Some of the larger objects caught on camera are pretty difficult to sample using other methods. Take jellyfish, for example – gelatinous zooplankton. If you try to catch a gelatinous organism in a net, it might be smashed into pieces by the force of the plastic net hurtling through the water.

Or, think about the challenge of capturing a piece of “marine snow.” Marine snowflakes, dubbed the “dust bunnies of the sea,” are aggregates of many bits of things all stuck together with transparent exoploymeric substances, the ocean’s snotty glue. These fluffy light snowflakes sink so slowly that if you try to catch one in a sediment trap, it may never happen.

  What’s the point? As marine particles sink - including phytoplankton, zooplankton, and detritus (plants, animals and dead stuff) - organic carbon gets transferred from the surface of the ocean down to deep, cold waters where it can be stored long-term. This is called the Biological Carbon Pump, and it has the ability to sequester carbon dioxide from the earth’s atmosphere on a global scale. To better understand it, we need to understand how much stuff is sinking and how quickly it is sinking. That depends on how large and how dense the particles are. The UVP shows us all of this, and gives images of the largest objects so we can see what they actually are…including the elusive gelatinous organisms and marine snowflakes.  

By Jessie Turner

Thursday, June 11, 2015

The color of the ocean

When you think of the ocean, you may find yourself envisioning a big blue body of salty water. But the ocean isn’t just uniformly blue, it’s a hypnotic spectrum of greens and blues, greys and whites and sometimes even red. The color of the ocean is a function of what’s is in it and how much – greener oceans are alive with little guys called phytoplankton, bluer oceans are thought of as lifeless ocean deserts, white oceans are indicative of coccolithophore blooms, grey oceans are born from extensive cloud cover, etc. We are working on the ocean optics/ocean color team to characterize the stuff that influences light propagation in the ocean.

On land, we use satellite images to detect changes in ocean color, which is linked to changes in how ecosystems work, and can be applied to a spectrum of questions concerning ocean health. Satellites detect the reflectance of the oceans at different wavelengths (under ideal circumstances, 60m deep in clear waters, whoa baby!) and can relate that to things like chlorophyll concentration and particle size (from 5-50 microns in diameter).  Ground truthing is critical. This necessitates worldwide cruises to validate the satellite information and explore the optical properties in greater depth.

On this cruise, we collect samples to understand the contribution of chlorophyll and other photosynthetic pigments, colored dissolved organic matter (CDOM), and non-living particles to light loss in the sun-lit layer of the ocean. In these waters, the top layer that receives light is about 80m deep, but it will shoal as we move into higher latitudes and into more productive waters because light is lost more when there’s more plankton in the water. We also put a radiometer into the ocean every day around solar noon to measure upwelling and downwelling light irradiance within the euphotic zone. (top 100m). This is used to calibrate the satellite measurements and also helps our understanding of how light interacts with particles in the ocean.

Understanding the dynamics of the electromagnetic spectrum from the ultraviolet to the infared ‘sheds light’ into the concentration and type of particles that are in our seas, which is important for ecosystem characterization and understanding the ocean’s critical role in stabilizing climate. Though it may be strange to think about studying the ocean from outer space, satellites lend a unique perspective to study our blue(ish) planet.

By Kelsey Bisson and Erik Stassinos

Deploying the spectroradiometer
Measuring irradiance in the water
Recording the data

Monday, June 8, 2015

North Pacific storm track: calm as can be

Group photo with flat ocean in background 
Ship display at 42.5ºN

Here we are at 42.5ºN, well within the North Pacific storm track. But wind speeds are hovering around only 1-4 knots, and the sun is out. Lucky us. I guess there is some advantage to doing this section in May/June rather than March (as was done during the earlier CLIVAR occupation in 2006, and during WOCE in 1991).

Saturday, June 6, 2015

Why do we care about CO2 in the ocean?

Well, we humans are emitting a lot of carbon dioxide, and about 40% of what we’ve emitted has been sucked up from the atmosphere by the ocean. The ocean can hold a lot of carbon dioxide because the carbon can hide in all of those various forms (see post below) although the ocean uptake rate might go down in the future.  The ocean soaking up carbon dioxide is both a good and a bad thing.  It’s a good thing because carbon dioxide in the ocean does not trap the heat our Earth is radiating back out into space, and therefore doesn’t contribute to global warming like carbon dioxide in the atmosphere does.  It’s a bad thing because all of this extra carbon means the ocean is becoming more acidic (arguably less basic) due to all of the extra carbonic acid being formed from carbon dioxide.  

Now, you don’t have to be afraid of your swim trunks dissolving in corrosive seawater anytime soon.  Even the most extreme projections of what might happen still have the ocean more basic than perfectly neutral drinking water, and way less acidic than Coke… but it is still a pretty big concern for the organisms that evolved in the basic ocean and, presumably, like it that way.  There are a couple of critters at or near the base of the ocean food chain that form shells out of a mineral formed from carbonate, which is the most basic of carbon dioxide’s many guises.  Computer model simulations suggest that the availability of carbonate could decrease by 50% by the year 2100 if we continue emitting carbon dioxide as we have.  There are other important creatures that make their shells out of the same mineral, including ones we eat (e.g. clams) and ones that create entire habitats that other species rely on (e.g. corals).  There’s a huge amount of ongoing research into what this would do to these critters and the creatures that rely on them, but I’ll sum it up by saying that I’m worried for the little dudes.  I’m just imagining the reverse situation of some sea creature venting gas into the atmosphere that dissolves our bones, and it’s making me unhappy!
By Brendan Carter
Taking CO2 water samples
CO2 lab


Wednesday, June 3, 2015

Brendan's guide to measuring CO2 (and subforms) in the ocean

Carbon dioxide is a sneaky molecule. It reacts with water to form carbonic acid, which is a pretty weak acid in the scheme of things, but an acid nonetheless. It is only stable in an acidic solution. In seawater, which is basic (i.e. not acidic), it breaks down to bicarbonate and carbonate. This means several things. For my purposes, it means if I want to measure the total amount of inorganic carbon in seawater, then I’ve got my work cut out for me. Carbon could be hiding as any of four different molecules counting dissolved carbon dioxide (and that’s just the inorganic stuff… don’t get me started on how messy things get when biology gets involved).  Luckily, we chemists are molecular bullies, and we have lots of tools at our disposal to flush the carbon out of hiding:         

Step 1:  Kill all the things!  We don’t want to risk biology doing any more damage than it already has to our pristine seawater chemistry, so the first thing we do after collecting water is poison it.  Weird, I used to feel bad for all of the bacteria and other plankton in my 300 milliliter samples... 

Step 2: Set aside a known amount of seawater.  This is what the vast majority of the doodads in the lab with me are for.  There are plastic and glass tubes, twisting all about, venting air, seawater, and acid in a confusing tangle.  Why is this a challenge?  Well, we have two problems.  First, we can’t lose any carbon while we’re setting the seawater aside, which means we have to keep the water isolated from air as much as possible.  Also, we’re on a rocking boat, which means we can’t use a scale to weigh how much water we have.  So, we do it by rinsing and filling a pipette (think a glass bulb, open on both ends) with known volume.  We keep the pipette at a specific temperature so we know the density of the seawater, and so the pipette doesn’t expand or contract too much and change its volume.  This means a lot of temperature control.  The AC says 70 °F, but that ice-furnace―blasting directly on my workstation―is fighting a Hawaiian summer and exhaust from all of the machines in here, so I’m estimating my subjective temperature is somewhere between “I’ll probably survive” and “at least if I die, my body will be well-preserved.”  

Step 3: Next we put our known amount of seawater into the “stripper.”  This is where we’re really chemical bullies… we acidify the heck out of the seawater with phosphoric acid.  MUAHAHAHA.  All that carbon that was hiding as bicarbonate and carbonate is abruptly forced into carbonic acid, which is constantly exchanging with dissolved carbon dioxide.  We’re also pumping large amounts of nitrogen gas through this acidified solution, so the carbon dioxide gets swept up into the bubbles of nitrogen and carried away (this is called sparging).  Within a couple minutes, all of the carbon has been removed from our beleaguered seawater. 

Step 4: We then pass our dissolved gas on to an ethanolamine mixture in a fancy piece of tech called a coulometer.  The solution sucks up the carbon dioxide, letting the nitrogen gas go.  It changes color as it does, so our instrument knows there’s carbon dioxide and starts electrocuting the solution to break it down.  As the carbon breaks down, the solution goes back to the original color.  The coulometer keeps track of how much electricity it dumped into the solution, and that tells us how much carbon was in our known amount of seawater.

Step X: I’m just noting here that there are a bunch of cleaning, checking, and calibration steps I won’t bore you with.  They’re boring and tedious, and I kinda love them.  Check out Zen and the Art of Motorcycle Maintenance if that last sentence made no sense.

So, this poor carbon was poisoned, acidified, sparged, reacted with ethanolamine, and electrocuted. As I said, chemists are bullies… but in the end, we have the information we want… the amount of inorganic carbon, in all of its various forms, in a known volume of seawater. Bingo!

By Brendan Carter

Sunday, May 31, 2015

Denim and Pool Day

Today was declared denim day (by our newly established science party morale chief) to make everyone look good. The weather has been great, so we also used the new pool (purchased in Hawaii) on the aft deck for the first time. However, as we are constantly heading further north, I suspect that only our die-hard Alaskan participants will be found in the pool in a few days or so.

Denim-wearers gathering in the CTD lab
The pool

Friday, May 29, 2015

Radiocarbon dating of organic material dissolved in seawater: How old is it?

The ocean contains far more than salts and living organisms. The next time you take a swim think about the many thousands of diverse dissolved organic molecules (DOM) you are swimming through. DOM is operationally defined as smaller than a bacterial cell (0.1µm). It includes viruses and large (such as DNA) to very small molecules (amino acids and sugars).  The world's ocean mixes every ~1500 years, however the age of DOM is much older (4-6,000 yrs) suggesting many of these molecules are not efficiently removed by bacteria and persist for multiple ocean mixing cycles. In this way, the large DOM reservoir (662 GtC) stores carbon and mediates Earth's climate on immediate to millennial timescales. 
Our group's goal on this cruise is to understand the relative cycling rates of these molecules by determining their radiocarbon (14C) ages . We are particularly interested in determining the sources and cycling of highly-aged DOM components with human-induced inputs, such as combustion products, which we call Black Carbon (BC). We collect filtered seawater from the Niskin bottles at many depths and freeze them on board until we can analyze them back on land at the UC Irvine, Keck Carbon Cycle Accelerator Mass Spectrometer (AMS) Lab.  

Freezer samples on board
Mass Spectrometer back on land

by Brett Walker

Tuesday, May 26, 2015

Underway at last

We are finally sailing, leaving Pearl Harbor on Memorial Day 2015. The failure of the compressor of one of the air-cons kept us in port a bit longer than expected. Six days to be exact, some of which will be added at the end of the cruise. By now, we have completed a CTD test cast around the 1000 m isobath as well as a bongo net test cast and are underway to our first real station along 152ºW. The weather is calm, and we are hopeful for a smooth trip (aka "bunny cruise")! 

Last view of Diamond Head Crater and Honolulu, learning about the CTD rosette and mounted instruments, pteropods from the bongo net test cast, and chief scientist (Alison Macdonald) and CTD student (Andrew Shao) working in the TV lounge (taking a break from the very cold computer room, brrr).

Sunday, May 17, 2015

Getting ready

The last occupation of the P16N Hawaii-Alaska leg took place in March 2006 on the R/V Thompson. Almost a decade later, we are about to head out into the northeastern Pacific again, this time on the R/V Brown. Leg 1 from Tahiti-Hawaii is already complete. See their blog posts here.

Picture taken from Bridge of R/V Thompson in 2006, somewhere along 152°W.