January 2012 Archives

Is Winter Getting Shorter?

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The average temperature of the earth has been rising steadily, and climate scientists are ver confident in their prediction that the trend will continue for the foreseeable future.  While global conditions can be forecast pretty well, relating global changes to local conditions is much harder.  One of the simplest climate predictions is that rising temperatures will lead to fewer days of winter-like weather.  Here is an animation of changes in the duration of winter across North America:

In the movie, red indicates a shorter winter at that location, relative to the average duration between 1871-2010.  I used a very human-centric definition of winter.  Winter was declared to start on the day where temperature falls below 5°C and stays below this level for five consecutive days.  Winter ended when temperature exceeded 10°C for five days.  More detail on the data is below.  

Not surprisingly, there is a lot of blue (longer than average winters) in the beginning and lots of red (shorter winters) at the end.  In between, you see red and blue blobs come and go.  Even early in the time series, there are some areas with shorter winters, and even at the end there are some areas with longer winters.  In any one location, winter duration fluctuates, but the general trend is towards shorter winters. For example, I plotted the winter durations for Maine (thin blue line) against the average duration for the whole region (thick black line).
WinterLengthAnom_5_10_5.jpgPositive numbers indicate longer than average winters. So, winters are definitely getting shorter over North America, and the trend is very consistent since the late 1970s.  The 30s and 40s tended to have shorter winters, while those in the late 60s and early 70s were longer.  Maine is much noisier, but tends to follow this overall pattern.  The period of shorter winters in the 1940s is more extreme in Maine, and only in the last couple of years have we exceeded those values. I would love to hear some recollections of the late 1990s: were winters really ~25 days longer than the last few years?  If you're not a fan of cold weather, this looks like a pretty good trend:  fewer days in the puffy jacket and fewer days running the old oil burner.  However, it's not all sunshine and roses (which of course will bloom earlier).  In Maine, mild winters allow the dreaded deer tick to flourish, making gardening an extreme sport.

Data Processing
The data for the animation and the figure were taken from the NOAA Earth System Research Lab's 20th C Reanalylsis (V2).  I downloaded the daily maximum temperatures and extracted North America.  Starting from midsummer in each year, I went through the next 365 days of data looking for a period where the temperature was 5°C or lower for 5 consecutive days.  The first period I found was declared to be the start of the following winter.  For example, if I started searching in June 1973, and found December 15 as the first winter day,my algorithm would say that the start of winter in 1974 was -15 days.  I then searched until I found five days of temperatures above 10°C and declared that to be the end of winter.  The duration was then the difference between the ending and starting dates.   If a location never fell below 5°, there was no
winter at that location.  Similarly, if the location was always colder than 5°, then the duration was 365 days.

I now have a map for each year with the winter durations.  To reduce some of the local variability, I computed a five year running mean at each location (1973 is now the mean of 1973-1977).  I then took the average duration at each location in the map and then subtracted the observed duration from the average, producing a map of anomalies.  In the movie, I interpolated on to a finer grid, to make the images less blocky.  Between each year, I inserted five images that were blendings of this year and the next.  This allows the movie to change smoothly.

Elephant Seals

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Editor's note: No, Karen's ship didn't run aground.  She is still safely on the water, we're just publishing this post out of order to save you from too many cute animal pictures in a row.  Plankton fans: don't worry, your day will come soon...

This entry is really an excuse to wow you with pretty pictures of seals.  Elephant seals are one of the species commonly seen around the Antarctic Peninsula and they were fairly abundant around Palmer Station.  Other seal species that live here include: leopard seals, Weddell seals, crab-eater seals and fur seals.  Elephant seals live in harems of females, for which male individuals fight.  It is therefore common to see one large male with several females.    

 An elephant seal smiles for the camera

Trying to reach that itch- not easy when you're HUGE!

Inter-species interaction?  Unlikely.

A group of elephant seals at the bottom of the glacier at Palmer Station- a great surprise in the middle of a lovely hike.

At the moment, little work is being done on seals in Antarctica.  Researchers opportunistically survey their populations for numbers and distribution.  Moms and pups are surveyed for their respective weights.  A study that ended a few years ago sought to understand the lipid (fat) transfer from mother Weddell seals to their pups; this work was conducted out of McMurdo Research Station.  I wonder what the trends are in different seal populations and whether each species is susceptible to different environmental factors, perhaps related to their respective food sources.  I also wonder how much the animals' distributions change over time- do the seals use one habitat for an amount of time and then shift to another?  Does this happen on the scale of one animal's lifetime?  Multiple generations?  Just some food for thought...so to speak.

1880-2011 Warming

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For those of you keeping score at home, NASA has concluded that 2011 was the ninth warmest year on record.  (All together now: We're number 9! We're number 9!)  Furthermore, nine of the 10 warmest years have occurred this century.  They've put together a mesmerizing visualization of temperature patterns since 1880 (white=mid 20th C average, blue=colder than average, yellow-red=warmer).

It's worth taking a stop in some specific years (this is easier if you download the mp4 file from the NASA site):

  • 1930s--notice the warming over the US.  The warming in the 30s was associated with the Dust Bowl period and one of the largest displacements of people in the US (think Grapes of Wrath).
  • 1916--one of the coldest years in the record. Only a few areas of above average temperatures.
  • 1960--a pretty good representation of the "mid century average".  The colors are muted and the splotches of orange and blue are scattered evenly around the globe.
  • 1978--the start of the current warming trend.  Start from here and watch the red appear!
  • 1997--very strong El Nino year.  Notice the cone of warm water centered over the Pacific.
  • 2010--the warmest year on record.  While most of the world is orange, notice how the warming is stronger in the Arctic, and to a certain extent, the Antarctic.  While the global average temperature in 2010 is ~0.5°C higher than average, the temps in the Arctic are almost 2°C warmer.
  • 2011--"cone shaped" pattern of cold water in the Pacific indicates La Nina conditions.


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Another update from austral graduate student Karen:

This research cruise is part of a Long Term Ecological Research Program (LTER), an NSF-funded project to study long-term change in a diverse set of ecosystems.  Palmer Station and the LTER cruise are the primary components of the Antarctic LTER.  Long-term research is expensive to support and does not turn out a lot of results in the short-term.  However, without it, people would have no way of knowing how the world is changing over time.  It is therefore exceedingly important.

LTER science covers many aspects of the ecosystem.  There are people studying gases and trace metals in the ocean, bacteria, phytoplankton (plant plankton), zooplankton (animal plankton), birds and whales.  Carbon flux is a major focus that crosscuts many of the different project teams.  

The group that I work with studies zooplankton and their role in the Antarctic carbon cycle.  Dr. Deborah Steinberg, from the Virginia Institute of Marine Science (VIMS), runs the project.  We conduct different kinds of net tows to sample the zooplankton at different locations and at different depths around the peninsula.  In addition, some of us are conducting experiments to look at fecal pellet production, gut evacuation rates and development rates.  Each of these aspects of zooplankton ecology directly relates to carbon cycling.
The rockin' zooplankton team working their magic aboard the LMG, LTER 2012.

Carbon cycling is important because carbon is one of three primary elements that simulate the growth of life in the sea; the other two are nitrogen and phosphorus.  In addition, carbon in the ocean can exist as carbon dioxide (CO2), a major player in greenhouse gas warming.  It is therefore of utmost importance to understand how carbon moves in the marine system, and under what conditions it remains in the sea versus exits into the atmosphere.  
The way we catch zooplankton is with large nets that are towed behind the boat.  We use nets made of different sized meshes to catch different sized organisms.  
Our two meter "metro" net is deployed off the stern of the ship.  We typically tow this net down to 120 meters.  For every regular sampling station, we take a tow with this net, and another with a smaller (one meter) net down to 300 meters.

Once we have our zooplankton samples onboard, we sort, identify and count all of the animals that we have caught; this takes quite a long time!  Some examples of animals that we typically catch include: krill, salps, amphipods, copepods and chaetognaths.  We also occasionally catch larval and juvenile fish and squid.
Kate and Miram take a gander at what we have caught in our latest tow.
A mélange of zooplankton swim around in a large beaker after being brought inside the lab; here you can see different ages and species of krill, chaetognaths and more.

We are not the only ones out here trying to catch zooplankton; whales are a great indicator of large numbers of krill in the area.  In fact, when we do a net tow in the presence of whales, we usually find big healthy-looking krill in the sample.
The head and dorsal fin of a humpback whale feeding near one of our sampling stations.
Humpback whale flukes- the patterns on the underside of humpback whale flukes are used to identify individual animals.  The longest animal migration on record was recorded after a humpback known to frequent American Samoa was sighted in Antarctica.  

The zooplankton community changes with the oceanographic conditions in different areas.  Nearshore, the water contains more phytoplankton, while offshore, the waters are less phytoplankton-rich.  We tend to find large schools of krill inshore, where phytoplankton is most abundant.  Offshore, less krill are seen but we also catch more salps, a type of gelatinous zooplankton.  Salps tend to be found in nutrient-poor waters, potentially indicating ecosystem niche-differentiation from krill.  

While tiny, zooplankton are an incredibly important component of the Antarctic ecosystem.  They are the link between the organisms converting sunlight into useable energy, and all higher trophic levels here. ¬ There is evidence that as the climate warms and ice conditions change, major changes in the zooplankton community will follow.  LTER scientists are seeking to describe and understand these changes, as they occur. 

A new generation

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I've just finished yesterday (just on time, as usual!) grading the final assignment of undergrads from the "Université du Québec à Rimouski" for a fall session class entitled "Functioning of Marine Ecosystems".

And yesterday something stroke me. When I was producing a report (not so long ago) supposed to describe the patterns and processes prevailing in a marine ecosystem, I had David Attenborough's voice in my head chanting "The sun shines relentlessly over the blue sea, providing a tremendous amount of energy capable of moving water masses and make microscopic life bloom..."

But I think that my students heard a David Suzuki of some sort warning "There is an urgent need to describe and understand the current state of the marine ecosystem in order to face the impacts of global change and the ever increasing human pressure over the ocean..."

The vast majority of those 20 pages reports supposed to describe some specific marine ecosystems (The Gulf of Maine, the Baltic etc) were presented that way, to the point where some almost lost sight of the purpose of the assignment and spent more pages listing the current threats to their systems than characterizing its state and dynamics.

During the past session we had a variety of lectures and discussions, they did several presentations on various relevant topics. I did my best to put forth a balanced approach, but these students definitely learned ecology in a context radically different from what prevailed until the end of the last century. Canadian Conservative Ministers of natural resources will have to learn living with those new "radicals"!


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Transmission from Karen Stamieszkin:

Warning: this is a somewhat gratuitous entry with way too many animal pictures

As the ship approaches Palmer Station, you get a beautiful view of mountains and glaciers sliding down into the Gerlache Strait.


Upon arrival at Palmer Station, we were given the opportunity to ride in small inflatable boats to Torgerson Island, a small island only a few minutes from the station.  There an experiment is under weigh, looking at the impacts of human visitation on nesting behavior of adelie penguins.  The entire island is inhabited by the penguins, and visitors other than scientists are excluded from half of the island. 

Adelie penguins on Torgerson Island, with Palmer station (left) and the LMG (right) in the background.

Adelies on Torgerson Island with a sailboat in the background; yes, that boat and its passengers crossed the Drake Passage- I feel like a whimp.

The scene on Torgerson Island appears at first glance to be one of nursery serenity, with moms and chicks snuggling up together and dads bringing rocks to beef up the already well-used nests.

A mother and her chick.

A male adelie brings his mate and chick a pebble for the nest.

However, after about one hour on this island, I realized that the penguins are a main course in the Antarctic food web, and that a whole community of predators surrounds the penguin rookery.

Here, a skua (the big brown bird in the foreground) devours a penguin chick which was still flapping its flippers when I grabbed my camera to take this picture- BRUTAL.

Penguins are such an important source of food for skuas that they have made their own nest only meters from the penguin nests.  They are so well camouflaged that I nearly stepped on top of this mother skua, making her shriek, calling in the male to fly around my head making threatening sounds.  Skuas are known for dive-bombing people and causing injury, so I backed away as fast as I could. 

While poking around the island, I also found a leopard seal lying lazily on an ice flow, just abutting Torgerson Island.  It appeared to have just feasted, likely on penguins.

This leopard seal sports the bloody grin of a predator with a full belly, as it floats on an ice flow next to the penguin rookery on Torgerson Island.

This harsh relationship between penguins and their predators represents an important link in the Antarctic food web.  Penguins eat krill, which feed on phytoplankton- tiny marine plants which turn the sun's energy into sugars.  Therefore, penguins are a link from the primary and secondary producers of the sea to top predators such as skuas and leopard seals.  The relatively small number of links in this food web represents a fairly efficient system.

Stay tuned...more animal pictures to come.  And some science too!


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Transmission from Karen Stamieszkin:

The Drake Passage is infamous for its trying conditions.  It has been a formidable foe to voyagers from all periods of human history because the entire Southern Ocean, which circumvents the Antarctic continent, is squeezed dramatically between the southern extent of South America and the tip of the Antarctic Peninsula.  You can think of it as taking a bunch of marbles rolling them around in a donut-shaped track.  In some places the track gets wider, and the marbles are spread out, but in some places, the track is very narrow, so the marbles have to pile on top of one another to get through.  Likewise, when the Southern Ocean squeezes into the Drake Passage, some water has to go up and some down, making the gigantic waves for which the Drake is known.  We had a relatively smooth crossing this time: only about 15-18 foot seas- no big deal (haha).

Here, a wave breaks over the lower deck.  I am taking this picture from two decks above the one being covered by the wave.

While traveling through the Drake, which takes 3 to 4 days depending upon conditions, we cannot conduct much science.  We do collect information about temperature and salinity in the upper 900 or so meters of the water column.  We call these collections XBTs and XCTDs, for the instruments used.  Both are small torpedo-like units that are dumped over the side of the boat from a "gun"; as they descend into the water, a very thin copper wire trails behind relaying information about the conditions the probe meets through a cable in the gun, to the computer.  The XBT only reads temperature, while the XCTD reads temperature and conductivity, a proxy for salinity.

The XBT probe.

Here, Nathalie holds the XBT gun before launching the probe.  Sidenote: Nathalie is a first grade teacher going to Palmer Station to help study flies that freeze solid in the Antarctic winter, can lose up to 30% of their body moisture, and survive the whole ordeal eating moss.  She will be doing education and outreach.

The temperature profiles tell us about how deep the water is mixed, indicated by a constant temperature.  Maxima and minima following the mixed layer indicate different bodies of ocean water of different origins.

In this picture, besides half of my face, you can see that there is a lot of noise caused by the rough seas at the surface, then a mixed layer down to about 50 meters, a temperature minimum, and finally a constant temperature to the bottom of the profile.  This cold subsurface layer is thought to be caused by the formation of dense, cold, salty water off of the Antarctic continent, which then sinks below the surface water of the Antarctic Circumpolar Current (ACC).  The water is particularly cold due to the conditions in which it forms.  It is relatively salty because as ice forms, fresh water is taken up and frozen, and salt is excluded, leaving saltier water behind.  The saltier and colder water is, the more dense, or heavy is it; fresher, warmer water is less dense, or lighter.  These principals of water density related to temperature and salinity in large part govern ocean water circulation world-wide.

Other activities that are popular during the Drake crossing include: sleeping, movie-watching, email checking, looking for whales and other critters, and of course, celebrating NEW YEARS! 

Happy 2012 to everyone- may it be a year of adventure and new discoveries!


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Transmission from Karen Stamieszkin:

Science is all about acronyms. The better an acronym for a proposed project is, the more likely it will get funded. While I say that somewhat in jest, it is true that anything with an acronym is more likely to be remembered and is almost always used in place of the full name. Throughout science blogs everywhere, acronyms abound- be warned and get used to it.

Punta Arenas is the most austral port and town in the world. It is one endpoint between which the research vessel the Lawrence M. Gould (LMG) bounces, the other of which is the Antarctic Peninsula and Palmer Research Station. When I think of Punta Arenas, a feeling of decadent decay is invoked; eating and sleeping in PA, as it's affectionately called by those working on the LMG, is like going back to a time when care was taken in every detail of construction; dark wooden moulding is the norm, glass atrium greenhouses serve as dining rooms, and brass-adorned underground bars are filled nightly with cigarette smoke and patrons.

One theory is that PA was a booming port town when the Straits of Magellan were the safest route from one coast of the American continent to the other. It is the largest town on the Straits, which serve as a safer passage compared with rounding the fearsome Cape Horn. It is thought that PA saw the end of its glory days with the construction of the Panama Canal, which eliminated the need for ships to sail the full perimeter of the continent to get from, for example, New York to San Francisco. The town now waxes and wanes with the Southern Ocean fishing fleet that calls PA home, as well as the Antarctic and Patagonian tourism industry.


A view of Punta Arenas from the research vessel Lawrence M. Gould as we depart from port.


The Straits of Magellan, under an interesting sky.

ON OUR WAY- the crossing

We departed from PA on December 29th. Filling ones time while making the crossing can be a challenge. While still in the Straits, it is possible to set up equipment, use the machines in the ship's gym, and generally go about life at a normal pace. I spent a lot of time looking for wildlife. There are always interesting birds following the ship, including different types of albatross and shearwaters.


A black-browed albatross.


A greater shearwater.

As we left the Straits and headed for the Drake Passage, we were visited by several groups of dolphins, some Commerson's dolphins, and some Peel's dolphins. Peel's dolphins are endemic to the area, and are therefore seen nowhere else in the world.

Some Peel's dolphins making their way toward the boat to ride its bow and stern waves; in the background you can nearly see the end of the American continent.


Peel's dolphins.


Peel's dolphins

Water Sampling and More

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Hi again!

Last time I mentioned that we collect water samples at multiple depths at a couple of spots when we do fieldwork.  How exactly do you get water from 7 specific depths simultaneously?  We use these nifty things called Niskin bottles!  Essentially, they're tubes with tops and bottoms that are open until a pole on the side is hit- then the top and bottom simultaneously close.  We attach these bottles to a cable, so they are spaced apart at certain intervals.  We then lower them all down, so each bottle is at a depth we want to sample.  We then put a weight at the top of the cable and let it go, to slide down the cable.  It hits the pole on the top Niskin bottle, shutting that bottle and releasing another weight which slides down to the second bottle, shutting that bottle and releasing another weight which slides down to the third bottle, and so on...  We then haul them all up (thankfully they're on a winch- it would be way too heavy to do by hand), take them off the cable and TA-DAH!  We have water samples from particular depths!  Didn't I say they were nifty?  


Attaching a Niskin bottle to the cable.  Hitting the white bar on the right  releases the top and bottom to close the bottle.  


The parking lot at Palmer- the 2nd boat from the right, Bruiser, is our trusty zodiac for fieldwork.

The L.M. Gould will be arriving again at Palmer tomorrow.  This time when it arrives we'll be beginning a month long research cruise.  There's 2 parts to the research going on here- what's happening at Palmer Station and the annual research cruise.  At Palmer, the different lab groups sample the area right around Palmer intensively for the entire spring to fall season.  However, everything we do is limited to be within a couple miles of Palmer (due to safety reasons).  In January, there's a research cruise that samples a 600 km x 200 km grid along the Antarctic Peninsula.  This allows us to study the changes occurring on a larger scale.  The types of sampling and experiments on the ship will be very similar to what occurs at Palmer Station, just on a larger scale.  As it's my first oceanographic cruise, it should be pretty interesting!  

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This page is an archive of entries from January 2012 listed from newest to oldest.

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