1800 miles to go...

according to the TV screen (which, if updated, gives our waypoints
and ETA) until we return to dry land. We're following a "great
circle" (extra credit?) back to P.A and the straits of Magellan. At
about 10 knots, we should be in sometime on the 26th. A little ahead
of schedule, but there's a lot of ocean and potential weather delays
until we get there. As of right now, it's smooth sailing though.

I'll probably write some reflections on the trip over the next week
or so, as I work on putting some of the data together for the final
cruise report. But if anyone has suggestions, or questions that have
have been left unasked, let me know (write a comment!).

I'm trying to switch back to a more traditional schedule, so I've got
to get to bed now -- before I get hungry, since I skipped midrats.
The rocking motion seems to help...

Fwd: 0901.6

And, speaking of sea ice, the (final?) weekly report!!!!!!

Back in the 1970s, NASA investigators divided the circumpolar
Southern Ocean sea ice pie into 5 pieces and began to monitor their
sea ice extents and concentrations. The overall ice extent has
increased since then, mainly due to changes in the Ross sector, in
contrast to the widely publicized declines in the Arctic summer ice
minimum. However, the Amundsen and Bellingshausen sector has bucked
the Antarctic trend, with the length of its sea ice season declining
by more than two months. This is comparable to Arctic changes over
the same period and, along the west side of the Antarctic Peninsula,
has been associated with one of the largest rates of regional surface
warming on the planet.

The Amundsen Sea differs from its Ross and Bellingshausen neighbors
by harboring broad, quasi-permanent areas of fast ice, held in place
by myriads of large, grounded icebergs. It experiences prevailing E/
SE winds, less conducive to ice export than the Ross Sea southerlies.
Since the melting point of ice in seawater decreases as pressure
increases, upwelling beneath its deep-rooted ice shelves will be
stronger than in the Bellingshausen Sea, where the ice shelves are
thinner. But like the Bellingshausen, its precipitation is relatively
high, leading to 'snow ice' formation. This occurs when seawater
floods ice floes with negative freeboards, sunk by their snow loads,
with the ocean to atmosphere heat flux essentailly making an end run
around the tattered sea ice blanket.

Is the Amundsen sea ice thinner now in response to increased
upwelling of deep water that has not lost all its heat to melting
glacial ice? Is its snow cover thicker due to increased precipitation
in an enhanced hydrological cycle? Are there more icebergs to ground
the fast ice and also drive cooling and upwelling, now that the
glaciers are moving/calving faster? Is sea ice production and melting
higher or lower because wind strength and directions have changed due
to the deepening of atmospheric lows along the continental margin? We
don't yet know the answers to these and similar questions, in part
because few sea ice measurements have been made prior to NBP09-01
over the large but remote Amundsen continental shelf.

In this context, the sea ice component of O-274 has occupied 20 ice
stations and bagged 90+ m of ice core along N-S and E-W transects,
noting that the amount retrieved for structural analyses is a record
compared to the 3.6 m length of the sea ice team. Their work has been
reliably supported by the RPS MTs and others, and extensively
photographed and videotaped, including provocative pictures of the
bottoms of sea ice floes. Along with visual and camera logging of
surface conditions underway, the sea ice measuring, sampling and
subsequent modeling will be compared with satellite records of the
sea ice cover, and with data from three deployed ice mass balance
buoys currently reporting to collaborators on the home front. When
all is said and done, we should have a much better understanding of
the role of sea ice in the Amundsen Sea's deep water heat sink.

Macrophotographs of snowflakes were taken during 8 of the 12 short
snow showers that punctuated the otherwise sunny summer weather
during the first 6 weeks of the cruise. These photographs are being
analyzed to determine the size distribution and crystal habits of
falling snow, to complement records of the timing and intensity of
snowfall events measured with photoelectric particle counters mounted
on the ship's ice tower. The timing and relative intensity of
snowfall measured on the ship during cruises NBP07-02 and NBP07-09
are well correlated with the timing and relative intensity of
precipitation forecast by the ECMWF and some other weather models. To
correlate the absolute magnitude of documented precipitation events
with forecasts and reanalyses, one must know the size distribution
and water equivalent mass contained in the falling crystals. Most
snow observed during the warm summer snowstorms consisted of rimed
dendrites, with more plates, sector plates and rare hollow columns
closer to the continent, and one snowfall event composed entirely of
ice needles up to 3.5 mm in length.

Work on the continental shelf concluded near the end of this week,
and for mile after mile on and north of the shelf we weaved our way
through what may be the largest iceberg graveyard in the Southern
Ocean. Their common presence in this deep region suggests a large
area of weak or waffling currents. The varied features on overturned
bergs provided a crash course on what the bottom surfaces of melting
ice shelves probably look like.

Hi everyone.

Feeling a little brain dead after a long quiet day as we transit to a
site in the middle of the southern ocean, so I can't think of
anything exciting to write about. I did get a question from DT's
class though so I think I'll just go with that.

The question was: is old sea ice denser than new sea ice?

That's a great question, but it's a very tough one to answer. My
guess is there is no simple rule relating density to age. Ice will
in general grow over time (as long as it's below freezing and the
water is cold), so we can generally say that old ice is thicker. But
the mass of the same size block of new and old ice is not as simple.
First of all, there are many types of sea ice (each of which has a
great name -- frazil, shuga, nilas, etc.), and each of which one of
which forms under different environments. The formation determines
the crystal structure which governs how tightly packed the ice is.
This crystal structure will change as the ice evolves and is heated
and cooled from above (by the atmosphere) and below (by the ocean).
Also involved in the aging is a very gradual moving around of salt,
which tends to form channels through the ice. Then snow (which is in
generally lighter than ice) falls on top of the sea ice and may or
may not be incorporated into the ice itself. All of these processes
(and I probably missed others) changes the density of sea ice (as
well as the characteristics that govern its effects on climate),
which make it difficult to generalize.

So if any of the students who asked this wants to consider pursuing
research, this question will probably still be around in some form
when they consider graduate studies.

Good Luck!

Re: batten the hatches: NBP returns to open ocean

sorry for the forwards, but thought this was worth relaying. I'll
try to take some pictures of the crossing. Could get exciting!

C

On Feb 14, 2009, at 4:42 PM, NBP, MPC wrote:

Hello all,

Just a quick note to remind you that we will be departing the smooth
existence of ice protected sailing sometime tomorrow, Feb 15 and will
again be subject to the large swells of the southern ocean. So if
you value what you have sitting on your desk, tie it down. If you
need assistance with any tie downs, please feel free to consult with
any of the RPSC techs. Please doublecheck any liquids and things in
hoods and fridges.

We should finish with CTD/mooring/ice coring in the morning tomorrow
and will then head north and west to the site for the big mooring, at
roughly 66 S, 129 W.

Cheers and Happy Valentines Day!

Fwd: Welcome back to the Dead Zone

Hi all,

This blog has at times suffered from out-of-date transmissions. We've
moved back into the "dead zone" over the past few days, so I expect
some slow responses and posting. Stick with us. Once we get back to
the Alive Zone (INMARSAT), I should be in 3x/day email communication
from here on out.

It's been nice to see the comments recently. I'm hoping to see more
when email kicks in again (no pressure, though)!

Begin forwarded message:

From: NBP System Administrator <admin@nbp.usap.gov>
Date: February 14, 2009 3:08:41 PM GMT-03:00
To: all_on_nbp@nbp.usap.gov
Subject: Welcome back to the Dead Zone

Please note we're once again out of INMARSAT range. Our last
successful email run was Friday, Feb 13 ~13:00 ship's time. Because
we are planning to be here for a rather short duration, we are
queueu'ing mail normally and we will wait until we are back in
INMARSAT range to send and receive mail from the ship. Looking at the
current plan, I expect we should start to see a signal again sometime
in the next 12-24 hours.

If you have urgent needs for off ship email before then, please
contact me.

For those of you who have not already sent that romantic missive to
that special someone for Valentine's Day (or made other
arrangements), may I suggest that nothing says I love you better than
a satellite phone call from the Amundsen.

(C.L.) Note on this last part -- romance comes in 7 minute increments
on the satphone, and is shared with the rest of the e-lab. Not
ideal. Sorry Liz.

carbon pumps and other assorted goodies

Hi all,

First, seems like my entry on my talk a few days ago sounded a little
downbeat. It wasn't meant to be -- just trying to reflect on how to
do it better next time -- all the feedback I've gotten since then
suggests that people were involved and are excited about it.

Next, weather. Calm as possible today. Very glassy water, scattered
with just very small chunks of sea ice and cluttered with medium and
large tabular icebergs. Can't really remember a day like this on the
two Antarctic cruises I've been on now. Very cool for photos: all
the ice reflects in the water below, you can see ledges beneath bergs
deep underwater, and there is just a very thin layer of forming sea
ice at the surface. The wake from the ship is really the only
disturbance to what would be a totally tranquil scene. Unfortunately
we wouldn't be able to experience it without a 300 foot ship tearing
up the picture.

Now, the plan. Exciting news this morning. Because of the light sea
ice, we're able to head back to the Getz ice shelf, which we had to
pass by a few weeks ago due to stormy seas, as referred to in the
weekly report. So Southward we steam! Still competing in the
pingpong tournament, but working my way through the losers' bracket.
It's a long way to the title from where I stand.

Finally, the carbon stuff. Got an interesting comment a while ago
from Roy aka Dad about how the oceans work with respect to Carbon
Dioxide.
"One highlighted the fact that the deep ocean is kind of a kidney for
CO2 (absorbs it and flushes it out of the atmosphere), but with a
super-long cycle it just can't keep up."

This is true, but it's really only one part of the story. I'll
elaborate in a very brief way here which doesn't do this topic
justice. But I'm not a very fast typer, so:

Oceans can be looked at as having two parts -- the surface, which is
exposed to the atmosphere and which can exchange gases, heat, and
freshwater (through evaporation and precipitation), and the deep,
which only very slowly exchanges with the surface. Deep oceans
"sequester" carbon because they hold way more than they would if they
were in equilibrium with the atmosphere. The only way for this to
happen is for carbon to move from parts of the ocean that have less
to those that have more. In order to make this work, we need "pumps"
-- processes which allow us to move carbon in the opposite direction
as the difference between the surface and deep (like moving water
uphill!) The two most important are referred to as the solubility
and biological pump. The solubility pump is put into action by the
sinking of cold water near the poles. Since CO2 is more soluble in
cold water than warm, and these cold water fill most of the ocean's
volume, more CO2 is locked up at depth than at the surface. The
biological pump works because phytoplankton use CO2 near the surface
of the ocean to grow (photosynthesis). They die/are eaten/decompose
and eventually sink. But as they sink, they are "remineralized" into
forms of dissolved CO2 by bacteria and other organisms. If they
break down below the level where the atmosphere interacts, the carbon
is trapped in the deeper water. Over the 1000's of years it takes
for some parts of the ocean to get back to the surface, accumulated
dead stuff can take a lot of carbon out of the air.

So the net effect of these pumps is to remove CO2 and they WILL
operate to bring down concentrations of CO2 in the atmosphere if
given enough time (1000's of years). But if we make our model a
little more complicated and look at what happens in different places
near the poles, we see both sources and sinks of carbon. In fact,
where we're traveling, there is a significant amount of upwelling
water (this is the "warm" stuff, CDW) which vents a large amount of
CO2 to the surface. Like a malfunctioning kidney (a very apt
metaphor, coming from me), the ocean may shift it's absorbtion/
venting balance if it is perturbed. More "stuff" may be left in the
bloodstream. Since the amount of CO2 in the atmosphere is so small
relative to the amount in the ocean, even a small change in these
pumps (e.g. changes in the temperature of the water, changes in
locations and strength of winds, dominant phytoplankton species) may
exert a strong (positive or negative) effect on atmospheric CO2.

Enough science for now. Will you be my valentine?

Chris

science talks and new ice.

Hola everyone,

I have strongly mixed feelings about giving "talks" about my work.
First of all there's a little nervousness and public speaking
anxiety. But I think one of the main problems I have is the lack of
interaction with the audience. Especially when the audience is mixed
-- some get bored while others are working hard to follow along. In
these situations, I feel like I drag trying to explain everything on
the slides. Talks are much different than teaching in this respect.
Even if I'm lecturing, my goal is to make sure students understand.
In research talks, I should relax that objective a little in order to
keep the pace (in fact I've received this advice before but I'm
trying to internalize it now). I felt a little let down after my
talk today, which tried to accomplish an overview of ocean modeling,
some thesis-related stuff, and some more cruise-related work.
Fortunately, I've gotten a huge amount of informative and
encouragement from the audience since finishing -- restoring faith
that the message got across and that the preparation was worth it.

In order to have really productive, brainstormy type talks on an
individual level, it's important to lay it out there in any form
(maybe unpolished) for people to digest as much as they can. This
may not be a revelation, but for me, it's important to realize that a
talk is really a stepping stone and not an endpoint.

Anyway, enough philosophizing. An exciting development over the past
few days, as we traverse areas of relatively thick sea ice on the
continental shelf break, is the appearance of "new ice". It's been
cold and relatively calm out and sea ice is starting to form (maybe
the summer is coming to a close already?). Though we've been off and
on in heavy "first-year" ice up to 2 or 3 meters thick, new sea ice
is much more exciting. Right when it forms, even when it's very
thin, the waves change and you only see the longer wavelengths. Then
you start to get "fingering nilas" -- which tends to break up and
fracture into thin interlocking segments. For some reason the process
is really exciting for me to watch. I'm hoping this will keep up
over the next few days, before we leave the ice for good. I expect
'll be spending some quality time on the bow if it does.