 |
| |
For
the third week of the AnSlope cruise, we moved to the
eastern end of our study area, somewhat north of the
continental slope of the Ross Sea. In order to
understand the impact of the margins on ocean stratification
and overturning, we have to stand a bit away from those
margins to see what waters drain away from the complicated
margin processes, hence our northern boundary condition
transect. Along the northern route, as we make measurements
of the ocean from top to bottom, we passed through pancake
ice. Pancake ice is newly formed ice, with thin small
floes that do little to impede the foreword motion of
the ship. They remind one of pancakes (the real thing
is available for breakfast nearly every day aboard the
ship). As the cold weather progresses, these pancakes
gets wider, thicker, freeze together, and soon become
a field of impassible ice. We reached older larger ice
floes towards the eastern end of the northern boundary
section, and rather than use fuel to break the last
20 nm to the intended end-point, we turned to the south
at 175°W, back to the continental margins to investigate
the margin processes that stir up the ocean in that
part of the Ross Sea. Our progress southward was often
slow, but we occasionally found some north-south trending
leads, or breaks in the ice that enables rapid movement.
The skill of the Captain Joe [Capt'n Joe Borkowski III]
and ice pilot Vladimir Repin in finding these leads
by 'reading' the subtleties of the ice, even as weather
conditions obscure the view, is so important to our
program.
We
believe that in the east, the dense shelf water is not
as salty as more melt water from the great floating
masses of glacial ice to the south reach the continental
margin. Some of this melt water contributes to the dense
plumes that descend into the deep ocean. We also think
we see evidence that not all of the glacial melt descends
to the deep -- some seems to spread out horizontally
at depths near 100 m. This is important if we are to
describe the complete glacial melt role in structuring
the ocean stratification.
We
wonder what surprises await us as we look at the ocean
condition in this part of the Ross Sea, which can be
considered the upstream source of some of the water
characteristics we see in the western Ross where the
AnSlope moorings are situated. We have an idea of what
is happening, but "real-world" science has
a habit of surprising our over simplified views of how
things work, and experience has us ready to be surprised.
This is what exploration is all about.
We
did have a nice deviation from the ice breaking and
data collecting routine with a three hour stop at a
thick ice floe. We were free to wander off the ship
and walk on 1-meter thick ice floating over 2 kilometers
of seawater. A long way down, and cold, with the air
at -12°C and the seawater just below the ice at
-1.9°C. Luckily no wind, and a little bit
of sun. Seeing the ship, our home for the 45-day cruise,
is quite a sight. A group of Emperor Penguins were near
by, but following Antarctic Convention, we let them
be; though a few good pictures were snapped (or more
accurately recorded on flash cards). What did they think
of us, in our bright red coats? I think it might
not have been too flattering.
I
often refer to the adventure of exploration and our
sense of discovery that is characteristic of field science,
but I should also stress the long hours of tedium. Like
your corner convenience store, we are a 24/7 operation.
As mentioned in earlier reports, this does bring the
group together in a shared experience, and the humor
and fun is the stuff that forms fond memories brought
up years from now.
|