Tuesday, January 20, 2009

miscellaneous items

Hi all -- Looks like email difficulties will plague the NBP for at
least the next week or so as we are going to be at the PIG ice front
and sending Autosub under the ice repeatedly over the next few days.
Yesterday's test mission successful, it is, as we speak, motoring
around underneath (30km in) the ice shelf. Cross your fingers that
all goes well.

In the meantime, I have been titrating and analyzing some model
simulations which ma give some insight into the flow in and around
the ice shelf. Despite the fact that oxygen calibration is necessary
(we corrected a sensor on the CTD that was not reading right
yeterday), it feels good to be contributing something (with the
model) that is unique. It's been a hard few days though as I've been
working the full 12 hours plus to get everything done. Oh yeah and
no weekends either.

A beautiful slideshow by Maria Stenzel, the photographer on the
cruise with us, tonight to break up the batch of samples. She has
done a tremendous amount of work photographic the Antarctic with
scientists. I think a bunch of her photos are online at National
Geographic -- I had seen many of them before both in NG as well as on
the walls of the NBP.

And in response to:

>>desert tortise has left a new comment on your post "oxygen pt 2
and PENGUINS!!!":
>>How does churning from berg movement and storms work with DO levels?

This is a great question -- off the top of my head, I can think of
two opposing effects. Wind-generated waves will break and entrain/
engulf bubbles -- this will raise DO levels (this is exactly what
we're trying to avoid when sampling). But my guess is that the
bigger effect of winds/berg movement is that they will mix water from
below the surface with a much lower dissolved oxygen. Icebergs will
have the additional effect of melting into the ocean. Since this
will make the ocean near the iceberg lighter and water will rise
along the base of the berg, this may also lower DO levels without
really "churning".

This is exactly the type of question that we ask when looking at the
data -- which effect is bigger? And which process -- bergs, winds,
sea ice, etc. -- are causing the mixing? And it's why having more
than one "tracer" helps distinguish what's really happening.

Keep sending questions and thoughts -- it I don't reply it's probably
because we're struggling to find the satellite and I haven't read it

1 comment:

  1. We are willing to wait for such great responses. No problem! The next student question is, in the slides I show them from my work off Monterey the deepest sample bottle has almost immediate condensation when brought up because of air temperature as compared to the water. Even though you are in the greater southern latitudes, is there apparent condensation on the deep tubes as compared to the ones nearer the surface?