Date: January 15
A note from Bob Anderson, who forwarded the report from K.Coale


Dear All,

An update from Kenneth Coale, Chief Scientist of the U.S. JGOFS APFZ
Survey-II cruise, describes the biological consumption and export of 50 to
60 micromoles/kg of dissolved SILICA from surface waters south of the APF
at 170 deg W.  It will be of great interest to see how carbon export is
coupled to this Si consumption.
regards,

Bob

The Weekly Report from Ken Coale, Chief Scientist


January 15
        We are continuing to SeaSoar south (63.5 by midday). Surface water
temperatures are still above 2.5 degrees whereas temperatures only 30
meters  below us are -1.  We have not yet found the surface manifestation
of the front,  yet the deep manifestation we passed two degrees ago.
Hydraulic fluid leak in  SeaSoar may be affecting the ability of the fish
to dive below about 280 m but  most of the important features are all
within this depth.  We believe that calm  weather since Process I has
resulted in the warming of these southern waters and  stabilized the water
column allowing phytoplankton to strip out silicate and  carbon dioxide.
Silicates are low (1 micromolar) and so is pCO2 (270 ppm).   This is very
suggestive of a previous bloom which we now see at the base of the  shallow
mixed layer.  We intend to follow this feature until the isopleths of
temperature shoal where we will, presumably, see an outcropping of the
subsurface fluorescence feature.  Underway measurements should help to
characterize this high fluorescence water mass.  No word yet on the sea ice
edge, yet messages are flying.

January 16
        The idea of a front is that strong gradients in temperature,
salinity or  velocity are encountered between water masses. We have been
watching surface  water temperatures creep monotonically to lower values
with surface isopleths of  temperature spread over hundreds of kilometers.
There seems to be no front down  here.  Winds are consistently from the
south and it appears that melt water is  dissipated rapidly from the ice
edge. These features were discussed in the  second science meeting held
today following the abandon ship drill. There are  numerous large tabular
ice bergs in the vicinity and the ship needs to maneuver  around them.
Debris from these bergs (growlers) are a source of some concern on  the
bridge, but 24 hour daylight and calm seas makes spotting these relatively
easy at SeaSoar speeds. The ice images that arrived today via fax confirm
sea  ice at about 69 deg, 30 min south.  Because of the lack of a strong
frontal  system and the distance to the sea ice, where no front is
guaranteed, a decision  to stop the SeaSoar at 2030 was made this morning.
We have pursued the notion  that the transect south represents a trip
backwards in time relative to bloom  formation and we have identified a
region of high plant biomass at about 64 deg  47 min S where chlorophyll
levels reached about 2 micrograms per liter.  Here at  67 deg 45 min S,
silicates are now back to about 60 micromolar and chlorophyll  is low, so
it appears there is such a thing as time travel.
        After such a long transcet the scientists are restless for some
water  column work. The officers and crew have supplied excellent support
durint this  first week and we look forward to more productive scientific
operations in the  weeks to come. For now we are readying for the SeaSoar
recovery and the  following station.

Kenneth Coale
Chief Scientist
JGOFS/AESOPS/ APFZ Survey II  (Kiwi Expedition Leg 8)