Hawaii Ocean Time-series (HOT)
in the School of Ocean and Earth Science and Technology at the University of Hawai'i at Manoa


HOT-42: Chief Scientist Report


Chief Scientist: D. HEBEL


HOT 42 Cruise Report
R/V Kila
23-25 Nov. 1992




Personnel List:
---------------

        Dale Hebel                      Chief Scientist         UH
        
        WOCE group:
        No representatives

        JGOFS group:
        John Dore                       Graduate Student        UH
        Chris Carrillo                  Technician              UH
                        
        Ancillary projects

        Emerson's O2 project:
        Chuck Stump                     Technician              UW

        Campbell's Picoplankton project:
        No representatives

        STAG:
        No representatives




Itinerary (approximate local time):
-----------------------------------

Monday, 23 Nov. 
        0830    Departed Snug Harbor
        1200    Arrived Kahe Pt. (Sta. 1)
        1600    Departed Kahe
Tuesday, 24 Nov.
        0200    Arrived ALOHA  (Sta. 2) 
        0230    Commenced hydrocasts
        1700    Completed hydrocasts
        1830    Departed ALOHA
Wednesday, 25 Nov.
        0730    Arrived Snug Harbor
                


Narrative:
----------

HOT 42 represented a major deviation from our routine cruise scenario.
The cruise was conducted aboard the R/V Kila with Ross Barnes as
Master.  The total cruise duration was approximately 48 hrs and due to
the lack of a conducting wire winch we were restricted to hydrocasts
composed of twelve 10 and 12 liter Nisken bottles hung from 1/4" (?)
kevlar line.  Due to the length of the kevlar line and the short cruise
time frame we were limited to casts within the upper 250 m.  Even if we
had additional line the Seacat internal recording CTD pressure
transducer was only rated to 500 m.  This did not represent a major
obstacle for the JGOFS component since most of our samples are
collected in the upper 250 m.  In addition to the relatively shallow
casts we did not deploy the sediment traps or primary productivity
arrays.

Although the cruise time frame was very short we were able to collect
most of our core water column samples both at Kahe Pt. and ALOHA.  This
was only possible due to relatively benign sea conditions.  At Kahe we
conducted the usual PNF and the first kevlar cast.  The cast went
smooth enough, however, a number of the samples were lost due to the
red silicon (?) O rings pulling out of the O ring groove.  These were
reseated and we did not experience a continuation of the problem,
however, we were assiduous to check the O rings after we cocked each
bottle on the following casts.  It is possible that the silicon elastic
band may have pulled the O rings out of the groove during our initial
cast or that they were not properly seated to begin with.  Another
problem which became apparent at Kahe was the apparent malfunctioning
of the transmissometer.  Although, the recordings were continued
through the remainder of the cruise it is unlikely that the data will
be good.  In addition, the salinity profiles were very noisy.  A
serious malady of  the short cruise time frame is that only limited
troubleshooting can be accomplished (usually during transit when you
need to sleep), and that once on station any equipment problems will
result in the loss of samples.

At station ALOHA 7 casts were completed.  Two were to 50 m for C.
Stump's respiration experiments and the remainder were 12 bottle casts
to 250 m where samples for both UW and UH were collected.  Samples
collected included DO, DOC, Chl a (f), inorg. nutrients, LLP, NOx, pH,
Alk, refrig'd Si, on-deck temp's, pCO2, UW DO, UW Oxy/Ar, Keeling DIC,
PPO4, PC, PN, HPLC pigments, bacteria, flow cytometry samples, and
salts.  The sample collection and processing  covered 18 hrs with a
cast and sample collection duration of approximately  1 hr each
conducted by  4 experienced personnel.  This does not include post
sample collection processing, Seacat data uploading, or station keeping
positioning.  In addition, 3 PNF casts were completed.

It should be emphasized that the primary factor in our limited sample
collection success was the relatively calm sea conditions and
secondarily the dedication of a very experienced scientific
contingency.  The very limited laboratory space and  load capacity are
real deterrents for high quality scientific work and will preclude
involvement of ancillary scientific endeavors. Although the Captain and
crew provided excellent support, it is my opinion, that the vessel is
substandard relative to our needs and should only be considered as a
last resort measure.
     


Weather:
--------
The weather was good at station ALOHA with light NNE winds ranging from
11-15 kts and mostly sunny skies.  Due to the uncharacteristic light
winds the sea state was relatively calm with the swell ranging from 2-3
m.


Equipment and methods:
----------------------
All equipment used on HOT 42 was atypical relative to past HOT
cruises.  We used our DSE winch with kevlar line and twelve 10 and 12 l
General Oceanic Niskin bottles.  Bottles were manually attached and
removed for each cast over a depth interval of 250 m.  At the terminal
end of the Kevlar line was an SBE-19 Seacat internally recording CTD
with transmissometer.  The conductivity and temperature sensors were
compared to our regular CTD sensors in the calibration laboratory prior
to the cruise as well as the voltage output of the transmissometer.  At
sea the salinity data was very noisy and the transmissometer did not
appear to work properly.  During the transit to Kahe Point the Kevlar
line was marked at 10 m intervals with the depth and orange fluorescent
paint starting at 250 m.  Five meter increments were also marked with
black paint but without the depth.  The Seacat was suspended 9 m below
the 250 m mark.  Niskin bottles were hung at either 10 m or 5 m
increments over the 250 m depth range as recorded on our cast data
sheets.


Ancillary programs:
-------------------

Investigator:                   Project:
-------------                   --------
Steve Emerson (UW)		O2, respiration, and DO 
				intercalibration 
Charles Keeling (SIO)           CO2 dynamics and inter calibration
Lisa Campbell (UH)              Picoplankton studies

Students:       
---------
No time or energy 

Others:
-------
Taro Takahashi                  pCO2 inter calibration  (C. Winn P.I.)