HOT-40: Chief Scientist Report
Chief Scientist: D. HEBEL
HOT 40 Cruise Report
R/V Moana Wave
20-25 Sept. 1992
Personnel List:
Dale Hebel Chief Scientist UH
WOCE group:
Fred Bingham Scientist UH
Sean Kennan Graduate Student UH
Rich Muller Technician UH
JGOFS group:
Ricardo Letelier Graduate Student UH
John Dore Graduate Student UH
Terry Houlihan Technician UH
Chris Carrillo Technician UH
Dan Sadler Graduate Student UH
Ancillary projects
Emerson's O2 project:
Chuck Stump Technician UW
Campbell's Picoplankton project:
Hector Nolla Technician UH
STAG:
Ken Shultis Elect. Tech.
Bradley Tolivar Deck Tech.
Itinerary (approximate local time):
-----------------------------------
Sunday, 20 Sept.
0900 Departed Snug Harbor
1130 Arrived Kahe Pt. (Sta. 1)
1600 Departed Kahe
1230 Arrived Aloha (Sta. 2) trap deployment site
Monday, 21 Sept.
0200 Completed sediment trap array deployment
0400 Arrived Aloha (center of circle), began CTD time series
Wednesday, 23 Sept.
0500 Completed Sta. 2 CTD operations
0900 Arrived Sta. 3 (23 25' N 158 W), conducted deep cast
1430 Departed Sta. 3, began Sean's CTD transect
Thursday, 24 Sept.
0330 Began tow-yos
1100 Completed sediment trap retrieval and resumed CTD
transect profiling
2100 Completed CTD transect profile
Friday, 25 Sept.
0700 Arrived Snug Harbor
Narrative:
----------
All aspects of the cruise went well with the exception of intermittent
albeit persistent pylon problems. All samples were collected and we
were able to maintain the cruise schedule.
Just outside the harbor, during the abandon ship drill, we happened
upon what appeared to be a surface accumulation of tricodesmium. The
extent was not large and no obvious surface accumulation was present at
Kahe. At Kahe we experienced problems with the transmissometer and
fluorometer which necessitated aborting the first cast. The problem
was found to be in the new transmissometer therefore we switched to the
old one. We used this throughout the cruise however we need to
determine what the problem is with new unit.
We deployed the sediment traps in the usual location and headed for the
center of the circle. Initial problems with the pinger temporarily
delayed deployment of the deep cast. After retrieval it was noted that
bottle S7 was missing both end caps and spring and that only 20 of the
23 bottles fired. We took a series of split samples for silica
(refrigerated), spiked some other samples and took a large number of
replicates from ~1400 m. These samples will be used to help resolve
the nutrient problems observed periodically since HOT 33.
All sampling has been going according to scheduling except for the
interruption of the 3 hr CTD intervals due to the necessity to pump the
ship's holding tanks. This caused a six hour hiatus since we needed to
deploy the primary productivity array before daylight once we were back
on station. I am unaware of a similar problem on other Wave cruises,
therefore, we should ask the Captain if this type of operation can be
completed before we arrive on station (center of circle), where the CTD
time series takes place. I am assuming that if the tanks are empty
they should have enough capacity for the 40-48 hrs we are on station.
We continue to experience sporadic multiple bottle trips and general
pylon problems. This resulted in a number of casts being repeated.
Fortunately, water demand was not high on this cruise and there were
enough casts to supply our needs. We have also ran a time course
taking samples for low level phosphorus (llp), low level nitrate and
nitrite (NOx), dissolved organic carbon (DOC) and pH from the 5 m
niskin on all casts (at least those where we were reasonably confident
that the bottle tripped at 5 m). In addition we took NOx samples at
Kahe, ALOHA and station 3. It will be interesting to see if we observe
any inshore-offshore gradient with the low level technique.
The remainder of the cruise was occupied by Sean Kennan's CTD profiling
and trap retrieval. We had been monitoring the drift track of the
traps and uncharacteristically they traveled in a southwesterly
direction. We had to curtail Sean's tow-yoing when we learned that the
traps were nearing the middle of the Kaui channel. Fortunately, the
tow-yoing was less interesting than anticipated so that activity was
not resumed after the trap retrieval. However, Sean continued his
profiling to just off Kahuku followed by a leisurely steam back to Snug
Harbor.
Weather:
--------
The weather was good throughout the cruise with light winds, mostly
sunny skies and calm seas during the first few days of the cruise.
Toward the end the winds picked up to normal trades (10-20 kts) with
concomitant seas. Skies remained relatively clear.
Equipment and methods:
----------------------
All equipment used on HOT 40 was standard for past HOT cruises. All
equipment function properly with the exception of the rosette pylon and
new transmissometer. The only equipment lost was 2 end caps and teflon
coated spring from one 12 l niskin on s2c1.
Ancillary programs:
-------------------
Investigator: Project:
------------- --------
Steve Emerson (UW) O2, respiration, and DO intercalibratin
Charles Keeling (SIO) CO2 dynamics and intercalibration
Paul Quay (UW) DIC13 dynamics (new production
estimates)
Lisa Campbell (UH) Picoplankton studies
Students:
---------
Ricardo Letelier Tricodesmium studies
John Dore NH4, NO2 and NO3 dynamics
Sean Kennan Intrusive salinity features
Dan Sadler Time series pH measurements
Others:
-------
Amy Baylor (student) Seawater collection for Loihi plume
comparison studies
Ted Walsh (Prj Mgr Anly Svc) Seawater diluent collection
Taro Takahashi pCO2 intercalibration (C. Winn P.I.)
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