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.)