SBI HLY-04-02 Final Cruise Report
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Final Report: Western Arctic
Shelf-Basin Interactions (SBI) Spring Cruise HLY-04-02 (15 May-23 June 2004) Edited by Jackie Grebmeier, Chief
Scientist University of Tennessee, Knoxville,
TN 37932 USA; email: jgrebmei@utk.edu |
A. Introduction
The 2004
oceanographic field phase of the Western Arctic Shelf-Basin Interactions (SBI)
project began on the USCGC Healy icebreaker on 15 May 2004. There are 18
research projects included in the ship-based program, ranging from hydrographic
measurements to biochemical tracers and biological studies of various trophic
levels. The goal of the SBI global change project is to investigate the
production, transformation and fate of carbon at the shelf-slope interface in
the Arctic as a prelude to understanding the impacts of a potential warming of
the Arctic. We worked initially in ice-free stations on the southern Chukchi
Sea shelf (Herald Valley [HV] transect), then moved into very heavy ice cover
in the Chukchi outer shelf to Arctic Basin line (East Hanna Shoal [EHS]
transect line). We terminated the EHS line at 2500m and proceeded SE past
Barrow to occupy the East Barrow (EB) line. Extremely heavy ice precluded our
occupation of the EB line and we moved over to the Barrow Canyon (BC) line via
a shortened transect north of Smith Bay (SB) line in the nearshore Beaufort
Sea.
The SBI project is an
interdisciplinary program, where physical, biogeochemical and biological
measurements are being made using a variety of sampling devices. CTD/rosette
sampling collected physical and hydrochemical samples. Thirty-five stations
were occupied during this cruise, with an additional 11 XCTD and 4 Video
Plankton Recorder deployments. A total of 48 scientists from nineteen
institutions in the United States, Bermuda, Canada, and Japan participated in
this interdisciplinary scientific endeavor.
In addition, a two-person BBC film crew joined us on June 11. Although
an Alaskan community participant was scheduled to participate in the cruise,
circumstances on land precluded that person joining the spring cruise.
In our sampling, we
used a CTD/rosette system for collecting physical and hydrochemical samples.
Subsamples from multiple CTD/rosette casts were used for primary production,
chlorophyll content, nutrients, particulate carbon, inorganic carbon,
biomarkers, microzooplankton, and radioisotopes. Various nets (vertical, bongo,
multi-net) were used to collect size fractions of micro-macro- and
meso-zooplankton for both population and experimental purposes. Benthic grabs
and cores were used to collect benthic fauna and sediment samples for
population, community structure, food web, chemistry and metabolism
studies. In-situ pumps were also used
to measure the activities of the particle-reactive radionuclide
thorium-234. Off-ship sampling by
lowering personnel to the ice occurred to undertake ice measurements and to
collect ice cores. Floating sediment traps were deployed and moored to an ice
flow for 12-24 hrs. Limited helicopter operations were used for ice
reconnaissance, river sampling and port logistics.
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Figure 1. Station
location and cruise track for the spring SBI cruise on the USCGC Healy (HLY-04-02). Due to
heavy ice conditions sampling was limited to the Chukchi Sea shelf, East
Hanna Shoal (EHS) west line and Barrow Canyon (BC) east line). |
During the cruise, ice conditions were
the main limiting factor for occupying only about half of the 5 transect lines
outlined in the HLY-04-02 cruise plan. Heavy ice over the outer shelf of the
Chukchi Sea made it slow going on the East Hanna Shoal (EHS) line, basically
keeping the ship at a slow pace until the upper slope. We were in heavy ice
past Icy Cape, only pulling into the northern limits of an open lead moving east
past Barrow. The other factor to be resolved during the cruise was limitation
on the availability of ambient seawater due to heavy ice conditions. The new
USCG science seawater system (SSW) clogged in heavy ice, thus we reverted to
the 2002 solution of filling and using the forcastle ballast tank. The USCG
engineering division connected the SSW system to the E-O-W forward ballast tank
and this tank was connected to the bow incubators through a spigot tree and
hoses. When the seawater in the ballast tank warmed up due to daily heating,
science requested a dumping of the water in transit and a subsequent refill on
station, which occurred using SSW. This situation especially occurred on sunny
days, and the “dump and pump” technique became standard operations between
stations. As the amount of open water in ice increased, engineering rigged a
fitting directly to the SSW system so that the ballast tank could be filled in
transit. Note that keeping the tank at 30,000 gallons kept the water below the
seawater line and thus cooled by the seawater surrounding the hull. It is anticipated that the summer cruise
will be able to directly use the SSW system without the ballast tank support.
Further information on the ambient seawater bow system is included in Appendix
A.
The Joint Office of
Science Support (JOSS) group of the University Corporation for Atmospheric
Research group maintained a shipboard field catalog during the cruise that
provided real-time data to scientists on the ship, which was mirrored to a
land-based system in Colorado. The JOSS site incorporated all the service group
datasets and preliminary analyses and acted as an instrument whereby scientists
could share their observations and preliminary analyses. The SBI field catalog
(with maps and event information at sea) can be found on the webpage: (http://www.joss.ucar.edu/sbi/catalog/).
Full details on the SBI project, the field cruise program and results to date
can be found on the SBI webpage http://sbi.utk.edu
and associated links on that web site. A highlight summary from the PI findings
for the spring SBI cruise will be posted on the SBI and JOSS webpages.
We were fortunate to have Patty Cie, a
Yelm Middle School teacher from Washington State, onboard the Healy during the
spring SBI cruise who provided daily updates on research and ship operations,
including spotlights on individual research groups, explained in layperson’s
terms. She was sponsored through the NSF Research Experience for Teachers (RET)
funding to Dr. Ken Dunton at the Marine Science Institute of the University of
Texas at Port Aransas. These daily updates are accessible through the website
and are linked to the SBI website (http://sbi.utk.edu/).
While aboard the cruise, she
also served as a team member with the Dunton/Schonberg food web sampling team.
Outreach activities during the cruise included two INMARSAT telephone -aided
Powerpoint presentations of cruise activities to her local Yelm school and via
web connections through the ARCUS TREC program to schools both in Washington
and Vermont.
The Captain, officers and crew of the
USCGC Healy provided outstanding support that was essential to the success of
the cruise goals. We appreciated the continued, professional support provided
by Captain Dan Oliver, Operations Officer Daryl Peloquin, Executive Officer
Bill Rall, Engineering Officer Greg Stanlick and Master Chief Navigator Joe
Gispert. Valuable support for science was provided by the lead Marine Science
Technicians Glen Hendrickson and Don Snider, and the other Marine Science
Technicians (Suzanne Scriven, Chad Klinesteker, Eric Rocklage, and Josh
Robinson), along with the Science Officer Neal Amaral. The Aviation Detachment
under the direction of Ed Beale provided essential logistical support for ice
surveys and limited science operations. In Nome and in Barrow, Andy Heiberg of
the University of Washington made himself indispensable to meeting the
logistical needs of the project as a whole. Also, in Barrow, we are grateful
for the assistance of the Barrow Arctic Sciences Consortium (BASC), including
Matt Irinaga and Glenn Sheehan, for their liaison activities with the Alaska
Eskimo Whaling Commission, and for assisting us logistically in the transfer of
personnel, equipment and samples to and from the ship. This work was
financially supported by the U.S. National Science Foundation, the Office of
Naval Research, and the U.S. Coast Guard.
C.
Summary of Science Reports
Stations occupied during HLY-04-02 were
on the Chukchi Sea shelf (HV transect), the Chukchi outer shelf to Arctic Basin
lines (East Hanna Shoal: EHS transect), stations near Pt. Barrow, and the
Barrow Canyon (BC) line. Table 1 provides a general summary of station
location, target depth, and station duration during the cruise. Note that there
is an interactive table with links to station maps and event logs for each
station on the JOSS SBI webpage (http://www.joss.ucar.edu/sbi/catalog_hly-04-02/index.html>.
The following science summaries include sampling collection information
and preliminary findings. There are also two appendices: Appendix A is the
summary of the ballast tank procedures developed during the cruise and Appendix
B is as report on the Healy
science system. The complete SBI hydrographic service team final report can be
found on the JOSS SBI website as a separate document in the shipboard reports
section <http://www.joss.ucar.edu/sbi/catalog_hly-04-02/index.html>.
The following sequence provides a
generic outline of the events undertaken at process stations. Modifications in
sequence were made depending on arrival time to station and PI needs.
|
Event
No. |
Event |
|
1 |
Ice team deployment |
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2 |
Sediment trap deployment |
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3 |
CTD-service cast (shallow and deep,
depending on station depth) |
|
4 |
Zooplankton hauls: ring nets
(vertical and oblique) |
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5 |
CTD-productivity cast |
|
6 |
Optics: active and passive, sometimes
also surface optics |
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7 |
CTD-biomarkers |
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8 |
Video plankton recorder |
|
9 |
CTD-zooplankton (every 2 days)
coincident with 4 vs 2 zoop hauls |
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10 |
Bongo or multi-net |
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11 |
CTD-radium casts |
|
12 |
Multi-corer |
|
13 |
van Veen grabs |
|
14 |
Multi-HAPS corer |
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15 |
Dredge |
Station Summary
|
STATION NO. |
DATE |
TIME (UTC) |
LATITUDE (N) |
LONGITUDE (W) |
DEPTH (m) |
DURATION |
|
HLY-04-02-001(BRS1)
|
05/17/04 |
20:51 |
65.673 |
-168.212 |
42m |
0.6 hrs |
|
HLY-04-02-002(BRS2)
|
05/17/04 |
23:00 |
65.678 |
-168.391 |
51 m |
0.5 hrs |
|
HLY-04-02-003(BRS3)
|
05/18/04 |
01:13 |
65.667 |
-168.553 |
53 m |
1.8 hrs |
|
HLY-04-02-004(BRS4)
|
05/18/04 |
04:16 |
65.682 |
-168.731 |
51 m |
0.4 hrs |
|
HLY-04-02-005(BRS5)
|
05/18/04 |
05:38 |
65.705 |
-168.883 |
50 m |
0.3 hrs |
|
HLY-04-02-006(HV1)
|
05/18/04 |
16:55 |
67.490 |
-168.928 |
50 m |
21.2 hrs |
|
Cota-2004_05-20-1 |
05/20/04 |
22:46 |
70.221 |
-167.635 |
51 m |
0.2 hrs |
|
HLY-04-02-007(HV2)
|
05/21/04 |
08:56 |
70.641 |
-167.288 |
56 m |
11.7 hrs |
|
HLY-04-02-008(productivity)
|
05/22/04 |
16:35 |
71.256 |
-162.089 |
47 m |
2.2 hrs |
|
HLY-04-02-009(EHS0)
|
05/24/04 |
15:55 |
72.007 |
-159.569 |
45 m |
18.4 hrs |
|
HLY-04-02-010(EHS0.5)
|
05/26/04 |
19:14 |
72.079 |
-159.590 |
48 m |
16.3 hrs |
|
HLY-04-02-011(productivity)
|
05/27/04 |
15:36 |
72.090 |
-159.583 |
48 m |
1.5 hrs |
|
HLY-04-02-012(EHS1)
|
05/28/04 |
07:52 |
72.244 |
-159.203 |
51 m |
0.7 hrs |
|
HLY-04-02-013(EHS2)
|
05/28/04 |
18:50 |
72.365 |
-159.006 |
52 m |
4.9 hrs |
|
HLY-04-02-014(EHS3)
|
05/29/04 |
13:15 |
72.479 |
-158.883 |
54 m |
1.0 hrs |
|
HLY-04-02-015(EHS3.1)
|
05/30/04 |
00:20 |
72.580 |
-158.741 |
74 m |
0.9 hrs |
|
HLY-04-02-016(EHS4)
|
05/30/04 |
09:22 |
72.637 |
-158.677 |
153 m |
20.8 hrs |
|
05/31/04 |
12:42 |
72.726 |
-158.588 |
225 m |
- |
|
|
HLY-04-02-017(EHS5)
|
05/31/04 |
20:49 |
72.719 |
-158.401 |
247 m |
19.1 hrs |
|
HLY-04-02-018(EHS5.1)
|
06/01/04 |
19:15 |
72.774 |
-158.396 |
295 m |
1.4 hrs |
|
HLY-04-02-XCTD_02
(EHS5.2) |
06/02/04 |
15:59 |
72.825 |
-158.271 |
410 m |
- |
|
HLY-04-02-VPR_01
(EHS5.2) |
06/02/04 |
16:27 |
72.826 |
-158.274 |
~410 m |
0.2 hrs |
|
HLY-04-02-019(EHS6)
|
06/02/04 |
22:15 |
72.852 |
-158.207 |
689 m |
27.0 hrs |
|
HLY-04-02-020(EHS9)
|
06/04/04 |
16:28 |
73.134 |
-157.792 |
2400 m |
23.0 hrs |
|
HLY-04-02-021(EHSX)
|
06/06/04 |
14:23 |
72.629 |
-157.390 |
398 m |
5.7 hrs |
|
HLY-04-02-022(SB1)
|
06/08/04 |
16:38 |
71.439 |
-154.298 |
28 m |
8.8 hrs |
|
HLY-04-02-022-b(SB1) |
06/10/04 |
18:05 |
71.465 |
-154.550 |
34 m |
1.4 hrs |
|
HLY-04-02-023(SB4)
|
06/11/04 |
20:47 |
71.691 |
-154.725 |
74 m |
9.6 hrs |
|
HLY-04-02-024(SB5)
|
06/12/04 |
12:46 |
71.776 |
-154.626 |
145 m |
18.7 hrs |
|
06/13/04 |
09:17 |
71.821 |
-155.161 |
216 m |
- |
|
|
06/13/04 |
10:37 |
71.868 |
-155.038 |
243 m |
- |
|
|
06/13/04 |
12:35 |
71.918 |
-154.803 |
375 m |
- |
|
|
06/13/04 |
13:48 |
71.969 |
-154.613 |
332 m |
- |
|
|
HLY-04-02-025(productivity)
|
06/13/04 |
14:15 |
71.975 |
-154.613 |
578 m |
1.0 hrs |
|
06/13/04 |
16:44 |
72.016 |
-154.484 |
631 m |
- |
|
|
06/13/04 |
19:16 |
72.063 |
-154.305 |
1396 m |
- |
|
Station Summary (cont.) |
|
|
|
|
|
|
|
STATION NO. |
DATE |
TIME(UTC) |
LATITUDE |
LONGITUDE |
DEPTH |
DURATION |
|
HLY-04-02-026(BC5)
|
06/13/04 |
22:07 |
72.096 |
-154.370 |
1184 m |
20.4 hrs |
|
HLY-04-02-027(BC6)
|
06/15/04 |
07:31 |
72.252 |
-154.488 |
1898 m |
17.4 hrs |
|
06/16/04 |
03:50 |
72.216 |
-154.554 |
~1500 m |
- |
|
|
06/16/04 |
05:10 |
72.167 |
-154.520 |
~1500 m |
- |
|
|
06/16/04 |
05:59 |
72.121 |
-154.524 |
~1500 m |
- |
|
|
HLY-04-02-028(BC4)
|
06/16/04 |
15:37 |
71.921 |
-154.867 |
545 m |
32.6 hrs |
|
HLY-04-02-029(BC3.1)
|
06/18/04 |
13:46 |
71.666 |
-156.204 |
~100 m |
4.8 hrs |
|
HLY-04-02-030(BC3.2)
|
06/18/04 |
19:20 |
71.625 |
-156.118 |
159 m |
1.4 hrs |
|
HLY-04-02-031(BC3)
|
06/19/04 |
02:24 |
71.583 |
-156.132 |
178 m |
26.2 hrs |
|
HLY-04-02-032(BC3.4)
|
06/20/04 |
06:03 |
71.548 |
-155.858 |
202 m |
2.2 hrs |
|
HLY-04-02-033(BC3.5)
|
06/20/04 |
08:53 |
71.532 |
-155.812 |
109 m |
0.9 hrs |
|
HLY-04-02-034(BC2)
|
06/20/04 |
15:53 |
71.397 |
-157.588 |
120 m |
15.6 hrs |
|
HLY-04-02-035(BC1)
|
06/21/04 |
12:50 |
71.085 |
-159.526 |
158 m |
4.0 hrs |
|
HLY-04-02-VPR_02
BC1.4) |
06/21/04 |
18:40 |
71.044 |
-159.332 |
72 m |
0.1 hrs |
|
HLY-04-02-VPR_03
(BC1.2) |
06/21/04 |
19:30 |
71.104 |
-159.517 |
68 m |
0.1 hrs |
Note: time, latitude, longitude and depth are for the start
time of each station.
PI Reports (by sequence of events
during standard process station):
1a. Service Hydrography Measurements
(PI: Jim Swift, Dean Stockwell (both onboard), Andreas Muenchow (ADCP); on
board team members: Doug Masten, Robert Palomares, Kristin Sanborn, Dan
Schuller,Jennifer Sheldon, Dave Huntley, and Dean Stockwell
The SBI Service
Measurement Program was represented on HLY0402 by David Huntley (University of
Delaware) working on ADCP, Dean Stockwell (University of Alaska, Fairbanks)
working on chlorophyll and other pigments, and a six person group from the UCSD
Scripps Institution of Oceanography working on CTD/rosette casts and salinity,
dissolved oxygen, and nutrient analyses.
The six persons were Doug Masten, Robert Palomares, Kristin Sanborn, Dan
Schuller, Jennifer Sheldon, and James Swift.
This report covers the activities of the SIO group.
The HLY0402 CTD
package included a SeaBird 911+ CTD with dual conductivity and temperature
sensors, an SBE43 dissolved oxygen probe, a fluorometer, a transmissometer, a
Haardt fluorometer, a PAR sensor, and an altimeter. A SeaBird Carrousel was used to control closure of 12 30-liter
Niskin bottles. The CTD operator sat
next to the CTD winch operator, and also had visual access to the starboard
staging bay (rosette room) and starboard A-frame launch area. This was a nearly ideal arrangement and it
worked very well.
Except for the last
two sites occupied during HLY0402, which were Video Plankton Recorder-only
stations, and a handful of XCTD profiles collected underway, the CTD package
was used at every station, with from 1-8 CTD casts per station. During a long mid-cruise traverse the
CTD/rosette package received service, during which 6 springs were replaced due
to rust developing on ends, and 12 end cap O-rings were replaced due to wear
damage. Although all of the 30-liter
bottles appeared to be in excellent condition, on most HLY0402 casts a good
seal failed to develop on one bottle (typically), resulting in a leaking
bottle. These were due in almost every
case to a portion of an O-ring slipping from its groove. In every case the suspect O-ring was
inspected, and replaced if necessary.
In general a different bottle then leaked. Full inspections were frequent, and at least twice during the
cruise all O-rings were. Care was used
to measure O-rings to locate those least likely to slip out, but to no
avail. This was the only notable
deficiency in the hydrographic measurements program. Because no solution was found, it bears further thought and
effort before the next SBI cruise with this package.
The Healy's Guildline
AutoSal salinometer was used to analyze salinity samples. The salinometer ran fine. Bottle salt data quality was excellent,
exceeding SBI data quality specifications.
An ODF oxygen
autotitrator was used to run bottle oxygen samples from SBI productivity and
service casts. The system ran well,
with very few overtitrations or backtitrations. Oxygen data quality was excellent, exceeding SBI data quality
specifications.
A six-channel
nutrient autoanalyzer was used to analyze samples, including those from the
main SBI stations as well as ancillary samples from 5 different shipboard
science groups. The autoanalyzer ran
well. Nutrient data quality was
excellent, exceeding SBI data quality specifications.
Data processing went
very well, with both CTD post-cast processing and bottle data examination up to
date at nearly all times during the cruise.
The placement of the CTD sensors and the design of the rosette as
compared to 2002 yielded noticeably cleaner CTD profiles. Also, the winch speed
controls were much smoother than in 2002, causing profiles with less
"shed-wakes". WHP-Exchange
format CTD and bottle data files were updated daily. Additionally, bottle data reports, available for each station and
updated as needed, provided both a quick tabular look at the data for each cast
and an easy-to-use format for examining the data comments. (The data comments form the basis for
assignment of data quality codes other than that for "good value".) Standardized CTD plots were generated for
each profile and made available. All
data, including raw values and comments, are archived by ODF.
Samples for pigment
analyses were drawn from a subset of the rosette bottles at service casts and
producitivity casts. The samples were analyzed on board by Dr. Dean Stockwell
from the University of Alaska Fairbanks. Six to eight depths per cast were
sampled and processed. In addition, samples were processed from some
bio-optical stations and for Dr. David Kirchman. Data entry into the JOSS data
server followed after quality control checks on spreadsheet information were
concluded.
Interpretative
activities related to the CTD/hydrographic data focused on preparation and
distribution of short reports on HLY0402 observations. The titles of the .pdf versions:
Diomede_staplots_allyears.pdf
EHS_2002vs2003_discuss.pdf
East_Hanna_Shoals_discuss.pdf
HLY0402_22to26_discuss.pdf
HLY0402_22to27_CTDdiscuss.pdf
HLY0402_22to27_halocline.pdf
HLY0402_BC_discuss.pdf
HLY0402_BC3_CTDdiscuss.pdf
HLY0402_BeringStrCTD.pdf
HLY0402_CTD_27_28_discuss.pdf
HLY0402_CTD_27_discuss.pdf
HLY0402_CTD_TvsS_note.pdf
HLY0402_sta16CTDdiscuss.pdf
HLY0402_sta24and26_discuss.pdf
HV02_botdata_comparison.pdf
SBI_brinewaters_note.pdf
ShelfBottomCircNote.pdf
SummerWaterDiscuss.ppt
In general,
hydrographic characteristics observed during HYL0402 are similar to those
observed during the HLY0201 spring cruise, which took place at about the same
time of year. There is a sense in the
data that the winter shelf waters in 2004 are slightly less saline, and hence
slightly less dense, than in 2002.
Nutrient distributions versus salinity on the East Hanna Shoals section
in 2004 were nearly the same as in 2002, though the vertical sections reveal a
stronger sense of shelf-slope similarity (or connection) in 2004 than in
2002. One should recall, however, that
the slope waters could be fed from the Herald Valley outflow, west of the
section, and may not necessarily have "slid off the shelf". Thus the similarity may be coincidental. [Preliminary ADCP velocities in the layer
just above (from Andreas Munchow) do, however, suggest off-shelf flow.] Halocline waters on the section just east of
Barrow Canyon showed a major intrusion of better oxygenated, lower nutrient
waters, splitting the low-oxygen, high-nutrient halocline waters into two
layers. A somewhat similar feature was
seen in the HLY0201 data, suggesting that this represents annual post-winter
injection of new halocline waters into the slope region. The water mass structure in the outer Barrow
Canyon region showed influences of both older and younger halocline
waters. In mid- and upper-Barrow
Canyon, the colder, higher-oxygen waters dominated, consistent with a view that
there is outflow of the colder upper-canyon waters into the mouth of the
canyon, where they mix with the warmer, lower-oxygen layers. These are highly preliminary observations
and can be expected to change when more time is available to study the data.
The full SBI service
final documentation is provided in Appendix A of this cruise report as well as
can be found on the SBI JOSS website http://www.joss.ucar.edu/sbi/catalog_hly-04-02/index.html.
1b. PI: Andreas Muenchow; onboard team member: David A.
Huntley, University of Delaware. ADCP
Introduction
The USCGC Healy has
two acoustic Doppler current profilers (ADCP) mounted in its hull. One is an Ocean Surveyor 75 kHz phased-array
system (OS75) and the other is a Broadband 153 kHz discrete-array system
(BB153). Both systems are up and
running, although the BB153 system is still being vetted to ascertain it’s data
collection reliability. The OS75 is
functioning in both the broadband and narrowband modes. Both the OS75 and BB153 systems integrate
acoustic data with the ship’s gyro, the aft P-code Trimble Centurion GPS and
the Ashtech attitude GPS data. All data
are collected onto the local computer and then manually transferred to the
archiving computer (SNAP1) for both systems.
The only change in
system operation since the 2004 shakedown cruise was the installation of a new
data/power cable connecting the BB153 transducer assembly to that unit’s deck
box. The success of that installation
will be reported in a future system report.
Data Collection
The BB153 is setup to
collect 50 6-meter bins and bottom track to 800 meters. Blanking is set to 4 meters.
The OS75 has four
distinct data collection setups. They
are designed for different depth requirements as follows:
Shallow - interleaved
broad- and narrow-band pings plus bottom track to 100m.
Broadband in 15 4m bins
Narrowband in 8 8m bins
Mid-water- narrowband
only plus bottom track to 400m
Narrowband in 50 8m bins to 340m
Mid-water 250+ -
narrowband only plus bottom track to 1100m
55 8m bins to 375m
Deep water –
narrowband only but no bottom track
55 8m bins
All OS75
configurations have 10m blanking.
Data is collected
onto the local machines and then transferred ‘manually’ to the archive
system. The operator completes this
file transfer each morning around 0730 via Windows Explorer copy and paste,
this leaves a copy of the file on the host computer to facilitate file number
advance. The manual transfer is
necessary due to a buffer overflow problem and system hang-up that occurs when
VmDas attempts to automatically write to the archival system at the same time
as it is collecting and writing data locally.
The system hang-up and buffer overflow do not occur when this feature is
disabled in VmDas.
Performance
The OS75 has performed
normally for most of the cruise, so far.
Both systems have been affected by vibration from ice breaking, the
intermittent power outages and some system instability primarily due to the
Windows operating system. The BB153 has
had more system instabilities than the OS75 including system lockup that could
only be corrected by “hard reboot” or disconnecting the power supply, VmDas
shutdown that was traced to the optical mouse, and the system computer
restarting without any user input. Both
systems have had numerous “ADCPCOMM timeout” errors, however this is simply a
dropped ping and if it does not stop data collection it is not an issue. Consistent NMEA buffer overflows were
occurring on both systems. The problem
was traced to the Ashtech GPS, which was sending data too fast (twice per
second). When the output was reduced to once per second, the buffer overflow
condition was corrected. The OS75 has
had intermittent operating system shut down without user input. The symptom of this is a blue screen and
loss of data collection. The solution
has been to reboot the computer and restart data collection. No indication as to why this is occurring.
Future
Recommendations
Currently the system
computers and the deck units for both ADCP’s are not vibration isolated. This is suspect in causing intermittent
hardware shutdown. I recommend that all
ADCP system parts be mounted similarly to the SDN computer system, which is
vibration isolated.
Both system computers
are currently running Windows 2000 and should be upgraded to Windows XP. This may help with the system
instability. VmDas will run acceptably
with this operating system. All unnecessary
programs should be removed from the computers during install.
A method of archiving
the local data should be found that is invisible to the VmDas software. The current “dual drive” system in the
software package does not function well and results in data loss when the
operating system shuts down.
2. Sea ice working
group: PI: Rolf Gradinger; onboard team members: Heike Merkel, Sarah Story, and
Kazu Tateyama
The sea-ice
working-group investigated the magnitude and the controlling factors of sea ice
algal primary production in the SBI region. Our objectives for the spring 2004
expedition included: 1) continuous under-way measurements of ice thickness with
an EM31 mounted to the ship’s bow, 2) standardized ice observations in two-hour
intervals, 3) sea ice core analysis for physical, chemical and biological
properties, and 4) measurement of properties of the under-ice water layer.
Under-way measurements
Ice observations
A total of 213 ice
observations were conducted in two-hour intervals between 5/17/04 and 6/21/04.
Each observation consists of a detailed evaluation of ice conditions (ice
concentration, type, sediment content, occurrence of ice algae) supplemented by
digital photography. Ice observations are available on-line in the SBI/JOSS
catalogue.
Continuous indirect ice thickness
measurements
Sea ice thickness
data were collected with an electro-magnetic inductive device (EM) starting May
19 until June 20. Equipped with a laser altimeter and a GPS, mounted on the
port side of the bow, this instrument measures continuously with a frequency of
10Hz the ice thickness and concentration, which will be averaged over 1 and 10
minutes intervals. Data were recorded over a time span of 422 hours in
total. The average combined ice and
snow thickness was 1.68m for this expedition. These data will be compared with data collected in the same region
in August 2003 by the Chinese icebreaker
Xuelon and with satellite microwave data.
Measurements at ice stations
Eleven ice stations
were conducted between May 21 and June 16. Ice thickness and snow depth
measurements were carried our by EM and with a snow stick (Table 1). The combined
distance of the survey line is 5,065 m with measurements being conducted every
5m.
For objectives 3 and
4, three to eight ice cores were taken at each station and used to determine
the vertical distribution of ice temperature and salinity, POC/PON, stable
isotope ratios (d13C, d15N), algal pigments, nutrient concentrations and algal
species composition in relation to the permeability of the sea ice.
Ice thicknesses of
the collected cores ranged between 0.7 to 2.1 m. The sea ice in the study area
was dominated by first year (FYI) sea ice with bulk salinities mostly above 3
as typical for FYI. Along the EHS transect, the algal pigment concentrations
varied greatly with a remarkable decrease towards the north, also supported by
the ice observation record. The maximum algal pigment content of 439 mg Chl a/l occurred in
the bottom layer of the first ice station, where also nutrient levels within
the ice were highest. The bottom concentration at the second ice station was by
a factor of 100 lower at similar ice nutrient levels. The algal pigment levels
in the cores collected along the Barrow Canyon line remained low. The regional
differences are related to changes in ice and snow thickness, light and
latitudinal gradients. Primary production measurements were conducted at nine
stations using stable isotope tracers (13C, 15N). Ice core sections (5cm
thickness each) were collected in the field and centrifuged at 1200 rpm in the
laboratory for porosity and permeability measurements to be conducted with X-ray
tomography and a specifically developed permeameter at UAF. The sections were
taken in continuous 5-cm increments for the bottommost 30 cm (6 sections) and
every other section was taken for the core sections above 30 cm (another 6
sections).
Under-ice measurements
Under-ice light intensities were
determined with a LICOR 4pi sensor. PAR values under the ice were between 0.1
to 20% of the incoming radiation, measured simultaneously with a 2pi sensor.
Under-ice temperature and salinity gradients were assessed with a hand-held CTD
system down to a water depth of 10 to 20m. We also measured under-ice currents
with two current meters in close proximity to the biological coring site for
later correlation of current speeds and directions to biological activity. While
an Acoustic Doppler Current Profiler (ADV) was deployed close to the ice-water
interface at depths between 0.50 and 1.80 meters and time intervals between 1
and 18 hours, the second current meter was deployed at a depth of 4 meters
below the ice-water interface for the duration of the station. Ship positions
and drift speeds were downloaded from the ship’s server for adjustment of the
local currents.
Table 1: Measurements conducted during ice stations in
spring 2004
|
Date |
Ice temperature |
Ice salinity |
Under-ice T/S |
Under-ice currents |
Light (PAR) |
Algal pigments |
POC/PON |
EM transect |
comments |
|
40521 |
x |
x |
x |
- |
x |
x |
x |
x |
FYI |
|
40524 |
x |
x |
x |
x |
x |
x |
x |
x |
MYI |
|
40526 |
x |
x |
- |
- |
x |
x |
x |
x |
FYI |
|
40530 |
x |
x |
x |
x |
x |
x |
x |
x |
FYI |
|
40531 |
x |
x |
x |
x |
x |
x |
x |
x |
FYI |
|
40602 |
- |
- |
x |
x |
- |
- |
- |
x |
- |
|
40604 |
x |
x |
x |
x |
x |
x |
x |
x |
FYI |
|
40611 |
x |
x |
x |
x |
x |
x |
x |
x |
FYI |
|
40612 |
- |
- |
- |
- |
- |
- |
- |
- |
bear encounter |
|
40614 |
x |
x |
x |
x |
x |
x |
x |
x |
FYI |
|
40616 |
x |
x |
x |
x |
x |
x |
x |
x |
FYI |
3. Primary Production, Bio-optics, and Remote Sensing of
Ocean Color
PI: Glenn Cota; onboard sampling team: David Ruble, Victoria
Hill and Xiaoju Pan
3.1 Objectives
Characterization of
bio-optical properties, the development of relationships between biological
properties of the water column and optical measurements. Collection of
validation points for SeaWiFS and MODIS.
3.2 Observations
Measurement of
primary productivity using c14 and nutrient uptake (nitrate and ammonium)
experiments at 6 light depths 100%, 50%, 30%, 15%, 5%, 1%. Discrete optical
measurements of absorption of particulate and soluble material, continuous
profile measurements of absorption, attenuation, backscatter, upwelling
radiance, and downwelling irradiance. Samples filtered for later analysis of
total suspended material and pigments (HPLC). Surface measurement of incidence
irradiance and surface reflectance, sunphotometer and ozone.
3.3 Progress
We experienced setup
problems with the new passive optical instruments, this has been resolved,
however data for the first week was unobtainable. Due to heavy ice conditions and almost continuous cloud cover
there have been no validation points for SeaWiFS or MODIS.
Experimental Observations
Experimental
observations have included primary production as well as nitrogen uptake.
Simulated in situ deck incubations continue to be problematic. The uncontaminated seawater system has been
out of service due to the ice conditions. The Coast Guard set up an alternative
flow-thru system using the forward ballast tank to hold water, which is then
pumped through the incubators. Temperature regulation in this system remains a
challenge, warming occurring as the ballast tanks can only be filled whilst on
station or in light ice conditions. Several production stations have been
missed, as the ship was unable to find open water within the time window.
|
Date |
SBI Station |
Secchi (m) |
HPLC |
Cell counts |
Primary Production |
15NO3 |
15NH4 |
|
5/18/2004 |
06 HV-1 |
4.6 |
+ |
+ |
+ |
+ |
+ |
|
5/21/2004 |
07 HV-2 |
6.4 |
+ |
+ |
+ |
+ |
+ |
|
5/22/2004 |
08 Prod |
6.6 |
+ |
+ |
+ |
+ |
+ |
|
5/24/2004 |
09
EHS-0 |
10.9 |
+ |
+ |
+ |
+ |
+ |
|
5/27/2004 |
11 prod |
7.2 |
+ |
+ |
+ |
+ |
+ |
|
6/01/2004 |
17
EHS-5 |
17.5 |
+ |
+ |
+ |
+ |
+ |
|
6/03/2004 |
19
EHS-6 |
20.5 |
+ |
+ |
+ |
+ |
+ |
|
6/04/2004 |
20
EHS-7 |
32.5 |
+ |
+ |
+ |
+ |
+ |
|
6/08/2004 |
22 SB-1 |
12.9 |
+ |
+ |
+ |
+ |
+ |
|
6/12/2004 |
24 SB-5 |
7.7 |
+ |
+ |
+ |
+ |
+ |
|
6/13/2004 |
25 Prod |
8.9 |
+ |
+ |
+ |
+ |
+ |
|
6/14/2004 |
26 BC-5 |
8 |
+ |
+ |
+ |
+ |
+ |
|
6/15/2004 |
27 BC-6 |
15.3 |
+ |
+ |
+ |
+ |
+ |
|
6/16/2004 |
28 BC-4 |
8.7 |
+ |
+ |
+ |
+ |
+ |
|
6/18/2004 |
29 BC-3.1 |
8.1 |
+ |
+ |
+ |
+ |
+ |
|
6/19/2004 |
31 BC-3 |
7.8 |
+ |
+ |
+ |
+ |
+ |
|
6/20/2004 |
34 BC-2 |
7.9 |
+ |
+ |
+ |
+ |
+ |
Phytoplankton pigment
(HPLC) and cell count sample samples have been collected from the surface and
the subsurface chlorophyll maximum at experimental and optical stations. At
several stations samples were also filtered through a 5um pore size in addition
to the usual 0.7um to provide size
fractionated HPLC data. At Barrow Canyon, deep chlorophyll peaks at ~100-150m
were found these were also sampled for HPLC and cell counts.
Optical Observations
Active optical
observations have been very successful, with data also collected at times when
experimental stations were unobtainable. Discrete absorption spectra of
particulate and soluble material have been made to compare with the active
profiles. Passive optics measurements at four stations were missed due to
instrumentation problems.. This has included surface optics (SO) and passive
optics profiles (PO), these problems have now been solved and it is hoped that
the high spectral resolution data now available will yield interesting results.
Few SO observations have been made due to 10/10th ice cover or wrong
ship – sun alignment.
|
|
|
|
|
SfcOpt |
Sun |
PassOpt |
ActOpt |
ActOpt |
|
Station # |
SBI Station # |
Secchi depth |
Water Depth |
SAS |
Micro Tops |
Pro/Ref |
AC9 |
HS6 |
|
200405181 |
06 HV-1 |
4.6 |
51 |
|
|
|
+ |
+ |
|
200405201 |
06.5 bio-opt. |
|
50 |
|
|
|
+ |
+ |
|
200405211 |
07 HV-2 |
6.4 |
50 |
|
|
|
+ |
+ |
|
200405221 |
08 Prod |