Final Cruise Report: Western Arctic Shelf-Basin Interactions (SBI) Spring Cruise HLY-02-01 (5 May-15 June 2002) Edited by Jackie Grebmeier, Chief Scientist University of Tennessee, Knoxville, TN 37922 USA email: jgrebmei@utk.edu

A. Introduction

The field phase of the Western Arctic Shelf-Basin Interactions (SBI) project completed a successful scientific mission to the Arctic on the new USCGC Healy icebreaker 5 May -15 June 2002. This was the first interdisciplinary research cruise to this region by a science vessel at this time of year. About a dozen interdisciplinary research projects were included in the ship-based program, ranging from hydrographic measurements to 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. Thirty-nine stations were occupied in the northern Bering Sea (test station), the Chukchi Sea shelf (Herald Valley [HV] transect), the Chukchi outer shelf to Arctic Basin lines (West Hanna Shoal [WHS] and East Hanna Shoal [EHS] transect lines), stations near Pt. Barrow, and the Barrow Canyon (BC) transect (Figure 1). Some regions in the study area had lighter ice cover than expected, although normal heavy ice limited sampling in the northwest region of the Chukchi Sea and the eastern most line in the Beaufort Sea.

The SBI project is an interdisciplinary program, where physical, biogeochemical and biological measurements were made using a variety of sampling devices. CTD/rosette sampling collected physical and hydrochemical samples. Subsamples from four CTD/rosette casts were used for primary production, chlorophyll content, nutrients, particulate carbon, inorganic carbon, biomarkers, microzooplankton, and radioisotopes. Various nets (vertical, bongo) 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 and metabolism studies. Off-ship sampling by lowering personnel to the ice occurred to undertake ice measurements and to collect ice cores. Shipboard marine mammal surveys from the bridge were undertaken by the US Fish and Wildlife Service (USFWS). Limited helicopter operations were used for ice reconnaissance, during which marine mammal imagery was possible during two sorties.

During the cruise the Joint Office of Science Support (JOSS) group of the University Corporation for Atmospheric Research group maintained a shipboard field catalog that provided real-time data to scientists on the ship and allowed them to track ship and station progress during the cruise. It also assisted the scientists in providing access to the service group datasets and preliminary analyses and acted as an instrument whereby scientists could share their observations and preliminary analyses. The catalog also allowed onshore PIs to follow the progress of the cruise and a limited number of products were mirrored back to a JOSS SBI catalog running in Boulder, Colorado. 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://utk-biogw.bio.utk.edu/SBI.nsf and associated links on that web site. In particular, a highlight summary taken from the PI findings for the spring SBI cruise can be found on the SBI and JOSS webpages.

Figure 1. Station location and cruise track for the spring SBI cruise on the USCGC Healy (HLY-02-01).

B. Cruise Overview and Issues

The cruise initiated in Nome, Alaska, had a test station in the northern Bering Sea, sailed through western Bering Strait and transited NW along the international dateline to the 100 m isobath of NW Chukchi Sea. This entry date and direction into the study region resulted from discussions with the Alaska Eskimo Whaling Commission (AEWC), who were concerned about our transiting through eastern Bering Strait and along the coastline during the spring bowhead whale migration. Despite efforts at communication between groups in Alaska and the SBI management, concerns continued to just before the cruise, specifically related to the timing of the project in May during the spring bowhead whale migration. As part of the resolution, the AEWC was kept informed of our research progress, which was fully available on the JOSS web site, including an updated station location map.

During the cruise, ice conditions were the main limiting factor for not completing two of the 5 transect lines outlined in the HLY-02-01 cruise plan. Heavy ice on the outer Herald Valley line in the Chukchi Sea, slow travel time around a major flow west of Barrow, and heavy ice over the East Barrow line inhibited our working these transect lines. It is estimated 2 days of ship time were lost due to ice-related delays in transit to specific science areas.

The other major limiting factor on the success of the mission was lack of ambient seawater from the start of the cruise. In spite of both scientist and Healy engineering efforts, it took weeks after the cruise started to find a satisfactory resolution of obtaining and maintaining ambient seawater flow for deck-board incubations. An initial NSF-supported refrigerated van system with recirculating pumps and storage tanks was unable to maintain ambient seawater temperatures. The ultimate resolution was provided by the USCG engineering division so that the ship connected a ballast water tank to the bow incubators through a system for providing 7 hose connections to the incubators. When the seawater in the ballast tank warmed up, science requested a dumping of the water in transit and a subsequent refill on station, which occurred using air operated pumps (AOPs) provided by the USCG. The positive attitude of the USCG in resolving this situation and collaboration between science and USCG enabled a viable resolution to the ambient seawater needs of the primary production and zooplankton groups. It should be noted that there was steady heating of the ballast seawater over the daily warming cycle, especially under clear skies. It was during such good weather that the “dump and pump” technique was most used. Further information on the ambient seawater bow system can be viewed in Appendix A. It should be noted that although it was speculated that these daily temperature swings in the deck incubators would be major problem for the summer SBI cruise, this has not occurred. Subsequent to the end of the spring SBI cruise the Engineering Officer, Neil Meister, had a second 7-hose connector system built and installed for delivering ambient seawater to both sides of the ship, which resulted in sufficient flow to maintain ambient seawater during the summer cruise most of the time.

The Captain, officers and crew of the USCGC Healy were very professional and helpful, being essential to the success of the cruise goals. We appreciated the continued, professional support provided by Captain David Visneski, Operations Officer Joe Segalla, Executive Officer Doug Russell, Engineering Officer Neil Meister, and Master Chief Navigator George Schwarz. Valuable support for science was provided by the lead Marine Science Technician Glen Hendrickson, and the other Marine Science Technicians (Sean Kuhn, Suzanne Scriven, Bridget Cullers, and Michael Hamerski), along with the Science Officer Mike Woodrum. The Aviation Detachment under the direction of Mike Platt provided essential logistical support for ice surveys and limited science operations. SBI land logistical support was ably provided by Andy Heiberg of the University of Washington.

C. Summary of Science Reports

Stations occupied during HLY-02-01 were in the northern Bering Sea (test station), the Chukchi Sea shelf (HV transect), the Chukchi outer shelf to Arctic Basin lines (West Hanna Shoal: WHS transect), stations near Pt. Barrow, and the Barrow Canyon (BC) line. Table 1 provides a general summary of station location, target depth, station duration, 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/).

The following science summaries include sampling collection information and preliminary findings. In addition, three appendices are attached: Appendix 1 is a summary of ballast tank information; Appendix 2 is the final service team hydrographic report, and Appendix 3a and 3b are the ADCP reports. All appendices, and a highlights summary (based on the current cruise report) can be found on the JOSS webpage: http://www.joss.ucar.edu/sbi/catalog - JOSS SBI Field Catalog.

Table 1. Station summary for the spring SBI cruise HLY-02-01.

STATION NO.	DATE	MAP	TIME(UTC)	LATITUDE	LONGITUDE	TARGET DEPTH	DURATION (HRS)	REMARKS
HLY-02-01-000	05/08/02	MAP	1900	64.96N	169.14W	50m	12.5 hrs	Event Log
HLY-02-01-001	05/10/02	MAP	0546	67.50N	168.91W	50m	19.32 hrs	Event Log
HLY-02-01-002	05/12/02	MAP	1810	70.63N	167.45W	50m	10.78 hrs	Event Log
HLY-02-01-003	05/14/02	MAP	1620	71.92N	166.24W	50m	9.88 hrs	Event Log
HLY-02-01-004	05/15/02	MAP	1859	71.62N	166.00W	50m	1.38 hrs	Event Log
HLY-02-01-005	05/17/02	MAP	0417	72.71N	161.24W	50m	3.58 hrs	Event Log
HLY-02-01-006	05/17/02	MAP	1702	72.91N	160.55W	75m	12.68 hrs	Event Log
HLY-02-01-007	05/18/02	MAP	0835	73.03N	160.48W	165m	12.35 hrs	Event Log
HLY-02-01-008	05/19/02	MAP	0145	73.24N	159.59W	500m	13.78 hrs	Event Log
HLY-02-01-009	05/19/02	MAP	1822	73.28N	160.11W	1200m	20.88 hrs	Event Log
HLY-02-01-010	05/20/02	MAP	2104	73.46N	159.85W	2000m	19.00 hrs	Event Log
HLY-02-01-011	05/21/02	MAP	1820	73.74N	158.95W	3000m	29.90 hrs	Event Log
HLY-02-01-012	05/23/02	MAP	1013	73.44N	157.53W	3000m	24.23 hrs	Event Log
HLY-02-01-013	05/24/02	MAP	1930	73.33N	158.19W	2400m	2.35 hrs	Event Log
HLY-02-01-014	05/25/02	MAP	0336	73.10N	158.16W	2100m	21.25 hrs	Event Log
HLY-02-01-015	05/26/02	MAP	0950	73.03N	157.93W	2000m	0.50 hrs	Event Log
HLY-02-01-016	05/26/02	MAP	2354	72.87N	158.26W	1100m	13.35 hrs	Event Log
HLY-02-01-017	05/27/02	MAP	1623	72.85N	158.48W	500m	16.87 hrs	Event Log
HLY-02-01-018	05/28/02	MAP	1522	72.74N	158.61W	200m	15.47 hrs	Event Log
HLY-02-01-019	05/29/02	MAP	1547	72.60N	158.74W	100m	10.22 hrs	Event Log
HLY-02-01-020	05/30/02	MAP	0813	72.46N	159.44W	70m	0.22 hrs	Event Log
HLY-02-01-021	05/30/02	MAP	1108	72.34N	159.71W	60m	0.25 hrs	Event Log
HLY-02-01-022	05/30/02	MAP	1530	72.24N	159.77W	50m	13.40 hrs	Event Log
HLY-02-01-023	06/01/02	MAP	1637	71.40N	158.13W	90m	2.12 hrs	Event Log
HLY-02-01-024	06/02/02	MAP	1537	71.81N	155.68W	100m	11.52 hrs	Event Log
HLY-02-01-025	06/03/02	MAP	0658	71.72N	155.41W	200m	0.38 hrs	Event Log
HLY-02-01-026	06/03/02	MAP	1525	71.55N	154.56W	40m	1.45 hrs	Event Log
HLY-02-01-027	06/04/02	MAP	0730	71.49N	153.90W	50m	4.93 hrs	Event Log
HLY-02-01-028	06/04/02	MAP	1610	71.70N	154.22W	90m	1.38 hrs	Event Log
HLY-02-01-029	06/04/02	MAP	1853	71.78N	154.40W	100m	0.50 hrs	Event Log
HLY-02-01-030	06/05/02	MAP	0000	71.83N	154.62W	200m	1.00 hrs	Event Log
HLY-02-01-031	06/05/02	MAP	0409	71.93N	154.82W	500m	15.18 hrs	Event Log
HLY-02-01-032	06/06/02	MAP	0120	72.06N	154.42W	1000m	20.88 hrs	Event Log
HLY-02-01-033	06/07/02	MAP	0722	72.19N	154.40W	2000m	19.57 hrs	Event Log
HLY-02-01-034	06/08/02	MAP	1810	72.53N	154.50W	3000m	21.43 hrs	Event Log
HLY-02-01-035	06/10/02	MAP	0015	72.18N	155.04W	1000m	2.43 hrs	Event Log
HLY-02-01-036	06/10/02	MAP	1630	71.90N	155.66W	125m	2.13 hrs	Event Log
HLY-02-01-037	06/11/02	MAP	0346	71.65N	155.76W	200m	10.60 hrs	Event Log
HLY-02-01-038	06/12/02	MAP	0100	71.55N	156.20W	160m	1.50 hrs	Event Log
HLY-02-01-039	06/12/02	MAP	1346	71.40N	157.17W	100m	11.85 hrs	Event Log

1. Hydrographic Measurements Team

Lou Codispoti: lead on-board co-PI; Jim Swift: lead PI; Kristin Sanborn, Dean Stockwell, Robert Palomares, Doug Masten, Charlie Flagg, Erik Haberkern, and Bob Williams: on-board team members

Preliminary Data Analysis:

Hydrographics-Over the length of the oceanographic cruise 135 conductivity-temperature-depth (CTD)/rosette casts to depths as great as 3,000 m were taken at 39 stations. "Raw" CTD plots were made immediately after each cast to guide sampling during subsequent casts. Edited data were mounted on the JOSS web site within ~ 24 hrs. Plots of our data in the form of vertical profiles, TS plots, histograms and sections have been completed and been made available to participants. We also performed nutrient analyses for samples collected from the ice, and for various incubation samples. These data were edited and provided to the PI’s who supplied the samples included CTD-temperature, CTD-salinity, CTD-dissolved oxygen, light transmission, fluorometric chlorophyll, fluorometric dissolved organic matter (cDOM; Haardt, fluorometer), and PAR (Photosynthetically Active Radiation) determinations. Bottle samples were analyzed for salinity, dissolved oxygen, ammonium, nitrate, nitrite, phosphate, dissolved silicon, urea and chlorophyll. . A complete description of the service team methods is provided in the “Service group Cruise Summary Report (FINAL) under Research Products (Station) at http://sbi/catalog_hly-02-01/station/. Information on the ADCP equipment on the Healy is provided in two documents, also on the JOSS web site: “Healy_ADCPs.doc” and “SBI_ADCP_Data_Collection”, both located at http://sbi/catalog_hly-02-01/station/adcp_results/.

The general Temperature and Salinity structure was more or less as expected. Interesting features included temperature fine-structure in the halocline and near the core of the Atlantic Water. Surface salinities of less than 30 were recorded as the ship moved eastward and offshore into the Beaufort Sea, presumably due to a general freshening of the surface waters as the cruise departed the region under the direct influence of the Bering Strait inflow, and to the accumulated effects of ice-melt and river runoff. Notably, at station 10 on the EHS line at the outer slope, water with temperatures above 0°C was encountered at a depth of ~35 m in a shallow temperature maximum. Shallow temperature maxima were also encountered at stations 8 and 9 on the EHS line, but did not appear to be so well developed. This bolus of water with temperatures >-0.5C disappeared on the next section occupied to the east (stations 12-22), but there was a relatively warm intrusion with colder temperatures present at the same approximate depths at several additional stations, including stations taken in Barrow Canyon further east off Pt. Barrow. It may also be worth noting that the T and Salinity vs depth profiles in Barrow Canyon seemed to vary more from station to station than they did in the sections outside of the Canyon, indicative of the dynamic nature of the both off- and on-shore current flow within this canyon. In addition, the western Chukchi Sea showed two regions of increased southeastward flow near the shelf edge: one right at the shelf break transporting shelf-origin water, and one a bit offshore and deep transporting warm Atlantic water. An eddy like feature was found centered near 100-150 m depth on the ESH line, with a warm center and cold water on either side of it, indicative of a strong shoaling of Atlantic water properties onshore. Understanding these features will aid in investigating how physical and biochemical products are transported from the shelf to basin.

The nutrient regime measured was more or less as expected, with high initial nutrient concentrations over the shelf near Bering Strait, decreasing as we proceeded eastward and seaward. Initially, nitrate concentrations at the sea-surface exceeded 15 micromolar (µM), phosphate exceeded 1.8 µM, and surface silicate concentrations exceeded 40 µM, but surface nitrate concentrations became small by the time we reached deep water. Phosphate and silicate were always present in appreciable concentrations, but nitrate was sometimes depleted, indicative of post phytoplankton bloom conditions. Although there was some variability, there was a strong onshore-offshore nitrate gradient in our first two sections (stations, 5-11 [EHS line] and 13-22 [WHS line]. Nitrate was relatively abundant near shore, with maximum surface concentrations >7 µM at the innermost station and decreasing to essentially 0 µM at the outermost station. Although high nitrate was characteristic of the study region, we did encounter conditions that suggested the initiation of an inshore phytoplankton bloom on the Barrow Canyon line. While we expected a strong decrease in nutrients as we departed the region under the direct influence of the Bering Strait inflow, the lack of nitrate in surface waters at the offshore stations was somewhat surprising since we arrived early in the "growing" season. Examination of the nitrate, dissolved oxygen, and chlorophyll data suggested an initial surface nitrate concentration of ~ 3 µM which has essentially been consumed by the time of our cruise. In other words, the spring bloom in this nutrient poor region may have already occurred, at least in the surface layer. Observations and comments on productivity in this region are scarce, so it is uncertain whether this early blooming is "normal" or related to the recent warming of the Arctic. Certainly, the ice seemed relatively thin to some of us in regions of nitrate draw down. We are also curious as to whether or not a later subsurface bloom may occur at the offshore sites since sunlight will continue to increase until 21 June and ice-cover will decrease until ~October, perhaps permitting sufficient light for phytoplankton growth to reach the uppermost halocline.

As we entered deep water, we encountered the expected nutrient maxima at about 125 m associated with Bering Strait/Chukchi waters that form the upper halocline. Nutrient concentrations in this maxima appear to be a bit lower than in the past, but whether this is correlated with the recent warming and freshening of the Bering Strait inflow, or simply a normal space/time related difference between our data and past experiments will require further analysis. As is typical, dissolved silicon (silicate) was the best nutrient for tracing this maximum because this nutrient is enriched 3-4 fold in the Bering Strait waters relative to the waters supplied to the Arctic from the Atlantic. The nearshore phytoplankton bloom appeared to be stripping nutrients from the surface waters whereas they were regenerated at depth and transported offshore. Evidence for this conclusion was provided by our observations of the highest subsurface silicate maximum in the Barrow Canyon section and by the light transmission data that suggested near surface and bottom layers were particle rich in the inshore portion of the Barrow Canyon section, with relatively clear layer in between.

Approximately coincident with the nutrient maxima was an N** star minimum, and a maximum in "lignin" as determined with the Haardt fluorometer. Negative N-double star suggests an excess

of the effects of denitrification over nitrogen fixation in a water parcel, and this parameter has

proven to be an excellent water mass tracer with the most negative values occurring in the Pacific influenced waters and positive values occurring in waters of Atlantic origin. In general, the distribution of this parameter is as expected with negative values entering via Bering

Strait and becoming more negative as the Pacific waters reside in the Arctic Ocean and are

subjected to the effects of denitrification in arctic shelf sediments. The Atlantic Waters enter with positive values that decrease a bit as these deeper waters reside in the Arctic. Observations in Fram Strait surface waters suggest that the Atlantic Water enters with an N** value of ~ + 2, and our data suggest that this value has decreased somewhat in the core of the Atlantic Water found during our cruise. There may be a substantial decrease in the Atlantic waters that form the lower halocline, but to calculate this, we have to sort out mixing processes between the upper and lower halocline. Results from the Haardt fluorometer may help us to do this, since the core of the maxima in these data appears to be slightly deeper than the N** mimimum. This suggests that the Haardt fluorometer maximum contains an appreciable component of waters from the lower halocline that are of Atlantic and riverine origin.

Ammonium concentrations over the shelf sometimes reached concentrations of several µM, and distributions of ammonium, nitrite and light transmission in our three cross-shelf sections suggest plumes of material coming off the shelf and entering the basin. Of course, the process is not strictly two dimensional as suggested by the sections, but the occurrence of such plumes in both sections suggests a mean cross-sectional transport from the shelf into the basin. Preliminary results from sediment metabolism experiments support an efflux of ammonium and silica from the sediments due to ongoing carbon transformation processes, results which support the shelf regeneration of biochemical products outlined previously. In general, nitrite and urea concentrations in the water column were low, and except for one high urea concentration the water column concentrations were low and essentially within the detection limit of our method. High urea concentrations did occur, however, in some of the ice samples.

2. Carbon and Nitrogen Cycling in Seawater

Charlie Farmer and Tadayasu Uchiyama: on-board team members; Dennis Hansell and Nick Bates: PIs

Measurements: Total Alkalinity, DIC (Total CO₂), Dissolved Organic Carbon, Total Dissolved Nitrogen, Particulate Organic Carbon, Particulate Nitrogen

Station	Gear Type	Samples Collected	Comments
000	CTD	Sampled Bottles 1, 2, 4, 5, 6, 7, 9, 10, 11, 12
001	CTD	Sampled all Bottles except 8	Bottle #8 did not fire
002	CTD	Sampled Bottles 2, 4, 5, 6, 9, 10, 11, 12
003	CTD	Sampled Bottles 2, 3, 4, 5, 6, 7, 8, 10, 12.	Water froze in Bottles prior to sampling
005	CTD	Sampled Bottles 1, 2, 3, 4, 5, 6, 7, 9, 11, 12
006	CTD	Sampled all 12 Bottles
007	CTD	Sampled all 12 Bottles
008	CTD	Sampled all 12 Bottles
009	CTD	Cast 3 Sampled Bottles 1, 5, 9, 11 Cast 4 Sampled Bottles 1, 4, 7, 8, 9, 10, 11, 12
010	CTD	Cast 2, Sampled Bottles 2, 5, 7, 8, 9, 10, 11, 12 Cast 3, Sampled Bottles 1,6,10, 12
011	CTD	Cast 3 Sampled Bottles 2, 9, 10, 11, 12 Cast 4 Sampled Bottles 3, 6, 7, 8, 9, 10, 11
012	CTD	Cast 1 Sampled Bottles 3, 8, 9, 10, 11, 12 Cast 2 Sampled Bottles 3, 4, 6, 8, 9, 11
014	CTD	Cast 1 Sampled Bottles 2, 6, 9, 11, 12 Cast 2 Sampled Bottles 3, 5, 7, 8, 9, 10, 11
016	CTD	Cast 1 Sampled Bottles 2, 7, 9, 11, 12 Cast 2 Sampled Bottles 2, 5, 7, 8, 9, 10, 11
017	CTD	Sampled all 12 Bottles
018	CTD	Sampled all 12 Bottles
019	CTD	Sampled Bottles 1, 3, 4, 5, 6, 7, 8, 9, 10, 11
022	CTD	Sampled all 12 Bottles
024	CTD	Sampled all 12 Bottles
027	CTD	Sampled Bottles 2, 3, 4, 5, 6, 7, 8, 10, 12
029	CTD	Sampled all 12 Bottles
030	CTD	Sampled all 12 Bottles
031	CTD	Sampled Bottles 3, 4, 5, 6, 7, 8, 9, 10, 11, 12
032	CTD	Cast 1 Sampled Bottles 1, 2, 3, 4, 5 Total Cast 1 Sampled Bottles 6, 7, 9, 10, 11 Cast 6 Sampled all 12 Bottles
033	CTD	Cast 1 Sampled Bottles 1, 2, 3, 4, 5 Total Cast 1 Sampled Bottles 6, 8, 9, 10, 12 Cast 6 Sampled Bottles 3, 5, 7, 8, 9, 10, 11
034	CTD	Cast 2 Sampled Bottles 1, 2, 3, 4, 5, 6, 7 Total Cast 2 Sampled Bottles 1, 8, 9, 11, 12 Cast 3 Sampled Bottles 3, 5, 7, 8, 9, 10, 11
037	CTD	Sampled all 12 Bottles
039	CTD	Sampled all 12 Bottles

Total dissolved Nitrogen were analyzed on board ship, other samples were preserved for return to laboratory for analysis. Currently analysis completed through Station 39, with data being stored on floppy disk, CD-RW and e-mailed to RSMAS for archive.

3. Primary Production, Bio-optics, and Remote Sensing of Ocean Color

Glenn Cota: onboard PI; Dave Ruble, Zhi-Ping Mei and Xiaoju Pan: on-board team members

There have been numerous clear days with good satellite coverage in the southwestern margins of the study area, which are sufficiently ice-and cloud free for extensive ocean color observations. There have been blooms north of Bering Strait, and to a lesser degree along the northwestern Alaskan coast and in areas of ice retreat. NASA has been providing images via ODU with less than a one day lag time, and there have often been multiple overpasses. The day regular sampling ceased (June 13^th) we conducted an open water optics station, which appears to suitable for validation of SeaWiFS and MODIS. This was easily the most important station of the cruise for bio-optical sampling and remote sensing.

Phytoplankton pigment (HPLC) and cell count sample samples have been collected from the surface and the subsurface chlorophyll maximum at experimental and optical stations.

Experimental observations have included primary production as well as nitrogen uptake. Urea concentrations remained below limits of reliable detection (Codispoti, pers comm.), but a number of experiments were run to evaluate utilization. Isotope dilution experiments were done only at select stations.

Simulated in situ deck incubations continue to be problematic. The recirculating supplemental seawater system was only marginally successful for small incubators, and the temperature were closer to ambient. The Coast Guard has set up an alternative flow-thru seawater system with ballast water for deck incubations, but temperature regulation remains challenged. A number of the experiments are compromised by elevated temperatures, and several experiments could not be set up. Several stations have been missed or compromised because the ship could not position properly or in a timely fashion.

Experimental Observations

Date	SBI Station	Secchi depth(m)	HPLC	Cell counts	Primary Production	13CO3	15NO3	15NH4	15N-Urea
5/10/2002	1	5.5	+	+	+	+	+	+
5/14/2002	3	5.5	+	+	+	+	+	+
5/15/2002	4	4.5	+	+	+	+	+	+
5/17/2002	6	15	+	+	+	+	+	+
5/18/2002	7	26	+	+	+	+	+	+
5/19/2002	9	22	+	+	+	+	+	+
5/20/2002	10	26	+	+	+	+	+	+
5/21/2002	11	30	+	+	+	+	+	+
5/23/2002	12	26	+	+	+	+	+	+
5/24/2002	13	19	+	+	+	+	+	+
5/25/2002	14	24	+	+	+	+	+	+
5/27/2002	17	17	+	+	+	+	+	+ IDE
5/28/2002	18	22	+	+	+	+	+	+	+
5/29/2002	19	17	+	+	+	+	+	+	+
5/30/2002	22	15	+	+	+	+	+	+	+
6/01/2002	23	15	+	+	+	+	+	+	+
6/02/2002	24	16	+	+	+	+	+	+	+
6/03/2002	26	10	+	+	+	+	+	+	+
6/04/2002	28	11	+	+	+	+	+	+	+
6/05/2002	31	16	+	+	+	+	+	+	+
6/06/2002	32	20	+	+	+	+	+	+	+
6/07/2002	33	16	+	+	+	+	+	+	+
6/08/2002	34-IS	34	+	+	+	+	+	+	+
6/10/2002	36	20	+	+	+	+	+	+ IDE
6/12/2002	39	5.5	+	+	+	+	+	+

Optical observations have been very successful, but their frequency is less than half that planned. Observations have included surface optics (SO), sun photometry (Sun), passive optical (PO) profiles, and active optical (AO) profiles at daytime stations. Quite a few SO and Sun photometry observations have been made between stations or at multiple times during suitable conditions at a station. These data will be invaluable for refining high latitude bio-optical algorithms. Passive optical observations are being made mostly in small open areas, but also in a variety of ice conditions to evaluate the influence of broken pack ice cover. Satellite validation measurements were impossible at all but the last station due to the prevalence of ice along the ship track.

Optical Observations

				SfcOpt	Sun	PassOpt	ActOpt	ActOpt
ORCA Station #	SBI Station #	Secchi depth	Water Depth	SAS	Micro Tops	Pro/Ref	AC9	HS6
200205081	0					+	+
200205101	1 (AM)	5.5	51				+
200205102	1 (PM)		53			+	+
200205121	2		51	+		+	+	+
200205141	3	5.5	47	+	7-8		+	+
200205151	4	4.5	47	+	9-10		+	+
200205171	6	15	45				+	+
200205181	7	26	171		13-14	+	+	+
200205191	9	22	1217	+		+	+	+
200205201	10	26	1891		17-18	+	+	+
200205211	11 (AM)	30