Expected Datasets from the Alpha Helix 2003 Bering Strait Cruise
(HX-274)
Mooring work:
All three moorings (see Table 1) were successfully and smoothly recovered and redeployed.
CTD and ADCP work:
A total of 123 CTD casts were taken along 8 different sections (see map, Figure 1, and sections in the appendices). The Bering Strait line (BSL) was CTDed twice, once at the start (BSL1) and once at the end (BSL2) of the cruise. At each major section (BSL, MBS, NBS, A3L, CHUK and EEXT) the CTD line was either preceded or followed immediately by an ADCP line run at 7 knots. The longer sections (PHL, CPL and CCL) could not be traversed twice and thus transit between CTD sections was undertaken at a compromise speed of ca. 8 knots, to acquire reasonable ADCP data whilst still maintaining quasi-synopticity of the line.
The CTD package carried sensors for temperature, conductivity, fluorescence, PAR and the comparatively new ISUS nitrate sensor.
Nutrient Analysis work (Whitledge, Thornton, Lee):
A total of 485 nutrient samples were taken and analyzed on board for silicate, phosphate, nitrate, nitrite and ammonia by Whitledge, Thornton and Lee. Preliminary section plots are included in the appendices. In addition, at many stations samples were taken at surface, mid water column and bottom for chlorophyll, and at some stations samples were taken for size-fractionated chlorophyll, fractionated on 20um, 5um and GF/F filters. At the four sites A2, A3, NBS12 and CCL15, primary productivity stations (stable isotope nutrient enrichment primary productivity experiments with 15N-labeled nitrate and ammonia and 13C-labeled carbon) were also run.
Chromophoric Dissolved Organic Matter (CDOM) and DOC
Analysis work and
sampling (Deal, Denton):
A total of 233 CDOM samples and 176 DOC samples were
taken at the 34 sites listed below. Some measurements of CDOM absorption
spectra were made on board, while most of the measurements were made in the
laboratory at the University of Alaska Fairbanks. The DOC samples will be
analyzed post cruise by Celine Guegen, IARC/Frontier.
CDOM and DOC seawater profiles were taken at 34 sites,
namely
July 1: BSL-1,2,3,4,5 and 6,A2P
July 2: A3,A2,A4
July 3: NBS-12,9,6 and 3
July 4: CHUK-1,4 and 8
July 5: PHL1,3,6,9 and 11, CPL2 and 6
July 6: CPL8,CCL20,15 and 10
July 7: CCL6,8 and 4, BSL1,3 and 5
A total of 346 water samples were taken for O18
sampling. Samples were taken at bottom, 5m and (where appropriate) midwater
column at all stations except some of the productivity stations (see bottle
list in the appendices). These samples were sealed with parafilm and
shipped to Lee Cooper at the University
of Tennessee for later analysis. To
ensure the integrity of the bottle samples, when possible salinity samples (ca.
200) were taken from the bottles used for O18 samples.
Seachest data and standard underway meteorological sampling was conducted for the duration of the cruise. These data will be combined with the CTD and ADCP data to elucidate spatial structures.
Mike Schmidt, NASA, kindly supplied to the cruise any Seawifs images collected during the science mission. Although extreme cloud cover prevented collection of a clear image of the entire work area, useful part-area images were collected. These 2-dimensional images (see the appendices will aid analysis of the highly spatially variable water mass structures in the region.