Composition of bottom sediments from the Gulf of California

Abundances of globules, micronodules and their aggregates composed of iron sulfides from bottom sediments of the Gulf of California have been determined together with studies of chemical composition of these sediments.

Downwelling solar irradiance, upwelling solar radiance, sky leaving radiance, and cloud cover observed during ARCHEMHAB study (on Maria S. Merian Leg MSM21/3) from 2012-07-26 to 2012-08-10

The need to obtain ocean color essential climate variables (OC-ECVs) using hyperspectral technology has gained increased interest in recent years. Assessing ocean color on a large scale in high latitude environments using satellite remote sensing is constrained by polar environmental conditions. Nevertheless, on a small scale we can assess ocean color using above-water and in-water remote sensing. Unfortunately, above-water remote sensing can only determine apparent optical properties leaving the sea surface and is susceptible to near surface environmental conditions for example sky and sunglint. Consequently, we have to rely on accurate in-water remote sensing as it can provide both synoptic inherent and apparent optical properties of seawater. We use normalized water leaving radiance LWN or the equivalent remote sensing reflectance RRS from 27 stations to compare the differences in above-water and in-water OC-ECVs. Analysis of above-water and in-water RRS spectra provided very good match-ups (R2 > 0.97, MSE<1.8*10**-7) for all stations. The unbiased percent differences (UPD) between above-water and in-water approaches were determined at common OC-ECVs spectral bands (410, 440, 490, 510 and 555) nm and the classic band ratio (490/555) nm. The spectral average UPD ranged (5 - 110) % and band ratio UPD ranged (0 - 12) %, the latter showing that the 5% uncertainty threshold for ocean color radiometric products is attainable. UPD analysis of these stations West of Greenland, Labrador Sea, Denmark Strait and West of Iceland also suggests that the differences observed are likely a result of environmental and instrumental perturbations.

Lower Jaramillo polarity transition records from ODP Holes 108-665A and 121-758B

Two records of the geomagnetic polarity transition at the beginning of the Jaramillo Subchron (0.97 Ma) have been obtained from sediments in the equatorial Atlantic (Leg 108, Site 665; 2.95°N, 340.33°E) and Indian (Leg 121, Site 758; 5.38°N, 90.35°E) oceans. Both cores yielded high-quality magnetostratigraphic results; however, the relatively low sedimentation rates, the weak magnetizations, and complex demagnetization behavior of some transitional samples suggest that the record of the transitional field behavior may be less reliable. In addition, variations in grain size preclude reliable paleointensity determinations although the remanence in both cores is apparently dominated by magnetite. Despite these possible complications, the two cores yield transitional paths that are neither far-sided nor near-sided. Together with published records that meet minimum reliability standards, the two equatorial records presented here suggest that the lower Jaramillo transitional field morphology was significantly nonaxisymmetric. The mean normal and reversed inclinations from both cores deviate from the inclination expected from a geocentric axial dipole, as noted in virtually all marine sediment cores. The observed inclinations provide further support for a polarity-dependent nondipole contribution to the time-averaged field.

Coccoliths in phytoplankton of the Eastern Bering Sea in August 2001

Based on results of field observations in August 1998, July 2000, and August 2001 composition and quantitative distribution of coccolithophorids in the middle part of the Eastern Bering Sea shelf between 56°052'N and 59°019'N was characterized. Emiliania huxleyi abundance, biomass, and population structure as well as role of species in the coccolithophorid community and phytoplankton as a whole were evaluated. Abundance of the species in the upper mixed layer in bloom areas was 1-3 mln cells/l and biomass made up 30-75 mg C/m**3. E. huxleyi share in total phytoplankton numbers and biomass at that reached 98% and 84% respectively. Significant spatial heterogeneity of E. huxleyi, quantitative distribution and population size structure, as well as asynchronism in population development in neighboring parts of the bloom area were shown. The time period, during which population structure in certain part of the area shifts from domination of juvenile cells without coccoliths to a phase of active detritus formation with dying coccolithophorid cells involved, may be estimated as two weeks. A conclusion is made that after anomalous E. huxleyi bloom in 1997 mass development of coccolithophorids became a characteristic feature of phytoplankton community's seasonal succession in the middle part of the Eastern Bering Sea shelf.