Satellite and Oceanographic Observations of the Warm Coastal Current in the Chukchi Sea

Selected infrared images obtained by the NOAA satellites have increased our understanding of the formation and extent of the Alaskan Coastal Current, a movement of relatively warm water from the vicinity of Bering Strait northward along the Alaskan coast past Point Barrow and eventually into the Arctic Ocean where it disperses. Oceanographic measurements made from an icebreaker during the same period give spot checks on the depth of the warm layer, as well as the outline of a downward trend of the current when it is blocked by the ice. A study of satellite and oceanographic observations over a seven-year period, 1974-1980, reveals many interesting features of the flow and shows the annual variability. The northward flow and the shape of the ice edge are interrelated in that the flow is partially blocked by the ice and the ice is melted by the oncoming warm water. The solar-heated waters in Kotzebue Sound, Norton Sound, and along the coast to the south are seen as a major source of the heat in the coastal current.Key words: satellite, infrared, temperature, current, ice edge, eddies, oceanography, Chukchi Sea, Bering StraitMots clés: satellite, infra-rouge, température, courant, bord de la glace, remous, océanographie, mer Chukchi, détroit de Bérin

Integrating sequence and array data to create an improved 1000 Genomes Project haplotype reference panel

A major use of the 1000 Genomes Project (1000GP) data is genotype imputation in genome-wide association studies (GWAS). Here we develop a method to estimate haplotypes from low-coverage sequencing data that can take advantage of single-nucleotide polymorphism (SNP) microarray genotypes on the same samples. First the SNP array data are phased to build a backbone (or 'scaffold') of haplotypes across each chromosome. We then phase the sequence data 'onto' this haplotype scaffold. This approach can take advantage of relatedness between sequenced and non-sequenced samples to improve accuracy. We use this method to create a new 1000GP haplotype reference set for use by the human genetic community. Using a set of validation genotypes at SNP and bi-allelic indels we show that these haplotypes have lower genotype discordance and improved imputation performance into downstream GWAS samples, especially at low-frequency variants. © 2014 Macmillan Publishers Limited. All rights reserved

Spring phytoplankton onset after the ice break-up and sea-ice signature (Adélie Land, East Antarctica)

The phytoplankton onset following the spring ice break-up in Adélie Land, East Antarctica, was studied along a short transect, from 400 m off the continent to 5 km offshore, during the austral summer of 2002. Eight days after the ice break-up, some large colonial and solitary diatom cells, known to be associated with land-fast ice and present in downward fluxes, were unable to adapt in ice-free waters, while some other solitary and short-colony forming taxa (e.g., Fragilariopsis curta, F. cylindrus) did develop. Pelagic species were becoming more abundant offshore, replacing the typical sympagic (ice-associated) taxa. Archaeomonad cysts, usually associated with sea ice, were recorded in the surface waters nearshore. Rough weather restricted the data set, but we were able to confirm that some microalgae may be reliable sea-ice indicators and that seeding by sea ice only concerns a few taxa in this coastal area of East Antarctica. Keywords: Ice break-up; phytoplankton; sea-ice signature; East Antarctica (Published: 10 January 2011) Citation: Polar Research 2011, 30, 5910, doi: 10.3402/polar.v30i0.591