AGU Journal Highlights -- July 3, 2008

1. Carbon enters deep Arctic Ocean mainly from continent edges

Scientists predict that the consequences of human-induced climate change will be greatly amplified in the Arctic, both on the surrounding continents and in the ocean. Changes in nutrient supply and diminishing sea ice extent have the potential to alter primary production, ecological structure, and carbon cycling in the Arctic Ocean. Currently, little information exists on carbon export and associated biogeochemical processes in the central Arctic Ocean, hindering predictions of how this system will respond to change. To address this knowledge gap, Hwang et al. analyze organic matter on particles settling out from the waters within the Arctic Ocean above the Canada Abyssal Plain. They find strikingly old radiocarbon ages (averaging about 1900 years) for the organic carbon. This, along with a spike in abundances of sediment from continental sources rather than deep-sea sources, suggests that the majority of the particulate organic carbon entering the deep Canada Basin is supplied from surrounding continental margins.

Title: Lateral organic carbon supply to the deep Canada Basin

Authors: Jeomshik Hwang, Timothy I. Eglinton, Richard A. Krishfield. Steven J. Manganini, and Susumu Honjo: Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, U.S.A.

Source: Geophysical Research Letters (GRL) paper 10.1029/2008GL034271, 2008; http://dx.doi.org/10.1029/2008GL034271

2. Magnetic patterns around Venus revealed

Venus lacks an intrinsic magnetic field. Instead, Venus's ionosphere acts as an obstacle to the supersonic solar wind that carries the interplanetary magnetic field. The interplanetary field drapes around the ionosphere, forming an induced magnetosphere. Recent research has shown that distinct physical regions in this induced magnetosphere are recognizable from variations and fluctuations within the Venusian magnetic field. Using data from the Venus Express spacecraft, launched in 2006, Vörös et al. study the statistical properties of these fluctuations, particularly within the magnetosheath, terminator, and wake. Their research uncovers several new structures and turbulence patterns within these regions, which may help scientists build more refined theories on the evolution of Venus's induced magnetosphere.

Title: Magnetic fluctuations and turbulence in the Venus magnetosheath and wake

Authors: Z. Vörös and M. P. Leubner: Institute of Astro- and Particle Physics, University of Innsbruck, Innsbruck, Austria;

T. L. Zhang, M. Volwerk, M. Delva, and W. Baumjohann: Space Research Institute, Austrian Academy of Sciences, Graz, Austria;

K. Kudela: Institute of Experimental Physics, Slovakia Academy of Sciences, Kosice, Slovakia.

Source: Geophysical Research Letters (GRL) paper 10.1029/2008GL033879, 2008; http://dx.doi.org/10.1029/2008GL033879

3. How porous, organism-rich layers form in Antarctic sea ice