Title: Sudden intensity increases and radial gradient changes of cosmic ray MeV electrons and protons observed at Voyager 1 beyond 111 AU in the heliosheath
Authors: W. R. Webber: Department of Astronomy, New Mexico State University, Las Cruces, New Mexico, USA;
F. B. McDonald: Institute of Physical Science and Technology, University of Maryland, College Park, Maryland, USA;
A. C. Cummings and E. C. Stone: Space Radiation Laboratory, California Institute of Technology, Pasadena, California, USA;
B. Heikkila and N. Lal: NASA Goddard Space Flight Center, Greenbelt, Maryland, USA.
4. El Nino related to changes in sardine spawning
The Pacific sardine, an important species for commercial fishing, spawns off the coast of California. The area and quality of its spawning habitat have been observed to vary from year to year, sometimes changing with El Nino-Southern Oscillation conditions, but smaller-scale mechanisms also play a role. To sort out the physical forcing mechanisms affecting sardine spawning, Song et al. used data assimilation, combining observational data on sea surface height, sea surface temperature, and salinity data with a physical ocean model. They then looked at how the physical mechanics could explain observed interannual variations in sardine spawning range and egg density.
The researchers find that increased wind-driven offshore transport during the
April 2002 and 2007 La Nina conditions led to extension of the sardine spawning
habitat farther offshore. In contrast, in April 2003, under El Nino conditions,
spawning habitat was smaller but of higher quality, leading to a higher density of
eggs and greater survival of larvae. Although there are still unknown factors that
control sardine eg
|Contact: Mary Catherine Adams|
American Geophysical Union