U.S. GLOBEC: Coupled Bio-physical Models for the Coastal Gulf of Alaska.
(Haidvogel, D. [Rutgers Univ.], Hermann, A. J. [NOAA Pacific Marine Environmental
Laboratory (PMEL)], Stabeno, P. J. [PMEL], Hinckley, S. [NOAA Alaska Fisheries
Science Center], M. Iskandarani [Rutgers], H. Arango [Rutgers], Rand, P. S. [North Carolina
State University]) A core
hypothesis of the US GLOBEC Northeast Pacific Implementation Plan is that
interannual to interdecadal variability in the circulation and hydrography of the
Gulf of Alaska drives changes in productivity of zooplankton in the coastal zone,
with consequent effects on the feeding success of salmonids and other species in
the Gulf. Production regimes in the Coastal Gulf of Alaska (CGOA) and the
California Current may covary on interannual to decadal scales, due to spatially
correlated changes in physical forcing. To address these issues for the CGOA, a
set of linked circulation models, coupled with a lower trophic level
Nutrients-Phytoplankton-Zooplankton (NPZ) biological model, and an
individual-based model (IBM) of salmon are used. Specific questions to be
addressed by this set of models include: 1) How do the relative strengths of the
offshore Alaska Current-Alaskan Stream and the Alaska Coastal Current (ACC)
affect exchange between the shelf and slope, and hence the supply of nutrients
and deep-sea zooplankton to the shelf area? 2) Can wind-driven Ekman flux account
for most of the transport of oceanic zooplankton onto the shelf, or are more
intricate cross-frontal processes involved? 3) How does interannual/decadal
modulation of the seasonal pattern of the ACC affect secondary production and
transfer to higher trophic levels on the shelf? Does a stronger ACC act to
enhance or reduce productivity on the shelf? 4) Does tidal mixing significantly
affect coastal production in the Gulf of Alaska? If so, can very low frequency
modulation of tides account for some of the decadal change in the coastal
dynamics, and hence production?
The proposed set of coupled (global/basin and regional/coastal) circulation
models are forced by realistic wind and river runoff time series. Output from the
coastal circulation model will be used to drive the NPZ model of the near-coastal
area encompassing the shelf and shelf break. Circulation and prey fields produced
in this manner will then be used as input to the spatially explicit IBM of
juvenile salmon. This set of models will comprise a significant advance over past
and existing models of the Gulf of Alaska, which have with few exceptions tended
to use either coarse spatial grids or simplified physics, which exclude
biologically relevant processes such as baroclinic instability in the coastal
zone.
This page was last updated on
March 15, 2007.
Maintained by:
Hal Batchelder
College of Oceanic and Atmospheric Sciences
Oregon State University
Corvallis, OR 97331-5503
phone: 541-737-4500; FAX 541-737-2064