2007 Annual Report - jamstec japan agency for marine-earth ...

"Global comparison of zooplankton time-series" and developed
a series of statistical methods for the effective regional comparison
of ecosystem changes. The Working Group plans to hold a
special session on this topic during the International symposium
"Effects of Climate Change on the World's Oceans" in May
2008, and publish a special issue of a scientific journal to present
the accomplishments of the working group activities.
We also conducted the study on the Pan-North Pacific
comparison of zooplankton time-series based on the stable isotope
ratio of the major zooplankton species, Neocalanus spp.
collected in the western, central and eastern North Pacific during
1960s - 2005 under the collaboration of domestic and international
organizations. From the interannual variation of
Nitrogen stable isotope of Neocalanus, we found the bottom-up
control of food web structures, which might be derived from
temporal variation in environmental conditions of the respective
regions. This study was funded by the Grant-in-Aid for
Scientific Research.
b-2. Comparative study of long-term changes in terrestrial and
marine ecosystems
We analyzed stable isotope ratio of Salmonid fish scales
taken in the Lake Baikal and western North Pacific for the past
50 years. We found the quasi-bi-decadal synchrony in the stable
isotope ratio of the fish, which inhabited in the completely
remote and independent ecosystems each other. This result suggested
that dynamics of the Okhotsk High and Aleutian Low
might influence the atmospheric and hydrographic conditions of
Siberia and North Pacific at the same timing in decadal scale.
b-3. Analysis of seasonal and interannual variability of chlorophyll
a and primary productivity using satellite data
We made a classification map in the North Pacific including
some marginal Sea Japan Sea, Okhotsk Sea and Bering
Sea based on magnitude of seasonal change standard deviation
and peak chl-a values during spring bloom using 11-
years' ocean color satellite data , and examined relationships
between chl-a concentrations and sea surface temperature
anomalies at each regions . The results show warmer sea surface
temperature corresponds to higher chl-a concentrations in
the Bering Sea and Oyashio regions. Contrastively, opposite
patterns were seen in Gulf of Alaska and Kuroshio regions. In
FY2008, we will examine those mechanisms in detail and discuss
the relation to climate change. As part of same research
using ocean color data, interannual variability of spring bloom
timing in the North Pacific was investigated. The results show
timing of spring blooms in northwestern and adjacent sea
around marginal sea region was earlier in El-Niño year
Warmer phase and later in La-Nina year Cooler phase.
On the other hand, opposite pattern was seen in offshore southeastern
region.Our two major research topics suggest that
oceanic environment or marine ecosystem response to climatic
forcing is different from each regions.
b-4. Development of pCO 2 model using satellite data
A model to estimate the partial pressure of carbon dioxide
pCO 2 for the North Pacific was developed using satellite
data last year In cooperation with Nagoya University. The
model derived pCO 2 results showed good agreement with shipboard
data within an error of 15-18 micro-atm. This method
suggests that it is possible to evaluate basin-scale pCO 2 trends
using remote sensing data. However, we cannot describe seasonal,
interannual variations and effects due to climate change
such as El-Niño and La-Nina events in detail. Now first version
of global algorithms was completed.
c. Modelling of interannual variability of marine ecosystem and
International collaboration
Using a global 3-dimensional marine ecosystem model
COCO-NEMURO combined with carbon cycle based on the
Fig.3 Left bottom: Time-series of nitrogen isotope ratio in the
scales of Ormul in Lake Baikal and pink salmon in the western North
Pacific the long-term trend is removed.
Right:Long-term variability of anomalous westerly velocities over the
Siberia and western North Pacific.
OCMIP Ocean Carbon-cycle Model Intercomparison
Project protocol, we have investigated the impact of climate
variability in the North Pacific such as the Pacific Decadal