Yusuke Yokoyama Lab Diary

2/13/2013

2/12/2013

Visiting JAMSTEC and Discussions at Hongo Campus

Hello, this is Jan-Rainer Riethdorf. I am currently a JSPS post doc in the Yokoyama lab.

On February 5th, I finally had the opportunity to visit the research facilities of JAMSTEC in Yokosuka and to discuss with Dr. Naohiko Ohkouchi and his group at the Institute of Biogeosciences. My current work here at AORI uses sedimentary nitrogen isotope ratios (δ¹⁵N) to reconstruct changes in surface nitrate utilization and therefore the biological pump in the Bering Sea. Dr. Ohkouchi is a specialist in the determination of compound-specific δ¹⁵N and after showing me the respective sophisticated laboratory equipment we discussed and agreed on applying this procedure to my Bering Sea samples.

For the following day Prof. Yokoyama organized a meeting with Dr. Naomi Harada and Dr. Yusuke Okazaki at Hongo Campus. I had not been at Hongo before and was quite impressed about the architecture of some buildings. Dr. Harada and Dr. Okazaki of the Paleoceanography Research Team (Environmental Biogeochemical Cycle Research Program, JAMSTEC) are experts on the paleoceanography of the North Pacific and its marginal seas and I was lucky to show them the results of my own research. We had very fruitful discussions and as a conclusion of this meeting we agreed to start joint international discussion with my colleagues at the Helmholtz Centre for Ocean Research Kiel (GEOMAR) and at the Alfred Wegener Institute for Polar and Marine Research (AWI, Bremerhaven) in Germany.

2/11/2013

This Week's New Paper ELSEVIER（2013.2/4-2/10）

☆Quaternary International☆

Volume 287, Pages 1-180（21 February 2013）

　Perspective on phytolith studies in Quaternary Research

（植物化石特集：南半球対象の研究が多め）

☆Quaternary International, in press☆

Influence of the Pacific Decadal Oscillation, El Niño-Southern Oscillation and solar forcing on climate and primary productivity changes in the northeast Pacific

R. Timothy Patterson, Alice S. Chang, Andreas Prokoph, Helen M. Roe, Graeme. T. Swindles

まだin pressですが、気になったので挙げました。北アメリカ西海岸の堆積物中の珪藻量や年層の厚さなどを調べて（AD1947-1993）、Wavelet analysisやPower spectrum analysisを行った結果、珪藻量から2-3年、4.5年、7年、9-12年の周期、年層の厚さから11-13年の周期が見られたことから、これらの周期をENSOや黒点数の周期と比較を行っています。また、PDOで有名な1976-1977年のレージームシフトが起こったタイミングに焦点を当てた議論も行っています。