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第267回 大気海洋物理学・気候力学セミナー のおしらせ

日　時： 4月 23日(木) 午前 09:30
場　所： 環境科学院　2階　D201

発表者： 張 偉 (大気海洋物理学・気候力学コース/D3)
Zhang Wei (Course in Atmosphere-Ocean and Climate Dynamics/DC3)
題名： HF Ocean Radar applied to drift ice remote sensing

発表者： 吉成 浩志（低温科学研究所 学術研究員）
Hiroshi Yoshinari (Institute of Low Temperature Science/PD)
題名： 噴火湾周辺におけるスケトウダラ仔稚魚の時空間分布の数値シミュレーション
Numerical simulations of spatio-temporal distribution of juvenile walleye pollock (Theragra chalcogramma) around Funka Bay

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HF Ocean Radar applied to drift ice remote sensing
(張　偉 Zhang Wei) 発表要旨：


With high temporal and spatial resolution, High Frequency (HF) 
ocean radars have become a key component of coastal ocean 
observing systems. Moreover, the ability of HF ocean radars 
observation is not limited to ocean current, but includes sea 
ice movement. In order to monitor the Soya Warm Current (SWC), 
two HF radars were deployed in Mombetsu area in August 2003. 
In winter, sea ice originated from the northern Okhotsk Sea and 
transported by the East Sakhalin Current reaches the northern 
coast of Hokkaido. At times, the ice drifts to within the Mombetsu 
HF radar coverage. In this study, we report HF ocean radar 
application in drift ice remote sensing. HF ocean radar operating 
at 24.56 MHz off Mombetsu observes drift ice position and radial 
velocity with angular and range resolution of 5o and 1.5 km, 
respectively. The detection range of sea ice is about 20 km, 
even reaches 30 km. The radial velocities of drift ice from 
HF ocean radar are compared with those from X-Band radar. 
The correlation between radial velocities observed by HF ocean 
radar and X-Band radar can reach 0.75. The present results indicate 
that the HF ocean radar can effectively measure sea ice movement.
 


Numerical simulations of spatio-temporal distribution of juvenile
walleye pollock (Theragra chalcogramma) around Funka Bay
(吉成 浩志Hiroshi Yoshinari) 発表要旨：

   Hidaka Bay, situated along the southwestern coast of Hokkaido, 
is an important spawning ground of the Japan Pacific population 
(JPP) walleye pollock (Theragra chalcogramma).  Previous studies 
have revealed that; 1) juvenile pollock are concentrated in 
Funka Bay, western side of Hidaka Bay, in April, 2) their 
distribution are apparently related to warmer water (i.e., 
T10 > 3.5 °C).  To elucidate the mechanism of intake and 
maintenance of juvenile Pollock in Funka Bay, we performed 
a numerical simulation so called "Climatological Run". 
In the simulation, particles were initially distributed uniformly 
in the surface layer of Hidaka Bay, then a time integration from 
January 1st was executed to determine the season, when the juveniles 
entered Funka Bay using ROMS (Regional Ocean Modeling System) 
climatological run.
   The particles started entering Funka Bay in March mainly, 
then flew anti-clockwisely in the Bay, and stayed there for 
about 1 month, which is consistent with the observational results.
   Executing "Individual Based Model (IBM) Experiments" simulating 
the growths of embryo and fork length, the qualitative results 
were consistent with the observational ones, whereas the quantitative 
results were not, implying that we need to drive "Hindcast Run" 
to reproduce the results of IBM more accurately.

* Notes from Yoshinari-san *
  All slides shown in this presentation is written in English.  
I will, however, make the presentation in Japanese.  You can, 
of course, make questions and/or comments in English or Japanese 
whichever you like in anytime you want.
Thank you in advance.

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