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$BBh(B 208$B2s(B $BBg5$3$MNJ*M}3X!&5$8uNO3X%;%_%J!<(B $B$N$*$7$i$;(B

$BF|!!;~!'(B 9$B7n(B 30$BF|(B($BLZ(B) $B8aA0(B 09:30
$B>l!!=j!'(B $B4D6-2J3X1!(B D$BEo(B2$B3,(B D201$B9f(B

$BH/I= $BF#:j(B $BJb(B ($BDc292J3X8&5f=j!&4D%*%[!<%D%/8&5f4QB,%;%s%?!<(B/$BGn;N8&5f0w(B) \\Ayumi Fujisaki, Post Doctoral Fellow, ILTS
$BBj!!L\!'(B $BIw$K$h$k(B Ice bands $B$H(B lee$BGH$N@8@.(B\\Formation of ice bands and lee waves by windows

$BH/I= $B@>3@(B $BH%(B ($BBgJ,Bg3X650iJ!;c2J3XIt(B/$B9V;U(B) \\Hajime Nishigaki, Lecturer, Oita University
$BBj!!L\!'(B $B1h4_B&%W!<%k0h$rH<$C$F3$Dl4_6-3&N.!'9uD,D>?JO)$X$N<(:6(B

\\Subtropical western boundary currents separating from bottom slopes with inshore pool regions: An indication to the Kuroshio near-shore path

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$BIw$K$h$k(B Ice bands $B$H(B lee$BGH$N@8@.(B \\Formation of ice bands and lee waves by winds

\\($BF#:j(B $BJb(B \\Ayumi Fujisaki$B!KH/I=MW;](B :

$BIw$KBP$9$kI91o$H(B $B3$MN$N(Blee$BGH$N7k9g1~(B 
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$B$r3j$j$d$9$/$J$C$F$$$k$?$a!"(Bsupercritical$B>r7o(B ($BI9(B 
$B1o0\F0B.EY(B > $B79050LAjB.EY(B)$B$rK~$?$7$d$9$$!#(BIce bands  
$B$O(B $BBP1~$9$k(B lee$BGH(B $B$h$j$bD9GHD9$H$J$k$,!"$3(B 
$B$l$O3$MN(B-$B3$I94V1~NO$,%m!<%Q%9%U%#%k%?$H$7$F:nMQ$9$k$+$i(B 
$B$G$"$k!#(B
Lee$BGH$KH<$&1tD>N.B.$O%*!<%@!<(B10^1m/day$BDx$K$b$J$j!"3$Dl(B 
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$B$3$N$h$&$J>.%9%1!<%k2aDx$OBg=[4D%b%G%k$G$7$P$7$PMQ$$$i$l$k(B2.5km,  
5km $B$H$$$C$?3J;R%5%$%:$G$O2rA|$G$-$J$$!#(B

A mechanism for the formation of ice bands is proposed as a  
coupled response of ice edge and lee waves to wind under the  
hydrostatic approximation. A high-resolution ice-ocean coupled model  
is used in an x-z domain with grid sizes (x,z)= (250m,1m). Under an up- 
ice wind, such that the Ekman transport is away from the ice edge, the  
nearly discontinuous surface stress between at the ice-covered and  
open seas generates lee waves. A thin layer of high-potential  
vorticity fluid under the ice is produced by the Ekman forcing,  
enabling the ice edge to rapidly slip over less stratified water. This  
is favorable for supercritical conditions when lee waves are  
generated. Ice bands are formed by the corresponding convergences and  
divergences. An analytical solution is derived to show that ice bands  
have longer widths than the lee-wavelengths because the ice-ocean  
stress creates the smoothing effect. Vertical motions associated with  
the lee waves have speed of the order of 10^1m/day, extend to the  
bottom, and contribute to deep vertical mixing and the subsequent  
melting of the ice. These small-scale features are not modeled well  
with 2.5 km and 5 km horizontal grids that are often used in ocean  
general circulation models.

$B1h4_B&%W!<%k0h$rH<$C$F3$Dl4_6-3&N.!'9uD,D>?JO)$X$N<(:6(B

\\Subtropical western boundary currents separating from bottom slopes with inshore pool regions: An indication to the Kuroshio near-shore path

($B@>3@(B $BH%(B \\Hajime Nishigaki$B!KH/I=MW;](B :

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$B$*$$$F$O6-3&N.$H1h4_?e$H$N6-3&$,L@3N$K$_$i$l$k$,!$K\8&5f$O$=$NNO3XE*M}2r(B
$B$rL\;X$7$?!#M}A[2=>r7o2<$N?tCMr7o$G9uD,$K;w$?%W!<%k0h$rH<$&N.$l%Q%?!<%s$,.$5$$!#$3$N3$0h$G$O!$>eAX6-3&N.$,3$DlB&$X$N(B
$B?JF~$rAK$^$l$k!#B>$N3$0h$G$O?eAX6-3&N.$O3$Dl4_$KC#$9$k!#6-3&N.$NN.NL$KBP$9$k46EY$r%1!<%9%9%?%G%#$GD4$Y$?!#N.NL$,(B
$BBg$-$$$H$-%W!<%k0h$O2u$5$l$k!#qMp$r$D$/$k!#(B

The dynamics of subtropical western boundary currents separating from
bottom slopes with inshore pool regions, where the water of the
subtropical gyre does not enter and the velocity is small, are
investigated. This study is intended to understand the dynamics of the
near-shore path of the Kuroshio, which have distinct boundaries between
the boundary current and the coastal water. Numerical experiments under
idealized conditions are made. The results show flow patterns with pool
regions similar to the Kuroshio under quite simple conditions. A deep
counter current is present on the lower bottom slope, which represents
observed deep currents. In this region, bottom-layer potential
vorticity gradient is small despite steep topography. In this region,
the upper boundary current feels the bottom slope and is kept from
moving farther westward. In the other region where the bottom-layer
velocity is very small, the upper boundary current is free from the
bottom slope and moves westward to the coast. The sensitivity to the
volume transport of the boundary current is investigated by case
studies. The pool regions are broken in cases with large volume
transports. It is indicated that these unsteady inshore regions are
produced by instability caused by an outcrop of the upper isopycnal,
which is led by a large baroclinic volume transport.

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$B?eED85B@(B
mail-to: mizuta@ees.hokudai.ac.jp