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$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
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\\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
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$BIw$KBP$9$kI91o$H(B $B3$MN$N(Blee$BGH$N7k9g1~(B $BEz$H$7$F$N(BIce bands $B$N@8@.5!9=$rDs0F$9$k!#?tCMe(B $B$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 $BIU6a$^$GE~C#$7!"3$MN$N1tD>:.9g$*$h$S3$I9M;2r$K4sM?$7$F$$$?!#(B $B$3$N$h$&$J>.%9%1!<%k2aDx$OBg=[4D%b%G%k$G$7$P$7$PMQ$$$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$Dl
\\Subtropical western boundary currents separating from bottom slopes with inshore pool regions: An indication to the Kuroshio near-shore path
($B@>3@(B $BH%(B \\Hajime Nishigaki$B!KH/I=MW;](B :
$B1h4_B&$K%W!<%k0h$rH<$C$F3$Dl4_6-3&N.$NNO3X$rD4$Y$?!#(B $B%W!<%k0h$H$O!$0!G.BS=[4D$N?e$,?JF~$;$:N.$l$, ?JO)$K(B $B$*$$$F$O6-3&N.$H1h4_?e$H$N6-3&$,L@3N$K$_$i$l$k$,!$K\8&5f$O$=$NNO3XE*M}2r(B $B$rL\;X$7$?!#M}A[2=>r7o2<$N?tCM r7o$G9uD,$K;w$?%W!<%k0h$rH<$&N.$l%Q%?!<%s$, .$5$$!#$3$N3$0h$G$O!$>eAX6-3&N.$,3$Dl B&$X$N(B $B?JF~$rAK$^$l$k!#B>$N3$0h$G$O? eAX6-3&N.$O3$Dl 4_$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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