function [msk_SB,msk_LB] = CreateDDrmask(grdO);

% function [msk_SB,msk_LB] = CreateDDrmask(grdO);
% Create mask for Small and Large Basin of Double Drake 

nc=24;
nr=length(grdO.drF);

maskW=ceil(grdO.HFacW(1:6*nc,1:nc,:));
maskS=ceil(grdO.HFacS(1:6*nc,1:nc,:));
maskC=ceil(grdO.HFacC(1:6*nc,1:nc,:));

%%%% Southern most latitudes of walls
%min(grdO.YC( find(grdO.HFacC(1:6*nc,1:nc,1) == 0) ))     %% C-points
%min(grdO.YC( find(grdO.HFacW(1:6*nc,1:nc,1) == 0) ))     %% U-points
%min(grdO.YG( find(grdO.HFacS(1:6*nc,1:nc,1) == 0) ))     %% V-points

%%%% Small-Basin Masks

mskSB_G=ones(6*nc,nc); mskSB_G(grdO.XG(1:6*nc,1:nc) < 90 )=0;
mskSB_C=ones(6*nc,nc); mskSB_C(grdO.XC(1:6*nc,1:nc) < 90 )=0;

maskW_SB = maskW .* repmat(mskSB_G,[1 1 nr]);
maskS_SB = maskS .* repmat(mskSB_C,[1 1 nr]);
maskC_SB = maskC .* repmat(mskSB_C,[1 1 nr]);

msk_SB.maskW=maskW_SB;
msk_SB.maskS=maskS_SB;
msk_SB.maskC=maskC_SB;

%%%% Large-Basin Masks

mskLB_G=ones(6*nc,nc); mskLB_G(grdO.XG(1:6*nc,1:nc) > 90 )=0;
mskLB_C=ones(6*nc,nc); mskLB_C(grdO.XC(1:6*nc,1:nc) > 90 )=0;

maskW_LB = maskW .* repmat(mskLB_G,[1 1 nr]);
maskS_LB = maskS .* repmat(mskLB_C,[1 1 nr]);
maskC_LB = maskC .* repmat(mskLB_C,[1 1 nr]);

msk_LB.maskW=maskW_LB;
msk_LB.maskS=maskS_LB;
msk_LB.maskC=maskC_LB;

return