function swn=clean_gould_sw(sw)
% swn=clean_gould_sw(sw) computes mean bias,
% adds bias to sw series and sets swn<5 to
% 0 to simplify plotting and hf calculations.
% 4/10/01

m=find(sw<1);
swb=mean(sw(m));
swn=sw-swb;
m=find(swn<5);
swn(m)=0*swn(m);
