clear all 

FNAME='/cluster/shared/noresm/inputdata/lnd/clm2/surfdata_map/surfdata_1.9x2.5_16pfts_Irrig_CMIP6_simyr1850_c170824_CLM4.nc';

PCT_NAT_PFT=ncread(FNAME,'PCT_NAT_PFT');
PCT_CFT=ncread(FNAME,'PCT_CFT');
PCT_NATVEG=ncread(FNAME,'PCT_NATVEG');
PCT_CROP=ncread(FNAME,'PCT_CROP');

for n=1:size(PCT_NAT_PFT,3)
  PCT_NAT_PFT(:,:,n)=PCT_NAT_PFT(:,:,n).*PCT_NATVEG/100;
end
for n=1:size(PCT_CFT,3)
  PCT_CFT(:,:,n)=PCT_CFT(:,:,n).*PCT_CROP/100;
end

PCT_PFT=cat(3,PCT_NAT_PFT,PCT_CFT); 

ncwrite(FNAME,'PCT_PFT',PCT_PFT);