!### 2015/04/12 Yuta Ando (Mie University)

program replace_undef
  implicit none
  real,parameter :: undef=-9.99e+08
  integer :: n,ios

  integer :: i,j,num
  integer,parameter :: imax=360,jmax=180,nummax=2000
  real :: sst(imax,jmax,nummax)


!***********************************************************************************************
!open and read data file
  open(10,file='./HadISST_sst.bin',status='old',form='unformatted',access='direct',recl=imax*jmax*4)
  n=0
  do num=1,nummax
    n=n+1
    read(10,rec=n,iostat=ios) ((sst(i,j,num),i=1,imax),j=1,jmax)
    if(ios/=0)then
      cycle
    endif
  enddo
  close(10)


!replace undef values (100% sea-ice-covered gridboxes are flagged as -1000 -> undef)
  do num=1,n
    do j=1,jmax
      do i=1,imax
        if (sst(i,j,num)==undef .or. sst(i,j,num)==-1000.) then
          sst(i,j,num)=undef
        endif
      enddo !i
    enddo !j
  enddo !num


!output files
  open(20,file='./HadISST_sst.bin',form='unformatted',status='replace',access='direct',recl=imax*jmax*4)
  do num=1,n
    write(20,rec=num) ((sst(i,j,num),i=1,imax),j=1,jmax)
  enddo !num
  close(20)

stop

end program replace_undef