ccc
cc The 2-dimentional annual discharge data from 1949-2004 were derived using the 
cc constructed (i.e., infilled) water year (Oct-Sep) flow from the downstream station 
cc (adjusted to river mouth using the ratio of flow rates at the river mouth and the 
cc station simulated by a river routing model forced by runoff fields from Fekete 
cc et al. 2002. For the largest 200 rivers only) from the 925 rivers, and then scaled 
cc up to account for contributions from the unmonitored areas (i.e., areas not 
cc covered by the 925 rivers). See following papers for more details: 

cc Dai, A., and K.E. Trenberth, 2002: Estimates of freshwater discharge from 
cc continents: Latitudinal and seasonal variations. J. Hydrometeorol., 3, 660-687.

cc Dai, A., T. Qian,  K. E. Trenberth, and J. D Milliman, 2008: Changes in continental 
cc freshwater discharge from 1949-2004. J. Climate, in press.

cc Because the infilling, adjustment to river mouth, and the scaling for 
cc unmonitored areas are done most reliably for annual flow, the time series
cc data were not done for monthly flow. One way to apply the annual flow data
cc (which are on a 1deg grid, with zero values for non-coastal boxes), one can 
cc make use of the long-mean annual cycle (at each 1deg box) from Dai and
cc Trenberth (2002), e.g., with the following Fortran codes:

cc
cc The binary data files were created on a Unix machine and are in big endian 
cc format.  
cc

ccc-------------------------------------------------------------------------
ccc Sample Fortran 77 codes to read water year discharge data and add a
ccc mean annual cycle to it:
ccc

ccc  Definition of the 1deg grid: the center of box (i,j) is at
ccc  lon = aln1 + (i-1)*di (from -180 to 180), lat = alt1+(j-1)*dj : 
      parameter(mi=360,mj=180,di=1.,dj=1.,aln1=-179.5,alt1=-89.5)
      parameter(iyrb=1949,iyre=2004,nyr=iyre-iyrb+1)
      real vann(mi,mj) ! water year discharge for each yr from Dai et al.(2008)
      real vmonavg(mi,mj,12) ! monthly climatology from Dai and Trenberth(2002)
      real vmon(mi,mj,nyr,12) ! constructed monthly discharge
      real ratio(mi,mj,12) ! annual cycle ratio


ccc   open input data files: These are the data files should be used.
ccc   created on a Unix machine (in big endian format): 
      open(1,form='formatted',file='/project/wcp/adai/runoff/'//
     $ 'runoff2ocean-mon-fromStn-1deg-2d.bin')
      open(2,form='formatted',file='/project/wcp/adai/runoff/qian/'//
     $ 'annual-dis-waterYr1949-2004-2d-scaled-con.bin')

ccc  To get the mean annual cycle coeff.:

     do mon=1,12
     read(1)((vmonavg(i,j,mon),i=1,mi),j=1,mj)    ! in Sv or E6 m3/s
     enddo
     
     do j=1,mj
     do i=1,mi

     sum=0.
     do mon=1,12
     sum=sum+vmonavg(i,j,mon)
     enddo
     if (sum.gt.0.) then
      sum=sum/12.  ! still in unit of Sv
      do mon=1,12
      ratio(i,j,mon)=vmonavg(i,j,mon)/sum  ! normalized by annual flow rate
      enddo
     else
       do mon=1,12
       ratio(i,j,mon)=1.  ! no seasonal variations if annual value=0.  
       enddo
     endif 

     enddo
     enddo


ccc  To create the monthly series by adding the mean annual cycle:

ccc  skip the two non-discharge records:
     read(2)
     read(2)

     iy=0

     do 100 iyear=1949,2004 ! for water yr 1949(from Oct 1948-Sep 1949) to 2004

     iy=iy+1  ! iy=1 for 1949

     read(2)vann   ! in Sv. Only coastal boxes have non-zero values. 

ccc  get the monthly data for water yr: iyear

     do 20 mon=1,12

     if (mon.le.9) then
      do j=1,mj
      do i=1,mi
      vmon(i,j,iy,mon)=vann(i,j)*ratio(i,j,mon)
      enddo
      enddo
     else if (iy.gt.1) then ! for the last year
      do j=1,mj
      do i=1,mi
      vmon(i,j,iy1,mon)=vann(i,j)*ratio(i,j,mon) ! flow in Sv for month=mon, 
      enddo                                      ! year = iyrb+iy1-1 
      enddo      
     endif 
     
 20  continue

     iy1=iy

 100 continue


     end

cccc----------------------------------------------------------------------