For documentation, see the following web page: http://www.cpc.ncep.noaa.gov/products/janowiak/cmorph.shtml
The appropriate reference for this data set is the following:
Joyce, R.J., J.E. Janowiak, P. A. Arkin and P. Xie, 2004: CMORPH: A Method that Produces Global Precipitation Estimates from Passive Microwave and Infrared Data at High Spatial and Temporal Resolution. J. Hydrometeorology, 5, 487-503.
The following information is excerpted from the "readme" file associated with this data set:
CMORPH 0.25 degree 3-hourly Information
Last Update: November 8 2004
The 0.25 degree 3-hourly CMORPH can be found on the ftpprd.ncep.noaa.gov
server in the /pub/precip/global_CMORPH/3-hourly_025deg/ directory
The data are compressed using the standard Unix compress function (files have a
suffix of ".Z"). Each file is composed of 16 direct access binary
("big_endian") records that are defined as follows:
Record 1: contains the merged microwave precipitation only for 00 UTC
Record 2: contains the "CMORPH" precipitation estimates for 00 UTC
Record 3: contains the merged microwave precipitation only for 03 UTC
Record 4: contains the "CMORPH" precipitation estimates for 03 UTC
.
.
.
Record 15: contains the merged microwave precipitation only for 21 UTC
Record 16: contains the "CMORPH" precipitation estimates for 21 UTC
All units are "mm/hr". Missing data are denoted by values of "-9999."
Each record contains a 1440 x 480 REAL*4 array of data which is oriented
from 0.125E EASTward and from 59.875N SOUTHward, with a grid increment
of 0.25 degrees of latitude and longitude. Thus, the grid locations
are the centers od a 0.25 degree lat/lon grid box. Note that these
estimates represent spatial averages, so the data are grid-centered,
rather than lattice-centered.
For example (1,1) is 0.125E, 59.875N
(2,2) is 0.375E, 59.625N, etc.
There is an associated GrADS ctl file with this data set:
CMORPH+MWCOMB_025deg-3hr.ctl
Below is FORTRAN code (run on an SGI) that will read the data sets:
program cread
c program cpc_advt+comb_read.f
parameter (IRMAX=1440, JRMAX=480, PMAX=2)
real*4 ssmipropREG(IRMAX,JRMAX,PMAX)
character*115 in1ssmipropREG
iyrmndy = 20031110
irec = 0
c Open input regional blended sensor rainfall file for 3
c hour CPC micro rainfall file
in1ssmipropREG = '/export-2/sgi109/irstat/blended_tech/cpc/data/02
&5deg/YYYY0M0D_3hr-025deg_cpc+comb'
write (in1ssmipropREG(54:61),'(i8)') iyrmndy
write(6,'('' file '',a88)') in1ssmipropREG
open (unit=15, file=in1ssmipropREG, access='direct',
& recl=1440*480*2*4, form='unformatted')
c Loop over 8 3 hourly periods for one day
do ihr = 0, 21, 3
irec = irec + 1
write(6,'(//,''proc 3 hr starting '',i8,i4)') iyrmndy, ihr
read (15, rec = irec) ssmipropREG
write (6,'(/,'' cpc combined MW '')')
do jreg = 271, 280
write(6,'(15(f5.1))') (ssmipropREG(ireg,jreg,1),ireg=1161,1175)
enddo
write (6,'(/,'' CMORPH '')')
do jreg = 271, 280
write(6,'(15(f5.1))') (ssmipropREG(ireg,jreg,2),ireg=1161,1175)
enddo
c End 3 hour loop
enddo
close (15)
stop
end