The product:
	The CPC Monthly PRECipitation REConstruction data set (PREC)
	from 1948-current

The PREC data set is an analysis of monthly precipitation constructed on a
	regular distributed grid over the global for the period from 1948 to the present.
	The land portion of this global analysis (PREC/L) is defined by optimum interpolation
	of gauge observations at over 17,000 stations collected in the NOAA/NCDC
	GHCN Version 2 and the NOAA/CPC CAMS data sets. After year 2009, the station reports
        are only from the CAMS because the GHCN v2 include very limit number of avaiable reports 
        in recent time period and the real time basis. The precipitaion anaysis is first defined 
        on 0.5 deg lat/lon grid points, then average to grid box with different resolutions.
        The oceanic precipitation analysis (PREC/O), meanwhile, is produced by EOF reconstruction of
	historical gauge observations over islands and land areas. The EOF modes are
	derived from EOF analysis of the satellite estimates for later years (OPI,
	1979-1998) with complete spatial coverage. The current version 1.0
	is based on the first 8 EOF global modes for each 4
	seasons and the first 4 EOF modes of the residual components of the 8 EOF
	global modes over Atlantic Ocean areas.

Spatial resoluction:
	2.5 deg lat/lon
        1.5 deg lat/lon
        0.5 deg lat/lon

Time period:
	1948-current

Missing value:
	-999.0

Unit:
	monthly mean rainfall amount in unit of 0.1 mm/day

Data description file:
	precl_mon_v1.0.lnx.1948-curr.gri0.5m.ctl

Data format:
	little_endian binary direct access
	big_endian binary direct access
        ascii sequential formatted

Ftp site:
	https://ftp.cpc.ncep.noaa.gov/precip/50yr/

Documents:
	https://ftp.cpc.ncep.noaa.gov/precip/50yr/gauge/0.5deg/format_bin_lnx/aboutProduct.txt

Process Steps:

1. get input of the CAMS monthly station reports
   cp /cpc/data/operations/cadb/output/eve.$trgyy$trgmm

2. merge CAMS stations to the pre-defined table of supper stations

3. interpolate the station reports to the regular lat/lon grid points

4. average to regular lat/lon grid box

5. copy the analysis to /cpc/data/...

6. copy the analysis to cpcrzdm ftp site
   /home/ftp/cpc/precip/50yr
   https://ftp.cpc.ncep.noaa.gov/precip/50yr/

References
	Chen, M., P. Xie, J. E. Janowiak, and P. A. Arkin, Global Land
    	  Precipiation: A 50-yr Monthly Analysis Based on Gauge
	  Observations, 2002, J. of Hydrometeorology, 3, 249-266.
	https://journals.ametsoc.org/doi/abs/10.1175/1525-7541(2002)003%3C0249:GLPAYM%3E2.0.CO;2


	Chen, M., P. Xie, J.E. Janowiak, and P.A. Arkin, 2004:  Verifying the
	 reanalysis and climate models outputs usinga 56-year data set of
	 reconstructed global precipitation.  14th AMS Conf. Appl. Meteor.,
	 11-15 January, 2004, Seattle, WA.
	https://ams.confex.com/ams/84Annual/techprogram/paper_70083.htm

Contact:
	Dr. Mingyue Chen
	NOAA
	5830 University Reserch Ct.
	CPC/NCEP Room# 3011, W/NP52
	College Park, MD 20740
	Tel:  (301) 683-3396
	E-mail:  Mingyue.Chen@noaa.gov