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STAR Satellite Rainfall Estimates

Hydro-Estimator - Digital Global Data Archive

The digital global data files here:

ANONYMOUS FTP site:, cd to /pub/smcd/emb/f_f/hydroest/world/world/

contain 1-hour Hydro-Estimator rainfall accumulations.

Date/Time Information

The files are named world1hr.YYYYJJJHH, where YYYY is the 4-digit year, JJJ the 3-digit Julian day, and HH the 2-digit hour (in UTC) at the end of the 1-h accumulation period. For instance, world1hr.200804200 contains rainfall accumulations ending 0000 UTC 11 February (Julian day 42), 2008.


The rainfall data are on a lat/lon grid with 8001 columns and 3111 rows. The file zworld.latlon2 contains the corresponding lat/lon points.

NOTE: Prior to 0000 UTC 11 February 2008, the files were 8000 columns by 3111 rows due to a programming bug that neglected to write the last column of data just west of the Greenwich Meridian. For files BEFORE this date, use zworld.latlon instead.


The 'world1hr' files are in ASCII. The first line contains the date and time (format '2i8') of the file. The date is in the format 1YYJJJ where YY is the last 2 digits of the year and JJJ is the Julian date; the time is HH0000 where HH is the hour in UTC. The date and time will be the same as that of the file name.

The remaining lines are in format 'i6' and contain a value ranging from 0 to 256 that is converted to rainfall accumulation (in mm) using the equation:

R = (value-2) * 0.3048

Note that a value of 0 means missing rainfall,while a value of 2 means no rainfall.

The 'zworld' files are also in ASCII. Each line contains the latitude and longitude, respectively of the corresponding data point in the 'world1hr' files: the first line of the zworld file gives the latitude and longitude of the northwest corner of the first data point in world1hr; recall that, because of the data, the first data point is the second line of the world1hr file. In general, the nth line of zworld matches the (n+1)th line of world1hr. The format is (2f9.4) with positive values indicating degrees north (latitude) and WEST (longitude)...careful, that is counter to the usual convention!