The Jaeger Surface Rain Gauge Observations data set consists of gridded
mean monthly global precipitation values for 1931 to 1960 over the
continents and 1955 to 1965 over the oceans. The data set volume is 126
Kbytes and is available by ftp.
In order to calculate monthly, seasonal, and annual variations of
precipitation over the whole globe, both hemispheres, and various
meridional zones, a ... gridding technique was used on data spanning 1931 to
1960 over the continents, and 1955 to 1965 over the oceans. For the
continental regions, the grid point values were obtained as eye estimates
from isopleth maps prepared from up-to-date climatic atlases containing
annual and monthly rainfall values, supplemented by other data sets.
Although it was initially intended to use data for the standard period
1931-1960, this did not prove possible for all regions.
Moller's (1951) method for estimating rainfall frequencies was adopted to
provide ocean precipitation data. Monthly percentage frequencies were
extracted from the mapped isolines of the US Marine Climatic Atlas (US
Naval Weather Service 1955-1965) and interpolated to the grid points. After
re-expressing the monthly frequencies as annual percentages, the values
were scaled to rainfall depth units using Geiger's (1965) precipitation map
to yield monthly precipitation means.