Mean seasonal and spatial variability in gauge-corrected, global precipitation

Publication Type Journal Article
Year 1990
Journal International Journal of Climatology
Organization Goddard Space Flight Center
Primary Author Legates, David. R.
Author Willmott, Cort J.
Volume 10
Issue 2
Pages 111-127
DOI 10.1002/joc.3370100202
Abstract A global climatology of mean monthly precipitation was developed using traditional land-based gauge measurements and shipboard estimates. The edited database contains 24,635 spatially independent terrestrial station records and 223 oceanic grid-point records. Corrected monthly precipitation observations were then interpolated to a 0.5 degree of latitude by 0.5 degree of longitude grid using a spherically based interpolation procedure. Precipitation is heaviest in the low latitudes and generally decreases toward the poles. Average intra-annual variability is positively correlated with average annual precipitation. Harmonic analysis depicted the marked effect that the seasonal migration of the Inter-Tropical Convergence Zone has on the timing of precipitation in equatorial regions. A double-maxima regime characterizes the seasonal precipitation cycle between the equator and about 10 degrees N, while heavy unimodal precipitation dominates the subtropics north and south of this region. Mid-latitude precipitation is generally less than in the tropics and is usually heavier over the oceans than over land. Rain gauge errors tend to be directly proportional to total precipitation, and amount to nearly 11% of the global catch. An undercatch of less than 5% occurs in the tropics, while > 40% is common at the poles. This illustrates the sizable influence of wind on gauge measurements of snowfall. Annual average global precipitation is approximately 1123 mm (gauge corrections considered), which is consistent with other reported values
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Notes Wes has the following URL listed. It is now broken: it also lists 2005 as the data year, which may mean that there is recent data associated with the methods in the paper.