REVIEW PRECIPITATION MEASUREMENTS AND TRENDS IN THE TWENTIETH CENTURY

• Main Authors: Mark Newa, Martin Toddb, Mike Hulmec, Phil Jonesd
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 2000
• Subjects: Antarc*; Antarctica
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.561.6701; http://www.mikehulme.org/wp-content/uploads/2007/04/2001-new_etal_ijc.pdf

Concern about anthropogenic climate change has heightened the need for accurate information about spatial and temporal variations in precipitation at the Earth’s surface. Large-scale precipitation estimates can be derived from either surface gauge measurements or by satellite remote sensing, both of which have shortcomings. Gauge measurements provide information about trends and variability of monthly precipitation throughout the entire twentieth century, but because of the lack of data from most ocean regions, this information is representative of only about 25–30 % of the Earth’s surface. In contrast, satellite (especially multi-platform) measurements provide spatially complete coverage at monthly to subdaily resolution, but do not extend back beyond 1974. Merged gauge–satellite datasets maximize (and minimize) the relative benefits (and shortcomings) of each source type. While these merged products only extend back to 1979, their importance will grow as we move into the new century. Precipitation gauge data indicate that global land precipitation (excluding Antarctica) has increased by about 9 mm over the twentieth century (a trend of 0.89 mm/decade), which is relatively small compared with interannual and multi-decadal variability. Within this century-long trend, global precipitation exhibits considerable variability on decadal time-scales, with departures of up to 40 mm from the century mean of about 950 mm. Regionally, precipitation has increased over most land areas, with the exception of tropical North Africa, and parts of southern