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AGU: Geophysical Research Letters



  • p variability
  • water cycle

Index Terms

  • 1833 - Hydroclimatology

Paper in Press


Changes in the variability of global land precipitation

Key Points
  • We report a reduction in P variability and explain how that arose.
  • The reason of the reduction of P variability is dry got wetter and wet got drier.
  • A new detection method is proposed to confirm the conclusion.


Fubao Sun

Michael L. L. Roderick

Graham D. D. Farquhar

In our warming climate there is a general expectation that the variability of precipitation (P) will increase at daily, monthly and inter-annual timescales. Here we analyse observations of monthly P (1940-2009) over the global land surface using a new theoretical framework that can distinguish changes in global P variance between space and time. We report a near-zero temporal trend in global mean P. Unexpectedly we found a reduction in global land P variance over space and time that was due to a redistribution, where, on average, the dry became wetter while wet became drier. Changes in the P variance were not related to variations in temperature. Instead, the largest changes in P variance were generally found in regions having the largest aerosol emissions. Our results combined with recent modelling studies lead us to speculate that aerosol loading has played a key role in changing the variability of P.

Received 30 July 2012; accepted 27 August 2012.

Citation: Sun, F., M. L. L. Roderick, and G. D. D. Farquhar (2012), Changes in the variability of global land precipitation, Geophys. Res. Lett., doi:10.1029/2012GL053369, in press.