Changes in the variability of global land precipitation

Authors

  • Fubao Sun,

    1. Research School of Biology, Australian National University, Canberra, ACT, Australia
    2. Australian Research Council Centre of Excellence for Climate System Science, Sydney, New South Wales, Australia
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  • Michael L. Roderick,

    Corresponding author
    1. Research School of Biology, Australian National University, Canberra, ACT, Australia
    2. Australian Research Council Centre of Excellence for Climate System Science, Sydney, New South Wales, Australia
    3. Research School of Earth Sciences, Australian National University, Canberra, ACT, Australia
    • Corresponding author: M. L. Roderick, Research School of Biology, Australian National University, Canberra, ACT 0200, Australia. (michael.roderick@anu.edu.au)

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  • Graham D. Farquhar

    1. Research School of Biology, Australian National University, Canberra, ACT, Australia
    2. Australian Research Council Centre of Excellence for Climate System Science, Sydney, New South Wales, Australia
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Abstract

[1] 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 monthlyP (1940–2009) over the global land surface using a new theoretical framework that can distinguish changes in global Pvariance between space and time. We report a near-zero temporal trend in global meanP. 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.

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