A reanalysis of worldwide annual trends in precipitation demonstrates that risk to human and environmental systems has been underestimated, according to a team of University of Maine researchers.
As a result, they found more than 38 percent of the global population and over 44 percent of land area have been experiencing overlooked precipitation trends. Conventional trend analysis approaches examine changes in mean annual precipitation over time, and erroneously assume that changes in high and low precipitation follow suit, according to Anne Lausier, a UMaine doctoral candidate in civil and environmental engineering and a National Science Foundation Graduate Research Fellow, and Shaleen Jain, associate professor of civil and environmental engineering.
The historical record of annual precipitation is summarized by the probability distribution function (PDF), where the frequency with which precipitation amounts within a certain interval occur and the probability of exceedance (non-exceedance) above (below) a given threshold can be readily estimated.
In their paper, “Overlooked Trends in Observed Global Annual Precipitation Reveal Underestimated Risks,” published in the journal Scientific Reports, Lausier and Jain present an innovative trend typology using quantile regression and offer a comprehensive analysis of overlooked trends worldwide. Their trend typology, rather than focusing on mean and median trends alone, extends analyses to the upper and lower tails of the PDF to assess the compounded influence of risk and variability at various thresholds.
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