Isabel De Lima (Portugal) 1; Shaun Lovejoy (Canada) 2
1 - Civil Engineering Department, University of Coimbra, Portugal; 2 - Physics Department, McGill University, Montreal, Canada
Adaptation to climate change requires the proper characterization of precipitation variability across wide ranges of scales, which in turn requires both data with adequate resolution and length as well as an appropriate theoretical framework. In particular, understanding whereas such variability is natural or of anthropic origin, or a combination of both, and to detangle the two components, is still a challenge, in part due to data and methodological limitations. Based on scaling analyses, and using different precipitation data/products, several ways forward have been suggested envisaging the clarification of these questions and are revisited.
One key point is to obtain an overall picture for precipitation. This includes understanding fluctuations in this process at different scales and the presence of different regimes. It is currently accepted that there is a trichotomy regarding atmospheric (scaling) regimes (weather, macroweather, climate – from higher to lower frequencies) that is also present in precipitation, as shown by different studies. In particular, the transition from the macroweather to the climate regimes (at scales of roughly a few decades) is important because it is when anthropogenic effects begin to dominate the variability in climate variables. With a focus on water-related issues and problems, and their potential intensification due to climate change, results obtained from precipitation scaling analyses of qualitatively different precipitation series, and the implications for better characterizing extremes and assessing changes in precipitation at different temporal and spatial scales, are discussed.
Special attention is given to results obtained using data that allow to investigate precipitation from monthly to centennial scales and in space from planetary scales down to grid scales of a few degrees, and to the way they compare to results obtained from local data analysis. The improved understanding of monthly to centennial scale precipitation variability opens new perspectives to quantifying (anthropogenic) changes in precipitation, and is crucial for identifying potentially strategic climate change adaptation measures related to water.