Using Historical Precipitation Patterns to Forecast Daily Extremes of Rainfall for the Coming Decades in Naples (Italy)

Nazzareno Diodato,Gianni Bellocchi

doi:10.3390/geosciences8080293

Nazzareno Diodato, Gianni Bellocchi

Open Access

https://doi.org/10.3390/geosciences8080293

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Journal: Geosciences	Publication Date: Aug 6, 2018
Citations: 10	License type: CC BY 4.0

Affiliation: VetAgro Sup, University of Clermont Auvergne

Abstract

The coasts of the Italian peninsula have been recently affected by frequent damaging hydrological events driven by intense rainfall and deluges. The internal climatic mechanisms driving rainfall variability that generate these hydrological events in the Mediterranean are not fully understood. We investigated the simulation skill of a soft-computing approach to forecast extreme rainfalls in Naples (Italy). An annual series of daily maximum rainfall spanning the period between 1866 and 2016 was used for the design of ensemble projections in order to understand and quantify the uncertainty associated with interannual to interdecadal predictability. A predictable structure was first provided, and then elaborated by exponential smoothing for the purposes of training, validation, and forecast. For the time horizon between 2017 and 2066, the projections indicate a weak increase of daily maximum rainfalls, followed by almost the same pace as it was in the previous three decades, presenting remarkable wavelike variations with durations of more than one year. The forecasted pattern is coupled with variations attributed to internal climate modes, such as the Atlantic Multidecadal Oscillation (AMO) and the Pacific Decadal Oscillation (PDO).

Highlights

Precipitation patterns indicate an increased frequency and intensity of extremes over mid-latitude land areas (20–50◦ N), with especially rapid changes since the 1990s [1]
We developed a statistical ensemble forecast approach in an effort to anchor the reality of daily maximum rainfall to the changes observed in the past, and replicate these changes in the near future
Based on the analytical framework and concepts discussed in previous papers [52,53], our analysis used a relatively simple soft-exponential smoothing approach for maximum daily rainfall forecasting in Naples (Italy)

Summary

Introduction

Precipitation patterns indicate an increased frequency and intensity of extremes over mid-latitude land areas (20–50◦ N), with especially rapid changes since the 1990s [1]. Precipitation patterns are a consistent feature in future projections from coupled climate models forced with increasing greenhouse gas (GHG). Atmospheric concentrations (e.g., [2]). These projections can be different based on a variety of Global. Climate Models (GCMs) [3,4,5,6] and the different parameter sets involved in the simulations under alternative GHG emission scenarios. Results from data-driven models corroborated the results by GCM projections [7,8,9]. Extreme events may be difficult to predict because they are characterized by a large uncertainty in the occurrence time and the magnitude of the event [17]

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Results

Conclusion