Contribution of Moisture from Mediterranean Sea to Extreme Precipitation Events over Danube River Basin

Danica Ciric,Raquel Nieto,Luis Gimeno,Alexandre Ramos,Anita Drumond

doi:10.3390/w10091182

Abstract

In the most recent decades, central Europe and the Danube River Basin area have been affected by an increase in the frequency and intensity of extreme daily rainfall, which has resulted in the more frequent occurrence of significant flood events. This study characterised the link between moisture from the Mediterranean Sea and extreme precipitation events, with varying lengths that were recorded over the Danube River basin between 1981 and 2015, and ranked the events with respect to the different time scales. The contribution of the Mediterranean Sea to the detected extreme precipitation events was then estimated using the Lagrangian FLEXPART dispersion model. Experiments were modelled in its forward mode, and particles leaving the Mediterranean Sea were tracked for a period of time determined with respect to the length of the extreme event. The top 100 extreme events in the ranking with durations of 1, 3, 5, 7, and 10 days were analysed, and it was revealed that most of these events occurred in the winter. For extreme precipitation, positive anomalies of moisture support from the Mediterranean were found to be in the order of 80% or more, but this support reached 100% in summer and spring. The results show that extreme precipitation events with longer durations are more influenced by the extreme Mediterranean anomalous moisture supply than those with shorter lengths. However, it is during shorter events when the Mediterranean Sea contributes higher amounts of moisture compared with its climatological mean values; for longer events, this contribution decreases progressively (but still doubles the climatological moisture contribution from the Mediterranean Sea). Finally, this analysis provides evidence that the optimum time period for accumulated moisture to be modelled by the Lagrangian model is that for which the extreme event is estimated. In future studies, this fine characterisation could assist in modelling moisture contributions from sources in relation to individual extreme events.

Highlights

There has been a rise in the number of extreme multi-day precipitation events occurring acrossEurope, even in areas characterised as being drier on average [1].These findings are consolidated by the results of other studies, which show that climate change and the presence of a warmer climate result in higher heavy rainfall events with varying durations but a reduction in summer precipitation throughout most parts of Europe [2,3].The Danube River Basin is an important international basin
It is characterised by diverse topography throughout the the year, which is due to significant and by the high amount of precipitation received throughout influences from the Mediterranean, Black Sea, the Atlantic Ocean, Ocean, and and the the basin basin itself itself [4]
Following the ranking method developed by Ramos et al [31,32] and using the daily high resolution (0.05◦ ) CHIRPS, we used the ranking of extreme precipitation events with different durations

Summary

Introduction

There has been a rise in the number of extreme multi-day precipitation events occurring acrossEurope (including the Danube region), even in areas characterised as being drier on average [1].These findings are consolidated by the results of other studies, which show that climate change and the presence of a warmer climate result in higher heavy rainfall events with varying durations but a reduction in summer precipitation throughout most parts of Europe [2,3].The Danube River Basin is an important international basin. Europe (including the Danube region), even in areas characterised as being drier on average [1]. These findings are consolidated by the results of other studies, which show that climate change and the presence of a warmer climate result in higher heavy rainfall events with varying durations but a reduction in summer precipitation throughout most parts of Europe [2,3]. It is characterised by diverse topography (including the Alps region) throughout the the year, which is due to significant and by the high amount of precipitation received throughout influences from the Mediterranean, Black Sea, the Atlantic Ocean, Ocean, and and the the basin basin itself itself [4]

Objectives

Methods

Results