Simulation of a flash-flood event over the Adriatic Sea with a high-resolution atmosphere\u2013ocean\u2013wave coupled system

Antonio Ricchi,Sandro Carniel,Mario Marcello Miglietta,Guido Cioni,Davide Bonaldo

doi:10.1038/s41598-021-88476-1

Abstract

On the morning of September 26, 2007, a heavy precipitation event (HPE) affected the Venice lagoon and the neighbouring coastal zone of the Adriatic Sea, with 6-h accumulated rainfall summing up to about 360 mm in the area between the Venetian mainland, Padua and Chioggia. The event was triggered and maintained by the uplift over a convergence line between northeasterly flow from the Alps and southeasterly winds from the Adriatic Sea. Hindcast modelling experiments, using standalone atmospheric models, failed to capture the spatial distribution, maximum intensity and timing of the HPE. Here we analyze the event by means of an atmosphere-wave-ocean coupled numerical approach. The combined use of convection permitting models with grid spacing of 1 km, high-resolution sea surface temperature (SST) fields, and the consistent treatment of marine boundary layer fluxes in all the numerical model components are crucial to provide a realistic simulation of the event. Inaccurate representations of the SST affect the wind magnitude and, through this, the intensity, location and time evolution of the convergence zone, thus affecting the HPE prediction.

Highlights

Recent studies[1,2] have shown that Heavy Precipitation Events (HPEs) in the Mediterranean coastal regions are in many ways dependent on Sea Surface Temperature (SST)
We investigate the relevance of the effect of small-scale sea surface temperature (SST) features, which are not resolved in the lower boundary conditions generally used to drive NWP models, for the proper simulation of rainfall amount and localization in this HPE
In order to compare the results from the different model setups, we first focus on the modelled SST field

Summary

Introduction

Recent studies[1,2] have shown that Heavy Precipitation Events (HPEs) in the Mediterranean coastal regions are in many ways dependent on Sea Surface Temperature (SST). SST magnitude and spatial patterns control the air-sea energy exchange, modifying the environment where precipitating systems develop by modulating evaporation[3], modifying the atmospheric low-level stability[4], and changing the amount of precipitable water through moistening of the marine boundary layer (MABL). In this way, the air-sea interaction affects the structure and organization of precipitating systems, their lifecycle, severity, propagation speed and track, impacting the rain intensity[1,5,6].

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