Analysis of the Precipitation Regime over the Ligurian Sea

Abstract

The regions surrounding the North West Mediterranean Sea are often sites of intense precipitation events, particularly during the autumn months. The many casualties and the high economic costs due to these events demand a continuous improvement in forecasting models in support of early warning systems. The main weather conditions that determine episodes of heavy rain over these regions are known, but the high number of processes and interactions taking place at different time and space scales makes it extremely difficult to increase the skill pertaining to their predictability. To deepen the knowledge of the phenomena, both numerical simulations and analysis of historical data sets are required. This paper presents the analysis of a five-year-long time series of rain data collected in the open Ligurian Sea from the fixed platform W1M3A and coastal stations. The analysis aims to characterize the main features of the precipitation over this area and its seasonal and annual variability. Furthermore, the work includes a description of the main atmospheric and oceanic surface parameters measured from the platform during some intense events that occurred in the period 2009-2013 and suggests to what extent offshore observations may contribute to improve the forecast of rainfall events.

Massive strandings ofVelella velella(Hydrozoa: Anthoathecata: Porpitidae) in the Ligurian Sea (North-western Mediterranean Sea)

“…Peaks of abundance of V. velella in the northern oceans are usually recorded in March (a data comparable to what is reported in the present paper), and again in August (Bieri 1977); the general lack of strandings in fall along the Ligurian coasts may be related to the different wind condition, as from July to February the dominant winds in the area come from the northern quadrant (Pensieri et al 2018), preventing the swarms to get close to the shores.…”

“…In the Ligurian Sea, the seasonal and spatial distributions of zooplankton are related to the physical structure of the Ligurian-Provençal Front: the main annual coastal current in the basin, up to 30 km from the shore, flows westward (Bethoux et al 1982;Casella et al 2011), from the Tuscany coasts towards France; it is possible to distinguish coastal and offshore zooplankton, the latter able to remain in the convergence area between the open sea and the coastal current (Boucher et al 1987;Sournia et al 1990;Astraldi & Gasparini 1992;Violette 1995;Millot 1999). Based on the collected data, we hypothesize that large swarms, consisting of a single cohort of colonies, may gather along this hydrological front in early spring (February-March) and be transported onshore, not subjected to the main East to West current, but moving according to the seasonal direction patterns of the predominant winds that, in the Ligurian basin, from March to June usually blow alternately from SE and N (Pensieri et al 2018). Under these conditions, the swarms may be divided in sub-clusters, spreading out in different periods and locations, depending on the local weather and hydrodynamic conditions (Figure 3).…”

Detection and Characterization of Meteotsunamis in the Gulf of Genoa

“…The number and intensity of these meteotsunamis strongly differ from one year to another and, although the time series is not long enough for a significant statistical analysis, a slight increasing trend in the recent years may have been detected. There is no a clear evidence of a particular seasonality; nevertheless, a high number of events are recorded on July, when the strongest air-sea interaction favors the development of intense mesoscale convective systems [65].…”

Integration of Underwater Radioactivity and Acoustic Sensors into an Open Sea Near Real-Time Multi-Parametric Observation System

“…The latter parameter is measured using the RAINCAP sensor that infers the cumulate by the acoustic impact of drops on the sensing element [ 24 ]. This instrument was recently used for its reliability to monitor rainfall on both land and at sea [ 25 , 26 , 27 ].…”