Confronto tra supercelle tornadiche in Giappone e Italia

Responsabili di progetto

Mario Miglietta, Hiroshi Niino

Accordo

GIAPPONE - JSPS - Japan Society for the Promotion of Science

Bando

CNR-JSPS 2016-2017

Dipartimento

Scienze del sistema terra e tecnologie per l'ambiente

Area tematica

Scienze del sistema Terra e tecnologie per l'ambiente

Stato del progetto

Nuovo

Proposta di ricerca

Although rare, severe tornadoes can occasionally affect Japan and Italy. Recently, a multi-vortex EF3 tornado affected Taranto in southeastern Italy on 28 November 2012, causing 1 death and estimated damage of 60 MEUR (Miglietta and Rotunno,2015). On 8 July 2015, an EF4 tornado struck the surroundings of Venice, causing 1 death, 72 injured, and damages for 20 MEUR. In Japan, a tornado affected Tsukuba on 6 May 2012, in Ibaraki Prefecture, damaged 890 houses, killed one person and injured 52 people. A F2 tornado affected the Saitama Prefecture in Japan on September 2, 2013, and injured 63 people.

The possibility offered by the internet to share tornado pictures have made it apparent that the impact of these events has been largely underestimated in both Countries in the past. The only climatology of tornadoes available in Italy shows that a severe event occurs in Italy every 1.5 years (Giaiotti et al., 2007), and that a significant fraction of Europe's deadliest recorded tornadoes affected Italy (Groenemeyer and Kuhne, 2014). Also, in Japan 20.5 tornadoes and 4.5 waterspouts occur on average every year, causing 0.58 average fatalities per year (Niino et al., 1997). Some tornadoes, causing more than 10 deaths, have been documented in the past and witness the unusual, but possible occurrence of severe vortices in Japan.

Such considerations emphasize the need for the respective National Weather Services of a warning system dedicated to the monitoring and prediction of localized severe convective events. Today, in Italy there are no procedures to warn for tornadoes, which appears rather inadequate considering their potential threat. Japan meteorological Agency (JMA) started to issue a notice for tornado watch in March 2008 and tornado probability nowcast in May 2010. However, the prediction skill between 2008 and 2013 is 4-5 %. The possibility of issuing skillful alerts for the prediction of these events requires several obstacles to be overcome, such as a deeper understanding of the relevant mechanisms necessary for their development.

In the present proposal, first the intensity and distribution of severe tornadoes affecting both countries will be analyzed to identify recursive patterns conducive to tornadogenesis, which will simplify the work of the forecasters in the analysis of these events. As tornadoes cover a limited geographical extension, they are generally not recorded by synoptic- and regional-scale station networks, while they are generally identified based on newspapers articles, chronicles, and, more recently, reports and photographs posted on the web. In this perspective, the comprehensive study in Niino et al. (1997) together with JMA's database for tornadoes and downbursts between 1961 and 2014 will be used for Japan, while the only available climatological study for Italy (Giaiotti et al., 2007 for Italy) will be updated using the extensive European Severe Weather Database (ESWD) defined in the last few years by ESSL (European Severe Storms Laboratory), which has not been exploited yet to define the climatology for the individual countries. Although the dataset probably does not include all events, we expect that the most intense events have been properly documented.

Japan and Italy are have similarities such that both are located at mid-latitudes, surrounded by seas, have complex orography and north-south elongated territory, which are different from the USA. Considering that many tornadoes occur near the coast, we expect that sea plays an important role, thus the theoretical framework developed for USA Midwest severe convective weather should be properly adapted to the peculiar Mediterranean and Japanese environment. To accomplish this task, different case studies will be investigated with numerical simulations: for Italy: the tornado in Taranto in 2012; the recent event near Venice; an intense supercell that developed in north-eastern Italy in September 2012. The results of these case studies will be compared with those for recent Japanese tornadoes such as Nobeoka tornado on 17 September 2006, in Miyazaki prefecture and Tsukuba tornado on 6 May 2012, in Ibaraki prefecture. Also, the characteristics of extratropical cyclones that cause tornadoes in Japan and Italy will be compared with USA tornadoes, analyzing the structure and environmental parameters (such as Storm Relative environmental Helicity and CAPE).

However, our task is not to simulate the actual tornado structure, which is out of the possibilities of a mesoscale simulation, but to represent the synoptic scale and meso-scale conditions conducive to tornadogenesis and to identify which ingredients (and instability parameters) play a key role. Additional high-resolution experiments will explore the sensitivity to different parameters and shed further light on the mechanisms responsible for storm triggering and development.

The topics analyzed in the present project will improve our understanding of tornadoes. The results will be beneficial for the research in the field: the outcomes will define better which morphological mechanisms can play a role in triggering and developing severe convection, extending the actual conceptual model, which is fit for the USA Midwest Plain.

The activity will be developed in close collaboration between Japanese and Italian researchers, with some reciprocal visits planned in the two years and one seminar each year. The project will benefit of the world-recognized expertise of prof. Niino in Fluid Dynamics and Mesoscale Meteorology, and the experience of dr. Miglietta in the analysis of intense convective weather events in the Mediterranean. Also, Richard Rotunno, from NCAR, Colorado, one of the major expert in the field, will participate in the project.

References:
Giaiotti et al., 2007: Atmos. Res., 83, 534-541
Groenemeijer and Kühne, 2014: Mon. Wea. Rev., 142, 4775-4790
Miglietta and Rotunno, BAMS, 2015, in press
Niino et al., 1997: J. Climate, 10, 1730-1756

Obiettivi della ricerca

Although severe tornadoes occasionally occur in Japan and Italy, sometimes producing severe damages and casualties, they received little attention by both the general public and scientists.
We expect that the common morphology in the two regions (e.g., complex orography and rough coastlines) may play a key role in tornadogenesis, differing somewhat the relevant mechanisms from the classical conceptual models developed for USA Midwest. For this reason, a parallel investigation for Japanese and Italian tornadoes could identify some key ingredients for the detection and forecasting of tornadoes. This is a necessary task for civil protection purposes, which cannot be further postponed, due to its dramatic social impact, possibly enhanced in a rapidly changing climate.
We expect the present project will: identify some risk scenarios; improve our understanding of tornadogenesis; adapt the theoretical framework developed for USA Midwest to the peculiar morphology of the two countries.
The results will be possibly exploited in the operational agencies to improve the diagnosis and the prediction of tornadoes.
The project will restart the collaboration with prof. Niino of dr. Miglietta, who was hosted for four months at Ocean Research Institute, University of Tokyo, in 2004, in the framework of a JSPS post-doctoral fellowship.
Young researchers will participate to the project, receving a great benefit of the proposed activity in an international high-level framework.

Ultimo aggiornamento: 14/05/2025