# Western Mediterranean Precipitation Extremes, the Result of Quasi-Resonant Sea-Atmosphere Feedbacks
## 3 Results  
During the 22 years of observation, 14 Mediterranean precipitation events have occurred in southeastern France in coordination with SST anomalies over western European seas (Figure 2b). A total of 11 EREs (numbered from 1 to 11) were identified from precipitation anomalies in the wavelet spectrum scale-averaged over the period range of 11.4 to 45.7 days, the amplitude of which is higher than the 95% confidence level. On the other hand, three events (numbered from 1\({}^{\prime}\) to 3\({}^{\prime}\)) occurred in conjunction with SST anomalies without however producing an ERE (Figure 2b,c). This is because, indeed, the conditions of quasi-resonance of the atmospheric water, SST feedbacks, require the co-evolution of the low-pressure system and the SST anomalies. However, these necessary conditions are not sufficient. Without the stabilization of the atmospheric blocking circulation the clustering of mesoscale lows cannot take place to completion. The questions that now arise are (1) how EREs develop when a quasi-resonance occurs, which implies the co-evolution of atmospheric water, SST feedbacks, as well as a relative \begin{table}
\begin{tabular}{c c c c c c c c c c c c} \hline \hline
**Event** & **SST1** & **SST2** & **SST3** & **SST4** & **SST5** & **SST6** & **SST7** & **SST8** & **SST9** & **SST10** & **SST11** & **SST12** \\ \hline
1 & & & & & x & x & x & & & & \\ \hline
2 & & & & x & x & & & x & x & & \\ \hline
3 & x & x & x & & & & & x & & & \\ \hline
4 & & & x & & & x & & & & & \\ \hline
5 & x & & & x & & x & & x & x & x & x \\ \hline
6 & & x & x & & & x & & x & x & & \\ \hline
7 & & & & & & x & x & & & & \\ \hline
8 & & & x & & & x & & & & & \\ \hline
9 & x & & x & & & & x & & x & & \\ \hline
10 & x & & x & x & & & & & x & x & \\ \hline
11 & x & x & & x & & & & x & x & & x \\ \hline
1\({}^{\prime}\) & & x & x & & x & x & x & & & & \\ \hline
2\({}^{\prime}\) & & x & x & & & & & & & x & \\ \hline
3\({}^{\prime}\) & & x & & x & & x & x & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: SST anomalies associated with rainfall events. stability of the atmospheric blocking circulation and (2) how EREs develop in the absence of coherent SST anomalies. In order to identify the different facets of the co-evolution of precipitation and SST anomalies over the different European closed or semi-closed seas, as well as on the Atlantic Ocean, each of the 11 EREs occurring in the southeast of France as well as EREs occurring exclusively in Italy (ERE 12) or Spain (ERE 13) are represented synthetically. For each ERE, two figures represent the ultimate concentration of precipitations, one for the amplitude of precipitation occurring during a single day (period range, 0.71 to 1.43 days) and the other during two successive days (period range, 1.43 to 2.9 days). Two pairs of figures represent the precipitation and SST anomalies within the period range of 11.4 to 45.7 days. For each pair, one figure is the amplitude of the anomalies independently of their date of occurrence and the other is the phase with respect to the time reference. The same time reference is used for both rainfall and SST anomalies, that is a time series of daily precipitation reflecting at best the ERE. Each figure therefore represents the complete evolution of the low-pressure system in its paroxysmal phase on a daily and bi-daily basis (only the amplitude of the precipitation matters because the phase would be very imprecise) as well as in the period range of 11.4 to 45.7 days representative of the clustering of mesoscale lows. On the other hand, the amplitude and the phase of SST anomalies in the same period range of 11.4 to 45.7 days reflect the harmonization of these anomalies. The joint representation of the amplitude and the phase of the SST and precipitation anomalies, in the same period range and with the same time reference, highlights the co-evolution of the anomalies.