This work was partly supported by the program ACI-FNS ‘‘Aléas
et Changements Globaux” of the French research ministry under
the project CYPRIM and the French Agence nationale de la recherche
under the project MEDUP. The authors are grateful to Joël Noilhan
for his continuous support during this research and his
previous work, which made this study possible. The authors are
also very grateful to the anonymous reviewers whose comments
and suggestions helped to improve the clarity of the text.