作者单位:Environmental Sciences, Informatics and Statistic DepartmentUniversity of VeniceVenice,Italy[1]Division of OceanographyIstituto Nazionale di Oceanografia e di Geofisica Sperimentale – OGSTrieste,Italy[2]National Oceanic and Atmospheric AdministrationNational Marine Fisheries ServiceWoods Hole,MA,USA[3]