Self-Organization Maps for Analyzing the Black Sea Bio-Physical Variability and Surface Wind Forcing

Abstract:

Spatial and temporal variability of the Black Sea surface circulation and chlorophyll-a concentration with the link to the surface winds is investigated using the self-organizing maps (SOMs) on the satellite data from Archiving, Validation, and Interpretation of Satellite Oceanographic data (AVISO), Sea-viewing Wide Field-of-view Sensor (SeaWiFS), and Quick Scatterometer (QuikSCAT). Six spatial patterns with temporal variability are identified for the surface currents: Pattern-1 (Sevastopol Cyclonic and Batumi Dipole Eddies, 21%) Pattern-2 (Cyclonic RIM Current and Anti-cyclonic Batumi Eddy, 16%), Pattern-3 (Anti-cyclonic Sevastopol and Batumi Eddies, 17%), Pattern-4 (Cyclonic RIM Current and Cyclonic Batumi Eddy, 21%), Pattern-5 (Anti-cyclonic RIM Current and Batumi Dipole Eddies, 15%), Pattern-6 (Anti-cyclonic RIM Current and Multi Eddies, 10%). The bi-modal characteristics has been changed in 1999-2009 with the fall bloom being more significant than the spring bloom. The surface circulation pattern-4 (cyclonic RIM current and Batumi eddy) is associated with the occurrence of the fall bloom. Evident connection of negative NAO and negative ENSO to the pattern-4 circulation implies the large-scale atmospheric effect. Possible connection of these patterns to the climatological indices, such as the North Atlantic Oscillation (NAO) and the East Atlantic/West Russian (EAWR), oscillation are also discussed.