Mesoscale eddies and wind variability in the northern Gulf of California

Surface mesoscale structures and wind variability in the northern Gulf of California (NGC) were analyzed using data from SeaWiFS (1 km) and QuikSCAT (1 day). The months of February and March were selected as representative of winter and the months of August and September were selected as representative of summer. Chlorophyll-a (Chla) and wind time series were constructed using 16 points to analyze temporal variability and wind magnitude-Chla temporal and spatial linear correlation. Wind components along and across the NGC were found to play an equally significant role regarding wind variability, contrary to what is currently recognized. Wind magnitude tended to be stronger in winter and had less wind direction variability than in summer. A bimodal wind pattern was registered for each season, each wind direction explaining less than 30% of total variability. The zone with minimum variability in wind direction and maximum variability in wind magnitude was located northwest of the NGC, the same area where wind magnitude-Chla correlation was significant (p < 0.05). Winter and summer surface circulation patterns are more complex than currently documented. Summer is characterized by numerous plumes and eddies (especially anticyclonic), some traveling from coast to coast, enhancing the exchange of suspended material. Winter varied greatly interannualy, also showing many plumes and eddies (especially cyclonic), but was very heterogeneous, opposite to summer. Significant summer correlation was mostly positive, whereas in winter the significant correlation was equally positive and negative, maybe as a consequence of higher nutrient availability during this season.