Observed Wind and SST Variability off the California Coast During
Summertime High Wind Events
Abstract
Sea surface winds off the California coast are characterized by high
wind events that occur in spring and summer. In June, a well-defined
wind event region is formed off the five major capes, extending
~300km offshore. In the present work, a satellite wind
product is used to study the spatial variability of these wind events.
High-speed and long-duration events primarily occur off Cape Mendocino,
whereas low-speed and short-duration events are more uniformly
distributed over the wind event region. Coastal buoy observations show
an anti-correlation between wind speed and sea surface temperature (SST)
during wind events: a decrease in wind speed accompanies an increase in
SST before the start of events, and an increase in wind speed
accompanies a decrease in SST after the start of events. Different SST
cooling patterns are observed within different categories of wind
events: (1) High-speed events lead to more SST cooling compared to
low-speed events. (2) Long-duration events lead to longer SST cooling
times compared to short-duration events. SST cooling is observed both at
nearshore buoy locations and at locations far from the coast. The
magnitude of cooling is about 1°C nearshore and 0.3°C offshore. A case
study of upper-ocean responses from mooring observations suggests that a
combination of enhanced wind-driven mixing and Ekman pumping processes
may explain SST cooling nearshore during wind events.