The Effects of Changing Climatological Variables on Upwelling along the Southern California Coast

Abstract:

A large part of the high productivity of CA current ecosystems can be attributed to Ekman upwelling of cold, nutrient-rich water, driven by north winds running parallel to shore. As meteorological (e.g. wind direction and velocity, atmospheric pressure fields, etc.) and oceanographic (e.g. sea surface temperature) parameters change in the context of climate change, it is unclear how ecosystems and the coastal upwelling on which they depend, will be impacted. To better understand the effects of meteorological and oceanographic forcing on coastal upwelling, eleven years (2005-2015) of data were taken from satellites, weather stations and data-collecting buoys located in and around the Santa Barbara Channel as part of the NASA Student Airborne Research Program (SARP). These data were then analyzed using regression and time-series cross-correlation statistics in order to identify trends in meteorological and oceanographic cycles, their relationship to localized upwelling (e.g. upwelling indices), and how climate change may impact upwelling. Results indicate that as temperature has increased over the last four years (as a result of the 'warm blob'), upwelling has decreased. They also indicate differences in the annual cycles of cross-shore pressure gradients during years of poor versus years when upwelling conditions are favorable. This documented dependence of the coastal wind on sea surface temperature could have important implications as our oceans change; elevated sea surface temperatures, such as those associated with the 'warm blob', may result in less coastal upwelling and lower ecosystem productivity.