Physical and biogeochemical variability off Baja California (Mexico): insights from numerical NPZD ocean models

David Rivas
Seminar Date: 
30. August 2019 - 13:15 - 14:00
Lecture room, Ground Floor, NERSC

Physical-biogeochemical Nitrate-Phytoplankton-Zooplankton-Detritus (NPZD)
numerical models are used to study the variability of nutrients and
phytoplankton biomass in coastal waters off Baja California Peninsula, a
region of high socioeconomic importance located in the southern California
Current System. The focus of these analyses has been the effects of
interannual climatic anomalies. For example, the year 2006 was anomalously
warm and with low chlorophyll (Chl) levels, associated with warm phases of
El NiƱo-Southern Oscillation (ENSO) and the Pacific Decadal Oscillation
(PDO) and a weakening of the North Pacific Gyre Oscillation (NPGO). The
year 2011, on the other hand, was a cold year with enhanced upwelling
during the spring, associated with cold phases of ENSO and PDO and an
intensification of the NPGO. The effects of the North Pacific "Blob"
have been also analyzed, which include an intense deepening of the
nutricline and the thermocline, and hence of the subsurface Chl maximum,
during the 2013-2016 period. Long-term changes in the
nutrients/phytoplankton fields along the Baja California Peninsula
associated to climate change have been also explored. Downscaling of a
global circulation model indicates that coastal upwelling overcomes the
increased stratification under high greenhouse-gas emission scenarios
(RCP6.0 and RCP8.5) by mid 21st century.