Upwelling and Circulation Dynamics in the Southern California Current System
Upwelling and Circulation Dynamics in the Southern California Current System

Author: Caroline Ford Lowcher

Publisher:

Published: 2023

Total Pages: 0

ISBN-13:

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Southern California is part of an eastern boundary upwelling system (EBUS). This region is ecologically productive and socioeconomically significant, and how EBUS will respond to future changes in climate is of scientific and societal interest. Long-term monitoring is a key component for assessing how EBUS will be impacted by climate change and long timeseries of mooring observations are the focus of this dissertation. Anomalous poleward flow was observed in southern California prior to and during the 2014 marine heatwave and 2015 - 2016 El Niño. Prior to the El Niño, local forcing drove a strengthened wind stress curl and a more persistent Southern California Eddy (SCE). The poleward recirculation of the SCE into the Southern California Bight (SCB) brought more waters from the California Current and North Pacific Subtropical Gyre closer to the coast. During the 2015 - 2016 El Niño, remote forcing drove persistent elevated coastal sea levels which forced poleward geostrophic flows and advected tropical waters into the SCB. A volume budget was performed for southern California and this motivated developing an upwelling index. The upwelling index includes cross-shore geostrophic transport by using sea level changes right at the coast, accounting for coastal processes such as coastally trapped waves. Low-frequency upwelling anomalies indicate decreased vertical transport during the 2014 - 2016 upwelling seasons concurrent with the large-scale climate phenomenon in these years. This upwelling index is a practical tool for analyzing upwelling requiring minimal in-situ observations. The upwelling forcing is valuable for assessing the physical impact on the coastal ocean, but it may not represent the oceanic response to upwelling. Multiple physical and biogeochemical properties are used to examine the coastal oceanic response to upwelling alongside the upwelling forcing. Event statistics are calculated using the long record of in-situ measurements, in addition to investigating the low-frequency in-situ anomalies. EBUS are susceptible to harmful algal blooms and a particularly pronounced red tide is examined alongside the physical processes that supported the red tide.

Predictability of the California Current System
Predictability of the California Current System

Author: National Aeronautics and Space Administration (NASA)

Publisher: Createspace Independent Publishing Platform

Published: 2018-06-19

Total Pages: 30

ISBN-13: 9781721521043

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The physical and biological oceanography of the Southern California Bight (SCB), a highly productive subregion of the California Current System (CCS) that extends from Point Conception, California, south to Ensenada, Mexico, continues to be extensively studied. For example, the California Cooperative Oceanic Fisheries Investigations (CalCOFI) program has sampled this region for over 50 years, providing an unparalleled time series of physical and biological data. However, our understanding of what physical processes control the large-scale and mesoscale variations in these properties is incomplete. In particular, the non-synoptic and relatively coarse spatial sampling (70km) of the hydrographic grid does not completely resolve the mesoscale eddy field (Figure 1a). Moreover, these unresolved physical variations exert a dominant influence on the evolution of the ecosystem. In recent years, additional datasets that partially sample the SCB have become available. Acoustic Doppler Current Profiler (ADCP) measurements, which now sample upper-ocean velocity between stations, and sea level observations along TOPEX tracks give a more complete picture of the mesoscale variability. However, both TOPEX and ADCP are well-sampled only along the cruise or orbit tracks and coarsely sampled in time and between tracks. Surface Lagrangian drifters also sample the region, although irregularly in time and space. SeaWiFS provides estimates of upper-ocean chlorophyll-a (chl-alpha), usually giving nearly complete coverage for week-long intervals, depending on cloud coverage. Historical ocean color data from the Coastal Zone Color Scanner (CZCS) has been used extensively to determine phytoplankton patterns and variability, characterize the primary production across the SCB coastal fronts, and describe the seasonal and interannual variability in pigment concentrations. As in CalCOFI, these studies described much of the observed structures and their variability over relatively large space and

Investigations of the California Current System
Investigations of the California Current System

Author: William James Crawford

Publisher:

Published: 2017

Total Pages: 251

ISBN-13: 9780355333701

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The California Current System (CCS) is undoubtedly one of the most well studied regions of the world ocean. The seasonal variability of equatorward upwelling winds allow for the development of a complex set of dynamical features while also sustaining a rich diversity of marine organisms. With use of the state-of-the-art Regional Ocean Modeling System (ROMS) 4-dimensional variational (4D-Var) data assimilation system, the circulation of the CCS is explored in varying capacities over the time period 1980-2010.