The California Current is characterized by strong regionality in both forcing and biological response. Such spatial heterogeneity is controlled by latitudinal gradients in the strength and seasonality of wind forcing, heating and light, as well as differences in coastal topography, nearshore bathymetry, freshwater runoff, and other factors, all superimposed on differences in the impact of basin-scale signals. Several recent studies, including 'State of the California Current' reports, have highlighted regional differences in the magnitude or nature of response of California Current System properties to large-scale climate forcing. Moreover, the power of different modes of climate variability in the North Pacific (e.g., PDO and NPGO) to explain dynamics in the California Current also appears to vary regionally. This session invites presentations that examine and/or compare regional differences in variability within the CCS (or the temporal evolution of such differences) at any level, ranging from physical conditions to higher trophic levels. We especially invite presentations that explore mechanisms and processes that generate pattern at regional scales, or the implications of such variability for understanding the CCS as a whole.
In the Eastern Pacific Ocean, the North Pacific Current splits into the southward California Current and the northward Alaska Current. These two strong boundary currents are associated with mesoscale eddies and smaller submesoscale variability. Both currents exhibit temporal variability on time scales from hours mostly associated with tides to seasonal-to-interannual time scales associated with ENSO and Pacific Decadal Oscillations. Coupling with the atmospheric wind and river discharge, these strong boundary currents play a very important role in modulating coastal upwelling and its impact on biogeochemical processes. Because of the large geographic extent and long time scales, modeling has always been considered as an essential component of the ocean observing system to better describe, understand and ultimately predict the eastern Pacific Ocean circulation and variability. This session invites presentations describing forward, data assimilative and nowcast/forecast model results from the California Current and Alaska Current and the associated variability including physical as well as biogeochemical and ecosystem/fishery processes. Presentations that model interactions between these ocean currents and overlying atmosphere and lateral boundary conditions from open ocean as well as river/estuary are also invited.
The California Undercurrent (CU) is an important but under-observed component of the subtropical eastern boundary currents of the North Pacific Ocean. Flowing counter to the prevailing equatorward flow of the California Current, the CU acts as a poleward pathway for nutrient-rich but oxygen-depleted equatorial water, spawns eddies that transport this water offshore, and may be an important retention mechanism for zooplankton and other organisms in the California Current System. In addition, the strength, vertical and cross-shore position, and core water properties of the CU may each exert an influence on the biogeochemical character of water that is brought onto the continental shelf during upwelling conditions, and hence could be important to coastal hypoxia and ocean acidification. Interest in the CU therefore spans a wide range of disciplines and includes studies from both the coastal and offshore domains of the eastern North Pacific. Despite advances in ocean observing such as satellite altimetry and the global array of Argo floats, the CU remains difficult to observe due to its subsurface structure and narrow cross-shore width. Extensive sampling from CalCOFI, along with opportunistic observation in other coastal programs, has provided a relatively well-resolved picture of the seasonal cycle of the CU, though its role in processes related to coastal hypoxia and ocean acidification, influence on source waters for coastal upwelling, and dynamical driving mechanisms, among many other topics, remain unclear and require continued study. In this session we welcome abstracts that relate to the theoretical, observational, or numerical study of the CU and its influence on biogeochemistry and biology in the eastern Pacific Ocean. In particular, we invite abstracts that address poorly-understood areas of the CU, such as long-term variability in transport and water properties, the influence of El Niño/La Niña phenomena on the CU, and the role of the CU in exchange between the outer shelf and continental slope.