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Abstract The California Current System is characterized by upwelling and rich mesoscale eddy activity. Cyclonic eddies generally pinch off from meanders in the California Current, potentially trapping upwelled water along the coast and transporting it offshore. Here, we use satellite-derived measurements of particulate organic carbon (POC) as a tracer of coastal water to show that cyclones located offshore that were generated near the coast contain higher carbon concentrations in their interior than cyclones of the same amplitude generated offshore. This indicates that eddies are in fact trapping and transporting coastal water offshore, resulting in an offshore POC enrichment of 20.9 ± 11 Gg year−1. This POC enrichment due to the coastally-generated eddies extends for 1000 km from shore. This analysis provides large-scale observational-based evidence that eddies play a quantitatively important role in the offshore transport of coastal water, substantially widening the area influenced by highly productive upwelled waters in the California Current System.
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The California Undercurrent as a Source of Upwelled Waters in a Coastal Filament
Abstract In the California Current System, cross‐shore transport of upwelled, nutrient‐rich waters from the coastal margin to the open ocean can occur within intermittent, submesoscale‐to‐mesoscale features such as filaments. Time‐varying spatial gradients within filaments affect net cross‐shore fluxes of physical, biological, and chemical tracers but require high‐resolution measurements to accurately estimate. In June 2017, theCalifornia Current EcosystemLong Term Ecological Research program process cruise (P1706) conducted repeat sections by an autonomousSprayglider and a towed SeaSoar to investigate the role of one such coastal upwelling feature, the Morro Bay filament, which was characterized by enhanced cross‐filament gradients (both physical and biological) and an along‐filament jet. Within the jet, speeds were up to 0.78 m/s and the offshore transport was 1.5 Sverdrups (3.8 Sverdrups) in the upper 100 m (500 m). A climatological data product from the sustained California Underwater Glider Network provided necessary information for water mass differentiation. The analysis revealed that the cold, salty side of the filament carried recently upwelled California Undercurrent water and corresponded to higher chlorophyll‐afluorescence than the warm, fresh side, which carried California Current water. Thus, there was a convergence of heterogeneous water masses within the core of the filament’s offshore‐flowing jet. These water masses have different geographic origins and thermohaline characteristics, which has implications for filament‐related cross‐shore fluxes and submesoscale‐to‐mesoscale biological community structure gradients.
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- Award ID(s):
- 1637632
- PAR ID:
- 10449264
- Publisher / Repository:
- DOI PREFIX: 10.1029
- Date Published:
- Journal Name:
- Journal of Geophysical Research: Oceans
- Volume:
- 126
- Issue:
- 2
- ISSN:
- 2169-9275
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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