Identification of the problem: the northeastern pacific (NEP) encompasses the gulf of alaska (GOALME) and the california current large marine ecosystems (CCLME)

A common driver of variability in both systems is the north pacific current (NPC), which forms the transition between the subarctic and subtropical gyres and bifurcates near the north american coast into the northward-flowing alaska current (AC) and southward-flowing california current (CC).variability in the strength and latitudinal position of the NPC, and its bifurcation, thus determines the physical and biogeochemical properties of the waters entering the GOALME and CCLME, with significant downstream ecosystem impacts. A poleward shift in the position of the NPC is a particularly robust feature in global climate models, and is projected to greatly impact regional trends in CC upwelling. This poleward shift is, in turn, projected to be reflected in the shifting distribution of sardine populations and core top predator habitat. Rationale: given the importance of the NPC variability, the overarching goal of this project is to investigate its historical role in providing connectivity between the GOALME and CCLME, assess its predictability on seasonal to interannual time scales, project its future variability, and explore the downstream ecosystem impacts in the coastal waters of the GOALME and CCLME across these timescales. We will analyze a set of high-resolution reanalyses and hindcasts, and outputs from retrospective near-term forecasts and future climate projections to: (1) understand the historical variability and changes in water mass properties, transport, and bifurcation latitude of the NPC and its connections to coastal waters along the CCS and GOA, (2) quantify and diagnose drivers of near-term forecast skill and predictability in the NPC, its bifurcation, and its downstream physical and biogeochemical properties, and (3) understand and examine how a projected future poleward shift of the NPC might alter water mass properties and transport and their downstream impacts. Summary of work to be completed: key elements of the work plan are to: (1) examine the historical variability and the connectivity between the GOA and CCS coastal waters through the large-scale variability of the NPC and its bifurcation, (2) quantify and diagnose near-term predictability and forecast skill using the CESM2 seasonal-to-multiyear large ensemble (SMYLE), and (3) evaluate and examine the robustness of future changes and downstream impacts of the NPC in the CESM2 large ensemble community project (LENS2) quantifying and forecasting the variability in the position of the foot of the shelfbreak front will lead to a better understanding of several environmental stresses to the shelf ecosystems as movement of the front is linked to fluctuations in bottom temperature anomalies, restriction in the spatial extent of the cold pool, and onshore limits in predator habitat. This proposed work is timely as IT addresses issues relating the recent mortality event of scallops in the region to fluctuations in multiple stressors related to the cross-shelf position of the shelfbreak front. The proposed work is directly relevant to noaas goals of improved advancing understanding of variability and change, with an emphasis on a mechanistic understanding of the relative importance of ocean drivers for shelfbreak front cross-shelf position. The proposed work involves development of a new index that is related to multiple stressors to the shelf ecosystem including temperature anomalies and habitat for predators. The proposed work will involve use of reanalysis products as well as regional models in addition to hydrographic data used to develop the index. Substantial effort will be made to communicate research results to nefsc scientists as well as the commercial fishing community. The PIS have extensive experience in interacting with nefsc scientists on management issues regarding squid and other