Quick question: in the last 72 hours, our 80 m moored SBE37 off Newport, OR (44.6°N) logged a 0.6 °C bottom-temperature jump and a 0.2 PSU freshening during weak winds, against the ongoing NE Pacific marine heatwave background. Are others seeing similar short pulses, and do you interpret them as remote downwelling signals or eddy-driven intrusions interacting with the current ENSO/NPGO state?
Saw similar 0.4–0.7 °C pulses at 70–90 m off Heceta Head during “weak winds” last fall; they lined up with a 2–3 cm bump at the South Beach tide gauge and brief poleward surface flow, so we called them remote downwelling signals… Practical check: pull the detided sea level at NOAA 9435380 (Station Home Page - NOAA Tides & Currents); if the setup leads your temp jump by a few hours it’s likely remote, but if not I’d lean eddy intrusion.
Last spring off Seal Rock, cross‑correlating bottom T/S with South Beach sea level (Station Home Page - NOAA Tides & Currents) nailed it — if the setup leads your temp jump by about 3–6 h it’s remote; otherwise we saw an eddy edge in HF radar. Small caveat: a quick freshet after rain can produce the 0.2 PSU without much wind.
Leaning downwelling: that “0.6 °C jump with 0.2 PSU freshening” at 80 m during calm winds screams a coastal-trapped wave/relaxation pushing surface-origin water downslope. Quick check I use is a T–S loop and Δσθ; if the pulse is density-light or near-compensated, it’s remote forcing, but if it’s denser with little S change, think an eddy filament along the usual isopycnals. Also peek at the IOOS HF radar archive for a 12–24 h northward burst off Newport (https://hfradar.ioos.us/) to bracket your 72 h window.
Had a similar 0.6°C bump at 80 m off NH10 during calm winds, and the tell was a tiny DO rise with a faint chlorophyll blip on the OOI Endurance shelf moorings — pointed to a relaxation push of surface-y water rather than an eddy. @OP if you can, peek at the same 72 h window on OOI (https://ooinet.oceanobservatories.org); if the bio signals don’t pop, I’d lean more toward a mesoscale intrusion.