A live(-ish) attempt at a coastal investigation
NOAA collects tide data along the California coastline. I wanted to see if tide gauges might show Kelvin waves moving along the coast.
Scroll to investigate ↓
Step 01
First thing – Kelvin waves aren't so much just “waves” as upwelling in water levels. There are both speedy surface waves and the slower internal waves that carry warm water.
Below, each line is an observed water level at a station, minus the tide prediction for that location.
Surface Kelvins – my term – can move at 200 meters/sec (~450mph). The internal waves bringing the heat travel slower at ~1–3 meters/sec.
Step 02
Looking at the daily cells in an attempt to make broader shifts up the coast visible.
Color is scaled to the loaded observations. If there isn't enough data per day, it shows as missing and is dark or empty.
Step 02 / A closer read
They are ordered by their distance from San Diego moving north.
A coordinated upwelling should, maybe, arrive progressively later as it travels north. Similar patterns may suggest it, but we cannot assume it.
The next chart gets more granular in three-hour station measurements around a station’s peak water level.
Step 03
Reading the latest observed days.
Each strip is a station’s own measurements. The callout line identifies a potential candidate peak from the southern reference gauge. The circles highlight nearby measured bins with similar heights.
Still not a clear sign of a Kelvin wave.
Step 03 / The question
Do similar changes show up farther north later, in a way that suggests they could be related?
The full dashboard keeps the coverage and lag tests alongside this visual check.
04
Copernicus satellite data adds a broader offshore reading. Each block is that point’s daily non-tidal sea-level change, compared with its preceding seven-day value.
These pull in large 0.125° gridded samples, roughly 12–14 km across, and sit farther offshore. They provide context for the coastal gauges, not a substitute for them.
04 / An overhead view
The satellite rows are offshore grid-cell estimates, not tide-gauge measurements. I included them to see whether broader sea-level change is visible beyond the coastline.
Conclusion