Virginia Scientist Studies Unexplained Sea Level Rise

... and fall: VIMS prof studying 'middle ground' sea-level change

While sea-level rise has become an everyday topic of conversation, research by professor John Brubaker of the Virginia Institute of Marine Science is throwing light on another, less-familiar component of sea-level variability. He studies “intra-seasonal” changes between rapid, storm-related surges and the long-term increases due to global climate change.

"These are cases when the water is just 'running high,'" Brubaker said in a release, "but not from an obvious direct cause of a storm. It isn’t necessarily windy, it’s just an elevated water level without a clear cause."

Intra-seasonal variability, which Brubaker says takes place over 10-90 days and can add or detract a foot or more from the predicted tide, is likely due to shifts in oceanic currents and large-scale movements of water masses along the coast.

I've observed such changes before.  Here, you can see some of the variations in this long term tide record from Kiptopeake, Virginia, on the ocean side of the Bay.  There's a lot of variation, larger than the annual signal of long term sea level rise, and on all kinds of time scales.  Certainly, short spikes and dips are caused by short term weather events, but we also see season and even perhaps year long variations from the trend.