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Figure 3: Time series plots.

• (A) Sea level at Fort Point (near the Golden Gate),
• (B) sea level at Jersey Point (San Joaquin River),
• (C) discharge, measured by an Ultrasonic Velocity Meter (UVM) at Jersey Point, and
• (D) the Root Mean Square (RMS) discharge at Jersey Point.

The data at Jersey point are used to evaluate the state of the tide during the drifter experiments because the Jersey point location is roughly in the center of the study area.

The amplitude of the tide wave diminishes as it propagates through the system, where the tidal range is reduced from roughly 2.2 yards at the Golden Gate (A) to 1.0 yard at Jersey Point (B). The differences in tidal amplitude between spring and neap tides are not only apparent in the Delta, the differences are actually a larger fraction of the total tidal range in the Delta. This is one reason why the tidal exchange and residence times vary significantly from spring to neap in the shallow areas studied in these web pages. The RMS discharge (D) quantifies the complicated spring/neap tidal cycle "interference" pattern seen in the sea level where spring tides are represented by peaks and neap tides by valleys on the RMS discharge plots.