Radar snap of waves

Decent crossing wave trains imaged off the south side of the inlet

This is an example radar image showing crossing wave trains on the shoal that extends from the south side of the inlet. We are analyzing these image sequences to see how well (or not) wave directions can be extracted and bathymetry estimated. Hope to have more soon.

Merge Images available

I’m not sure if this is well known yet, but Argus merged images are available on the web at http://cil-www.oce.orst.edu/RIVETmerge.  They are posted as they are collected and consist of snap, timex, var, bright and dark images for every 1/2 hour.  The upper half of the page is rectifications for the large inlet area at 2.5 m resolution.  If you continue down you will see equivalent images for the west side area at 1.0 m resolution.  Click on thumbnails to see full res images.  Further explanations will be posted soon (after I teach), but a nice example snap from 1100 today is attached below (with luck) – check the small scale features in very shallow water around x=-150, y = -450.  Tres cool (and it looks like people are surveying based on dark image tracks).

New River Inlet Plume

Here are some photographs of the New River Inlet plume that were taken during the morning low tide on Wednesday, May 2 (low tide was 10:49 EDT) form the APL-UW Cessna 172. These photographs were taken between 10:30 and 11:00 EDT. Multiple lobes of the plume may indicate flow through different channels in the inlet. A secondary plume characterized by a darker color (e.g., forth photograph) was visible during this time, possibly indicating a source of sediment from further upstream.

Day 2 of drifter releases

Today was day 2 of drifter releases.   Everything went very well with the exception of possibly dinging the WHOI location 55 with our Whaler.     We did three releases.   The first was during a strong ebb tide.    The 2nd was an attempt to capture the transition from ebb to flood.    Two drifter track images are shown below.     The first image is approximately 15 minutes after the drifters were released.    They were released in clumps of 5 at different locations in the navigation channel.   This was as the ebb tide was becoming weaker, but still offshore propagation is quite clear.

May 2nd Drifter tracks at New River Inlet on superimposed bathymetry at the end of an ebb tide. Filled circles with numbers represent drifter locations, and the colored curves the tracks. May 2nd drifter tracks on the transition to flood tide ~1 hr after the previous image. Note the loopback of the drifters and the convergence onto a single streamline as they propagate up the inlet.
May 2nd drifter tracks on the transition to flood tide ~1 hr after the previous image

About an hour later as the tide had switched from ebb to flood, the drifters had turned around in a loop and headed back up the inlet (see image above)  The very interesting thing is that all the drifters began coming together onto a single streamline as they converged at the inlet bend near Can #10.

The next release was on a strong flood tide.  The 34 drifters were released offshore of the shoal to the south-west.     The drifters rapidly crossed the shoal and spread out on the inside of the inlet.  Again, the drifters started organizing themselves by where they were released offshore (see image below).

May 2 - release 3 - Drifter tracks at New River InletMay 2nd release 3 Drifter tracks at New River Inlet.
May 2nd release 3 drifter tracks at New River Inlet
May 2nd release 3 Drifter tracks at New River Inlet

Later on nearly all the drifters have converged on this one particular line.   From the boat it was very neat.   Like a train of drifters coming at your.   You could see them relatively spread out and then they would converge onto the line.     Below is a photo the Dennis Darnell took from the SIO Whaler.

Photo of the drifter train along a convergence (scum) line (photo: Dennis Darnell)

 

Two more days of drifters, then a day for turning around instruments, and then dye.