Example Merged Rectifications

Here are example merged Argus products that we will be putting on the web. If you have suggestions for changes, let us know. For example, we will add instrument locations as we learn them. The first is a large area time exposure showing the shoal configuration. The second in a small area snap that shows fierce crossing wave patterns.

Delft3D model simulations posted

From Ad Reneirs & Patrick Rynne:

We’ve posted the latest model predictions for NRI for the 28th-29th at the link below.
Please click on the .zip file link in the center of the page.


we are driving up today, predictions will be more timely in the days ahead once we get

-Patrick & Ad

Below is an image on flooding tide from the model simulation showing current vectors on top of the bathymetry from Apr 16/17.    Although the comparison is qualitative, note the difference in how far offshore the ebb tide jets relative to the NEARCOM simulation.

New NRI NEARCOM model results on the Apr 16/17 Bathy (Tom, Julie, & Fengyan)

The UDEL folks have posted new NEARCOM model results on their website.   The basic conditions are the same.  One M2 tidal cycle, with normally incident Hsig=1 m, and then varying the drag coefficient.     It is hard to tell from these simulations how far offshore the tidal jet goes.    We will be simulating drifter trajectories on these model currents and posting that soon.

Initial Timex Images

Attached (with luck) are initial time exposure images from today at 1700 EST (1800 EDT??). We surveyed this evening and will be doing image geometries tomorrow then will run routine rectification maps thereafter. But we thought people might be interested in the shoal geometries.

Delft3D simulation on the new FRF bathymetry – first results (w. Rynne & Reniers) – updated

Today we have near gale force winds at New River Inlet.     But there are model simulations to work up.     As readers will recall, the FRF did a recent (Apr 16/17) bathymetry survey after the dredging of the main channel.   The upshot is that the main channel is still very shallow and narrow.     We have done two test dye releases (see earlier posts).   In contrast to model predictions based on bathymetry ~ 1 year old (see earlier posts w/ NEARCOM tide / drifter  and Delft3D tide / dye  results) where there is a strong tidal jet that strongly advects stuff many km offshore,  the dye both time just ooozed over the southern ebb shoal or out the new channel and northern part of the shoal.    Clearly there was no strong tidal jet.     Also,  Britt & Steve also have found that tidal velocities are basically in phase with tidal elevations, ie, progressive, whereas the models were predicting a 1.5 hr lag (half progressive/standing).   So both NEARCOM and Delft3D are being re-run with the new bathymetry.   Here are some preliminary results from Delft3D run with just tidal forcing and a dye release.

First analysis of the tides.   See the image below.   Contrast this with the analysis on older bathymetry

As can be seen the tidal velocities are very strong inside the inlet but decrease rapidly at and offshore of the shoal (not here log10 velocities is colored).   Bathymetry contours (4, 6, 8 m depth) are shown as dashed.

More interesting is the dye simulation.   Now ~42 hours (previously only 20 hours) of the model has been finished, however this dye simulation is very different from previous simulations on the old bathy. See the youtube video below. It is clear that the dye behaves very differently oozing evenly out over the entire shoal rather than in a jet.   The dye does not make it as far offshore.    This is qualitatively consistent with our preliminary dye deployments.   Note that there is no wind or stratification in this run.  All the other model parameters (eddy diffusivities, etc.) were the same as the previous run.

For ease of comparison, take a look at the dye simulation with the old bathymetry but the same conditions (below). Clearly quite different.


Summary of RIVET target deployment locations

I was talking to Jesse McNinch this morning about compiling deployment locations for all the instruments that have been deployed.    Many deployed instruments don’t have yet an accurate processed GPS location.   However, target deployment locations have been put together by various PIs in coordination.   Jesse thought it would be useful to see the target locations.     So I’ve put together the  WHOI (Britt/Steve), SIO (Falk/Bob), UNH (Lippmann), and SIO Metbuoys (Terrill) target deployment locations in one kml file.     An image is shown below.      Note these are ONLY target locations.     Final deployment locations will be different.   For example the UNH ADCP 3 is deployed farther to the SW than indicated.

Generally.  Red are WHOI (Britt/Steve) – the red circles are ADV, red circle w/ black dot are ADCP.    SIO ADVS (denoted SIO-V[1-8]) are white squares w/ black dot.   SIO ADCPs are magenta circles (denoted SIO-A[1-4]).   SIO Wirewalkers are open white diamonds.    UNH ADCPs are in green.    The SIO Metbuoys are not easily visible here but are in the .kml file.

When final deployed positions are known we will post them here.

Day 1 of SIO (Feddersen/Guza) deployments

Today was the first day of the SIO Feddersen/Guza deployments.   We installed all the pipes to mount Nortek Vectors, EcoTripplets, and marker poles at five locations denoted V1, V2, V3, V7, & V8.    For reference see the deployment map below.   The vector locations are labeled.     The idea is to be able to measure the dye dilution as dye is carried alongshore up and downcoast from the inlet – and the ADV current meters are to measure fluxes.     It is unlikely that there will be a strong tidal jet carrying tracer far offshore.   In our two test dye deployments the dye just went along the coast essentially.

Next up on Wed is 3 tripods at locations V4, V5, and V6.  These we’ll need the help of the LARC.    In the meantime  WHOI (Raubenheimer/Elgar) are cruising with their deployments and UNH has 2/3 ADCPs deployed.    Things are cooking!


Tidal elevation and currents: progressive or standing?

Inlet goons:

We deployed a current meter for 24 hours near the mouth of the inlet, just offshore of the
access road (where UW is building a condo complex out of pipes).

The currents  are close to in-phase with the tides. High tide=strong  flood, low tide=strong ebb. Slack is 90-degrees out of phase relative to a sinusoid, and thus slack is about 3 hours after high or low tide. The plot shows this.

The green dots are the pressure in dbars (close to m), so about a 1.2 m tide range on April 20-21, 2012. The blue dots are the currents along the channel (major axis) (1.25 m/s ebb (at low tide) and 0.8 m/s flood (at high tide)).

For this 24 hr period, max flood was maybe 1/2 hr before high tide, max ebb was maybe 1/2 hr before low tide.

Yesterday (April 23) the ebb was almost 3 knots (1.5 m/s) up the channel a km or so (around the bend) (drifting boats with GPS). Our marker floats were pulled under and we could not see them until the flow slowed way down! These are interesting conditions in which to work. The divers are tough as nails and a little bit insane, so they are getting the job done.

[Plot by Sean Kilgallin and Seth Zippel, data provided by Britt Raubenheimer, CAR-E, Danik, Jenna, Levi, Regina, David drove boats and hauled lines and heavy frames up and down in wicked currents.]