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Release #3 – at the mouth of the Tijuana River Estuary

Our 3rd dye release was 12 October and we sampled through 13 October. It was the most ambitous release yet. We pumped 30 gallons of dye into the Mouth of the Tijuana River Estuary on an ebbing tide over 2 hours. Rob was leading the dye release and here he is at the estuary mouth as dye is flowing:

Rob Grenzeback, research associate

Rob Grenzeback, research associate

We had shoreline instruments from 3 km south of the border in Mexico all the way up to Coronado. We had a boat from CICECE/UABC and 2 SIO boats + jetski in the water and of course the plane. The dye raced out of the inlet and headed north along the beach toward the end of seacoast drive. It then started to peel offshore in large bands. It was very impressive particularly with how good the waves were. The hydrodynamica project got some great pics – see:  https://instagram.com/p/8wCx3iCcvN/?taken-by=hydrodynamica

Eventually, the dye spread further offshore in a large plume with a variety of bands moving north along seacoast drive and the shoal of the Slough offshore.

R3_IMGa

But by the end of 12 Oct it never really went north of the IB pier. See the photo below.

R3_IMGeWe hunted for dye the next day and that story will be told once we’ve unraveled it all.

CSIDE MX Dye release simulation!

Below is a movie of a MX dye release similar to the other rleases that Nirnimesh has put together.    The dye release location here is at the very southern part of Playas Tijuana, where we will be doing our dye release.     Again, Nirnimesh is simulating the week from 9/30-10/7 2014 for moderate waves from 200 deg south, similar to the previous movies.   The movie lasts for a week.  The first dye release lasts 2 hours and the 2nd release lasts 6 hrs.   From these simulations it really does seem that the surfzone is a leaky pipe in exchanging with the shelf.  The proof will be in the actual dye release experiment.

  • Left panel is temperature anomoly (subtracting T=18 deg C), Right panel is dye concentration (ppb) in log scale.
  • Each frame is one hour. The counter (dT) indicates how long since the dye release.
  • About 100 L of Rhodamine WT was released over (2 hrs/6 hrs) for each releas,  a realistic amount of dye.
  • Magenta dots are planned instrument locations

CSIDE US/MX border dye release simulation

Nirnimesh has completed another round of dye release simulations to help us prepare for the upcoming dye releases.   For this release Nirnimesh is simulating the week from 9/30-10/7 2014 for moderate waves from 200 deg south.     The movie lasts for a week.  The first dye release lasts 2 hours and the 2nd release lasts 6 hrs.   In this case the dye makes it up to Navy SSTC north property but not quite to Coronado and the second releases exchanges significantly offshore.

* Left panel is temperature anomoly (subtracting T=18 deg C), Right panel is dye concentration (ppb) in log scale.

* Each frame is one hour. The counter (dT) indicates how long since the dye release.

* About 100 L of Rhodamine WT was released over (2 hrs/6 hrs) for each release.  This is a realistic amount of dye to be released.

* Magenta dots are planned instrument locations

 

Now it is interesting to contrast this release with what happens with larger south swell.   The video below is for the same conditions but waves that are 1.4X bigger.

 

What happens here is that the larger waves drive a stronger alongshore current and the dye just rockets all the way up to Coronado.   This could have significant implications for pollution transport.  But remember, this is just a model of two short dye releases for very specific conditions.   These simulations are only representative of what could happen.

Dye releases can start as early as 14 September!

 

ADCP boat mount for the Sally Ann

Kent and the SIO machine shop have fabricated a sweet ADCP mount for the Sally Ann.   This will enable tracer flux calculations from the coupled ADCP and towed aray measurements.    Kent got it done on Friday and did the first test mount Friday late afternoon up at Seaweed Canyon.   Pretty awesome.

20150828_161027_resized

First Test of MCIP carts

On Wed 26 August, we had the first full field test of the MCIP carts which went really well.  A MCIP cart stands for Mobile Cart Instrumentation Platform.  An instrumented MCIP is shown in the first picture of the gallery below. It is basically a steel wheelbarrow that can roll into the surfzone. It has a range of instrumentation, including an ADV current meter, pressures sensor, thermistor, dye fluorometer, turbidity sensor, pitch/yaw/roll, and GPS, that go to a data acquisition system.

This system enables easy measurements of surfzone quantities. Normally it is much more intensive to deploy an instrumented tripod in the surfzone. This can be easily and rapidly deployed!

With these easy conditions on the test day it was no sweat. We got the MCIP out to waist deep water, locked it into place and then let it take data. On this day we did not actually put dye in the water so we did not take any dye measurements, but we do have temperature measurements over an hour.

MCIP_Temp_Test

What is very interesting is that the ocean is unusually warm for Southern California (25 deg C is 77 deg F!!!). But also over an hour the temperature changes by about 0.7 degC (1.3 deg F). What causes these large and fast fluctuations?

New pre-experiment CSIDE dye release simulations: comparing 2hr and 6 hr releases

In the previous post we presented the first dye simulation that Nirnimesh has done.  That simulation was for a release that totalled 2 hrs.  Now, Nirnimesh has performed an identical experiment for dye released for 6 hrs and compared the two.  The modeling details are the same:  This is with the COAWST model that couples waves and currents and has a 20 m grid resolution.  This simulation is for a period of time in Fall 2014 with northward winds.  Nirnimesh also sent in waves with significant wave height of 1 m, peak period Tp=14 s, and offshore angle of 200 deg.   He did two dye releases separated by about 3 days.


* Left panel is temperature anomoly (subtracting T=18 deg C), Right panel is dye concentration (ppb) in log scale.

* Each frame is one hour. The counter (dT) indicates how long since the dye release.

* About 100 L of Rhodamine WT was released over 2 hrs for each release.  This is a realistic amount of dye to be released.

* Green square is dye release location, Magenta dots are planned instrument locations/

* Both dye releases are at high tide.

Now the movie above is for surface temperature and dye.  It does not address the question of what dye does in the vertical.  ROMS works in vertical layers called sigma layers.  Each sigma layer fills up a part of the water column.   Below is a movie of the dye field on different sigma layers.   Note the differences between near bottom (left) and surface (right) panels!

Also, it is important to remember that in each movie the depth z varies on the sigma layer.  The way it works is that z = sigma * depth.    So the panels go from bottom to surface from left to right.   But they are not  fixed depth levels.

First pass at a dye release simulation in the CSIDE study region

Nirnimesh has performed the first dye release simulation in the CSIDE study region.  This is with the COAWST model that couples waves and currents and has a 20 m grid resolution.  This simulation is for a period of time in Fall 2014 with northward winds.  Nirnimesh also sent in waves with significant wave height of 1 m, peak period Tp=14 s, and offshore angle of 200 deg.   He did two dye relases separated by about 3 days.

* Left panel is temperature anomoly (subtracting T=18 deg C), Right panel is dye concentration (ppb) in log scale.

* Each frame is one hour. The counter (dT) indicates how long since the dye release.  The movie goes fast!  You can slow it down in the youtube controls

* About 100 L of Rhodamine WT was released over 2 hrs for each release.  This is a realistic release.

* Green square is dye release location, Magenta dots are planned instrument locations/

* Both dye releases are at high tide.

 

This is a first pass!  We are going to do many more simulations to figure out best release and sampling strategy!

 

Wave modeling for the San Diego South Bay Region

As part of the CSIDE modeling efforts,we are interested in performing some numerical dye releases for the CSIDE experimental region, the San Digo South Bay. In an earlier post, the 50 m grid size ocean circulation (ROMS) model solution developed by Nirnimesh Kumar was highlighted. That simulation did not have waves, and Nirnimesh is working on putting waves into the simulation by coupling SWAN and ROMS.

First, he wanted to understand the dramatic range of wave height variation that can occur in this region due to bathymetric focusing of the wave field.  So Nirnimesh used SWAN only to simulate incident waves with significant wave height Hs=1 m, peak period Tp=14 s, and a range of incident wave angles from 180 deg to 280 deg.   These are shown below.   What you can clearly see is the dramatic variability in wave height along the stretch of shoreline from North Island, to City of Coronado, Silver Strand State Park, City of Imperial Beach, Border Field State Park and Tijuana.    These wave height variations could very likely have strong effects on dye evolution in this region!   We are excited to get numerical dye experiments going and also the real thing!

 

wave_height_and_direction_san_diego_bight

 

Simulation of the San Diego South Bay Region: July-Nov 2014

Nirnimesh Kumar, our intrepid COAWST (coupled ROMS/SWAN) modeling expert has been grinding away developing a numerical model for our study region: The San Diego South Bay.   His latest creation is really spectacular

These simulations show evolution of sea surface temperature and depth-averaged velocities from July 1, 2014 to December 1, 2014 in Southern California including Imperial Beach. The grid resolution is 50 m.  The model includes tides, winds, air-sea fluxes, and lateral boundary condition.   But it does not yet include waves (that is coming).   This simulation uses parent boundary conditions from a larger set of numerical solutions with larger grid size.  The largest parent grid is 1 km and was supplied by Chris Edwards at UC Santa Cruz.

Once we have the waves coupled, the eventual goal with these simulations is to use them to simulate dye release experiments (a mock pollution event) so that we can help design our dye release experiments.

 

scripps oceanography uc san diego