Daily Archives: September 13, 2017

Throwback… Wednesday? Airborne IR perspective of flow past Pt Sal from the pilot experiment

For a little airborne perspective on the flow around Point Sal I’ve posted this time series of IR orbital flights around the point that we flew in 2015. You’ll note several interesting features including: strong southward flow; turbulent surface flow over the submerged bathymetry just off of the point; several cooler rip plumes north of the point; and a convergent (and eastward propagating) front just offshore of the rips.

ptSal_IR_2015Jul01_Movie

Transects and Boxes

Yesterday, September 11th, the Kalipi crew got over the afternoon hump with the arrival of numerous slicks and red biological growth on the water surface. It did help us not want to jump into the water. The energy was high until the end of the day!

Jenny and Una observe and sample the convergence line, because they give a dam (Go Beavs!).

Pelican caught between the Oceanus, a mooring (teeny tiny white speck), and slick spots.

Jim and Jenny make alterations to the CTD, wrapping lead weights around the CTD itself.

 

Today, the Kalipi crew spent the day running surveys using the side-mounted ADCP and the fast profiling CTD in a box pattern by Pt. Sal. We enjoyed the wonderful views and company while we caught things at the bottom of the ocean. We made things a little challenging for the CTD team with sharp turns made by a new boat driver in training (that would be me…Una). We were able to see more internal wave slicks today as well. All is well aboard the Kalipi!

Jenny, Matt, and Taylor getting ready for a fun filled day.

Sea lions wishing us farewell from Port San Luis Pier.

Internal waves in the sky over internal waves in the ocean!

Una on standby with the Sally Ride on the horizon.

 

-Una Savić

Flow Separation South of Pt Sal Today

As the Sally Ann and Sounder drove the box patterns,  we first noticed that the flow just west of Pt Sal was to the south.  Then to the south of the Pt running east into the bay were seeing strong surface slicks extending south offshore of Pt Sal indicative of flow separation.  Below is a view north to the point and south down to Vandenburg.

We were doing tow-yo CTD and ADCP surveys through these fronts.  It was quite remarkable how intense the southward flow was and the shift across these boundaries.   An example of this is shown below.  This is the last E-W transect we did south of Pt. Sal.  The top panel shows the top and bottom velocity vectors.  Farther offshore the flow is >30 cm/s to the SSE.   The vertical structure is also interesting w/ a surface front at about time 12.8 hours.   Then farther onshore the flow velocity is much weaker and potentially slightly northward (plot by Derek Grimes)

The CTD tow-yos also show similar type of features.  Here are all the casts from the first and second pass around our Pt Sal box in a 3D view with the point bathymetry embeded.  Note the fronts in the E-W leg south of the point  (note this is in a x-y coordinate system with x in the +east and y in the +north directions – plot by Mike Kovatch).

Then in the afternoon the internal bores really hit the point hard.   The interaction of the flow separation and internal bores will be very interesting to study.

Sounder transects near Pt Sal

Here’s an example of the persistent southerly flow and separation that we have seen the last few mornings with the Sounder and Sally Anne (SIO whaler) running ADCP transects around Pt Sal.  Sally Ride is on this transect now, so we should soon see what this looks like during other phases of the tide.

 

ADCP transect mid-day on 12 Sep 2017 going from west to east.

scripps oceanography uc san diego