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Sproul Pt. Sal survey

Since the first Intensive Operations Period (IOP 1) in September/2017, results from the different groups have been coming together to reveal a complicated plot around Pt. Sal, with lots of topographic wakes, recirculation south of the point, ridiculously sharp fronts and some really aggressive high-frequency internal waves.

Between about noon on the 12th until 9 am on the 13th, we tagged along the other vessels, repeating an L-shaped track in between the Sally Ride and the Sounder. The collective goal of our Inner Shelf Armada was to observe the flow around the cape and try to understand, among other things, how vorticity is produced by the separating tidal flow and how a background, subtidal along-shelf flow might influence this process.

R/V Sproul’s track with flow-through temperature.

All vessel tracks throughout the Pt. Sal survey (~12th-14th Sep/2017).

We crossed what looks like some high-frequency internal wave packets, visible in temperature, velocity and acoustic backscatter. A very sharp front (an internal bore?) with ~2 C change across just two neighboring uCTD profiles was encountered next, with a step-like signature also in the deep chlorophyll maximum and ADCP backscatter. There was a persistent, generally southward larger-scale flow for the entire survey, which lasted for almost a complete tidal cycle.

We had business in the Oceano Array and had to leave early on the second day of surveying, but hopefully by stitching the measurements above together with those from the other 5 vessels (see here, here, here and here) we will learn something about the phenomenology of sharp fronts, headland eddies and incoming high-frequency internal waves around Pt. Sal.

SIO student cruise wrap-up

After 240 hours of hard work and 4,970 towed uCTD casts, we are happy to add SCoNE (point Sal Coastal circulatioN Experiment) to the list of successful student cruises made possible by the UC Ship Funds Program.
We wish to thank everyone who worked to make this experiment a reality, including the Science Party and the Crew of the R/V Robert Gordon Sproul. André is very grateful for the awesome mentoring provided by Jen MacKinnon, Amy Waterhouse and Kate Adams, and for the hard work Spencer Kawamoto, Paul Chua, Jonny Ladner, Liz Brenner, Mary Huey, Eva Friedlander and many others put in preparing for and executing this amazing and unprecedented coordinated effort with the other groups involved in the Inner Shelf DRI.
More on the Sproul’s story and science coming soon!
André Palóczy and Kate Adams.
R/V R. G. Sproul‘s Crew
Chris Welton        (Captain)
Paul Dempster    (1st Mate)

Katherine Pogue (2nd Mate)

Wayne Lacy         (Cook)
Ernie Bayer          (Chief Engineer)

The SCoNE Science Party gathered on the bow of the R/V Sproul. From left to right: Kate Adams (on top photo) Spencer Kawamoto (on bottom photo), Julia Dohner, Praneeth Gurumurthy, Sahra Webb, Jess CG, André Palóczy, Jeff Coogan, Alice Ren, Manuel Gutiérrez-Villanueva, María Hernández. Center: Jeremiah Brower. Anacapa Passage is seen in the background, with Santa Cruz and Anacapa Islands on the right and left, respectively. Photo credits: Spencer Kawamoto (top) and Kate Adams (bottom).

Feddersen Group’s nearshore moorings deployed

Yesterday (Sep/01) the Feddersen Group finished deploying their moorings with thermistor chains (T-chains) and sea spiders with upward-looking current meters (ADCPs). Check out more about their work on their recent blog post.

Below are a few maps showing the positions of the deployments (magenta diamonds). The red stars are the planned deployment positions for the remaining moorings, going in the water over the next couple of weeks. Keep an eye on the deployment map as new moorings pop up there.

 

Deployed (magenta diamonds) and planned (red stars) mooring positions.

Below are some zoomed-in views of the mooring lines.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Ship ops teleconference notes – June/20/2017

Call minutes – Inner Shelf DRI ship ops (June/20/2017)

Attendees: Amy Waterhouse, Jen MacKinnon, André Palóczy, Ata Suanda, John Colosi.

SIO aircraft group (Luc and Ken):

  • Make sure some of the flights overlap with ship tracks. Want to look for surface signature of IWs and track them. Also interested in fronts and flow separation at Pt. Sal.

  • Will arrive at Pt. Sal on Sep/10 to set up. Can start flying on the 11th, but very flexible.

  • Observations/instrumentation: Directional surface wave spectrum (SSH from the LIDAR at ~30 cm horizontal resolution), surface temperature and surface velocity from feature tracking (from IR cam). Also surface wave breaking (from the visible-band cam).

  • Swath: For surface velocity ~2 km, for waves and fronts ~1 km – 200 m.

  • Flight speed: 50 m/s.

  • Flight times are weather dependent. If foggy, no flight.

  • Can send phone pictures to people in the ships.

General remarks:

  • Luc/John: During the pilot, saw more IW beams reaching Pt. Sal propagating from W to E or from SW to NE.

  • Luc/John: IWs were more energetic South of Pt. Sal (Between Pt. Arguelo and Pt. Conception).

  • Ata: A crude way of removing the barotropic tide from the ship data is to subtract the vertically-averaged velocity averaged over the ship track.

  • Jen: For the headland eddies module: How much vorticity is inshore/offshore of the 20 m isobath around Pt. Sal?

Ship ops teleconference notes – June/05/2017

Call minutes – Inner Shelf DRI ship ops (June/05/2017)

Attendees: Amy Waterhouse, Jen MacKinnon, Jack Barth, André Palóczy, Chris Chickadel, Melissa Moulton.

Info from UW aircraft group (Chris and Melissa):

  • Interested in surfzone-inner shelf exchange, fronts and surface signature of IWs and bores.

  • Can fly up to 8 h/day, refuel after 4 h and return to survey. ~1 h of transit.

  • Will be flying during 11-19/Sep and 5-14/Oct.

  • Instruments: IR and visible cameras, also surface currents. Resolution of ~6 m after processed.

  • The only real-time data available is from the visible-band camera.

  • Along-shore surveys up to 20 km, about ¼ South of Pt. Sal and ¾ North of it, up to SL Obispo.

  • Cross-shore surveys. Can cover the nearshore while Ken and Luc cover the offshore.

  • Melissa: Could do short ~45 min flights, or longer ones. Synopticity/coverage trade-off.

  • Interested in combining the subsurface ship data with the synoptic aircraft data. Will be able to 1) Sample interesting features found by the ship group and 2) Inform the ship group of interesting features.

Discussion on model sampling analyses:

  • Jen: Add white noise to simulate instrumental error.

  • Jen: Look how sampled model output changes as f(noise level, # of ships, sampling pattern).

  • Jack: Look at how aliasing changes with different sampling patterns with 2+ ships. Examples:

    • 2 ships sampling parallel lines (along- or cross-shelf) in opposite directions?

    • 2 ships sampling a bow tie pattern in between two isobaths.

    • 2 ships sampling parallel lines (along- or cross-shelf) in the same direction?

    • 3 ships sampling parallel isobaths in the same direction (e.g., Oceanus at ~100 m, Sproul at ~30 m and Kalipi at ~10 m)?

  • Jack: Calculate eddy cross-track transports (e.g., u’T’). Use as a metric.

General remarks:

  • Chris: Live radio communication: APL has one radio, Ken and Luc might have another one.

  • Chris: May be able to have live position information from an online product by NASA.

  • Jack: Daily evening meetings during experiment.

  • Jen: Headland eddies module will benefit greatly from aircrafts + ships + drifters synergies.

TODO:

  • André:

    • Sample the 3 test boxes (North/South of Pt. Sal and off Pt. Sal) and write meso-/submesoscale module summary.

    • Ask Manu about hi-freq (5-15 min) model output. Also discuss with Ata.

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