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Sun sets on turnaround cruise

The R/V Oceanus offloaded personnel early this morning in Monterey Bay, bringing to a close the ship’s role in the second intensive operating period (IOP). The Oceanus weathered some sizable swells this past week and is currently steaming up to Newport with hopes of dodging another incoming storm in the north. This research vessel never sleeps.

To commemorate the hustle and bustle we have seen aboard these last twelve days, here is a science GIF (the best type of GIF, if you ask me!) from October 6th.

Mooring redeployment at dusk on October 6th aboard the R/V Oceanus

This sequence is from redeploying our second mooring (MS50-T). You can see us standing in a line on the deck of the ship, holding instruments in hand as we wait for the top float to be released overboard.

I have to admit that the feeling of putting those first few moorings back in the water– after an exciting and frenzied 24 hours between recovery and redeployment– was that of pride and relief: pride for how much we had accomplished in a short amount of time, and relief that the instruments were going back into the ocean where they belonged. As engineer Pavan Vutukur said when he saw the mooring returned to the water with numerous of his lab’s GusT instruments attached:

“Now that they’re going back? I feel so much better.”

We look forward to seeing those instruments again at the end of October. But for now, the sun has set on the second IOP aboard the Oceanus.

— Jenessa Duncombe and the R/V Oceanus team

The Kalipi kicks off another week on the water

The Kalipi is back in action starting today. The OSU group recovered the 10-meter temperature string mooring and the ADCP lander this morning. The seas were glassy calm and the instruments were all returned ondeck safely. The recovery could not have gone better. As Jim Lerzcak said when we brought the lander onboard: “There’s nothing like the warm fuzzy feeling when an ADCP comes back pinging.”

The five of us will be running CTD and ADCP surveys for the rest of the week from the Kalipi. Look for us out there, Oceanus, Sounder, and Sally Ann!

— Jenessa Duncombe and the Kalipi team

Jim Lerczak showing excellent

cotter-pin-removal form

Hoisting a lander onboard:

85% winch and 15% muscle

All smiles after a successful recovery

(from left to right: Jack McSweeney,

Dean Henze, Taylor Eaton,

Jim Lerczak)

Check out these internal waves

Dispatch from the R/V Oceanus

Tow-yo sampling is not the most invigorating of field work. It involves watching a screen and calling out depths every few minutes as the CTD moves up and down in the water column. This continues for hours on end (our October 5th sampling lasted for eight hours straight).

To fight against the inevitable hebetude, we have all adopted our own strategies. Steve likes to make up rhymes. Maddie drinks espresso. Dean watches the live CTD temperature and salinity plots and ponders the oceanographic processes behind them. Personally, I like to save a slice of pie from dinner and eat it very very slowly.

The good news is that the monotony is worth it. The results of our recent tow-yo survey on October 5th captured an internal wave propagating up the shelf, visible in the series of plots below. The plots show temperature over depth along the inner and mid-shelf for four consecutive transects. As you can see in the plots, the internal wave is evident moving along the sharp temperature interface. The wave moves up the shelf before flattening out into a surge as it nears shore. See also how the wave displaces the warm pocket of nearshore water towards the west (best seen by comparing plots 2 and 3). In the last two plots, you can see the next shore-ward propagating internal wave making an appearance.

Something else to note is the seasonal characteristics of the mixed layer. The upper layer is very well mixed and homogeneous in temperature down to about 20 meters. These plots are quite a contrast to the profiles from September, which were stratified throughout the water column and lacked a mixed layer. In this case, the increase in wind must be the culprit. We have certainly been feeling the effects of the windy weather on-board.

We plan to sample more internal waves and other interesting features with the tow-yo in the days ahead. We will also increase our sampling to a continuous 26 hours. We hope a longer record will help us better resolve the waves’ propagation and serve as a valuable addition to the remote sensing efforts and mooring array data. It might also mean that we’ll need more pie.

– Jenessa Duncombe and the R/V Oceanus team

Figures courtesy of Steve Pierce

Sea life stowaways

Data are not the only things our instruments have brought back to the surface. Several sea critters have become quite attached to our landers. In one case, a tan spotted sea anemone had made a home on the lander’s bottom shaft. Marnie gently evicted the critter overboard.

Another lander brought up three small brown spotted octopuses, which promptly skittered off the tripod as soon as it hit the deck (see two videos here and here). The little guys are surprisingly agile, even with their eyes closed. You can hear Sarah as she holds one of the octopuses in her hands saying, “it’s so sticky!”. We helped them jump ship after some oohs and ahhs.

Several additional landers have brought more eight-legged visitors. Does anyone recognize the species? Please let us know if you do. This is the problem with a boat full of only physical oceanographers and engineers!
– Jenessa Duncombe and the R/V Oceanus team

 

Marnie, the sea anemone rescuer.

Times up, buddy.

 

 

 

 

 

 

 

 

 

 

 

One of the octopuses, mid-escape. Make sure to you don’t miss our two videos (links above in main text).

Our first peek at mooring data

We recovered our deepest mooring (MS100-T) from 100 meters first thing on Wednesday morning. The data has now been downloaded and we have two plots to share!

The figures below show temperature contours plotted over depth for several hours selected from two separate days. For those unfamiliar with the MS100-T mooring structure, the line has 26 thermisters spread over about 100 meters and have been deployed since the beginning of September.

Plotting temperature over several hours, we can see vertical oscillations of temperature on short time scales. In these plots, the vertical displacement of isotherms is around ~20-30 m at the onset of the wave and the wave period is approximately ~15 minutes. We believe these vertical displacements are caused by solitons propagating by the mooring. The data sequence shows many of these wave packets in the time record. We selected these time sequences to serve as an example.

We look forward to giving this a closer look in the coming months. For now, we have the data (high-fives all around!) and have since redeployed MS100-T successfully.

 

– Jenessa Duncombe and the R/V Oceanus team

scripps oceanography uc san diego