Posts Tagged ‘thermocline’

Cook CTD sensor working great

Wednesday, June 16th, 2010

So we plotted some CTD data from yesterday's casts and it appears this sensor is functioning well. There does not appear to be any lags, meaning the CTD does not show any delay when reading the temperature data on the down and up casts at the thermocline.  When this occurs, we do not get an accurate reading of the position and strength of the thermocline.  The plots below show the results of yesterday's casts and we determined some good news.

The first plot shows one entire down and up cast from June 15, 2010.  The other two plots are zoomed-in figures of the upper 250m of the water column and also the water column between 250m - 850m.  Both of the zoomed-in figures show a randomness in the data, meaning that the results are an indication of the oceans natural currents.  The CTD doesn't show any delays in the readings between the thermocline where you have a change from warm to cold waters.  If that were the case, we would have seen a difference in the up and down casts.

We also saw a similar result with the salinity profile.  Below is a plot displaying the salinity data.

We are going to continue to monitor the CTD over the weeks ahead and we will keep everyone updated with how it is functioning.

-Colin

Testing New Waters

Monday, November 9th, 2009

Hello all,

This week's temperature data has continued to show us that the thermocline position is steadily moving downward. Last week, we saw the thermocline starting at slightly above 40 meters where as this week we see it starting at just below 60 meters. The thermocline does not appear to be as strong as it had been in the past weeks. As far as the glider is concerned, these changes in the thermocline will not reflect in a change in the flight pattern. Below is a plot of this weeks temperature data.
nov3-nov9-temp-plot

Currently, we are constructing a trans-Atlantic contour plot using the data from RU27's CTD casts throughout her journey. We are trying to find a way to insert this data into Google Earth in a 3d visual model. We recently came across Google Earth 5 and have high hopes that it will be able to support our massive contour plot. We will keep you updated weekly on the changes in the thermocline position and strength as we strive to create our 3d model.

Colin & Abe

Focusing on the Thermocline

Tuesday, October 27th, 2009

Hey everyone,

Over the past couple of days, the most noticeable change in the water column has been the thermocline position and strength.  On October 24th, the temperature change within the 35-80 meter displacement was very gradual.  There was no large change in decreasing water temperature within a small distance, as we have seen in the past.  However, this trend tends to fluctuate and it is difficult to predict how the thermocline will appear in the next couple of days; the plots shown below are the most recent example.  The CTD data from October 26th shows a large decrease in water temperature within barely 20 meters.

ctd-oct-24-therm

water column temp.-oct-26

As of this past week, bottom water temperatures have been hovering just above 13.5 degrees C. and there has been little change.  In addition, battery life is not too much of a concern relative to time because we have just below 50% left and bottom water temperatures do not seem to pose any threat either.  The main issue is dealing with the bio-fouling and slowing down barnacle growth. Staying below the thermocline, as well as the pycnocline, helps with limiting biology growth because we would be avoiding most of the nutrients.  Since the thermocline is constantly changing, our group will continuously keep track of the thermocline positions, as well as strength.  Also, we are continuing to look for some sort of archive of past underwater data for Spanish waters but the search continues.  RU27 is approaching the finish line and each group is working hard to get her to cross it.

-Colin and Abe

Keeping a Close Eye on Underwater Weather..

Tuesday, October 20th, 2009

Hey everyone,

Our assignment this semester involves the monitoring of Ru27's CTD (conductivity, temperature, density).  Throughout the summer, Ru27 experienced little threat in terms of bottom water temperatures compared to what we have seen recently.  The temperature at the bottom of RU27's flight depth averaged roughly around 16 degrees near the end of the summer, but it began to get much cooler as the Fall semester continued.  As October approached, bottom water temperatures around 120 m. hovered around 13.5 degrees C and, at one point, reached just below 13 degrees C.  At this point, RU27's battery capacity needs to be scrutinized as the temperatures change throughout the remainder of her flight.  The contour plots below show how the temperature within the water column has changed since mid-September.  Two important things to notice is the constant change in the thermocline and how the bottom water temperatures have changed within a month.

First Week of Fall SemesterWeek 4 of Fall Semester

On October 15th (Thursday), we attempted to change the inflection depth to 80 meters, which was something we have never done before with RU27.  Our group spoke with Dave and he mentioned that this was due to the increasing biology growth.  The idea was to slow the barnacle growth by staying in much cooler waters and also to stay below the picnocline.  Above the thermocline and picnocline is where all the nutrients will be because they can't get below that large change in water structure. Therefore, changing the inflection depth to 80 meters would stunt biology growth since they cannot get access to the nutrient-rich part of the water column.  The only concern of changing the inflection depth to 80 meters was the possibility of Ru27 aborting her mission.  Unfortunately, the test did not work out as planned and a pressure sensor on the CTD was damaged in the process.  However, we still continue to search for the best flight pattern for Ru27 in order to avoid further biology growth and possible battery harm. We will continue to communicate with Dave and also update CTD plots throughout the semester.

Cheers,

Colin and Abe