Today (Monday, October 3rd, 2011), a complete cleaning (CTD validation, cleaned all sensors, chains, lines, and spar) was done at the CREWS Station in La Parguera, Puerto Rico, by Wessley Merten. The groundtruth validation sensor was placed on at 0945 and was removed at 1324.
Monday, October 03, 2011
Wednesday, August 31, 2011
Basic Cleaning in August
Yesterday, Tuesday August 30th, Wess Merten conducted a thorough basic cleaning and
assessment of the CREWs station in La Parguera. I conducted a surface
inspection, underwater inspection/cleaning, optical sensor cleaning, and
a CTD sensor cleaning. I also very carefully removed some biofouling
that has accumulated on some of the cables. In addition, all four brass
filters were replaced on the
CTD's. After more than 3 hours underwater the station looks great! A complete cleaning will be conducted next week.
Friday, July 29, 2011
Light Sensor Failure, Station Downtime
The CREWS station at Media Luna reef (near La Parguera, Puerto Rico) experienced a complete power loss on July 14th and has since been recovering slowly. This is strikingly similar to an incident that took place in April of 2010, just over one year ago.
In both cases it is believed that the integrity of the deeper of the two underwater light sensors was compromised and it became flooded. This led initially to the loss of data messages from the sensor but, as the flooding became more severe, resulted in the short-circuiting of the station's entire power supply and therefore a complete loss of power. Following a remote analysis which in both cases identified the deep light sensor at the likely cause, the instrument was retrieved to the surface and removed, and its cable end securely plugged. At this point the station was operable once again but completely drained of battery reserves, and it took (is taking) several weeks for it to replenish its battery reserves by means of its solar panels. A detailed timeline of the two incidents follows:
In 2010, the instrument failed on April 14th and the station lost power just over a day later on the 15th. Unfortunately we here in Miami didn't notice the station's failure before the weekend and so we let three days go by before first contacting UPR on April 19th, a Monday. Wess made several trips to the station and took photos but he couldn't remove the failed sensor until we shipped out a dummy plug for the cable. This meant that it was over a week later that the instrument was removed (April 23rd) and another 4 days before the station started transmitting again (April 27th). The total downtime was almost 12 days. Following the resumption of station transmissions, it took about 17 more days before the station's voltages returned to normal levels.
Compare this to what happened this year: the deep light sensor failed on July 12th (Tuesday) and I noticed this by chance less than two days later on July 14th (Thursday). This means we were able to request help from UPR even before the station lost power, which it did later on the 14th. Francisco responded quickly and by the afternoon of the 15th (Friday) he reported that the instrument had been removed from the station. With so little time between station failure and repair, the station started transmitting again after only two days, for a total downtime of less than 3 days. As of this writing (12 days since transmissions resumed), station voltages have not yet returned to normal levels and it may be another week before the station can maintain steady and reliable transmissions 24 hours a day.
At right is a graph of the station's battery levels so far in 2011, with voltage plotted against day-of-year. [Please click on the image for a larger version.] Note the usual diurnal cycle of voltages, rising to almost 14 V every day in the sunlight and falling to just below 12.75 V overnight. There was an unexplained disruption of this pattern in the month leading up to the sensor's failure, which may or may not have been caused by the problems with this sensor. The graph clearly shows that the station battery levels have not yet returned to normal.
Until we can inspect the recovered light sensor, it is too soon to say whether there may be some specific and ongoing risk to this type of sensor at this particular depth at this particular station. The only other similar incident in CREWS history was judged to be the result of a failure at the connection point of the instrument cable, possibly compounded by a cable insufficiently tied down and therefore subject to a violent whipping back and forth in the ocean currents (this was at the Jamaica CREWS station, in 2008). However, the 2010 sensor failure at La Parguera was of a different nature: in that case, the failure point was a puncture of the sensing surface of the instrument, on top. If this month's failure was also due to a puncture at the top of the sensor, it may signal that our deployment strategy for these light sensors should be reviewed.
The AOML team here in Miami are extremely grateful to our UPR colleagues for their super-quick response to this incident. A reduction of downtime from 12 days in 2010 to less than 3 days this year is an amazing thing to report.
In both cases it is believed that the integrity of the deeper of the two underwater light sensors was compromised and it became flooded. This led initially to the loss of data messages from the sensor but, as the flooding became more severe, resulted in the short-circuiting of the station's entire power supply and therefore a complete loss of power. Following a remote analysis which in both cases identified the deep light sensor at the likely cause, the instrument was retrieved to the surface and removed, and its cable end securely plugged. At this point the station was operable once again but completely drained of battery reserves, and it took (is taking) several weeks for it to replenish its battery reserves by means of its solar panels. A detailed timeline of the two incidents follows:
In 2010, the instrument failed on April 14th and the station lost power just over a day later on the 15th. Unfortunately we here in Miami didn't notice the station's failure before the weekend and so we let three days go by before first contacting UPR on April 19th, a Monday. Wess made several trips to the station and took photos but he couldn't remove the failed sensor until we shipped out a dummy plug for the cable. This meant that it was over a week later that the instrument was removed (April 23rd) and another 4 days before the station started transmitting again (April 27th). The total downtime was almost 12 days. Following the resumption of station transmissions, it took about 17 more days before the station's voltages returned to normal levels.
Compare this to what happened this year: the deep light sensor failed on July 12th (Tuesday) and I noticed this by chance less than two days later on July 14th (Thursday). This means we were able to request help from UPR even before the station lost power, which it did later on the 14th. Francisco responded quickly and by the afternoon of the 15th (Friday) he reported that the instrument had been removed from the station. With so little time between station failure and repair, the station started transmitting again after only two days, for a total downtime of less than 3 days. As of this writing (12 days since transmissions resumed), station voltages have not yet returned to normal levels and it may be another week before the station can maintain steady and reliable transmissions 24 hours a day.
At right is a graph of the station's battery levels so far in 2011, with voltage plotted against day-of-year. [Please click on the image for a larger version.] Note the usual diurnal cycle of voltages, rising to almost 14 V every day in the sunlight and falling to just below 12.75 V overnight. There was an unexplained disruption of this pattern in the month leading up to the sensor's failure, which may or may not have been caused by the problems with this sensor. The graph clearly shows that the station battery levels have not yet returned to normal.Until we can inspect the recovered light sensor, it is too soon to say whether there may be some specific and ongoing risk to this type of sensor at this particular depth at this particular station. The only other similar incident in CREWS history was judged to be the result of a failure at the connection point of the instrument cable, possibly compounded by a cable insufficiently tied down and therefore subject to a violent whipping back and forth in the ocean currents (this was at the Jamaica CREWS station, in 2008). However, the 2010 sensor failure at La Parguera was of a different nature: in that case, the failure point was a puncture of the sensing surface of the instrument, on top. If this month's failure was also due to a puncture at the top of the sensor, it may signal that our deployment strategy for these light sensors should be reviewed.
The AOML team here in Miami are extremely grateful to our UPR colleagues for their super-quick response to this incident. A reduction of downtime from 12 days in 2010 to less than 3 days this year is an amazing thing to report.
Tuesday, May 17, 2011
LPPR1 Seabird Electronic tempearture loggers
Recently, the Coral Reef Early Warning System or CREWs station in La Parguera had two additional instruments on-board to collect data for researches at Rosenstiel School of Marine and Atmospheric Science. Known as Seabird Electronic tempeature loggers (currently in beta field trails), two of these instruments were placed just below the surface and ~18" down to monitor diurnal warming of Parguera's inshore shallow water. The following summation of their research was written by Xiaofang Zhu a graduate assistant at the Rosenstiel School of Marine and Atmospheric Science:
Coral reefs are very sensitive to thermal stresses and recent studies have suggested the daily warming phenomenon in the shallow water, along with weekly temperature averages can affect coral bleaching. This study is interested in the detailed physical processes of diurnal warming, including the timing, amplitude and vertical temperature profiles. To reach this goal, a Seabird temperature logger is added along with the existing 2 CTDs to help understand the warming phenomenon at 3 different depths, and to construct a vertical temperature profile.
Below is a graph (click for larger view) of the agreement between the existing CTD temperature sensors and the Seabird Electronics temperature loggers as plotted by Xiaofang.
Unfortunately, both Seabird instruments are not active on the station at this moment due to technical difficulties. I will keep you posted when they are back on-board the station.
Coral reefs are very sensitive to thermal stresses and recent studies have suggested the daily warming phenomenon in the shallow water, along with weekly temperature averages can affect coral bleaching. This study is interested in the detailed physical processes of diurnal warming, including the timing, amplitude and vertical temperature profiles. To reach this goal, a Seabird temperature logger is added along with the existing 2 CTDs to help understand the warming phenomenon at 3 different depths, and to construct a vertical temperature profile.
Below is a graph (click for larger view) of the agreement between the existing CTD temperature sensors and the Seabird Electronics temperature loggers as plotted by Xiaofang.
Unfortunately, both Seabird instruments are not active on the station at this moment due to technical difficulties. I will keep you posted when they are back on-board the station.
Tuesday, May 03, 2011
Complete Cleaning in May
Today (Tuesday, May3rd, 2011), a complete cleaning (CTD validation, cleaned all sensors, chains, lines, and spar) was done at the CREWS Station in La Parguera, Puerto Rico, by Wessley Merten. The groundtruth validation sensor was placed on at 0900 and was removed at 1230. All surface and subsurface sensors were standing proud to the sea. All rigging, lines, baseplates, sensors, and the spar were cleaned. The waters were really clear today which made a clean station look really great.
Tuesday, March 29, 2011
CREWS Basic Clean in March
Today, Tuesday March 29th, Wess Merten conducted a basic cleaning and assessment of the CREWs station in La Parguera. I conducted a surface inspection, underwater inspection/cleaning, optical sensor cleaning, and a CTD sensor cleaning. I also very carefully removed some biofouling that has accumulated on some of the cables. In addition, all four brass filters were replaced after finally removing the sleeves from the CTD's. The station looks great!
Tuesday, March 01, 2011
Complete Cleaning in March
Ah, it was great to get back in the water after a month on the sidelines. Today (Tuesday, March 1st, 2011), a complete cleaning (CTD validation, cleaned all sensors, chains, lines, and spar) was done at the CREWS Station in La Parguera, Puerto Rico, by Wessley Merten. The groundtruth validation sensor was placed on at 12:05 and was removed at 16:15. All surface and subsurface sensors were standing proud to the sea. All rigging, lines, baseplates, sensors, and the spar were cleaned which left the station looking great. The only hang up was that I was still physically unable to unscrew three of the four "screen holders" on the CTD's to replace the copper screens (any suggestions on how to get them loose?).
Thursday, January 20, 2011
Complete Cleaning in January
A complete cleaning (CTD validation, cleaned all sensors, chains, lines, and spar) at the CREWS Station in La Parguera, Puerto Rico, was done Thursday , January 20th, 2011 by Wessley Merten. The groundtruth validation sensor was placed at 1:30 and was removed at 17:00. All surface and subsurface sensors were standing proud to the sea. All rigging, lines, baseplates, sensors, and the spar were cleaned which left the station looking great. The only hang up was that I was physically unable to unscrew three of the four "screen holders" on the CTD's. During the next basic clean I'm going to bring a tool to aid in carefully and properly unscrewing the covering to remove and replace the old screens.
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