Complete Cleaning in December

A complete cleaning (CTD validation, cleaned all sensors, chains, lines, and spar) at the CREWS Station in La Parguera, Puerto Rico, was done Friday, December 10th, 2010 by Wessley Merten. The groundtruth validation sensor was placed at 12:15 and was removed at 15:30.  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. 

Maintenance Operations, November 8th - 12th

In the week of November 8th - 12th, a team from the Atlantic Oceanographic and Meteorological Laboratory (AOML) traveled from Miami to La Parguera, PR, to work on the CREWS station located near the Media Luna reef. The main purpose of this trip was to perform our annual swap-out of all meteorological and oceanographic instruments on the station, but we had several additional jobs to do, as will be described below. The AOML team consisted of LTjg Rachel Kotkowski (NOAA Corps) and Mike Jankulak (University of Miami). We were joined in the field by Wess Merten (University of Puerto Rico), who in our absence makes monthly trips to clean the station and connect its "groundtruth" CT. Wess has been writing detailed entries in this blog and has also been instrumental in diagnosing the station's ills from afar (one notable example of this from earlier this year is described below).

We started out (on Tuesday the 9th) with a brief survey of the station's underwater supports to make absolutely certain that it was safe to climb. We observed nothing unexpected. This first photo on the left, taken on Tuesday, shows the lower hounds, lashings and base plate attachment.

A second photo seen at the right, taken Thursday (when visibility was unusually clear for this location), shows the "trailer hitch ball" beneath the pylon, the pivot point for the entire structure. Clicking on any of these photos should lead to the (larger) original versions of each picture.

After a quick survey to document conditions and take some photos, we set to work swapping out the underwater instruments. These operations differed from routine swapouts in two ways. For one, there was no "deep" light sensor to remove since this instrument had been removed in April after its failure and flooding caused the station to go offline for about 12 days. You can follow the progress of this event in previous postings to this blog, including the station's initial power failure, the first survey of the station after going offline, the removal of the suspect instrument, and the station's subsequent recovery. So we were not required to remove a "deep" light sensor before installing the fresh instrument.

Secondly, during the course of last year's maintenance visit it became clear that the station's "shallow" light sensor was not properly supporting the instrument and holding it steady and upright. This is documented in the blog post from that visit, which also includes a photo of the offending mounting bracket. Thus we decided in this visit to replace this sensor mount with the solid-platform type mount that we use at our newer stations. The "deep" sensor's mount had undergone a similar upgrade several years previously. The new shallow light sensor and mount are shown in a picture at left.

Our first day's underwater work concluded with the replacement of both CTDs, shallow and deep. After that, I climbed the pylon to remove all aerial instruments and electronics for replacement and reprogramming on land, except for the surface light sensor, which was left in place due to lack of time. The station was therefore powered down on Tuesday, November 9th at 20:26 UTC (4:26 PM local time), and remained offline until everything was reconnected on Thursday, November 11th, at 15:51 UTC (11:51 AM local time).

Wednesday's work began with the removal of the surface light sensor; at this station, this is the most stubborn of the three instrument masts and the one which requires the most effort to remove. Another very important goal of this trip was to replace the station's navigational light. The nav light is a crucial safety feature of the station, because it warns mariners to keep their distance when conditions are dark, and its flash pattern is listed on navigational charts. We had been hearing many second-hand reports that the nav light was no longer flashing. Wess attempted to verify these reports first-hand by visiting the station at sundown but he in fact was able to document that the nav light was still working at least partially. [My best guess at this point in time is that the light was slowing failing, either because its batteries could no longer hold a full charge or because its solar panels were blocked or failing, and that it probably wasn't powerful enough to continue flashing throughout an entire night. In fact, when we arrived in La Parguera on Monday night we could not find the familiar flashing beacon when we looked for it from the hotel's seafront, and the light post-removal did not continue to flash steadily for a full day on the workbench as it should have.] In any case, the nav light had been targeted for replacement on this trip simply because of its age (over five years since deployment of this pylon), and on this Wednesday morning I removed the light at the top of the pylon and installed its replacement. The final picture in this blog entry will show the new nav light, which I was able to observe flashing from the hotel seafront on Wednesday night, Thursday night, and very early Friday morning, so we are confident that the replacement light is fully functional.

Once Wednesday's aerial work was complete, we turned our attention to one more side-project for this trip: the installation of two standalone temperature loggers (see picture at right). This equipment was provided to us by UM/RSMAS student Xiaofang Zhu, who is particularly interested in shallow-water temperatures at both the La Parguera and Little Cayman CREWS stations. Xiaofang plans to use the data from these two temperature loggers, supplemented by data from our two CTDs on the station. She had given us a list of considerations for positioning the instruments on the pylon, which would naturally have to be adapted in the field to conditions as we found them, such as the depth of the Shallow CTD and the positions of the upper "hounds" (which are the four attachment points for the eight chains-and-spectra which support the pylon). We were able to place the two temperature loggers, one above the other, between the Shallow CTD and the water's surface. However, there remains some question about whether the Shallow CTD is correctly reporting its instrument depth (since it seems like it was much shallower than expected). The upper tip of the upper temperature logger was observed to be breaking the surface on Thursday morning, on a very calm day when the tide was coming in (and only a few hours before high tide), so there is some concern that the instrument's lower end (where the temperature sensor is in fact located) might also be above the water's surface at low tide. Still, Xiaofang has decided for the present to leave the instruments as they are, and she plans to work with Wess to collect more objective measurements of instrument depth and distances between instruments. Her software, cables and tools have been left in Wess' care and he may be able to work with Xiaofang to download her data after a month or two.

This concluded our work for Wednesday, and the rest of the day was spent in the lab, replacing the aerial instruments on their masts, reprogramming the data logger and other electronics, and running the new program on the workbench with all available instruments connected.

Thursday morning was the calmest day yet, and visibility was extremely good for this location, which generally has very murky conditions. We were surprised and pleased to find that we could see the ocean bottom from the boat. Rachel took the opportunity to snorkel around the area and take some pictures of nearby corals (see photo at left). Many of her photos showed the telltale signs of a bad bleaching season in the area, which Wess tells us was unusually bad this year although not as bad as 2005.

Thursday's work was all about reinstalling everything that had been removed on Tuesday and Wednesday: the surface light sensor, the integrated "weather transmitter," the anemometer and electronic compass, and the control package of electronics which we call the "brain." This was accomplished in about two hours, and then the station was powered on and a radio link was used to verify from the boat that all instruments were correctly reporting. After that, it was just a matter of tying down all loose cables (both above and below the surface) and plugging up the external openings of the "brain" chamber's conduits. A photo at the right shows the deep CTD and light sensor (note the similar platform-type mount for the light sensor, which is now several years old) after their cables had been tied down.

A final photo (at left) will serve to illustrate two points. One, note the newly-replaced navigational light (centrally located, just above the bird). This new light has its solar panels on top, and since it is located directly beneath the (square, white) satellite transmission antenna, it may not receive a lot of direct sunlight throughout the day. Still, it is believed that it will receive more than enough light to keep it fully powered, and the light is "smart" enough to adjust its intensity downward if it determines that it is too low on power to keep flashing at full intensity until morning. Also, its location beneath the satellite transmission antenna (which has a protruding cable) probably shields it from acting as a convenient bird roost or having its solar panel dirtied and blocked with bird guano.

The second thing to observe in this photo is the bird itself. Believed to be some kind of booby, this bird and others like it are an extremely common sight at this station. We have been told that up to four boobies have been observed at one time sitting on this station. One booby was sitting on the station lid when I first started climbing the pylon on Tuesday, and bravely stood its ground until I reached the top. While I was working, multiple boobies circled the station and at times seemed as though they might attempt a landing, even with me there. It is certainly true that of all of the CREWS stations, this station's instruments are most covered in guano when they are retrieved. There are a few implications of this bird activity for instrument and station operations.

Some of the station surfaces are more suited as resting spots than others. The station lid, the transmitter antenna, the Vaisala "weather transmitter" (or WXT, which provides data for winds, temperature, humidity, barometric pressure and precipitation) and the surface light sensor each in their own way provides a comfortable resting spot. Let us consider each in turn.

There is no adverse effect to the use of the station lid as a bird roost, other than a mild "yuck" factor for the pylon climber. It seems possible that the presence of a bird on the satellite transmission antenna could lead to garbled or blocked transmissions, but in fact this has not been a problem at this station. This CREWS station, termed LPPR1 by AOML and known as LPRP4 by the National Data Buoy Center (NDBC), has the best transmission success rate of all of our stations. With regards to the WXT, we have actually had ongoing problems with wind measurements by this instrument for many years, and I believe the main problem to be bird-related. There may also be a strong impact on the reliability of precipitation data, although the WXT's temperature, humidity and barometric pressure data are not believed to be impacted. The good news is that all of our newest WXT instruments have come with bird-deterrent spikes pre-installed, and following our work in this week this station features a WXT bird-deterrent for the first time in its history. So I am very hopeful that the WXT wind data will be more accurate in the coming year.

Let me briefly discount bird influences for the anemometer (which pivots enough in higher winds that it is probably not a good perch, although the presence of bird guano suggests it may be hosting bird visits in unusually calm circumstances) and the navigational light (which, as stated above, does not offer much headroom for these rather large birds). Then we are left with the surface light sensor. Unfortunately, this is still a concern. Last September, in advance of this visit, I contacted Biospherical, which is the manufacturer of all of our light sensors. My question was whether they sold any add-on bird deterrent mechanism for their surface light sensors (like Vaisala does for the WXTs). In fact they do not sell such a thing, so it will be left to us at AOML to come up with something on our own. Because it is certainly the case that the surface light sensor provides a welcoming perch for these birds, and it has been observed many times to be acting as a bird roost. We also see this effect in the data, when the average light levels reported by the surface sensor may fall lower than the underwater sensor light levels for a period of some hours in the middle of the day. This is probably the result of the sensor being blocked by birds, and this is a challenge that we should address in the the coming year so that we can test a new bird deterrent in next year's visit. Obviously the main challenge will be to bar the birds from landing on the flat sensor surface without in any way affecting the levels of light that reach the sensor.

In any case, this brings to a close a very long description of an extremely successful field trip. We offer our thanks to everyone concerned (UPR, UM, NOAA) for being willing to work through Thursday's government holiday. And as always, our appreciation goes to Wess Merten, Francisco Pagan, Milton Carlo, and everyone else at UPR's Isla Magüeyes for taking care of the station all year and providing support with boat ops, diving support, tanks and lab space when we visit. Muchas gracias!

CREWS Station Basic Cleaning in October

On Monday October 18th 2010 Wess Merten conducted a basic cleaning and assessment of the CREWs  in La Parguera. I conducted a surface inspection, underwater inspection/cleaning, optical sensor cleaning, and a CTD sensor cleaning.  One of the stations surface floats has disappeared sometime between this basic cleaning and te complete cleaning on October 5th.  There is only one remaining. 

CREWS Station Complete Cleaning in October

A complete cleaning (CTD validation, cleaned all sensors, chains, lines, and spar) at the CREWS Station in La Parguera, Puerto Rico, was done Tuesday, October 5th, 2010 by Wessley Merten. The groundtruth validation sensor was placed at 11:53 and was removed at 15:15pm. All surface and subsurface sensors were visibly intact. All rigging, lines, baseplates, sensors, and the spar were cleaned, but need more attention later this month.  There were reports that the groundtruthing sensor was not transmitting or receiving data during the last complete clean.  Therefore, prior to plugging the sensor  I examined the interface and didn't see a source for a loose/bad connection.  In addition, I inspected the cable that the sensor connects to and besides the significant biofouling that was removed I did not discover any damage. 


The next cleaning will be performed within two weeks. 

LPPR1 ICON/CREWS Navigation Light On-site Validation

This evening Wess Merten and Duane Sanabria went out to visit the CREWS station to perform a basic clean and validate that the light was or was not working after the end of civil twilight (~18:51). I recorded three videos: one at 18:55, another at 17:00, and the last at 17:19. The videos can be seen in movie format in the embeded movie below. The light is working, but does it work all the time?




When I arrived to the station today there were 4 brown boobies resting amongst the sensors. This is the most birds I have seen roosting atop the station.

In unrelated but related news, I spotted a juvenile Lionfish(5cm)on the outskirt of the station's reef while cleaning the peripheral lines.

CREWS Station Complete Cleaning in September

A complete cleaning (CTD validation, cleaned all sensors, chains, lines, and spar) at the CREWS Station in La Parguera, Puerto Rico, was done Tuesday, September 7th, 2010 by Wessley Merten and Duane Sanabria. The validation CTD was placed at 8:55am and was removed at 12:25pm. All surface and subsurface sensors were visibly intact. All rigging, lines, baseplates, sensors, and the spar were cleaned, but need more attention later this week. Since the last cleaning significant biofouling has grown on the many of the stations surfaces.

The navigational light has been out for the past month. This is according to local fisherman who use this station as a navigational beacon at night.

The next cleaning will be performed within the next week.

CREWS Station Complete Cleaning in May

A complete cleaning (CTD validation, cleaned all sensors, chains, lines, and spar) at the CREWS Station in La Parguera, Puerto Rico, was done May 27th, 2010 by Wessley Merten and Duane Sanabria. The validation CTD was placed at 8:45am and was removed at 12:15pm. All surface and subsurface sensors were visibly intact. All rigging, lines, baseplates, sensors, and the spar are very clean. New screens were placed on the deep and shallow CTD's.

Station back Online

The La Parguera ICON station is back online following the removal of an underwater light sensor by Wess Merton of UPR. This means that all told the station was offline for about eleven and a half days. The removal of the "deep" light sensor appears to have solved the power problems and the station has in fact recharged itself much more quickly than expected. In addition, all other instruments on the station appear to have returned to their prior states of operation. That is to say, other than the two sensors which were known to be malfunctioning (the acoustic wind sensor on the Vaisala Weather Transmitter, and the pressure sensor on the Falmouth "shallow" CTD), all station electronics appear to have survived this adventure unscathed.

As a reminder, the timeline of the station's failure and recovery is as follows:

• Wednesday, April 14th: last station transmission sent at 11:22pm local time.
• Monday, April 19th: remote analysis suggests that the station has lost power due to the failure of its deep light sensor. Parts required for removal of the instrument are shipped to UPR from AOML.
• Friday, April 23rd: the failed light sensor is removed.
• Tuesday, April 27th: first post-recovery transmission is received at 2:22pm local time.

The station's battery levels normally oscillate between about 12.7 V (nighttime lows) and 13.9 V (daytime highs). Right now (see graph at right, which shows hourly battery levels over the past month) the battery levels are still low but they are recovering a little every day and are expected to return to normal levels after a few more weeks.

CREWs Deep BIC removal on April 23rd

On Friday April 23rd I went out and removed the Deep BIC as requested. Below are photos from the morning. The first is the sensor prior to removal.



In this photo the sensors cable had been removed from the spar by cutting the cable ties holding it in place. The deep CTD was wound up in the same orientation as the Deep BIC; this instruments cable was fixed back to its original position prior to the maintenance. Once the Deep BIC's cable was loose, the sensor was removed by unscrewing the two screws at the end of the mount.



Once at the surface, the sensor was gently laid on its side on a towel while I carefully removed the biofouling that had colonized the cable. Some mussels had managed to grow near the interface between the cable and the sensor possibly allowing a mode of entry for water to the sensor. After the biofouling was removed the cable was unplugged from the sensor and a female adapter plug was placed on the end of the sensors cable. This cable was wound up and placed on the spar as depicted in the photo below.

CREWs Station Surveillance

Surveillance was conducted this morning (Wednesday April 21st) at 9 am to verify that all in-water and above-water sensors were present, intact, and not hanging on by a thread for some odd reason. This survey was conducted after the station went unexpectedly offline last Thursday, April 15th. I'm happy to report that everything was present and visually intact, however an internal cause (i.e. failed cable, water logged sensor) may be the culprit of the outage and would not have been apparent during the visual census. Below are photos of the station from the surveillance.

Station Offline, probable power loss

[This is a slightly modified version of an email message sent out Monday morning, April 19th, 2010.]

The executive summary is this: our ICON station in Puerto Rico has gone offline as of last Thursday, April 15th at 10pm local. Judging from the data reported by the station immediately before the outage, I believe that we have a flooded instrument and a total loss of power. I do not believe that the station is continuing to store data locally. I do not believe the station will come back online on its own.

The faulty instrument is the "deep" light sensor, or BIC (see the timeline below for details on why I believe this to be the case). I would recommend that our local collaborators try to visit the station as soon as they can to verify that there hasn't been a more serious structural failure of any kind. They should also disconnect the deep BIC as follows:

1. Remove the sensor from its mount and retrieve it with its cable, still connected, to a boat at the surface.
2. Dry off the connector and disconnect the instrument. Cap the cable end with a "dummy plug." [This will require a female-style dummy plug, we may have to ship some to UPR for this purpose if they don't have any.]
3. As a safeguard, I would recommend coiling the instrument's cable and affixing it to the pylon above the surface of the ocean (just in case there was damage to the cable itself). There should be some long cable ties in our large red "NOAA" box.

Note that this procedure *may* allow the station to return to full power on its own, but it could take several weeks for the solar panels to recharge the batteries. In the Jamaica incident, it was about 10 days before transmissions resumed, and not all instruments came back online when the station resumed transmitting.

The following is a timeline of events before the station failure, reconstructed from the station's final data reports. All times are given are local times (Atlantic Standard Time, UTC-4, which is currently the same time as our EDT here at AOML).

• Wed Apr 14, noon: Very large rain event reported, the strongest such event reported since last summer. Winds were somewhat elevated but not unusually so (gusts stayed below 15 knots).
• Wed Apr 14, 7pm: By this time the Shallow CTD has reported a significant drop in salinity (the Deep CTD reports a smaller drop in salinity at about 4pm). This is probably related to the rain event, and may or may not suggest large movements of water (i.e., currents).
• Wed Apr 14, 8pm: Just after sunset, the Deep BIC shows a rapid drop in power before going permanently offline. The rest of the station appears to be operating normally at this time.
• Thu Apr 15, 9am: Sunrise begins to affect the station power levels, which begin to rise in their normal diurnal cycle.
• Thu Apr 15, 10am: The station experiences a sudden voltage drop. Depending on which reading you look at, it seems like a drop of 1 V in magnitude.
• Thu Apr 15, 10pm: Over the next 12 hours the power levels fall off steadily. When they reach about 11 V (at 10pm local), all transmissions cease and have not resumed. It appears as though at 11 V the station can no longer power the transmitter. It is likely that the datalogger continued to log data locally for several hours after this but at about 9 V all operations would cease.

See also the description of a similar event in 2008 at the Jamaica ICON station, and the follow-up message about restoration of power following the removal of the failed instrument.

Note: we are making arrangements to ship some female dummy-plugs (suitable for capping the ends of the underwater cables) to the UPR team.

regards,

Mike J+

CREW station basic cleaning in April

On Tuesday morning (~1015 am), April 13th, 2010 Wess Merten and Duane J. Sanabria conducted a basic cleaning and assessment of the CREWS Parguera. We conducted a surface inspection, underwater inspection/cleaning of lines, and an optical sensor cleaning. Everything was visually intact.

CREWS Station Complete Cleaning in March

A complete cleaning (CTD validation, cleaned all sensors, chains, lines, and spar) at the CREWS Station in La Parguera, Puerto Rico, was done Friday, March 26th, 2010 by Wessley Merten and Duane Sanabria. The validation CTD was placed at 8:45am and was removed at 12:15pm. All surface and subsurface sensors were visibly intact. All rigging, lines, baseplates, sensors, and the spar are very clean. New screens were placed on the deep and shallow CTD's. Upon arrival to the station, a bird was perched atop one of the surface sensors that flew away shortly thereafter (see photos below).

CREWS Station Complete Cleaning in February

A complete cleaning (CTD validation, cleaned all sensors, chains, lines, and spar) at the CREWS Station in La Parguera, Puerto Rico, was done Friday, February 26th, 2010 by Wessley Merten and Duane Sanabria. The validation CTD was placed at 8:45am and was removed at 12:15pm. All surface and subsurface sensors were visibly intact. All rigging, lines, baseplates, sensors, and the spar are very clean.

CREWS Station Basic Cleaning in January

On Thursday morning, January 28th, 2010 Wess Merten, Duane J. Sanabria, and Derek Soto conducted a basic cleaning and assessment of the CREWS Parguera. We conducted a surface inspection, underwater inspection/cleaning, optical sensor cleaning, and a CTD sensor cleaning. Below is a photo from our dive after the cleaning.

CREWS Station Complete Cleaning in January

A complete cleaning (CTD validation, replaced all brass screens, cleaned all instruments, chains, lines, and spar = tower) at the CREWS Station in La Parguera, Puerto Rico, was done Friday, January 15th, 2009 by Wessley Merten and Duane Sanabria. The validation CTD was placed at 8:45am and was removed at 12:15pm. All surface and subsurface sensors were visibly intact. All rigging, lines, baseplates, sensors, and the spar are very clean. Atop the spar, two boobies were persistent on keeping their vantage point over their fishing grounds.