June 2015

The Buccoo Buoy was inspected on 23 June 2015. All fouling was removed from anchor lines, buoy base and metal frame. The sonde was removed and cleaned.  All probes except for ph were fully calibrated and passed the QC. The error in the picture below was noted, even after two attempts at calibrated. The error was overidden and the sonde redeployed.

 

The main buoy was also open and the dessicant replaced. All circuitry seemed fine within the buoy and all external connectors were intact.

All three ports for the RM Yound RH/Temp were also tried to see if this will correct the exisitng problem (no data is currently being colected), however there was no change to the status of the instrument.

New anodes are required for the sonde and the main buoy.

The Sontek ADP was retrieved and the data downloaded. The battery was changed and the instrument redeployed. 

Can this information also be hosted online with the CREWS data?

Anchor rope fouling

ADP

Buoy base fouling

Anode disintegration

Probes to be cleaned

Fouling growing beneath casing

Mild erosion on sonde

Voltage trends at Buccoo Reef, 2013-present

This post is expected to be the last of a series of posts to share the results of my recent evaluation of data produced by all of the CREWS/CCCCC buoys over their lifetimes, from 2013 to the present.  This post will briefly discuss the curious downward trend over time in voltage minima that is common to all three operational buoys.

This trend was first remarked upon in an email conversation between myself and Matt Previte of YSI on January 7th and 8th, 2015.  We had had occasion to examine the voltage levels at the Little Cayman (CCMI2) buoy because on December 29th, 2014 it had suffered a complete loss of power.  Subsequent to discovering that power failure I posted an analysis of 2014 voltage levels for CCMI2 with particular attention to the final month of data.  In this post I remarked:

Note the unexplained, slow downward trend of low voltages throughout the year.  This is not obviously related to the final loss of power but it is still curious.

Matt's email to me on January 7th touched upon that subject very briefly:

I'm also surprised by the gradual, overall decline in min/max of the daily battery voltage. I'll ask around to see if anyone else has thoughts on that. It wasn't below operational levels and batteries due wear, but seemed a little odd.

My own January 8th reply to this remark included the following:

I'm pretty sure I've seen similar patterns at (some of?) the other buoys, but I will have to let you know next week if I can back up that statement with real data. [...] I agree that the gradual low-voltages decline is mildly worrying without being hugely alarming.

In fact I did not follow up on this subject as promised until now, since I've just spent several weeks looking at trends in all of the CREWS/CCCCC data, and indeed the gradually-declining trend of voltage minima appears in the data from all three operational buoys.

For this post, we examine the voltage trends at Buccoo Reef, Tobago (BUTO1).  Voltages are sampled every five seconds and then at 10-minute intervals the minimum voltage from the last ten minutes is reported.  This graph shows voltage minima reported by the Met datalogger (green) and the Main datalogger (red) as well as their difference (in blue, equal to Met - Main).  The first two parameters are graphed on the left axis and the third on the right, with both axes sharing the same scale but offset from one another by 11V.

Please click on this image to see it in larger form.

The most notable feature of this graph is the station's failure from May 15th to August 11th, 2014.  There is also a short period of initially charging the batteries following the first deployment on November 27th, 2013.  Data for this analysis were last refreshed on June 9th, 2015.

At this station the Main voltages were slightly lower than the Met voltages (by 0.108V on average) so my subsequent analysis of battery minima focuses on the Main voltages.

My informal analysis looked for the 'lower edges' of the minima to try to quantify how much they were decreasing over time and how quickly.  This is a largely subjective evaluation.  For BUTO1, this 'lower edge' was about 12.75V at deployment time once batteries were fully charged (after six days).  This edge crept lower still by about 0.1V every 4-9 months until at present I estimate it to lie at about 12.42V, for a loss of about 0.33V overall.  The downward trend at this station slowed in the later part of the dataset (i.e. the trend may have decelerated slightly).

Similar analyses were carried out for this buoy's sister stations at Speyside / Angel's Reef, Tobago (ARTO1) and at Little Cayman, Cayman Islands (CCMI2).  Two of the stations (BUTO1, ARTO1) reported lower Main voltages on average and one (CCMI2) reported lower Met voltages.  All three stations exhibited a gradual downward trend in voltage minima, losing on average 0.1V every 4-8 months, with some slight changes in pace noted (decelerating at BUTO1, accelerating at ARTO1, constant at CCMI2).  There was also one reversal of this trend noted at CCMI2 following that station's power loss and redeployment in early 2015.

The complete analyses for the other voltage minima, including graphs, may be found at this link for ARTO1 and at this link for CCMI2.

(signed)
Mike Jankulak

Junction Box Humidities at Buccoo Reef, 2013-present

This post is part of a series of posts to share the results of my recent evaluation of data produced by all of the CREWS/CCCCC buoys over their lifetimes, from 2013 to the present.  This post will discuss the diagnostic relative humidity (RH) data collected from inside two of the buoy's junction boxes: the 'Main' and 'Met' junction boxes which house the Main and Met dataloggers, respectively.  Overly high humidities within either of these junction boxes could lead to a failure of the buoy's controlling electronics and lengthy interruptions in the data stream.

By way of example please see this post from the Little Cayman station log (including photos), which concludes that a "catastrophic power loss" was caused by "condensation" within the "solar panel junction box."  To my knowledge there are no diagnostic RH sensors deployed in the solar panel junction boxes at any CREWS/CCCCC station but this serves as an important lesson about the damage that moisture incursion can have on station operations.  In this case the Cayman station was nonoperational for 73 days and when redeployed it was found that communications with the WXT (Vaisala's 'Weather Transmitter') had failed, which may indicate another yet-undiagnosed effect of junction box condensation at that buoy.

The following graph shows the Buccoo Reef (BUTO1) diagnostic RH values plotted over the buoy's deployment lifetime to date (through June 9th, 2015).  The red line is RH maxima as measured within the Main junction box and the green line is RH maxima as measured within the Met junction box.

Please click on this image to see it in larger form.

The large gap in data is from when the station was entirely offline due to a power failure, from May 15th to August 11th, 2014.  The highest spike in the Main RH (red line) occurred on November 13th, 2014, while the buoy was undergoing maintenance on land and was likely measured at a time that the junction box was open to the moist outside air.

Note that these data report only the maximum RH seen in a ten-minute period of those raw values collected every five seconds.

A natural question is how humid is too humid?  I have heard it suggested that these junction box humidity maxima should not exceed 20%, and BUTO1's Met junction box RH data shows that this is an entirely attainable goal and can be regarded as a reasonable target.  However, at what point should overly-high RH values prompt remedial intervention?  I have for many years run CREWS programming tests inside my office which has had the side-effect of collecting a long-term dataset of indoor RH values, in an environment that is dry enough to prevent any damage from moisture or condensation.  Based on these somewhat accidental datasets I would suggest that RH values up to 50% may be considered tolerable, but that prolonged measurements of diagnostic humidity in excess of 50% should be considered cause for immediate reparative action.

The story told by these data, then, is twofold:  the Met junction box (green line) remains extremely dry throughout the buoy's lifetime, but the Main junction box (red line), despite starting out very dry, has grown more humid over time to the point where RH has remained between 60% and 80% since the November 13th, 2014 maintenance operation (with 99.1% of all reported values falling within this range during this period).

Based on our ad hoc standard, then, BUTO1's Main junction box started its deployment acceptably dry but humidities gradually increased until they began exceeding our targeted level of 20% after three months.  We cannot know what the Main RH levels were like during the station's mid-2014 power failure but immediately upon resumption of operations the Main RH levels were alarmingly high and have remained strictly higher than 50% humidity in 98.5% of Main RH measurements reported since that time (August 11, 2014).  Therefore this station can be said to have a persistent and long-lasting problem with moisture incursion into the Main junction box which should be attended to at the earliest opportunity.  [This station's Met junction box, on the other hand, requires no humidity intervention whatsoever.]

Similar analyses have been conducted at this station's sister buoys located at Speyside / Angel's Reef, Tobago (ARTO1) and at Little Cayman, Cayman Islands (CCMI2).  A pattern that is common to all three of these buoys is that the Main RH levels are all presently at alarming levels, after starting out acceptably low during initial deployment and increasing much more quickly than the Met RH levels do.  This might suggest a design or construction problem with the moisture seals on the Main junction box, or a lack of clear deployment instructions regarding proper sealing of the junction boxes and the use of fresh desiccant.

The Met RH patterns at the three buoys range from BUTO1, where Met RH levels start low and stay low throughout the buoy's entire lifetime, to ARTO1, showing a mildly-increasing trend of Met RH levels that is not yet any cause for alarm, to CCMI2, where Met RH levels began low but increased quickly and are presently at levels that are alarmingly high.  There does not seem to be any reason to suspect a systemic problem with the Met junction box design, construction, or deployment practices as there is in the case of the Main junction boxes.

The complete analyses for the other RH diagnostics, including graphs, may be found at this link for ARTO1 and at this link for CCMI2.

(signed)
Mike Jankulak

WDirDiff/Compass data from Buccoo Reef, 2013-present

This post is part of a series of posts to share the results of my recent evaluation of data produced by all of the CREWS/CCCCC buoys over their lifetimes, from 2013 to the present.  This post will discuss the offsets (WDirDiffs) between the wind directions reported by the analog anemometer manufactured by RM Young (RMY) and the sonic wind sensors on Vaisala's Weather Transmitter (WXT).  Ideally these offsets should be less than 5° in absolute value.  This post will further discuss the raw directions reported by the buoy's Compass.

For reference, some important milestones in this station's lifetime are as follows:

• 11/27/2013: initial deployment
• 5/15/2014 - 8/11/2014: station offline due to a power failure
• 11/12/2014 - 11/13/2014: buoy brought to land for a maintenance operation
• 2/2/2015 - 2/3/2015: buoy brought to land for a maintenance operation

The following graph shows the differences in wind directions reported by the two wind sensors (red, on the left axis) and the raw directions reported by the compass (blue, on the right axis).  All directions are reported in degrees of compass but note where the scales are different by a factor of 6x and the zeroes offset, with the WDirDiff axis running on the left from -30° to +30° but the Compass axis running on the right from 0° to 360°.  A negative WDirDiff would indicate that the reported WXT wind directions are lower than the corresponding analog anemometer values.

Please click on this image to see it in larger form.

First of all, note the four different "regimes" of compass directions.  They alternate between averages that are roughly 180° offset from one another, with the transition times coinciding with periods when the buoy was believed to have been brought back to land and then redeployed (details below).  I am not familiar with CREWS/CCCCC buoy design but I believe these buoys are deployed at the midpoint of mooring lines attached to two anchor points on the ocean floor, and this pattern suggests to me that the Buccoo Reef buoy has on occasion been attached to its mooring in a manner that is 180° twisted from its prior attachment.  To my knowledge this is not indicative of any problem, however, no such pattern has been noted at this station's sister buoys (see below) to date.

The second thing to note from this graph is that the WDirDiffs average over the buoy's lifetime is -18.6°.  This is of concern because it falls outside of a range explainable by the specifications of the anemometer (± 5° accuracy) and the WXT (± 3° accuracy).  It suggests that one or both of the wind sensors are not properly oriented on the buoy in a manner consistent with correction to magnetic north using the direction offsets measured by the compass.  As of this writing it is not known which of the two reported wind directions is likely to be (more) accurate.  The WDirDiff averages are slightly different during the different compass "regimes" described above but these differences are within the range of accuracies of the wind sensors and may not be significant.

The exact statistics of WDirDiff averages and Compass averages per "regime" are as follows:

• 11/27/2013 - 5/15/2014: WDirDiff -19.8°, Compass 205.1°
• 8/12/2014 - 11/12/2014: WDirDiff -17.7°, Compass 30.0°
• 11/12/2014 - 2/2/2015: WDirDiff -19.3°, Compass 204.6°
• 2/2/2015 - 6/9/2015 (present): WDirDiff -17.1°, Compass 32.3°

Similar analyses carried out at this buoy's sister stations at Speyside / Angel's Reef, Tobago (ARTO1) and Little Cayman, Cayman Islands (CCMI2) found that the both the ARTO1 and CCMI2 Compass directions were stable throughout their deployment lifetimes to date.  At ARTO1 the lifetime WDirDiff average is -11.4°, which suggests that the ARTO1 wind instruments may not be properly oriented although they are not as divergent as the BUTO1 instruments.  At CCMI2 the WDirDiffs average through the end of 2014 (after which time WXT wind directions are not available for comparison) is +1.5°, which is entirely reasonable and consistent given the specifications of the two wind sensors.

The complete analyses for the other WDirDiff/Compass averages, including graphs, may be found at this link for ARTO1 and at this link for CCMI2.

(signed)
Mike Jankulak

AirT/RH performance at Buccoo Reef, 2013-present

This post is part of a planned series of posts to share the results of my recent evaluation of data produced by all of the CREWS/CCCCC buoys over their lifetimes, from 2013 to the present.  This post will discuss the performance of the analog instruments which measure air temperature (AirT) and relative humidity (RH).  These analog reading serve as a basis of comparison for AirT/RH measurements reported by the Vaisala Weather Transmitter (WXT) which also reports wind, barometric pressure and precipitation data.

At Buccoo Reef the analog AirT/RH sensor lasted 90 days before the RH data went bad on February 25, 2014.  [All instruments on a CREWS/CCCCC buoy are intended to produce usable data for an entire year.]  The buoy was offline due to a power failure from May 15 to August 11, 2014, and was brought briefly to land on November 12-13, 2014 and on February 2-3, 2015.  After the November 2014 maintenance operation both the AirT and RH data were bad, and as of this writing they are still bad.  An earlier post in this blog suggests that the AirT/RH sensor was "reinstalled" during the February 2015 maintenance operation and was at that time "working properly," but there is no hint of good data in the hourly data records from this time.

The following are graphs of AirT (top, in °C) and RH (bottom, in %) from the Buccoo Reef buoy's lifetime, from 2013 to the present.  Values reported from the analog sensor under discussion are in blue and values from the WXT are in red.  Data are shown through June 9, 2015.

Please click on this image to see it in larger form.

Based on this data record the BUTO1 (Buccoo Reef) buoy's AirT/RH sensor performed reasonably well for 90 days out of the buoy's 469 operational days, or about 19% of the time.  Its longest stretch of proper operation was 90 days, or about 3.0 months.

Similar analysis performed on this buoy's sister stations at Speyside / Angel's Reef, Tobago (ARTO1) and Little Cayman, Cayman Islands (CCMI2) found that the ARTO1 instrument performed reasonably well for 181 days out of the buoy's 557 operational days, or about 32% of the time, and the CCMI2 instrument performed reasonably well for 376 days out of the buoy's 506 operational days, or about 74% of the time.  The ARTO1 sensor's longest stretch of proper operation was 181 days, or about 6.0 months, and the CCMI2 sensor's longest stretch of proper operation was 226 days, or about 7.4 months.

The complete analyses for the other AirT/RH sensors, including graphs, may be found at this link for ARTO1 and at this link for CCMI2.

(signed)
Mike Jankulak

EXO Sonde performance at Buccoo Reef, 2013-present

This post is part of a planned series of posts to share the results of my recent evaluation of data produced by all of the CREWS/CCCCC buoys over their lifetimes, from 2013 to the present.  This post will discuss the performance of the EXO Sondes, which were deployed to collect sea temperature and salinity data but are also capable of monitoring other 'water quality' parameters such as turbidity, algae, fDOM, pH and DO.

At the Buccoo Reef buoy (BUTO1), performance by the EXO Sonde has been generally poor.  The Buccoo EXO was first deployed on November 27, 2013 and this analysis is based on data collected through June 4, 2015.  Although this period spans a total of 554 days, BUTO1 experienced one prolonged outage in the summer of 2014 and a few shorter maintenance operations that brought the buoy temporarily to land, so that the actual length of deployment over this period was only 464 days, or about 15 months' worth.

Here is a graph of sea temperature (°C, in blue) and salinity (PSU, in red) from BUTO1, plotted against decimal year:

Please click on this image to see it in larger form.

Over the course of the last year and a half, the EXO Sonde at Buccoo has had six periods of time during which the EXO could be said to have produced reasonable sea temperature and salinity data:

• Nov 27, 2014 to Jan 29, 2014 (63 days, after which SeaT and Sal both go bad)
• Mar 19, 2014 to May 15, 2014 (57 days, after which the buoy loses power)
• Nov 13, 2014 to Jan 17, 2015 (65 days, after which Sal goes bad)
• Feb 3, 2015 to Feb 12, 2015 (9 days, after which Sal goes bad)
• Mar 17, 2015 to May 2, 2015 (46 days, after which Sal goes bad)
• May 12, 2015 to June 4, 2015 (23 days and counting)

Based on these statistics the EXO's conductivity probe, which reports both sea temperatures and conductivities (from which salinities are calculated), has performed reasonably well for 263 days out of the buoy's 464 operational days, or about 57% of the time.

A similar analysis performed on this buoy's sister station at Speyside / Angel's Reef, Tobago (ARTO1) found that that EXO performed reasonably well for 190 days out of the buoy's 552 operational days, or about 34% of the time.  The complete analysis for that EXO may be found at this link.

(signed)
Mike Jankulak