2015 Annual maintenance

Following servicing and repair by YSI (much appreciated), the sonde was received in Trinidad and Tobago in December 2015.

Over the period 7-8 December ARTO1 will undergo annual maintenance, which would involve bringing the unit to shore for a thorough inspection of all instruments and the re-installation of the sonde.

7th Dec 2015 (day 1)

No obvious damage was noted to any of the above water instruments. Fisher folk and other boaters continue not to moor on the unit.(....for now!!!). As expected the base and anchor ropes were laden with large colonies of barnacle, especially as the unit has not been visited since the EXO2 was removed for repair. The buoy base, ropes and sub surface floats did not seem to be compromised as a result of the fouling.

The unit was brought to shore, cleaned and inspected. Interface with the ARTO1 could only be established by serial connection. The RF and modem methods were unsuccessful. This seems to be a recurrent problem in interfacing with the units, especially for the purposes of data back-up, as logistically it is not always feasible to serial connect to the main data logger. (Ideas??)

The WXT was adjusted to align more with the RM Young anemometers, as recommended by Mike, This will be looked at again later tonight and before re-deployment tomorrow. The current disparity between the two units seems to be between 5-7 deg.

Some pooled water was noted within the main bulkhead. The O-ring was replaced for good measure, and desiccant is currently drying, to be put into the buoy tonight. RH levels will be checked in the morning.

No pictures for now, maybe tomorrow.


8th Dec 2015 (day 2)

We ran into some problems with the oven (not a drying oven, just a regular one), so I was not able to let the dessicant dry for as long as required prior to redeployment. I'll keep an eye on this as it is currently ~45% RH in the Main Buoy. If needed, in the near future I'll have to dry out the dessicant again and re-install into the buoy, however I will not bring the buoy in for this (it will be tricky).

The depressurization valve seems to be slowly corroding and may have to be changed at the next annual maintenance trip if not sooner. Again, I'll keep an eye on this.

Cell and RF connections were still unsuccessful, and serial connection was working fine. All data was downloaded and backed up.

All connections and ports were clean and unbroken.

The met data logger humidity was not checked due to an oversight. This will be monitored over the next few months.

The EXO2 was installed and all seemed functional. A new umbilical cord should be acquired to reduce the strain on the connector cable to the sonde. Also, some sacrificial anodes should be acquired. A dummy plug currently fills a vacant slot and the anode  on the outside of the buoy are near fully dissolved.

9th Dec 2015

Cellular connections were established after re-setting the Loggernet pathway.

Oceanographic instruments are down

The ARTO1 sonde will be removed 21 July 2015, to be sent to YSI for inspection.

June 2015

mantenace work on the Angel Reef buoy was conducted on 24 June 2015. Anchor ropes and subsurface floats were moderately fouled with barnacles.

The EXO2 sonde removed and cleaned. Copper coating was still intact, however the aperture for the tem/conductivity probe was fouled, so this probe was removed, thoroughly cleaned and a fresh copper coating re-applied. The new Chl-a sensor was reinstalled. All probes were calibrated, however the temperature readings on all calibrations was off. The attached is an example.

While the calibrations were accepted by the KOR software, the temperature reading were wrong. By the end of the calibrations, room temperature water read ar 8deg C and air temp read as 13 deg C. Possibly the temperature probe is comprimised.

 The dessicant in the main buoy was not replaced on this exercise due to unfavourable weather conditions.

The ADP was recovered, data downloaded, battery replaced and redeplyed.  Can the data from this instrument also be hosted with the CREWS data?

The next scheduled maintence for this unit will be in late July/early August

Voltage trends at Speyside / Angel's 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 Speyside / Angel's Reef, Tobago (ARTO1).  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.

This is a remarkably smooth graph with no obvious interruptions or deviations from pattern, starting from the station's first deployment on November 25th, 2013 and continuing through June 9th, 2015, when data for this analysis were last refreshed.

At this station the Main voltages were slightly lower than the Met voltages (by 0.047V 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 ARTO1, this 'lower edge' was about 12.85V at deployment time.  This edge crept lower still by about 0.1V every 5-8 months until at present I estimate it to lie at about 12.57V, for a loss of about 0.28V overall.  The downward trend at this station seems slower in the early part of the dataset (i.e. the trend may have accelerated slightly).

Similar analyses were carried out for this buoy's sister stations at Buccoo Reef, Tobago (BUTO1) 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 BUTO1 and at this link for CCMI2.

(signed)
Mike Jankulak

Junction Box Humidities at Speyside / Angel's 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 Speyside / Angel's Reef (ARTO1) 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.

That first, lone spike above 75% in the Main RH (red line) occurred on October 23rd, 2014.  Not long after that the Main RH values climb above 50% and stay there for life, with the final <50% reading occurring on November 17th, 2014, just after this station's November 10-13 recovery to land and redeployment.  The dataset's only spike above 90% humidity occurred on January 13th, 2015.

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 the lifetime of Met junction box RH data from the Buccoo Reef, Tobago CREWS/CCCCC buoy 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 largely below 20% humidity throughout the buoy's lifetime (with 99.7% of readings falling below this mark), although there are isolated >20% spikes and midway through the dataset there begins an obvious though gradual trend of increasing humidity.  The buoy's original non-increasing (almost exclusively below 6%) pattern seems to end on September 18th, 2014, and December 25th, 2014 is the last reported Met RH measurement to fall below 10% apart from two isolated reading during a maintenance operation on February 4-5, 2015.  There is no immediate cause for alarm regarding Met RH levels but this parameter's increasing trend should be closely monitored.

On the other hand the Main RH numbers start low but show a much more quickly increasing trend.  Our targeted 20% level is first exceeded on March 19th, 2014 but thereafter 97.7% of readings fall above the 20% humidity level.  Our tolerable 50% level is first exceeded on October 23rd, 2014 but thereafter 94.5% of readings fall above the 50% level.  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.

Similar analyses have been conducted at this station's sister buoys located at Buccoo Reef, Tobago (BUTO1) 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 BUTO1 and at this link for CCMI2.

(signed)
Mike Jankulak

WDirDiff/Compass data from Speyside / Angel's 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:

• 11/25/2013: initial deployment
• 11/10/2014 - 11/13/2014: buoy brought to land for a maintenance operation
• 2/4/2015 - 2/5/2015: 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 the Compass averages suggest that this buoy has been deployed in the same orientation throughout its entire lifetime to date.  See the report of WDirDiff/Compass averages for the Buccoo Reef station for an example where this does not appear to be the case.

The second thing to note from this graph is that the WDirDiffs average over the buoy's lifetime is -11.4°.  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.

Similar analyses carried out at this buoy's sister stations at Buccoo Reef, Tobago (BUTO1) and Little Cayman, Cayman Islands (CCMI2) found that the BUTO1 Compass directions can be divided into four distinct "regimes" with subsequent regime averages offset from one another by roughly 180°, and the CCMI2 Compass directions were stable throughout its deployment lifetime to date.  At BUTO1 the lifetime WDirDiff average is -18.6°, which suggests that the BUTO1 wind instruments may not be properly oriented and are even more divergent than the ARTO1 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 BUTO1 and at this link for CCMI2.

(signed)
Mike Jankulak

AirT/RH performance at Speyside / Angel's 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 Speyside / Angel's Reef the analog AirT/RH sensor lasted 181 days before the RH data went bad on May 25, 2014.  [All instruments on a CREWS/CCCCC buoy are intended to produce usable data for an entire year.]  The buoy was brought briefly to land on November 10-13, 2014 and on February 4-5, 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 "previously removed" during the November 2014 maintenance operation and was then "successfully re-installed" during the February 2015 maintenance operation, 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 Speyside / Angel's 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 ARTO1 (Speyside / Angel's Reef) buoy's AirT/RH sensor performed reasonably well for 181 days out of the buoy's 557 operational days, or about 32% of the time.  Its longest stretch of proper operation was 181 days, or about 6.0 months.

Similar analysis performed on this buoy's sister stations at Buccoo Reef, Tobago (BUTO1) and Little Cayman, Cayman Islands (CCMI2) found that the BUTO1 instrument performed reasonably well for 90 days out of the buoy's 469 operational days, or about 19% 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 BUTO1 sensor's longest stretch of proper operation was 90 days, or about 3.0 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 BUTO1 and at this link for CCMI2.

(signed)
Mike Jankulak

EXO Sonde performance at Speyside / Angel's 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 Speyside / Angel's Reef buoy (ARTO1), performance by the EXO Sonde has been generally poor.  The Speyside EXO was first deployed on November 25, 2013 and this analysis is based on data collected through June 4, 2015.  Although this period spans a total of 556 days, ARTO1 experienced a few short maintenance operations that brought the buoy temporarily to land, so that the actual length of deployment over this period was only 552 days, or about 18 months' worth.

Here is a graph of sea temperature (°C, in blue) and salinity (PSU, in red) from ARTO1, 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 Speyside has had four periods of time during which the EXO could be said to have produced reasonable sea temperature and salinity data:

• Nov 25, 2014 to Jan 22, 2014 (58 days, after which Sal goes bad)
• Mar 20, 2014 to Jun 6, 2014 (78** days, after which Sal goes bad)
• Sep 11, 2014 to Sep 22, 2014 (11 days, after which Sal goes bad)
• Mar 26, 2015 to May 8, 2015 (43 days, after which Sal goes bad)

**The 78-day period from March 20th to June 6th, 2015 includes a moment on May 20th when salinities abruptly drop by about 1 PSU and then continue to fall slowly for 17 days before becoming very obviously corrupted.  The May 20th drop occurs at the time when the EXO appears to have been physically disconnected from the buoy for two hours, judging from the absence of voltage data.  An actual salinity drop coincident with this (presumed) maintenance operation is not likely, though it is not clear whether this salinity drop should call into question the integrity of the salinity data record prior to this time or subsequent to it.  This analysis avoids the question by giving the EXO the benefit of the doubt and assuming that both pre- and post-drop data are reasonable, up until the probe very obviously fails on June 6th.  However a more conservative analysis would score this performance as 61 days (pre-drop) or 17 days (post-drop) of reasonable data, rather than the 78 days listed here.

As of this writing the conductivity probe at ARTO1 is nonfunctional, and has reported corrupted salinity data since May 8th and corrupted sea temperatures since June 3rd.

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 190 days out of the buoy's 552 operational days, or about 34% of the time.

A similar analysis performed on this buoy's sister station at Buccoo Reef, Tobago (BUTO1) found that that EXO performed reasonably well for 263 days out of that buoy's 464 operational days, or about 57% of the time.  The complete analysis for that EXO may be found at this link.

(signed)
Mike Jankulak

May 2015 maintenance - Angel Reef

The Buccoo Buoy was inspected on 11 May 2015. While the anchor ropes and metal base required cleaning, the sonde, probes and protective case were relatively unfouled. Badic maintenace was conducted on the sonde. None of the probes required the copper antifouling tape to be replaced.  The sacrificial anode was replaced.

A calibration was not conducted on this trip, and the sonde was cleaned and re-installed.

Data from the Sontek ADP was collected. The unit seems to be working fine and the data looks good.

The status of RMY RH sensor remains the same.

March 2015 maintenance - Angel Reef

ARTO1 was inspected ans serviced over the period 14-17 March 2015.  Minimal cleaning was required at this site. Anchor ropes and buoy base were cleaned.

The copper coating on the sonde probes was still intact and in good condition and was not replaced. Calibration of probes was conducted.  However, the sonde was in re-installed until a 7 days later. The probes were maintained in a moist environment until the sonde could bere-installed.

The RMY temp/RH installed the previous month was not collecting data. The unit was inpsected and reinstalled, but the problem persists. On further correspondence with C-ARMs two other options will be looked at to correct the problem.

The Sontek ADP was also deployed on this trip.

Cellular communication was confirmed, but no RF communication could be achieved on the day.

The next visit is scheduled for the end of May 2015

February 2015 maintenance

Following the annual maintenance check conducted over the period 10-13 November 2014,  a further check was conducted from 4-5 February 2015.  The buoy was brought to shore and most instruments were functioning and we had no problem connecting via RF but there was no cellular connection. TheRMY tem/RH MET sensor previously removed in Nov 2014 for servicing was successfully re-installed.

The EXO2 sonde was calibrated and reinstalled.  The Conductivity/Temp sensor seems to be defective.  Temperature reading were quite low (as much as 15 deg C below ambient- ambient was checked against a handhelp YSI temp/conductivity probe). This seems to be a recurring problem. OIn september 2014 the Cond/Temp probe was found to be faulty, which was eventually returned to and replaced by YSI.

Minimal fouling was noted, but the unit was repainted with anti-fouling paint.  All anodes and copper coating seemed intact. and the probe would not calibrate conductivity. All was downloaded from both loggers.