some observations about buoy status

The following are some observations I'd like to share about the CCMI2 data stream. Recently I have been reviewing the data all active buoys, graphing them, and making note of instrument failures or diagnostics concerns. In the case of the CCMI2 this covers the period of time since the buoy was repaired and redeployed in March of 2016.

• Based on details sent to me in email and supported by contents of the data stream, I would estimate that the buoy was redeployed on March 12th, 2016 at about UTC 19:00. The buoy's compass is a good indicator of the timing of a buoy being towed to its deployment spot followed by a buoy solidly anchored in place. This suggests that there may have been a typo in the blog update about deployment, which spoke of a March 13th redeployment.
• Buoy diagnostics indicate that immediately post-deployment both junction boxes (the "Met" JB clamped to the inside of the tower, and the 'Main' JB sitting in the well of the buoy) started out with extremely dry conditions, both around 5% RH. Since then the Met JB has stayed low but the Main JB has climbed to > 20%. This is not yet cause for concern but it suggests that further attention may be required to the Main JB desiccant, o-rings and grease.
• The analog RH/AirT sensor (and RM Young product) has been offline since redeployment in March, although we continue to receive humidity and temperature data from the Vaisala WXT. Note that of the five CREWS buoys that are currently operational, the analog RH/AirT sensor is malfunctioning at four of them. However, based on my direct observations of this instrument at the never-deployed Calabash Caye buoy in Belize, there is reason to believe that the instrument itself may not be at fault, but rather there may be some insufficiency of buoy wiring, some degradation of signal, that leads to voltage reading problems with this analog sensor. I say this because even while the Calabash datalogger was failing to record correct voltages from the instrument, those same voltages measured directly at the instrument terminals were completely accurate.
• In the first few weeks after deployment, WXT wind speeds were strangely lower than those reported by the analog RM Young anemometer. I cannot explain this but based on the overall data set I would trust the anemometer data over the WXT during this time. By the end of March the numbers were back in sync and the phenomenon has not recurred. Wind directions were unaffected throughout, as were wind gusts. Very strange.
• The 10-minute BIC and CTD data tables continue to drop records. If that logger program is ever updated then it should go through some careful testing to make sure there are no skipped scans or watchdog resets. It might be that the Main program, between instrument polling and copying data from the met logger and programmed delays, is just running too long and happens to exceed its 10-second scanning time every now and then.
• NXIC CTD performance is mixed since redeployment. The instrument depths aren't reporting, although that's not a huge problem since the buoy-mounted CTD is essentially at a constant depth, with the buoy rising and falling with tides. Sea temperatures look good but the salinities appear to have fouled for a while, roughly May 31st to July 27th. A sharp uptick on July 27th suggests possibly some local intervention/cleaning although to my knowledge no such visit has been reported.
• Since March there have been isolated instances where copying of records from the Met->Main dataloggers has failed. Month by month, March onwards, there were 40, 30, 5, 20, 25 hourly records that failed to copy (counting through the end of July). This isn't a huge problem since I can patch the missing data using records read from the Met logger directly, but it might be indicative of a loose connection or a corroded contact on the umbilical cable that runs between the two boxes. Or it might be another symptom of the hypothesized timing fault (see above) that is dropping records from the CTD and BIC 10-minute tables.

(signed) Mike J+

Crews Buoy Overhaul

With our Crews Buoy down for multiple months I was eager to get back to Little Cayman to address the issues plaguing our installation as well as to do some serious maintenance to the buoy's running gear. The good news was that the buoy was already on shore so I could get to work straight away.
         Upon arrival Feb 15th I took stock of our situation and proceeded to start diagnosing issues. Initially the buoy was blowing a fuse to the CR1000 data logger in the Battery Junction box, which in turn basically shut down all the comms (cellular and RF) so the buoy was completely silent. The main problem was that upon replacing the fuse it would wait approx 48 hours to blow! After checking continuity and finding this to be good through the whole wiring system from the instrument back through to the fuse holder and all the way to the CR1000 data logger, I decided to remove the innards of the battery junction box to the lab for closer inspection. After tearing down to the heart of the CR1000 we found corrosion on a small electrical component on the circuit board.

During this process I was helped by Paul Maneval whose programming knowledge was invaluable to the installation of the new CR1000. Also I would like to thank Jon Fajans for quickly sourcing a CR1000 for us and updating the OS on it for us. Due to the fact that there are two CR1000 data loggers in the buoy that need to be simpatico in order function correctly we then had to update the one in the Met junction Box to the same OS as the new one. We also had to transfer the old CR1000 files to the new one in order for all the systems to function as they did in the past. This did require some trial and error but eventually all systems were operable. Of note, it is important to have a field laptop that still has RS232 connections and ethernet connections otherwise field maintenance would be impossible. Luckily we still have a tough book floating around. I suspect these will be like dragons teeth shortly.
                    After sorting out the main issue we also found our WXT520 to be dead. This has also been replaced with a back up unit. I also replaced the instrument cables to the surface Bic, U/W Bic and CTD as these were suffering from salt spray erosion and U/V radiation to the point that inner wires were showing at multiple bends in the cables.
                  The running gear connecting the buoy to the ocean floor has also been replaced with new lines and float buoys. New zincs have been added to the buoy's U/W frame. New desiccant has been added to the instrument canisters. In all this has been our most thorough maintenance operation and should be good for the next two years.
                  The buoy was splashed and re-deployed March 13th 2016 and should have been sending good data around 3pm eastern time.
                 

December 13th 2015

Shortly after I left to head back to the US from our annual maintenance of the Crews Buoy our buoy developed a communications problem. In as much that we lost all RF and Cellular comms rendering any contact impossible. This could have been due to any number of issues so a return trip was planned to get the buoy up and running as soon as possible.
             The buoy was pulled out by the Little Cayman team and brought on shore Monday December 2nd. Shortly after I arrived we opened up the Battery Junction Box and had a thorough inspection of the 12v power supply and controller. Upon closer inspection it was found that the fuse that protects the CR1000 data logger had blown. This in turn controls the cellular modem and RF401 so was immediately diagnosed as the issue concerning communications. With this fuse replaced we waited 48hrs to determine if the fuse would blow again and if there was an underlying issue with the fuse circuit. After 48hrs we determined that the buoy was fit to be re-deployed and that the issue was an anomaly perhaps created by a weak fuse or a small power spike. I also took this opportunity to inspect the Met Junction box fuses and replace the desiccant in both Junction boxes.
              The buoy will be re-deployed when a suitable weather window is observed and with any luck we will get back to business of collecting data!

Annual Crews maintenance Oct 2015

Greetings From the Crews project in Little Cayman. During the month of October we completed the annual maintenance of our Crews buoy. The buoy has now been successfully deployed for 2 years and is holding up well given the rigors of an open ocean environment. The running gear and attachment system is in excellent condition.
             The team at NOAA and AOML continue to support our staff with the various issues that pop up when sophisticated ocean and meteorological instruments are deployed. Below is a list of the procedures followed to keep the buoy in optimal condition for the coming year.

1. New bottom paint and general spruce up.

2. Install WXT520, replace WXT520 power and comms cable, configure WXT520 and test. OK

3. Install re-calibrated Surface Bic. 

4. Install re-calibrated U/W Bic.

5. Make new instrument mount for CTD, Program and install and test re-calibrated CTD. OK

6. Inspect battery junction box, found to be dry, no need to wipe with cloth although desiccant was shot. Replace desiccant, new 'O'ring and pressure test vessel to -5psi for 20 mins. OK

7. Current RH in the Met junction box is around 25% so deemed to be good. This was repaired extensively  on my last trip in July so should be good until Oct 2016

8. Check solar junction box. OK

9. Check RF comms. OK

10. Check Cel comms (Mike J)

misc operations during July of 2015

[The following post is a back-dated reconstruction based on email records. In examining this buoy's 2015 data set I realized that there is a gap in data that did not have any explanation recorded on the maintenance log.]

Between July 6th and 22nd, 2015, there were a number of operations carried out on the buoy (including a recovery to land and subsequent redeployment).

Things kicked off on July 6th when Jon Clamp attempted to resolved the WXT failure (see this blog post for details) by replacing the sensor on-site.  Details can be found in an email of July 6th:

Here is the latest update. The WXT that was loaned by AOML has been swapped out on the buoy on site July 6th at around 11am. We did not bring the buoy to shore as I am hoping that this will be the hoped for quick fix. As far as the cellular telemetry is concerned I was not aware of any problems, although this seems to be becoming an increasingly common occurrence. I can get in touch with the cellular supplier to see if there are any issues on our end. Other than that I am hoping the WXT is sending data. I also plan on installing our new base station RF 401 so that we can start receiving data again via radio.

Another email from Jon on July 7th contained some more details:

The visit to the buoy was on Monday July 6th at about 11am which was when the WXT swap out was achieved. Just as a heads up for all. The YSI style buoy is very difficult to perform on site intricate maintenance due to it being a floating buoy as opposed to the previous static stick. There is far too much movement in the buoy to perform intricate electrical diagnostics as there is a real danger of sea water ingress.

The swap out was done by removing the old WXT via the twist bayonet style mount and the cable was removed via the threaded collar. Prior to installing the refurbished WXT I applied some electrical contact grease to the female part of the WXT plug. I was sitting atop the buoy whilst in a fair sea and installed the refurbished WXT. At no point during this visit did I power down the station. I have not looked at any of the internal connections in the junction boxes. The WXT cable was not visually in bad shape and the coupling was also free and easy to manipulate.

The plan was to swap out the instrument as I knew this could be achieved on site. If we are not receiving data then we will have to go to the next step and pull the buoy for a complete inspection. Bearing this in mind we are due to swap out the CTD and PAR in October so we were trying to minimize the number of times we have to pull the buoy out.

We do have pictures and video which we can incorporate into the blog.

I have also brought  2lb of desiccant with me for replacement of the existing desiccant if we end up pulling the buoy out.

The overly large cellular bills were a clerical error and have been cleared up. The changes in the IP address are something that is beyond my knowledge so would need some guidance on how to establish a better system for getting timely data. I assume this would be a dedicated IP address. It may be that we could inquire with the other cellular provider on island. We are currently with Digicel so will check with Lime.

I will be installing the new radio in the next 2 days so hopefully will be able to look at the data ourselves to establish if the buoy instruments are performing as they should.

Jon's references to "cellular telemetry" and "changes in the IP address" refer to questions that I raised on July 6th when I was first told about the WXT swap and asked to check if the new instrument was working correctly.  I replied:

AOML lost contact with the Little Cayman buoy about 18 hours ago, at UTC 22:51 on July 5th.  This would have been about 5:51pm yesterday, local Cayman time.  I checked the last-reported data and there is no sign of any improvement from the WXT.

In retrospect this appears to have been entirely coincidental. CCMI's cellular provider gives them what is known as a "dynamic" IP address.  This means the provider owns a range of IP addresses and, whenever a subscriber device connects, it is assigned one of those IP addresses randomly.  The problem is that neither CCMI nor AOML knows what the range of possible IP addresses is. We have made our best guess based on observations of what IP addresses have been used in the past, but every now and then the buoy's IP address randomly jumps outside of that range and AOML's firewall blocks its attempts to send us data.

It now appears that the buoy jumped to an unexpected IP address on the day before the WXT swap operation.  On July 13th I was able to confirm this with our AOML firewall manager and we opened up access for the buoy to call us from its new address.  At this time I was able to report that the new WXT was not communicating any better than the old one had.

Judging from the data record, the next thing that happened was that the buoy was recovered to land on July 17th at about UTC 1400. On July 18th I received the following email (and attached diagrams) from Jon Clamp:

As the follow up to the conversation below here are the results of my investigation into the failed WXT comms.

Monday July 6th.
The WXT 520 was swapped out with a known repaired and calibrated unit from AOML. This was done on site at the buoy in the hopes of a quick fix. This was not the case as the WXT did not resume its connection.

Friday July 17th.
I pulled the buoy out and have inspected the brain canister. This was found to be in good condition. Upon opening it there was some humidity but nothing to cause concern, a paper towel was all that was needed. The CR1000 and all connections are corrosion free and in good order. All the fuses are intact and corrosion free. I would say with confidence that there are no connection issues inside the canister.

The canister itself had a good seal at the o-ring and there are no nicks or cuts. The glued seal at the top of the canister seems to be holding and looks in good condition.

I next moved to the WXT connection cable and did a continuity test to see if we have an issue with the cable. I have attached the YSI connection drawing and also my findings with respect to the continuity. I might be wrong but think the issue is in the cable. Please advise on this based on the attachments.

My next scheduled task on the buoy is in October where I will be replacing the U/W Bic, surface Bic and CTD. It would seem that it would be good policy to replace all the cables at this time to avoid any other potential connection issues. I am unable to get the cable made up in the Cayman Islands so am leaning towards a) putting the buoy back together with a known fault and rectifying with a new set of cables in October b) making a separate trip back with a new cable and replacing it on site, perhaps August.

I have also installed a new RF401A base station, new cable and antenna so comms to the station are available. Due to having to install new drivers etc for this to run I am not able to automatically connect the Buoy every 10mins for downloads. This is a programming issue with loggernet and I am a bit of a neanderthal when it comes to this so if anyone can help that would be great (manual connection is available and I have been doing this everyday). I am concerned with interrupting the cellular connection so have not made any attempt to sync this. The current RF401A operates at baud rate 38400, pak bus 1, comm port 5 if that helps.

On July 20th I replied by email to Jon, saying:

Looks like your WXT cable is missing a connection to the WXT plug's pin #2.  That is Vin+, or the one that supplies power to the WXT.  This means the WXT has no power, so it's not surprising that it isn't operational.

I also sought some clarification about the language we were using to describe the three junction boxes.  Jon had been talking about a "brain canister" and said that it was the box with the datalogger, but there are loggers in both the "met junction box" (an external canister that is hose-clamped to one of the tower legs) and the "main junction box" (a large enclosure hollowed out in the body of the buoy itself).  Jon followed up that same day with more information about the "canister" he'd been inspecting:

Thanks for the clarification, I will refer to it as the "met junction box” (MJB). However, I decided to perform a pressure test rather than a vacuum test on the “MJB” and unfortunately we have numerous leaks at the glued joint that attaches the cover to the body of the MJB. At this point we will either have to try and seal this (Thinking JB weld for a quick field fix) or replace the box.

Later on July 20th, Matt Previte of YSI weighed in with this email and picture:

1) As Mike mentioned in one of his responses, we DID find a problem with some of the MJB’s with the glue application. This was found after I came to Little Cayman because I was testing/replacing them, as necessary, on subsequent deployments. I think adding some kind of caulk or silicone around the outer edge of that seal should help temporarily. I’m not sure whether JB Weld is appropriate for plastic or not. Long term we need to look at fixing or replacing that cylinder for your October haul out. I’ll inquire here for that and let you know.

2) I did want to point out that there is a fuse within the Met Junction for the WXT. Though that won’t matter if you can’t get continuity through the cable between V+ on the WXT connector and pin 2 on the Pi-connector. However, there may be a grey inline junction on the WXT cable (see attached picture). It may be worth opening that cylinder to see if moisture has somehow seeped in and caused corrosion. I do not hear about this frequency of moisture intrusion, but it may be that these Caribbean conditions are simply pushing past our normal experiences. And we will need to find ways to beef-up the builds to be extra robust.

In the late evening of July 20th Jon sent this update (and photos):

I have attached pictures of my MJB work around. I have put a bead of 5200 on the inside of the canister and put 6 stainless screws on the cover to hold it in place as I do not want the cover to pop off in the future. I have exposed it to a pressure test of +5psi for 20 mins and all seems to be well. The solar jnx box that we repaired April 15 is still in good condition since the repair and the battery box is also good and holds a -5psi vacuum for 20 mins. All desiccant has been has been exchanged. I plan on re-deploying without the WXT in the next 48 hours.

Hopefully we are back on line shortly.

On the next day, July 21st, Jon sent another update about what he'd learned concerning the WXT cable, after having been prompted by Matt's talk about the grey inline junction on the WXT cable:

Based on your thoughts I investigated the inline junctions. There are two grey cylinders incorporated into the WXT cable. The first one I opened, the wiring and soldered joints were in good shape. The second one however had water inside and the soldered connection at the white wire had corroded away causing the loss of power to the WXT. I decided to cut the cable back at six inch intervals toward the pie connector in an attempt to get good wire.Unfortunately this corrosion of the white wire had worked its way all the way back to pin 2 on the pie connector and had actually detached from pin 2 (I cut open the pie connector to confirm this) So after thinking I could possibly get a fix on the cable we are back to re-deployment without the WXT. We will need to get a new cable made up for this.

I will let you all know shortly when the buoy is re-deployed and back on site.

That same afternoon Jon sent another update:

Ok all inspections are done, I briefly disconnected the batteries for inspection so you may see that in the data. As of July 21st 13.30pm (Cayman) all systems are up (except WXT) The buoy is located on land at the station. The plan is to launch the buoy July 22nd at 13.00 (Cayman) The buoy should be on site at its mooring by 16.00 (Cayman). Please can you check to see that there is communication via cellular before I splash the buoy.

Judging from the data record (with particular attention to how the directions reported by the compass are hugely variable while under tow and then settle down once the buoy is moored again), the buoy was redeployed and reporting from site as of UTC 2100 July 22 2015.

One last note, after the buoy was redeployed I was examining its data feed on July 31st and I noticed a jump in compass/wind directions.  I sent Jon the following email and graph:

I got the chance this week to sit down with the post-operations Cayman data feed, and I noticed something is up with the electronic compass.

For the station's entire lifetime to date, the compass has averaged around 236°. This is just an arbitrary direction that is used to correct the wind directions on the two wind sensors (analog and WXT) so that they are calibrated to magnetic north.

After your recent maintenance operations on land, the compass readings jumped about 55° higher, to 291°. I cannot be sure but this *appears* to have changed the trends in normal wind directions reported by the analog anemometer, too. I am attaching graphs of these two parameters (wDir1, ECompDir) over the entire lifetime of the buoy. Obviously I cannot be sure about the WXT directions since that sensor is offline.

The most likely explanation is that the electronic compass is pointed differently than it was before your operations. I know you said that you removed the "met" junction box and relocated it temporarily to a lab that was entirely separate from the buoy. It seems likely that when the met JB was remounted onto the buoy, it was rotated about 55° from where it used to point.

I do not know if this box-pointing procedure is documented anywhere. We are right now meeting with Matt Previte of YSI here in AOML and he is going to send us any "deployment instructions" documentation that he can lay hands on, so that might be mentioned somewhere. But if I understand his explanation correctly, then the Met JB, the analog anemometer, and the Vaisala WXT must all be mounted to point in the same direction. Not north, necessarily, but you must choose an arbitrary "fake north," either the leg of the buoy or possibly a spot on the horizon, and point all three of these sensors in the same direction. I'm told that the top of the Met JB is translucent specifically so that you can see the markings of the electronic compass "north" on the inside when you mount it.

Matt says when he deploys buoys in person, he points the compass directly to the tower leg that it is clamped to. Then the other two instruments are pointed, not at that same tower leg (because then they'd both be 45° off from where they should be) but best-guess "parallel" to how the compass/JB is pointed. The reason this sounds so awkwardly phrased is that I'm describing a process that I've never witnessed and may not fully understand myself. Matt will hopefully chime in with any needed corrections or clarifications, and if there exists any documentation of this wind-sensor-orientation procedure I'm sure he can forward you copies as well.

Anyhow for now I can just apply an ad hoc wind direction correction to the data feed. This will correct the data and "fix" the graphs like the ones I've attached here to eliminate this data jump. But you should make a note and, the next time the buoy comes to land, you will want to have a closer look at the direction that the Met JB is pointing. You will know that it should be rotated about 55° from where it points presently and for guidance you can try to gauge how the anemometer and WXT are pointing.

Jon and I exchanged a bunch of messages that day but in the afternoon he sent me this:

It is a calm day today so I am going out to the buoy to re- orient the MJB. This only requires loosening two hose clamps and rotating the MJB 55* center clockwise. I have made up a pattern to perform this. Expect to see the changes by 1600 Cayman time.

This adjustment corrected the compass/wind direction discrepancies I had noted and the 55° adjustments I had coded were applied only to data in the period between July 20th and 31st.

-- Mike Jankulak

Voltage trends at Little Cayman, 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 Little Cayman, Cayman Islands (CCMI2).  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 features of this graph are as follows: an obvious dip in voltage from October 14th - 29th while the station was on land for maintenance; a loss of data during the period from December 29th, 2014 until March 12th, 2015, caused by the station's power loss and subsequent redeployment; and an unexplained voltage dip at the end of the dataset beginning June 1st, 2015.  Data for this analysis were last refreshed on June 9th, 2015.

At this station the Met voltages were slightly lower than the Main voltages (by 0.057V on average) so my subsequent analysis of battery minima focuses on the Met 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 CCMI2, this 'lower edge' was about 12.79V at deployment time.  This edge crept lower still by about 0.1V every 3-6 months until the power failure on December 29th, 2014, at which point (apart from obvious power irregularities) I estimate this lower edge to have been at about 12.52V, for a loss of about 0.33V overall.  Following redeployment this trend appears to have reversed itself somewhat, with a lower edge at about 12.60V for a short-term gain of about 0.08V.

Similar analyses were carried out for this buoy's sister stations at Buccoo Reef, Tobago (BUTO1) and at Speyside / Angel's Reef, Tobago (ARTO1).  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 ARTO1.

(signed)
Mike Jankulak

Junction Box Humidities at Little Cayman, 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 Little Cayman (CCMI2) 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.

Some obvious features of the above graph are as follows: initial buoy deployment was on October 23rd, 2013; the Main RH levels (red) ceased to fall below 20% on November 16th, 2013; there is a nine-month period when Main RH levels (red) remain strictly above 60% (January 17th - October 27th, 2014); there is a break in data lasting from the station's power failure (December 29th, 2014) until redeployment (March 12th, 2015); and there is a two-week period (April 30th - May 14th, 2015) during which there were no Met RH updates (green) because the Met logger's program stopped running (a situation believed to have been caused by excessive watchdog errors, indicating a potential programming/timing problem).  Note that the station's annual maintenance operations took place October 14th - 29th, 2014, throughout which RH data continued to be collected.

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) begins nicely stable and largely below 10% for about six months, a pattern which starts to be disrupted on April 10th, 2014.  On June 6th, 2014 the pattern shifts significantly above 10% for the first time, and this increasing pattern becomes quite obvious on August 7th, 2014, which is the last Met RH report to fall below 10%.  This only becomes worrisome on October 29th, 2014, the date of buoy redeployment after its annual maintenance operations, which also happens to be the Met RH's last report to fall below the 20% humidity threshold.  Met RH values remain in the worrisome-but-not-alarming range (above 20% but below 50%) from October of 2014 to May of 2015, but following the two-week period of non-updates of Met RH data (i.e. beginning May 14th, 2015, see above) Met RH values are well into the >50% alarming range, with 97.2% of Met RH reports rising above 50% humidity.  In the final 6 days of data examined in this report, in fact, all of the Met RH reports are above 90% humidity.

The Main RH numbers for this station are even more concerning.  These numbers started low but spiked quickly.  Less than one month after initial deployment the Main RH numbers rose above 20% and never recovered, beginning November 16th, 2013.  Two months after that, on January 17th, 2014, the Main RH numbers rose above 60% humidity and remained there until the buoy's annual maintenance operations nine months later in October.  Following those operations Main RH levels dropped slightly but remained at >50% humidity for 97.2% of the time.

These diagnostics indicate that there are presently serious humidity problems in both of the Main and Met junction boxes at this site, with the Main junction box problems being pretty much constant over the lifetime of the buoy to date and the Met junction box problems starting slow but becoming very serious over the last few months.  Given that this is the site where junction box condensation was blamed for a very serious power failure, both of these humidity concerns should be attended to at the earliest possible opportunity.

Similar analyses have been conducted at this station's sister buoys located at Buccoo Reef, Tobago (BUTO1) and at Speyside / Angel's Reef, Tobago (ARTO1).  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 ARTO1.

(signed)
Mike Jankulak