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.