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+