This post, written in August of 2016, describes what was learned through a careful examination of this buoy's data record during its lifetime to date.
The first thing to note is that although this buoy has suffered several extended outages, it has never lost power. This is a completely different situation from its sister buoy at
Catuan Wreck (Boca Chica), which suffered
a 3-month complete loss of power beginning a few weeks after initial deployment. Unlike the CWDR1 buoy, the PPDR1 buoy's data record is complete and unbroken, which suggests that its outages have been caused by communications problems, most likely problems with its cellular service provider, modem or account.
Judging from the archive of automated CREWS uptime alerts the PPDR1 buoy had communications lapses on December 13th and 24th and then a longer outage beginning on December 31st. This first outage appears to have ended on January 20th but a longer outage then began on March 16th and lasted until May 31st.
Due to idiosyncratic record-retention settings on the meteorological data tables that are copied between the buoy's two dataloggers, the buoy's full data history was not recoverable from the 'main' logger but could be patched by drawing on records from the 'met' logger. As a result, our archives of this buoy's data are unbroken.
Another problem found in the data record is with this buoy's WXT (the Vaisala 'weather transmitter' that measures wind and precipitation acoustically as well as air pressure, temperature and humidity). The data strongly suggests that the WXT was not securely mounted on this buoy and its base may have worked itself loose in the first few weeks after deployment. The buoy was deployed December 11th, the first signs of WXT looseness were on December 24th, the problem became more serious December 27th, and all data from the WXT ceased on March 22nd. This may suggest that the WXT fell off the station entirely, which is what happened at the
South Water Caye buoy while it was parked in a cove awaiting evaluation and repair.
Judging from the compass direction data, the buoy was probably recovered from its deployment site on May 30th and redeployed on May 31st. There also seems to have been a 40-minute power outage on May 30th. This activity coincides with the restoration of cellular service and the resumption of WXT data, all of which strongly suggests manual intervention by DR locals and/or YSI support people, although to my knowledge no report of such an intervention has been received by AOML/CHAMP.
Subsequent to this May 30th - 31st repair, there is some evidence in the data record of communication problems between the two buoy dataloggers (most seriously for 18 hours on July 8th) but no further sign of cellular communications problems.
The buoy's analog RH/AirT sensor (an RM Young model) has experienced some problems. The humidities reported by the instrument grew unbelievably large towards the end of March and to date have not been corrected. Air temperatures from the same instrument are more believable but in the last few days of July there are hints of growing discrepancies relative to the WXT temperatures, and I would trust the WXT data over the RM Young instrument in this case. Note that this same model has experienced repeated failures at buoys throughout the network (including at
Buccoo Reef,
Angel's Reef / Speyside,
Little Cayman, and
Calabash Caye) but at Calabash Caye at least there was reason to believe that the instrument itself was not at fault, but instead there was something about the buoy wiring, some degradation of signal, that led to voltage reading problems with this analog sensor. However even while the CCBZ1 buoy was failing to record correct voltages from the instrument, those same voltages measured directly at the instrument terminals were completely accurate.
Diagnostic data suggest that, as with most other buoys in this network, humidity levels are unacceptably high in the 'main' junction box. There was a small, short-lived reduction in main RH during the May 30th - 31st timeframe which lends further support to the theory that some sort of local intervention was taking place. Humidity levels in the 'met' junction box, by comparison, have remained acceptably low.
The EXO sea temperatures seem believable but the salinities have drifted lower throughout the buoy lifetime to the point where they are no longer believable. This may simply be due to lack of regular in-field calibrations. The EXO's modular sensors are said to require recalibration every 1 - 2 months (exact requirements vary by sensor) but there is no suggestion in the data record that any such calibrations have been performed in the nearly eight months since initial deployment. As far as the other EXO measurements go, they all appear to depart from normal levels around July 3rd - 8th and do not recover. This impacts turbidity, chlorophyll, blue/green algae and fDOM. Strangely, the EXO voltage levels (which are uniquely 6V on most other buoys) drop to 0V shortly after initial deployment and remain so until early April, when they begin to range noisily between 0V and 6V.
Despite the various concerns discussed above, the meteorological data (apart from the troubled analog RH/AirT sensor) are generally strong, following the May 31st repair of the WXT, and at this time I am testing a new feed of PPDR1 meteorological data from AOML/CHAMP to NDBC.
Mike J+
