Normally a CREWS station is visited once every year and its oceanographic and meteorological instruments are swapped out, its programming is updated, and its locally-stored data are recovered. This trip was different from our usual swapouts in several important ways:
- The last swapout operation at this station was in November of 2010, nearly two years ago. This current trip had been in the planning stages since January of 2012 but personnel shortages had made it impossible before now. Therefore the station's instruments, cables and other hardware had had almost twice as long as usual to degrade and might be expected to be in worse condition than usual.
- Since the last swapout, this station had suffered three power failures. The first failure (described here) was on July 14th, 2011, and was remotely diagnosed as a failure of the deep light sensor. Fortunately the University of Puerto Rico was able to react quickly and the failed sensor was removed on July 15th, and station operations started coming back online two days later.
- The second failure was on February 27th, 2012, and this time the shallow CTD was indicated by the data record to be the most likely cause. The UPR folks were too busy to visit the station until another team from AOML arrived in the week of March 12th - 16th to replace the station's support lines. The shallow CTD was removed during these operations and the station regained power a bit more than two weeks later, on March 31st. At the time that operations resumed, the deep CTD was found to be offline as well.
- Then after another two weeks, the station lost power a third time and never recovered. The cause of this third power failure remained unknown up until the time of this current August/2012 swapout operation. Since there had been this many problems with power failures, and since this station's electronics and cables were originally deployed more than six years ago, we made the decision to replace all of the station's underwater cables on this trip.
- In September of 2011, after the first of the three power failures described above, I conducted an analysis of the station's recent record of dropped satellite transmissions. This analysis revealed that the station's "daylight" transmission success rate was about 86%, which was lower than we'd like but still not that bad, but its "dark" transmission success rate was only 57%, which was terrible. This strongly suggested that the station was more likely to supply enough power to the transmitter while its solar panels were providing additional power to the system, whereas when powered by only the batteries there was often not sufficient power. Given that the batteries were then halfway through their sixth year of deployment (and an additional year has now passed since that analysis took place), and given additionally that the batteries had been fully drained by more than one short-circuit event, we decided to replace the batteries on this current swapout trip.
- One final difference in this year's swapout was that we had elected to try a different make of CTD in this year's deployment. Instead of deploying our usual RDI/Teledyne (formerly Falmouth) CTDs, this year we elected to deployed two refurbished SeaBird Microcat SMP37 CTDs. These CTDs require different programming and their maintenance needs are different from the Teledyne CTDs.
- On a minor note, this swapout would also be the first such operation to be conducted with the new CREWS travel laptop, following the failure of the old laptop's battery supply. The new laptop runs Windows 7 compared to the old laptop's Windows XP, and the old laptop had a built-in serial port whereas the new laptop requires the use of a USB-to-Serial adaptor.
There was some last-minute doubt about the timing of this trip with the formation of TS Isaac and its effects on UPRM (in the week before this operation) and Miami (in the days before we were scheduled to fly out of Fort Lauderdale). In the end, however, the trip was able to go ahead as planned and we (Pamela and Mike) arrived in La Parguera Monday evening, ready for work to begin on Tuesday morning.