WDirDiff/Compass data from Speyside / Angel's Reef, 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 offsets (WDirDiffs) between the wind directions reported by the analog anemometer manufactured by RM Young (RMY) and the sonic wind sensors on Vaisala's Weather Transmitter (WXT).  Ideally these offsets should be less than 5° in absolute value.  This post will further discuss the raw directions reported by the buoy's Compass.

For reference, some important milestones in this station's lifetime are as follows:

• 11/25/2013: initial deployment
• 11/10/2014 - 11/13/2014: buoy brought to land for a maintenance operation
• 2/4/2015 - 2/5/2015: buoy brought to land for a maintenance operation

The following graph shows the differences in wind directions reported by the two wind sensors (red, on the left axis) and the raw directions reported by the compass (blue, on the right axis).  All directions are reported in degrees of compass but note where the scales are different by a factor of 6x and the zeroes offset, with the WDirDiff axis running on the left from -30° to +30° but the Compass axis running on the right from 0° to 360°.  A negative WDirDiff would indicate that the reported WXT wind directions are lower than the corresponding analog anemometer values.

Please click on this image to see it in larger form.

First of all the Compass averages suggest that this buoy has been deployed in the same orientation throughout its entire lifetime to date.  See the report of WDirDiff/Compass averages for the Buccoo Reef station for an example where this does not appear to be the case.

The second thing to note from this graph is that the WDirDiffs average over the buoy's lifetime is -11.4°.  This is of concern because it falls outside of a range explainable by the specifications of the anemometer (± 5° accuracy) and the WXT (± 3° accuracy).  It suggests that one or both of the wind sensors are not properly oriented on the buoy in a manner consistent with correction to magnetic north using the direction offsets measured by the compass.  As of this writing it is not known which of the two reported wind directions is likely to be (more) accurate.

Similar analyses carried out at this buoy's sister stations at Buccoo Reef, Tobago (BUTO1) and Little Cayman, Cayman Islands (CCMI2) found that the BUTO1 Compass directions can be divided into four distinct "regimes" with subsequent regime averages offset from one another by roughly 180°, and the CCMI2 Compass directions were stable throughout its deployment lifetime to date.  At BUTO1 the lifetime WDirDiff average is -18.6°, which suggests that the BUTO1 wind instruments may not be properly oriented and are even more divergent than the ARTO1 instruments.  At CCMI2 the WDirDiffs average through the end of 2014 (after which time WXT wind directions are not available for comparison) is +1.5°, which is entirely reasonable and consistent given the specifications of the two wind sensors.

The complete analyses for the other WDirDiff/Compass averages, including graphs, may be found at this link for BUTO1 and at this link for CCMI2.

(signed)
Mike Jankulak

AirT/RH performance at Speyside / Angel's Reef, 2013-present

This post is part of a planned 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 performance of the analog instruments which measure air temperature (AirT) and relative humidity (RH).  These analog reading serve as a basis of comparison for AirT/RH measurements reported by the Vaisala Weather Transmitter (WXT) which also reports wind, barometric pressure and precipitation data.

At Speyside / Angel's Reef the analog AirT/RH sensor lasted 181 days before the RH data went bad on May 25, 2014.  [All instruments on a CREWS/CCCCC buoy are intended to produce usable data for an entire year.]  The buoy was brought briefly to land on November 10-13, 2014 and on February 4-5, 2015.  After the November 2014 maintenance operation both the AirT and RH data were bad, and as of this writing they are still bad.  An earlier post in this blog suggests that the AirT/RH sensor was "previously removed" during the November 2014 maintenance operation and was then "successfully re-installed" during the February 2015 maintenance operation, but there is no hint of good data in the hourly data records from this time.

The following are graphs of AirT (top, in °C) and RH (bottom, in %) from the Speyside / Angel's Reef buoy's lifetime, from 2013 to the present.  Values reported from the analog sensor under discussion are in blue and values from the WXT are in red.  Data are shown through June 9, 2015.

Please click on this image to see it in larger form.

Based on this data record the ARTO1 (Speyside / Angel's Reef) buoy's AirT/RH sensor performed reasonably well for 181 days out of the buoy's 557 operational days, or about 32% of the time.  Its longest stretch of proper operation was 181 days, or about 6.0 months.

Similar analysis performed on this buoy's sister stations at Buccoo Reef, Tobago (BUTO1) and Little Cayman, Cayman Islands (CCMI2) found that the BUTO1 instrument performed reasonably well for 90 days out of the buoy's 469 operational days, or about 19% of the time, and the CCMI2 instrument performed reasonably well for 376 days out of the buoy's 506 operational days, or about 74% of the time.  The BUTO1 sensor's longest stretch of proper operation was 90 days, or about 3.0 months, and the CCMI2 sensor's longest stretch of proper operation was 226 days, or about 7.4 months.

The complete analyses for the other AirT/RH sensors, including graphs, may be found at this link for BUTO1 and at this link for CCMI2.

(signed)
Mike Jankulak

EXO Sonde performance at Speyside / Angel's Reef, 2013-present

This post is part of a planned 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 performance of the EXO Sondes, which were deployed to collect sea temperature and salinity data but are also capable of monitoring other 'water quality' parameters such as turbidity, algae, fDOM, pH and DO.

At the Speyside / Angel's Reef buoy (ARTO1), performance by the EXO Sonde has been generally poor.  The Speyside EXO was first deployed on November 25, 2013 and this analysis is based on data collected through June 4, 2015.  Although this period spans a total of 556 days, ARTO1 experienced a few short maintenance operations that brought the buoy temporarily to land, so that the actual length of deployment over this period was only 552 days, or about 18 months' worth.

Here is a graph of sea temperature (°C, in blue) and salinity (PSU, in red) from ARTO1, plotted against decimal year:

Please click on this image to see it in larger form.

Over the course of the last year and a half, the EXO Sonde at Speyside has had four periods of time during which the EXO could be said to have produced reasonable sea temperature and salinity data:

• Nov 25, 2014 to Jan 22, 2014 (58 days, after which Sal goes bad)
• Mar 20, 2014 to Jun 6, 2014 (78** days, after which Sal goes bad)
• Sep 11, 2014 to Sep 22, 2014 (11 days, after which Sal goes bad)
• Mar 26, 2015 to May 8, 2015 (43 days, after which Sal goes bad)

**The 78-day period from March 20th to June 6th, 2015 includes a moment on May 20th when salinities abruptly drop by about 1 PSU and then continue to fall slowly for 17 days before becoming very obviously corrupted.  The May 20th drop occurs at the time when the EXO appears to have been physically disconnected from the buoy for two hours, judging from the absence of voltage data.  An actual salinity drop coincident with this (presumed) maintenance operation is not likely, though it is not clear whether this salinity drop should call into question the integrity of the salinity data record prior to this time or subsequent to it.  This analysis avoids the question by giving the EXO the benefit of the doubt and assuming that both pre- and post-drop data are reasonable, up until the probe very obviously fails on June 6th.  However a more conservative analysis would score this performance as 61 days (pre-drop) or 17 days (post-drop) of reasonable data, rather than the 78 days listed here.

As of this writing the conductivity probe at ARTO1 is nonfunctional, and has reported corrupted salinity data since May 8th and corrupted sea temperatures since June 3rd.

Based on these statistics the EXO's conductivity probe, which reports both sea temperatures and conductivities (from which salinities are calculated), has performed reasonably well for 190 days out of the buoy's 552 operational days, or about 34% of the time.

A similar analysis performed on this buoy's sister station at Buccoo Reef, Tobago (BUTO1) found that that EXO performed reasonably well for 263 days out of that buoy's 464 operational days, or about 57% of the time.  The complete analysis for that EXO may be found at this link.

(signed)
Mike Jankulak

May 2015 maintenance - Angel Reef

The Buccoo Buoy was inspected on 11 May 2015. While the anchor ropes and metal base required cleaning, the sonde, probes and protective case were relatively unfouled. Badic maintenace was conducted on the sonde. None of the probes required the copper antifouling tape to be replaced.  The sacrificial anode was replaced.

A calibration was not conducted on this trip, and the sonde was cleaned and re-installed.

Data from the Sontek ADP was collected. The unit seems to be working fine and the data looks good.

The status of RMY RH sensor remains the same.

March 2015 maintenance - Angel Reef

ARTO1 was inspected ans serviced over the period 14-17 March 2015.  Minimal cleaning was required at this site. Anchor ropes and buoy base were cleaned.

The copper coating on the sonde probes was still intact and in good condition and was not replaced. Calibration of probes was conducted.  However, the sonde was in re-installed until a 7 days later. The probes were maintained in a moist environment until the sonde could bere-installed.

The RMY temp/RH installed the previous month was not collecting data. The unit was inpsected and reinstalled, but the problem persists. On further correspondence with C-ARMs two other options will be looked at to correct the problem.

The Sontek ADP was also deployed on this trip.

Cellular communication was confirmed, but no RF communication could be achieved on the day.

The next visit is scheduled for the end of May 2015

February 2015 maintenance

Following the annual maintenance check conducted over the period 10-13 November 2014,  a further check was conducted from 4-5 February 2015.  The buoy was brought to shore and most instruments were functioning and we had no problem connecting via RF but there was no cellular connection. TheRMY tem/RH MET sensor previously removed in Nov 2014 for servicing was successfully re-installed.

The EXO2 sonde was calibrated and reinstalled.  The Conductivity/Temp sensor seems to be defective.  Temperature reading were quite low (as much as 15 deg C below ambient- ambient was checked against a handhelp YSI temp/conductivity probe). This seems to be a recurring problem. OIn september 2014 the Cond/Temp probe was found to be faulty, which was eventually returned to and replaced by YSI.

Minimal fouling was noted, but the unit was repainted with anti-fouling paint.  All anodes and copper coating seemed intact. and the probe would not calibrate conductivity. All was downloaded from both loggers.

Speyside CREWSannual maintenance

The Speyside CREWS was given an annual maintenance check over the period 10-13 Nov 2014. The buoy was brought to shore and all instruments were functioning and we had no problem connecting via RF but there was no cellular connection.  All data for the last year was downloaded from both loggers and is now in the hands of TT IMA.  The programs were re-loaded and the electronics were reset.  Cellular communications was restored immediately afterward.  The RMY temp/RH is in need of service/calibration  but all other MET sensors seem to be measuring accurately.  The Temp/RH was removed for service and sonde recalibrated  prior to re-deployment on the 11 Nov 2014.

On the previous basic servicing (September 2014), the sonde was not functional due to erupted batteries in the battery well.  These were replaced.  The Temp/Cond was also found to be faulty, which was eventually returned to and replaced by YSI.

The breakage of the wiper parking garage has been noted as a regular problem with the CREWS inhibiting the proper settling of the wipers, and may be something the design team should look at.