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Data Quality Report
Ruth Lawless, June 2001
Data Currency Voyage Description Logging System Data Sampling Interval
Data Gaps Software Data Quality
Data Start Time: 07 May 1990 11:15 UTC
Underway Data End Time: 04 July 1990 05:40 UTC
This was the maiden voyage of the RSV Aurora Australis. Marine science trials were conducted in the vicinity of Heard Island. Marine science support personnel were provided on board, but underway data were quality checked well post-voyage (June 2001).
|16 May||Heard Island|
|17 May - 20 June||Marine Science|
|21 June||Heard Island|
DLS data types were logged.
4. Data Sampling Interval: 60 seconds
5. Data Gaps
All logged parameters have the following data gaps:
Back to Data Quality of Checked Parameters
Underway data were quality checked using Java based software created by Gordon Keith and Peter Wiley. Depth data were already processed; it is not documented when, how and by whom this was done.
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7. Data Quality
of Checked Parameters
The following is a description of what criteria were used to flag data as "good" or "bad". Underway data users should also refer to the section on Data Gaps.
Bathymetry (Water Depth)
There is no documentation relating to the processing protocol or quality of these data.
Ship’s Heading (SH)
SH is a measurement of the direction that the bow of the ship is facing.
These data were accepted as good.
Ship’s Speed (SS)
Ship's Speed data are derived from the electromagnetic current meter output (Ship's Log). SS is a measurement of ship's speed through the water and is directly affected by waves.
Ship's Speed data are all believable with respect to the ship's schedule and capability and have therefore been left as good.
Fluorometer Value (FLU_VALUE)
All FLU_VALUE data were rejected because:
As the USW supply to the thermosalinograph passes through many metres of piping and warms up before reaching the sensors, TSG_TEMP data are not an accurate measure of sea water temperature and were rejected as a matter of routine.
Water Temperature – low resolution (W_TEMP)
All W_TEMP data were rejected because:
Data from both air temperature sensors were marked bad where they differ by more than about 0.3º C. Most data were rejected based on this criterion.
Barometric Pressure (BAR)
All BAR data were accepted as good.
Humidity Port and Starboard (HUMID_P and
The humidity sensors are located close to the air temperature sensors and humidity data are therefore also affected by exhaust air from the funnel, although to a lesser extent. When a sensor is downwind of the funnel, humidity data are sometimes decreased relative to the unaffected sensor. As with air temperature data, humidity data could not be quality checked with respect to apparent wind direction due to continuous problems with the anemometer during this voyage.
Traces from both sensors were marked bad where values differ by more than about 10%. Extreme outliers were also rejected.
Photosynthetically Active Radiation (LICOR_R)
Note that this sensor is affected at times by shadows from the ship's superstructure.
Apart from extreme outliers, all LICOR data were accepted as good.
Wind Direction True Port (WDPT) and Wind
Speed True (WSPT)
According to the programmer's report and logbook for this voyage, the anemometer was unreliable throughout. All data from this sensor were therefore marked bad.
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Author and date not recorded
HIMS - 8.5.90 to 4.7.90
COMPUTER LOGGING STATUS REPORT
1. Data Logging System
The DLS had been subject to unexpected crashes to the tune of about
34 days, and about half as many again deliberate shutdowns to correct other
problems. The magnetic tape drives that log DLS data have been giving
serious problems re-establishing logging after DLS reboots. Because of the
tape drive problems most of the recorded tapes have not been readable by
any "CHART" application and have required maintenance work with VMS
utilities to try and rtecover the data. Some of the LAN data files contain
rubbish both within the file and at its end. Other problems with the
plotter and graphics screens have continued throughout.
The CTD logging to the PC has continued throughout the voyage with no
problems from the underwater unit and only a few problems with the PC. The
bottle rosette and firing electronics have suffered damage. A single network
data transfer has failed and a memory parity problem has occurred
on the PC. All attempted CTDs have been logged.
The XBT C has "HUNG" or "CRASHED" on a number of occasions and the MK9
interface to the PC has also hung a number of times. A few XBT drops have
been lost due to DLS problems occurring at the time of the drop. The
quality of the XBT data has been generally poor with the most
unsatisfactory results occurring in the coldest waters. It is possible that
mechanical wire damage due to cold water may be the reason for the poor
Both these instruments have required no attention throughout the voyage.
However both instruments have been subject to the frequent and well known
problem of the sea water pumps shutting down without notice and destroying
the validity of the data logged.
5. MAGNAVOX MX1107 SATNAVS
Two MX1107's are in use. The principle unit is in the computer room
secondary unit is on the bridge. Initially the computer room unit was
controlling the DLS graphics displays, but repeated bouts of wild behaviour
as GPS windows waxed and waned has necessitated the invocation of the
backup unit. Observation has confirmed that a fault exists by virtue of the
following symptoms -
1. The unit can deliver lat/long positions up to 200 miles in error.
2. It fails to recover from a soft GPS initialize.
3. At various times or after a GPS initialize, it fails to see transit
or GPS satellites.
6. STEEDMANS MET SYSTEM
The Steedmans system has been plagued with problems. Initially th wind
vane was replaced with the backup due to mechanical wear. Then the
replacement unit worked itself loose from its mount several times and
delivered erratic wind data. The Steedmans EMS-16 CPU appears to be
corrupting data or dropping digits from the data streams it is passing to
both the DLS and the MET PC. Other problems such as faulty sensor wiring
have caused data loss during the voyage. The water temperature sensor
appears to have been affected by RFI. Other sensors may be affected as well but
more rigorous examination of the data will be required to test for this.
7. EA200 DEPTH SOUNDER
The EA200 has had much difficulty maintaining bottom lock at speeds
than a few knots. The echogram shows very little acoustic noise but many
instances of loss of echo. The loss of echo has resulted in two problems
for its digital data outut. One is that is often does not return a value.
The other is that it frequently locks on to a sync pulse from another
sounder, or just returns an erroneous depth value. The extent to which this
has taken place probably means much of the data logged by the DLS is
erroneous and cannot be recovered.
8. VAX SYSTEMS
The two VAX systems, the 2000 & 3600 have performed well. Only one
occurrence of the 3600 bug-checking, possibly due to the notorious TK70
interface problem. A great deal of programming has been done to process &
plot the CTD results, modify, add and append data to the databases, and to
manipulate and verify the results from other data collected. Due to a poor
installation of VMS and the layered products the system suffers from mixed
and incorrect software versions of system utilities. This has resulted in
some incompatibilities with the Kingston systems.
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