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This table identifies
the types of sensors used on TAO moorings and lists their accuracies.
Most instrumental accuracies listed are based on pre-deployment and post-recovery
calibrations and are the root mean square drift of a group of sensors.
Mechanical current meters and current profilers accuracies are based on
intercomparisons between co-located instruments. References where available
are indicated by [#] in the comments column and listed at the end of the
tables. Accuracies of sensors which are new to TAO moorings (longwave
radiation, barometric pressure) or which have not yet been evaluated by
TAO (water pressure) are those specified by the manufacturer and are indicated
by [M].
In cases where sensors
are paired with PMEL supplied electronics (e.g., analog to digital boards)
calibrations include both the sensor and PMEL electronics. Accuracies
listed here (with the exception of currents) do not include environmental
factors such as wind (on rainfall) or buoy motion(on radiation). Measurement
ranges listed are generally those over which the sensors are calibrated.
The ranges over which a sensor will operate (determined by the sensor
and/or PMEL electronics) are listed in parenthesis if they significantly
exceed the calibration range.
The array is presently
maintained with Next Generation ATLAS moorings, sensors for which are
shown in the top (blue shaded) table. Sensor specifications for standard
ATLAS and early current meter moorings (both of which are no longer in
use) are shown in the bottom table.
A comparison of ATLAS,
TRITON, and IMET mooring meteorological sensors from a land-based intercomparison
study at the Woods Hole Oceanographic Institution in May-June 2000 shows
that in general the three systems measure to equivalent standards of accuracy.
The full report of this intercomparison is contained in footnote [13]
below.
Next
Generation ATLAS Mooring Sensors
| Measurement |
Sensor type |
Manufacturer: Model # |
Resolution |
Range |
Accuracy |
Comments |
| Wind speed |
Propeller |
R. M. Young: 05103 |
0.2 m s-1 |
1-20 m s-1
(0.4 - 36 m s-1)
|
±0.3 m s-1 or 3% |
[7] |
| Wind direction |
Vane |
R. M. Young: 05103 |
1.4° |
0-355° |
5° - 7.8° |
[7]
See also footnote to [7] |
| Fluxgate compass |
E.G.and G. or KVH: 63764 or LP101-5 |
1.4° |
0-359° |
| Air temperature |
Pt-100 RTD (Resistance Temperature Recorder) |
Rotronic Instrument Corp.:
MP-100
|
0.01°C
|
14-32°C
(0-40°C)
|
±0.2°C |
[12] |
| Relative humidity |
Capacitance |
0.4 %RH realtime
0.02 %RH delay mode |
55-95 %RH
(0-100 %RH)
|
±2.7 %RH |
[12]
|
| Rainfall |
Capacitance |
R. M. Young: 50203-34 |
0.2 mm hr-1 |
0-50 mm |
±0.4 mm hr-1 on 10 min filtered
data |
[6] |
Downwelling shortwave radiation
|
Pyranometer |
Eppley Laboratory: PSP-TAO, Delrin case |
0.4 W m-2 |
200-1000 W m-2
(0-1600 W m-2)
|
±1% |
[M] Evaluation underway |
| Downwelling longwave radiation |
Pyrgeometer |
Eppley Laboratory: PIR-TAO, Delrin case,
3-output (1) |
0.1 W m-2
0.03°C
|
200 W m-2
@ 20°C (thermopile only)
|
±1% |
[M] Nominal calibration values used
for case and dome thermistors |
| Barometric pressure |
Pressure transducer |
Paroscientific: MET1-2 |
0.1 hPa |
800-1100 hPa |
±0.01% of reading |
[M] |
| Sea surface and subsurface temperature |
Thermistor |
PMEL: NX ATLAS using YSI (Yellow Springs
Instruments) thermistor 46006 |
0.001°C |
6-32°C
(0-40°C)
|
±0.02°C |
[9]
Evaluation of accuracy underway |
| Sea surface and subsurface temperature |
Thermistor |
Sea Bird Electronics: SBE16, SBE37 |
0.001°C |
1-31°C
(-5-35°C)
|
±0.003°C |
[3]
|
| Salinity |
Internal field conductivity
cell |
Sea Bird Electronics: SBE16
(Seacat) |
0.0001 S m-1
|
3-6 S m-1
(0-6 S m-1)
|
±0.02 psu |
[3]
Based on SBE16 only. SBE37 assumed comparable.
Accuracy of ATLAS module under evaluation |
| SBE37 (Microcat) |
0.00001 S m-1 |
| Sea Bird cell with ATLAS module |
0.002 S m-1 |
| Water pressure |
Transducer |
Paine: 211-30-660-01 |
0.03 psi |
400-800 psi
(0-1000 psi)
|
±0.25% full scale (1000psi) |
[M] |
| Ocean current (profile) |
Acoustic Doppler Current Profiler |
RD Instruments: Narrow band, 150 kHz |
0.1 cm s-1
0.006
|
(0-256 cm s-1) |
±5 cm s-1,
±2.5°
|
[5] [11] |
| Ocean current (single
point) |
Dopper Current Meter |
SonTek: Argonaut |
0.1 cm s-1
0.1°
|
(0-600 cm s-1) |
±5 cm s-1,
±5°
|
[10] |
Standard
ATLAS and Early Current Meter Mooring Sensors
| Measurement |
Sensor type |
Manufacturer: Model # |
Resolution |
Range |
Accuracy |
Comments |
| Wind speed |
Propeller |
R. M. Young: 05103 |
0.2 m s-1 |
1-20 m s-1
(0.4 - 36 m s-1)
|
±0.3 m s-1 or 3% |
[7] |
| Wind direction |
Vane |
R. M. Young: 05103 |
1.4° |
0-355° |
5° - 7.8° |
[7]
See also footnote to [7] |
| Fluxgate compass |
E.G.and G. or KVH:
63764 or LP101-5 |
1.4° |
0-359° |
| Air temperature |
Pt-100 RTD (Resistance Temperature Detector) |
Rotronic Instrument Corp.:
MP-100
|
0.04°C
|
14-32°C
(0-40°C)
|
±0.2°C |
[2] |
| Relative humidity |
Capacitance |
0.4 %RH realtime
0.02 %RH delay mode |
55-95 %RH
(0-100 %RH)
|
±2.7 %RH |
[2]
|
Downwelling shortwave radiation
(Current Meter Moorings) |
Pyranometer |
Eppley Laboratory: PSP |
1.3 W m-2 |
700 W m-2
(0-1600 W m-2)
|
±2% |
[2] |
| Sea surface temperature |
Thermistor |
PMEL: Standard ATLAS SST sensor using
YSI (Yellow Springs Instruments) thermistor 46006 |
0.001°C |
14-32°C |
±0.03°C |
[2] |
| Sea surface temperature |
Thermistor |
PMEL: Current meter mooring SST sensor
using YSI thermistor 46006 |
0.001°C |
14-32°C |
±0.01°C |
[2] |
| Subsurface temperature |
Thermistor
|
PMEL: Standard ATLAS sensor using YSI
thermistor 46006 |
0.001°C |
6-32°C
(2-35°C)
|
±0.09°C |
[2]
|
| Subsurface temperature |
Thermistor |
PMEL: Mini Temperature Recorder (MTR)
using YSI thermistor 46006 |
0.001°C |
6-29°C
(-2-34°C)
|
±0.01°C |
Accuracy based on unpublished PMEL calibrations |
| Subsurface temperature |
Thermistor |
EG&G VACM |
0.001°C |
1-31°C |
±0.05°C |
[8] |
| Subsurface temperature |
Thermistor |
EG&G VMCM |
0.006°C |
1-31°C |
±0.05°C |
[8] |
| Subsurface temperature |
Thermistor |
Sea Data TR-2, TDR-2 |
0.01°C |
1-31°C
(-5-35°C)
|
±0.05°C |
[8] |
| Sea surface and subsurface temperature |
Thermistor |
Sea Bird Electronics: SBE16, SBE37 |
0.001°C |
1-31°C
(-5-35°C)
|
±0.003°C |
[3]
|
| Salinity |
Internal field conductivity cell |
Sea Bird Electronics: SBE16 (Seacat) |
0.0001 S m-1
|
3-6 S m-1
(0-6 S m-1)
|
±0.02 psu |
[3]
|
| Water pressure |
Transducer |
Paine: 211-30-660-01 |
0.03 psi |
400-800 psi
(0-1000 psi)
|
±0.25% full scale (1000psi) |
[M] |
| Ocean current (single
point) |
Savonious rotor and vane |
EG&G VACM |
0.005 cm s-1
2.8°
|
(2-300 cm s-1) |
±3-7 cm s-1,
±5.6°
|
[4] |
Ocean current
(single point) |
Orthogonal Propellers |
EG&G VMCM |
0.01 cm s-1
1.4°
|
(0.9 - 340 cm s-1) |
±3-7 cm s-1,
±2.5°
|
[4] |
| Ocean current (profile) |
Acoustic Doppler Current Profiler |
RD Instruments: Narrow band, 150 kHz |
0.1 cm s-1
0.006
|
(0-256 cm s-1) |
±5 cm s-1,
±2.5°
|
[5] |
References:
[1] Fairall, C. W.,
P. O. G. Persson, E.F. Bradley, R. E. Payne and S. P. Anderson, 1998:
A new look at calibration and use of Eppley Precision Radiometers. Part
I: Theory and Application. J. Atmos. Ocean. Tech., 15, 1229-1242.
[2]
Freitag, H.P., Y. Feng, L.J. Mangum, M.P. McPhaden, J. Neander, and L.D.
Stratton, 1994: Calibration procedures and instrumental accuracy estimates
of TAO temperature, relative humidity and radiation measurements. NOAA
Tech. Memo. ERL PMEL-104, 32 pp.
[3]
Freitag, H.P., M.E. McCarty, C. Nosse, R. Lukas, M.J. McPhaden, and
M.F. Cronin, 1999: COARE Seacat data: Calibrations and quality control
procedures. NOAA Tech. Memo. ERL PMEL-115, 89 pp.
[4] Halpern, D., 1987:
Comparison of upper ocean VACM and VMCM observations in the equatorial
Pacific. J. Atmos. Ocean. Tech., 4, 84-93.
[5] Plimpton, P.E.,
H.P. Freitag, and M.J. McPhaden, 1995: Correcting moored ADCP data for
fish-bias errors at 0°,110°W and 0°,140°W from 1990 to 1993. NOAA
Tech. Memo. ERL PMEL-107, 49 pp.
[6]
Serra, Y.L., P.A'Hearn, H.P. Freitag, and M.J. McPhaden, 2001: ATLAS self-siphoning
rain gauge error estimates. J. Atmos. Ocean. Tech.,18, 1989-2002.
[7]
Freitag, H.P., M. O'Haleck, G.C. Thomas, and M.J. McPhaden, 2001: Calibration
procedures and instrumental accuracies for ATLAS wind measurements. NOAA.
Tech. Memo. OAR PMEL-119, NOAA/Pacific Marine Environmental Laboratory,
Seattle, Washington, 20 pp.
| Footnote:
This study discovered a systematic error in standard and NextGeneration
ATLAS wind directions of approximately 6.8° in the counterclockwise
direction. This error was present possibly as far back as 1984. Modifications
were made to the NextGeneration ATLAS system in 2000 to correct this
error in subsequent deployments, and archived NextGeneration ATLAS
wind directions were corrected (both daily averages and high resolution
datasets) on 28 March 2002. See /tao/proj_over/vane_correct.html.
Standard ATLAS wind directions have not been corrected in the archives
since the exact time when the error began to affect the measurements
is unknown. Standard ATLAS were used exclusively between 1984 and
1996 when NextGeneration ATLAS moorings began to replace them. By
November 2001, the standard ATLAS had been phased out and the array
was comprised entirely of NextGeneration systems. Expected RMS error
for standard ATLAS wind direction is 7.8° (of which 6.8°
is a bias) while expected RMS error for NextGeneration ATLAS wind
directions is about ±5°
with no appreciable bias. |
[8] McCarty, M.E.,
and M.J. McPhaden, 1993: Mean seasonal cycles and interannual variations
at 0, 165E during 1986-1992. NOAA Tech. Memo. ERL PMEL-98, 64pp.
[9]
A'Hearn, P.N., H.P. Freitag, and M.J. McPhaden, 2002: ATLAS module temperature
bias due to solar heating. NOAA Tech. Memo OAR PMEL-121, NOAA/Pacific
Marine Environmental Laboratory, Seattle, WA, 24 pp.
[10]
Freitag, H.P., M.J. McPhaden, C.Meinig, and P.Plimpton, 2003: Mooring
motion bias of point Doppler current meter measurements. In: Proceedings
of the IEEE Seventh Working Conference on Current Measurement Technology,
San Diego, CA, 13-15 March 2003, IEEE, Piscataway, NJ, 155-160.
[11]
Plimpton, P.E., H.P. Freitag, and M.J. McPhaden, 2004: Processing of subsurface
ADCP data in the equatorial Pacific. NOAA Tech. Memo OAR PMEL-125, NOAA/Pacific
Marine Environmental Laboratory, Seattle, WA. 41pp.
[12]
Lake, B.J., S.M. Noor, H.P. Freitag, and M.J. McPhaden, 2003: Calibration
procedures and instrumental accuracy estimates of ATLAS air temperature
and relative humidity measurements. NOAA Tech. Memo. OAR PMEL-123, NOAA/Pacific
Marine Environmental Laboratory, Seattle, WA, 23 pp.
[13]
Payne, R.E., K. Huang, R.A. Weller, H.P. Freitag, M.F. Cronin, M.J. McPhaden,
C. Meinig, Y. Kuroda, N. Ushijima, R.M. Reynolds, 2002: A comparison of
buoy meteorological systems. WHOI Technical Report
WHOI-2002-10. Woods Hole Oceanographic Institution, 67 pp.
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