Sensor Specifications

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TAO Refresh Mooring Sensors

The TAO Refreshed System transitioned to a commercial off the shelf sensor and a satellite system (Iridium), already proven within NDBC's coastal and offshore weather and oceanographic buoy systems, that will allow the Array to meet requirements for hourly resolution time series data and high-frequency weather phenomena. The new data collection and communications systems will provide in real-time the comprehensive data that was normally only-available once the sensors are recovered every 12 months. The most cost-effective approach for sensor replacement was to use sensors time-tested and proven in the Triangle Trans-Ocean Buoy Network (TRITON) Array developed and operated by the Japan Marine Science and Technology Center (JAMSTEC).

SensorPMEL TAO LegacyJAMSTEC TRITONNDBC TAO Refresh
Wind SensorRM Young 05103RM Young 05103 w/ WHOI 7050-ARM Young 05103
Compass EG&G 63764 or KVH LP101-5 N/ASparton SP3003D
Air Temperature/Relative Humidity Rotronic MP-101ARotronic MP-101A w/ WHOI 7030-ARotronic MP-101A
Sea Surface Temperature/Sea Surface ConductivityPMEL ATLAS ModuleSeabird SBE 37-IM MicroCATSeabird SBE 37-SM MicroCAT
Sea Temperature/PressurePMEL ATLAS ModuleSeabird SBE 37-IM MicroCATSeabird SBE 39-IM
Point Source Current Speed and DirectionSonTek Argonaut-MDSonTek Argonaut-MDSonTek Argonaut-MD
Short Wave Solar RadiationEppley PSP-TAO w/ PMEL InterfaceEppley PSP w/ WHOI 7070-AEppley PSP w/ PSI Interface
Long Wave Solar RadiationEppley PIR-TAO w/ PMEL InterfaceN/AEppley PIR /w PSI Interface
Rain GaugeRM Young 50203-34 w/ PMEL InterfaceScientific Technology ORG-115RM Young 50203-34
BarometerParoscientific MET 1-2Paroscientific MET 1-485Paroscientific MET1

The instrumental accuracies listed below are based on pre-deployment calibrations. The post deployment calibrations and the root mean square drift of a group of sensors is still being determined for Refresh Ocean Temperature Sensors (SBE39). Manufacture and initial tests indicate the drift to be small. The Wind sensors, Air Temperature\Relative Humidity (AT\RH) sensor, Sea Surface Temperature\Conductivity (SSC) sensors, Long Wave Radiations (LWR), and Short Wave Radiation sensor (SWR) and Point Source Current Sensors are the same sensors used on the TAO Legacy buoys. Determinations of instrumental accuracies conducted by PMEL are used for Refresh. The accuracies listed are based on pre-deployment and post-recovery calibrations and are the root mean square drift of a group of sensors.

MeasurementSensor TypeManufacture/ModelResolutionRangeAccuracyNotes
Wind SpeedPropellerRM Young/051030.2 m s-10 to 35 m s-10.3 m s-1 or 3%8
Wind DirectionVaneRM Young/051031.4 °0 to
359 °
5 °8
Air TemperaturePt100 RTDRotronics/MP101A0.01 °C-40 to +60 °C0.2 °C8
Relative HumidityHygromer C94Rotronics/MP101A0.4%0 to 100%2%8
PrecipitationCapacitanceRM Young/502030.2 mm0 to 50 mm1 mm3,4,10
Downwelling Shortwave RadiationPyranometerEppley Laboratory/PSP0.4 W m-20 to 1600 W m-2±1%3
Downwelling Longwave RadiationPyranometerEppley Laboratory/PIR0.1 W m-20 to 500 W m-2±1%3,4
Surface Air PressurePressure TransducerParoscientific/MET1-20.1 hPa800 to 1100 hPa0.1 hPa or 0.01%3
Sea Surface TemperatureThermistorSeabird/SBE 370.001 °C-5 to +35 °C0.01 °C5,8
SalinityInternal field conductivity cellSeabird/SBE 370.00001 S m-10 to 7 S m-10.02 psu1,8,9
Temperature (Ocean)ThermistorSeabird/SBE 39IM0.001 °C-5 to +35 °C0.01 °C5,6
Pressure (hydrostatic)Strain element within silicon diaphragmSeabird/SBE 39IM (Druck sensor)0.002% full scale0 to 600 dBar0.1% full scale7
Ocean Current SpeedDoppler Current MeterSonTek/Argonaut MD0.1 cm s-10 to 600 cm s-15 cm s-12
Ocean Current DirectionDoppler Current MeterSonTek/Argonaut MD0.1 °0 to
359 °
±5 °2
Compass Heading3-axis, tilt-compensated digital compassSpartan 30000.1 °0 to
359 °
0.8 ° 
Notes:
1 Surface salinity measured at all sites. Subsurface capability available at selected sites at depths 10, 20, 40, 60, 80 or 10, 25, 75, 100, 125 m.
2 For point velocity measurements, current meters shall be placed at 1 to 5 depths in the upper 200 m with at least one within 10 m of the surface. Current should be measured at all flux reference sites and at other selected sites.
3 At flux reference sites only.
4 Required only if an outside agency provides longwave radiation and rain sensors.
5 SBE 37 Micro CAT and SBE 39’s thermistor accuracy and stability (typical drift is less than 0.002 °C per year).
6 Subsurface temperature available at 10 depths on mooring.
7 The SBE 39’s optional pressure sensor, developed by Druck, Inc., Compensation of the temperature influence on pressure offset and scale is performed by the SBE 39’s CPU.
8 Sensor in use on Legacy ATLAS moorings.
9 Salinity is computed from measurements of temperature, pressure, and conductivity using the Practical Salinity Scale (PSS-78) and therefore salinity error is a function of the errors in the measurement of temperature, pressure and conductivity. For NDBC TAO Refresh, conductivity and temperature are measured on TAO refresh buoys near the ocean surface and salinity is computed using an assumed pressure at nominal depth, with pressure error assumed to be zero. Conductivity and temperature accuracies are as stated for the SBE-37 Conductivity-Depth Sensor. In computing salinity using PSS-78, temperature must first be converted to temperatures based on the International Practical Temperature Scale (IPTS-68) on which the PSS-78 is based. The TAO Refresh Conductivity-Temperature sensor measures temperature in the International Temperature Scale (ITS-90) and is reported in ITS-90. In computing salinity, temperature is converted from the ITS-90 to IPTS-68 prior to the salinity computation.
10 Accuracy to be determined.


NextGeneration ATLAS Mooring Sensors

The table below identifies the types of sensors used on NextGeneration ATLAS 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 ATLAS moorings (longwave radiation, barometric pressure) or which have not yet been evaluated (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 NextGeneration 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 Improved METeorological (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.

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 Corrected NextGeneration Atlas Wind Directions. . 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.