| Sensors and calibration systems | Return |
1. Sensors
The m-TRITON buoy are designed to measure surface meteorological parameters and water properties in upper ocean for understanding large-scale ocean dynamics, ocean-atmospheric interactions and Indian Ocean's role in climate. The buoy can observe 5 variables near the ocean surface, namely, surface winds, air temperature, relative humidity, shortwave radiation and precipitation. For oceanographic variables the buoy can observe temperature at 12 layers from surface to 500 m, salinity at 5 layers from surface to 100 m and currents at 10 m.
The sensor specifications for the m-TRITON buoy in the Indian Ocean is shown in Table 1 and 2. We basically follow the requirement for CLIVAR/GOOS Indian Ocean mooring array. The depth of sensors were determined after the in-situ field test in the Indian Ocean.
Table 1: m-TRITON meteorological sensor specifications
WindVector
speed
direction
Young 05106
0-60 m/s
0-360 deg
0.1 m/s
0.1 deg
0.3 m/s
± 1-2 deg
3.13 m
Shorwave Radiation
Eppley PSP
± 1-3 %
Air Temperature
-40-60 degC
0.05 degC
Relative Humidity
± 2.0 %
Precipitation
± 1 mm
2.82 m
Table 2: m-TRITON under water sensor specifications
CTD
Conductivity
Temperature
Pressure
SBE37-IM
0-7 S/m
-5-35 degC
0-1450 psia
0.0001 S/m
0.0001 degC
0.002 % F.S.
0.0003 S/m
0.002 degC
0.15 % F.S.
TD
Temperature
Pressure
-5-35 degC
0-1450 psia
0.0001 degC
0.002 % F.S.
0.oo2 degC
0.15 % F.S.
Currents
0.1 % to 0.5 cm/s
2. Calibration systems
The calibration systems are in common with these of TRITON buoys. The reference sensors are listed in Table3. These reference sensors are calibrated once per year by standard instruments in Japan, except for the temperature and conductivity sensors, which are calibrated by Sea-Bird Electronics. All sensors for mooring were calibrated at manufacturers before delivery, and these were re-calibrated at JAMSTEC before mooring. After mooring, these sensors were calibrated again for detect time drift of each sensor.
For temperature and conductivity sensors we use a calibration systems made by Sea-Bird Electronics. The differences between the manufacturer's calibration and ours were within 0.005 degC in temperature and 0.001 S/m in conductivity.
Table 3: Reference sensors in our calibration systems
Shortwave Radiation
Pyranometer Model PSP
0-1400 W/m^2
7 W/m^2
± 0.5 % F.S.
Relative Humidity
10-98 %
0.02 %
±0.5 %
Temperature
± 0.001 degC
Conductivity
Budenberg Dead-Weight Tester Model 480LA and Paroscientific digiquartz pressure sensor 42K-105
