Measurements within OTC

English

The marine network consist of a variety of ships and fixed station installations covering the open ocean and coastal areas, and for this purpose the network is divided into 3 categories; Voluntary Observing Ships (VOS), Fixed Ocean Stations (FOS), and Marine Flux Towers (MFT).  We are also working towards getting Repeat Ocean Stations (ROS) accepted as a station type. For each category the required parameters (called core parameters) and the frequency of measurements are defined in the table below. The table also defines the criteria to become a Class 1 and Class 2 station. This classification is a part of the ICOS station labelling process.

 

Platform type

Type

Parameters

Frequency

open/coastal

Criteria1

Class

VOS

Core Sea surface xCO2  Nearly continuous ± 2 μatm 1&2
Core Intake temperature2 Continuous ± 0.05 °C 1&2
Core Water vapour pressure3 Continuous ± 0.5 hPa 1&2
Core Equilibrator pressure4 Continuous ± 2.0 hPa 1&2
Core Equilibrator temperature2 Continuous ± 0.05 °C 1&2
Core Atmospheric xCO2 Quasi-continuous ± 1 μatm 1
Desirable Sea surface salinity Continuous ± 0.03  
Desirable Atmospheric pressure/sea level pressure Continuous ± 1 hPa  
Desirable Dissolved oxygen Continuous ± 1%  
Desirable TA Discrete ± 3 μmol kg-1  
Desirable pHT Continuous ± 0.01  
Desirable DIC Discrete ± 1.5 μmol kg-1  
Desirable Atmospheric flask samples for CO2, CH4, N2O Discrete As determined by the ICOS FCL  
Desirable Chlorophyll-fluorescence Continuous 2%  
Desirable Wind speed/wind direction Continuous or discrete    
Desirable Atmospheric temperature Continuous or discrete    
Desirable Dissolved inorganic nutrients (nitrate, NO3; phosphate, PO4; silicate, Si(OH)4) Discrete    
Desirable δ 13C Discrete ±  0.1‰  
Desirable CH4 Discrete/continuous ±  1% of atm. saturation  
Desirable N2O Discrete/continuous ±  1% of atm. saturation  

FOS

discrete

Core

Two out of four:

- DIC 
- TA
- pCO2
- pHT

> 1 yr-1/1 month-1

 

± 1.5 μmol kg-1
± 3 μmol kg-1 
± 1 μatm 
± 0.005

 

1&2
1&2
1&2
1&2

Core Sea temperature > 1 yr-1/1 month-1 ± 0.002 °C 1&2
Core Sea salinity
- CTD
- bottle samples

 

> 1 yr-1/1 month-1
 

 

± 0.002
± 0.001

 

1&2
 

Core

Two out of three

- nitrate (NO3)
- phosphate (PO4)
- silicate (Si(OH)4)

> 1 yr-1/1 month-1

5

± 1%
± 1-2%
± 1-3%


1

Core

Dissolved oxygen

- Winkler
- sensor

> 1 yr-1/1 month-1
± 0.5%
±1%

 

1
1&2

Core

Pressure

> 1 yr-1/1 month-1 ± 3 dBar

1&2

Desirable Chlorophyll - /1 month-1 ± 1%  
Desirable DOC - /1 month-1 ± 2%  
Desirable CFC-11/CFC-12
SF6
> 1 yr-1/1 month-1 ± 1 (<5)%
± 1.5 (<5)%
 
Desirable CH4 > 1 yr-1/1 month-1 ± 1% of atm. saturation  
Desirable N2O > 1 yr-1/1 month-1 ± 1% of atm. saturation  
Desirable δ 13C > 1 yr-1/1 month-1 ± 0.04‰  
Desirable Δ 14C > 1 yr-1/1 month-1 ± 5‰  
Desirable CDOM (~300 nm) - /1 month-1 ± 0.01 m-1  

FOS

(quasi-) continous

Core pCO2 > 1 day-1/ > 3 day-1 ± 5 μatm 1&2
Core Sea temperature > 1 day-1/ > 3 day-1 ± 0.02 °C 1&2
Core Sea salinity > 1 day-1/ > 3 day-1 ± 0.03 1&2 
Core Dissolved oxygen > 1 day-1/ > 3 day-1 ± 1% 1
Core pHT > 1 day-1/ > 3 day-1 ± 0.01  1
Core Pressure > 1 day-1/ > 3 day-1 ± 3 dBar 1&2
Desirable Atmospheric xCO2 > 1 day-1/ > 3 day-1 ± 1 μatm  
Desirable Atmospheric pressure > 1 day-1/ > 3 day-1 ± 1 μatm  
Desirable Wind speed > 1 day-1/ > 3 day-1 ± 0.01 m s-1  
Desirable Chlorophyll > 1 day-1/ > 3 day-1 ± 0.5 μg L-1  
Desirable Nitrate (NO3), phosphate (PO4), silicate (Si(OH)4) > 1 day-1/ > 3 day-1 ±10%  
Desirable Atmospheric temperature > 1 day-1/ > 3 day-1    
Desirable CH4 > 1 day-1/ > 3 day-1 ± 1% of atm. saturation  
Desirable N2O > 1 day-1/ > 3 day-1 ± 1% of atm. saturation  
Desirable CDOM  - / > 3 day-1 ± 0.01 m-1  
Desirable Irradiance  - / > 3 day-1    
Desirable PAR  - / > 3 day-1    
MFT Core Atmospheric CO2 1h ± 1.5%  1&2
Core  CO2 flux  1h ± 5% 1&2
Core  Atmospheric pressure  1h ± 0.1%  1&2
Core  Wind speed 1h ± 0.5 m/s 1&2
Core  Wind direction 1h ± 6 ° 1&2
Core  Atmospheric temperature  1h ± 0.2 °
ventilated6
1&2
Core  Atmospheric humidity 1h ± 1%  1&2
Core Friction velocity 1h ± 5% 1&2
Core H2O flux 1h ± 5% 1
Core Sensible heat flux 1h ± 5% 1
Core Sea surface pCO2 > 3 day-1  ± 5 μatm 1
Core Sea temperature > 3 day-1 ± 0.02 °C 1
Core Sea salinity > 3 day-1 ± 0.03  1
Desirable Precipitation 1h WMO guidelines  
Desirable SW_in, LW_in 1h    
Desirable PAR/PPFD 1h    
Desirable Water-side mixed layer depth > 1 day-1    
Desirable Atmospheric mixed layer depth > 1 day-1    
Desirable Significant wave height 1h    


1The numbers refers to accuracy of measurements.
2Difference between intake and equilibrator  temperature should not exceed 1.5°C.
3If the headspace gas analysed is not dried completely prior to measurement.
4This should be the absolute pressure.
5The accuracy refer to samples without conservation. If conservation is used (chloroform is the preferred method) the accuracy is doubled.
6A flow thru system of air, to prevent radiation problems to the temperature signal. Necessary for high quality measurements of atmospheric temperature.