Carbon dioxide analyzers

Three systems have been installed for different, mostly overlaping periods:

• From December  2011 to August 2014, custom-made CO2 analyzer.
  
• From May 2014 to March 2016, system upgraded to a Picarro ESP-1000 analyzer measuring both CO2 and CH4.
• From June 2016 to October 2016, the custom-made CO2 was used as a backup as the Picarro ESP-1000 had an internal failure.
• From September 2016 onwards, system upgraded to a Picarro G2401 analyzer measuring CO2, CO and CH4.

The custom-made CO2 analyzer is based on a Licor 6252 differential, non-dispersive, infrared (4.26 nm) gas analyzer.  Air is pumped trough the instrument where two optical cells are used: one for the sample and the other for a reference gas. The internal pressure and temperature are controlled. As measurements should be performed in dry air, ambient moisture is trapped in a cooling system (ethanol at <-60ºC) prior to the entrance of the instrument.  CO2 concentrations are stored with a one-minute resolution. Four-point calibrations are semi-automatic and perormed monthly.

The Picarro instruments, both ESP-1000 and G2401, use cavity ring-down spectroscopy technology to detect CO2, CH4 and CO with a tunable laser.  It is automatically calibrated every 2 weeks using a four-point calibration.

In all cases, traceable standard gases are used. Target gases comply with the WMO  inter-lab compatibility goal.

Contact person in CHC: Isabel Moreno

Custom-made CO2 analyzer (based on a Licor 6252)

Picarro ESP-1000 for CH4 and CO2

Picarro G2401 for CO2, CO and CH4