Carbon dioxide (CO2) and methane (CH4) analyzers

Three systems have been installed at Chacaltaya to measure greenhouse gases:

• From December 2011 to August 2014, custom-made CO2 analyzer.
• From May 2014 to March 2016, the system was 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, the system was upgraded to a Picarro G2401 analyzer measuring CO2, CO and CH4.

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

The Picarro instruments, both ESP-1000 and G2401 models, use cavity ring-down spectroscopy technology to detect CO2, CH4 and CO with a tunable laser.  They are 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: Laura Ticona

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

Picarro ESP-1000 for CH4 and CO2

Picarro G2401 for CO2, CO and CH4