Greenhouse gas detector feels the heat in Africa

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Scientists from CarboAfrica, a program to study the carbon cycle and other greenhouse gases (GHG) in Sub-Saharan Africa, have installed a rugged GHG monitor (the Picarro G1301) at a remote field site in equatorial West Africa – the Station de Géophysique de Lamto.

This Ivory Coast location is a particularly challenging spot for remote monitoring equipment because of its very high humidity and ambient temperatures that can easily exceed 40°C. The Picarro G1301 uses WS-CRDS (wavelength-scanned cavity ring down spectroscopy) technology to deliver simultaneous and continuous measurements of both methane (CH4) and carbon dioxide (CO2) at a precision of parts per billion. Immunity from cross-talk enables it to achieve this precision with ambient samples, without the need for drying or any other purification.

The Picarro analyser is located in a small building adjacent to a 50m tower allowing data to be taken automatically and continuously via a tube terminating at the top of this tower. It has now been operating without any servicing or calibration since late July 2008. The Lamto GHG program is operated by scientists from the CarboAfrica participants, including the CEA (Commissariat a l'Energie Atomique) in France and the University of Cocody in Ivory Coast. The instrument was first evaluated by a CEA team at the Laboratoire des Sciences du Climat et de l'Environnement, located in Saclay, France, for several months before deployment in Africa. On site, the instrument is under the supervision of Dr Adam Diawara.

CEA co-director Philippe Ciais, said: ‘At CarboAfrica, we are setting up a network of monitoring sites throughout Africa, in response to the critical lack of field GHG data from this continent. We need this data to understand the entire GHG picture in Africa, from the natural sink capacity of forested areas to the impact of jungle fires on total GHG emissions.’

Ciais added: ‘We selected the Picarro G1301 for several reasons, including its stable performance over a wide range of temperature and humidity, and its precision, which well exceeds our minimum requirement of 100 ppbv. In addition, it’s simple to operate, and importantly for this remote location, the very low drift of the instrument eliminates the need for maintenance or frequent calibration.’