We are currently in the process of implementing a GHG monitoring network of the Metropolitan Area of Barcelona, which will consist of online-gas analyzers (CO2/CH4/H2O PICARRO analyzer G-2301) in five locations to capture the heterogeneity of the city and various forms of land-use: Collserola forest (Fabra), Llobregat peri-urban agriculture, the coastline (ICM), an urban park amidst highly built area (IDAEA), and densely-used highway in outskirts of the city (ICTA). The data is public access and will soon be able to be downloaded directly from this site. Three stations are now up and running: ICTA (since 2020), IDAEA (since 09/2021), and Fabra (since 02/2022), and the GHG concentrations of the previous day can be visualized by clicking over the map.
About the equipment and calibrations: The air inlet location (lat, lon, masl) is specified for each site on the interactive map. The Picarro instrument uses cavity ring down spectroscopy technique to measure CO2, CH4 and H2O data every 10 seconds at a frequency of 1 Hz with a precision of <200 ppb for CO2, <1.5 ppb for CH4 and <150 ppm for H2O according to manufacturer’s specifications. The measured values are corrected for water vapor and a linear calibration is performed periodically in the laboratory using six NOAA reference gases. An auxiliary pump is used to conduct the air to the instrument at a flow rate of 8 L/min through a 20m 1/2″ diameter Synflex piping.