Abstract: Cities cover only ~3% of the world’s surface yet originate 70% to 80% of global CO2 emissions[1,2] and are expected to continue growing as urban migration continues and intensifies. Cities are projected to shelter ~70% of the world’s population by 2050[3] . Managing urban emissions is vital to address the climate crisis and meet the objectives established by the United Nations Framework Convention on Climate Change and the Paris Agreement. To achieve this, we need to not only quantify and monitor emissions[4] , but most importantly, attribute them to specific sources[5-10] . The current state-of-art-method uses “inverse modeling” [11] to infer emissions through a combination of bottom-up emission inventories[12-14] and a small number of strategically placed high-precision direct atmospheric measurements[15-17] . The METROCLIMA-GHG Network commenced its operations in early January 2020, initially setting up stations at UNICID (UND) and Pico do Jaraguá (PDJ). Subsequently, in April 2020, instruments for measuring CO2 and CH4 concentrations, along with carbon isotopes in both gases, were added at IAG. It’s worth noting that prior measurements of CO2 and CH4 (2019) existed at PDJ and IAG stations; however, these lacked calibration gas checks. In August 2020, the ICESP station (ICP) was successfully installed. Since November 2022, modifications have been carried out in the greenhouse gas monitoring systems aimed at increasing the reliability of measurements. These monitors are sensitive to the material applied to the system during sample injection and also to the amount of water contained in the samples. To enhance measurement reliability, physical modifications are being made to the measurement systems, primarily concerning the previously installed tubes and connections. Additionally, a drying system is being added to reduce water content in the samples. Given that these are continuous monitoring stations, methodologies are being developed for automatic calibration and continuous verification of data quality. Here we will present the network structure, the implemented modifications along with the calibration plan and primary results from the first urban greenhouse gas in Latin America.

Keywords: Urban Network; Greenhouse gas; METROCLIMA; São Paulo emission