"Observational capabilities are a critical component for advancing surface-atmosphere interactions science. This includes state-of-the-art capabilities for analyzing trace gas fluxes in support of the wider Earth science research community as well as the development of cutting edge technology that will lead the community toward a new generation of analytical capabilities needed to improve Earth system models. Here it is proposed to develop a comprehensive research program allowing the investigation of the exchange of reactive (volatile organic compounds (VOC), NOx, O3, CO, CH4) and non-reactive (H2O, CO2) trace constituents at the surface-atmosphere interface based on novel time-of-flight mass spectrometry coupled to chemical ionization. Methods developed and tested within this project have the potential to lead to a long-term research program at the host organization aimed at the development of comprehensive instrumentation for eddy covariance measurements of reactive trace gases and aerosols and their application to atmospheric research. The proposed research activity will therefore provide new tools to the environmental monitoring community (e.g. the fluxnet communities such as CarboEurope or NitroEurope). Eddy flux systems developed and tested within this project will be evaluated at a newly established research flux site (i-BOX) at the host organization, targeting the investigation of trace gas exchange processes in orographically complex terrain in an Alpine valley, which is also subject to intense air pollution problems. Technology proposed within this project will ultimately provide critical data aiding in developing cost-effective control strategies and shed light on potential synergistic and antagonistic effects between air pollution and climate change regulation."