Resumen de Implementation, development and evaluation of the gas-phase chemistry within the Global/Regional NMMB/BSC Chemical Transport Model (NMMB/BSC-CTM)
Air pollution is a serious issue that affects human health, the environment and the climate at levels from local to global scales. The main processes that affect air pollution levels are: emissions, chemistry, transport and deposition. Air quality models (AQMs) are mathematical tools that describe relevant physicochemical processes and quantify concentrations of air pollutants. Therefore, AQMs can be used to develop and detail measures taken to reduce air quality problems. Several AQMs are currently used and they have undergone a rapid evolution in recent years. Computer capacity has increased during the last decade enabling us to use higher spatial resolutions and more complex parameterizations schemes that resolve more complex atmospheric processes. Moreover, previous research has shown that the feedbacks between meteorology and chemistry are important in the context of many research applications. Therefore, this increase in computing power allows accurately simulate those feedbacks (online modelling). Online models are becoming more used in the atmospheric community. The NMMB/BSC Chemical Transport Model (NMMB/BSC-CTM) is being developed through an ongoing team effort at the Earth Sciences Department of the Barcelona Supercomputing Center (BSC). The main motivation for this thesis is to contribute in the development of a unified fully coupled chemical weather prediction system able to solve gas-aerosol-meteorology interactions within a wide range of scales on local to global domains that can be used in both operational and research applications. In this sense, the focus in this Ph.D. has been on the development and evaluation of the tropospheric gas-phase chemistry within the online Global / Regional atmospheric model NMMB/BSC-CTM. With the meteorological core NMMB as the starting point, different parameterizations of several atmospheric chemistry processes such as dry deposition, photolysis, wet deposition, gas-phase chemistry, and stratospheric ozone handling have been reviewed, implemented and evaluated during this Ph.D. thesis. A complete spatial, temporal and vertical model evaluation of the relevant chemical species using different observational data has been performed in this Ph.D. thesis. Observational data has included ground-monitoring stations, ozonesondes, satellite data, climatologies and, aircraft campaigns. This is the first time that the gas-phase chemistry of the NMMB/BSC-CTM has been evaluated on a regional and global scales over a full year. Concerning the model evaluation in the regional scale, we had the opportunity to participate in the Air Quality Model Evaluation International Initiative (AQMEII) Phase2 which aims to intercompare online coupled regional-scale models over North America and Europe. In this sense, we were participating in this initiative in the European runs with NMMB/BSC-CTM model. The model evaluations have shown a good agreement with observations. Overall, the model performance corresponds to state-of-the-art regional and global AQMs.
