Methodology

MEIC is a comprehensive model for emission inventory development, including the unified source categorization, emission factor database, technology-based method, and high-resolution emission processing system on the cloud computing platform. The MEIC model integrates the whole process from the basic input data to model-ready 3-D emission files required by air quality models. It can generate multi-year, multi-chemical emission inventories at different spatial scales and seamlessly connect with air quality models.

Source categorization >

MEIC model covers six types of anthropogenic emission sources, including stationary combustion, industrial processes, mobile source, solvent use source, agriculture source, and waste treatment. According to the difference of pollutant generation mechanism and emission characteristics, each type of emission source can be divided into four levels: sector/industry, fuel/product, combustion/production technology, and end-of-pipe control technology. From the first level to the fourth level, a complete classification system of emission sources is established step by step, and the fourth level is taken as the basic calculation unit of emission inventory. The current version of the MEIC model includes more than 700 anthropogenic sources.

Dynamic methodology >

Regarding the characteristics of complex compositions and rapid change of pollution sources in China, the MEIC model is developed using technology and process-based methods, which resolves the quantitative relationship between emissions and technology turnover. Energy consumption, combustion/industrial/control technologies, and emission factor database are fully coupled to estimate emissions accurately. Each calculation unit is mapped to the activity database, technology turnover model, and emission factor database, which enable MEIC to update quickly by capturing the technology and activity levels changes.

For power, cement, and steel industries, MEIC uses the process-based method to develop unit-based emission inventories. For each piece of equipment, MEIC tracks its technology evolution to dynamically represent the emission variation induced by technical progress and more stringent emission standards.

For residential sources, the MEIC model is based on tens of thousands of household survey data covering most provinces in China, which systematically corrects the statistical errors of residential coal and biomass fuel consumption in the energy statistical yearbook, provides a more accurate activity level and technology distribution parameterization scheme for the establishment of residential emission source model, and reduces the uncertainty of residential emission inventory.

For on-road vehicles, MEIC develops a high resolution and comprehensive emission inventory based on county-level activity database, meteorological model, emission factor model, and traffic flow survey, which improve the spatial and temporal resolutions from province to county and from annual to hourly, respectively.

Multi-scale high resolution emission processing system >

MEIC developed a multi-dimensional high-resolution emission processing system to generate model-ready gridded emission input for air quality models. The emission processing system composes three modules for temporal allocation, spatial allocation, and speciation. The temporal module allocates annual emissions to hourly emissions based on the monthly, weekly, and daily profiles. The spatial module allocates point and area sources to 3-D grids by using spatial and vertical distributions. The speciation module is developed using the profile-assignment approach. Emissions of total NMVOC and PM are firstly split into individual species and then mapped into various chemical mechanisms that are configured in chemical transport models, such as SAPRC99, SAPRC07, CBIV, CB05, CBMZ, RADM2, RACM, GEOS-Chem, and MOZART.

Cloud computing platform >

The MEIC model allows online calculation and download of gridded emission inventories by using efficient algorithms for big data and cloud-computing technologies. The MEIC model provides high-resolution and model-ready emission inventories for air quality and forecasting models. Users can require, customize, and access demanded data on-line through the cloud-computing platform.