Dynamically consistent formulations in meteorological and air quality models for multiscale atmospheric studies. Part II: Mass conservation issues

Eulerian air quality models that require gridded meteorological inputs have to adapt to recent advances in meteorological models for fully compressibl e atmosphere. When the input meteorological data are recast with a robust f ully compressible governing set of equations, chemistry-transport models ca n follow the dynamic and thermodynamic descriptions of the meteorological d ata closely. For evaluating mass consistency in meteorological data, one ma y rake advantage of the characteristics of the governing set of equations a pplicable for a specific vertical coordinate system. This paper discusses h ow the data from meteorological models should be used in air quality simula tions. It proposes a general methodology to conserve mass of trace species in air quality models by maintaining consistency in the wind and air densit y fields. Limitations of several simplifying assumptions on atmospheric dyn amics are also discussed. In summary, it attempts to bridge the information gap between dynamic meteorologists and air quality modelers by highlightin g the implication of using different meteorological coordinates and dynamic assumptions for air quality simulations.