Summertime tropospheric ozone over China simulated with a regional chemical transport model 1. Model description and evaluation

Abstract

A three‐dimensional regional chemical transport model, extended from the Regional Acid Deposition Model (RADM) and aimed at studying the distribution and budget of tropospheric ozone and its precursors over China, is presented. The model domain covers the China region with a horizontal resolution of 100 km. In the vertical, the model extends up to the pressure level of 10 mbar for meteorological simulation, and to the local thermal tropopause for chemical integration. The meteorological fields for the model run are provided with the Fifth‐Generation National Center for Atmospheric Research (NCAR)/Penn State Mesoscale Model (MM5). In addition to updated surface emissions, aircraft emissions and lightning NOx sources are taken into account. The initial fields and lateral boundary conditions for most chemical tracers are provided with a global chemical transport model for ozone and related chemical tracers (MOZART). The model simulation is performed for the period July 1–15, 1995, which appears to be representative of meteorological conditions in summertime over China. The model results are compared with surface measurements of ozone and its precursors in China, ozone soundings in Japan, and MOZART results for the China region. The daily variation as well as geographical and vertical distribution of O3 concentration is generally well simulated by the model. It is indicated that surface ozone is controlled by photochemistry in eastern China and by transport processes in western China. Large‐scale transport of O3 and its precursors from the highest‐source‐emission regions to remote areas and the free troposphere is simulated.