Evaluation of ensemble approach for O3 and PM2.5 simulation

Yu Morino*, Satoru Chatani, Hiroshi Hayami, Kansuke Sasaki, Yasuaki Mori, Tazuko Morikawa, Toshimasa Ohara, Shuichi Hasegawa, Shinji Kobayashi

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)


Inter-comparison of chemical transport models (CTMs) was conducted among four modeling research groups. Model performance of the ensemble approach to O3 and PM2.5 simulation was evaluated by using observational data with a time resolution of 1 or 6 hours at four sites in the Kanto area, Japan, in summer 2007. All groups applied the Community Multiscale Air Quality model. The ensemble average of the four CTMs reproduced well the temporal variation of O3 (r=0.65-0.85) and the daily maximum O3 concentration within a factor of 1.3. By contrast, it underestimated PM2.5 concentrations by a factor of 1.4-2, and did not reproduce the PM2.5 temporal variation at two suburban sites (r=~0.2). The ensemble average improved the simulation of SO42-, NO3 -, and NH4 +, whose production pathways are well known. In particular, the ensemble approach effectively simulated NO3 -, despite the large variability among CTMs (up to a factor of 10). However, the ensemble average did not improve the simulation of organic aerosols (OAs), underestimating their concentrations by a factor of 5. The contribution of OAs to PM2.5 (36-39%) was large, so improvement of the OA simulation model is essential to improve the PM2.5 simulation.

Original languageEnglish
Pages (from-to)150-156
Number of pages7
JournalAsian Journal of Atmospheric Environment
Issue number3
Publication statusPublished - 2010 Dec
Externally publishedYes


  • CMAQ
  • Chemical transport model
  • Ensemble average
  • Ozone

ASJC Scopus subject areas

  • Environmental Science(all)
  • Atmospheric Science


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