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- Title
Why models perform differently on particulate matter over East Asia? - A multi-model intercomparison study for MICS-Asia III.
- Authors
Jiani Tan; Fu, Joshua S.; Carmichael, Gregory R.; Syuichi Itahashi; Zhining Tao; Kan Huang; Xinyi Dong; Kazuyo Yamaji; Tatsuya Nagashima; Xuemei Wang; Yiming Liu; Hyo-Jung Lee; Chuan-Yao Lin; Baozhu Ge; Mizuo Kajino; Jia Zhu; Meigen Zhang; Liao Hong; Zifa Wang
- Abstract
This study compares the performances of twelve regional chemical transport models (CTM) from the third phase of Model Inter-Comparison Study for Asia (MICS-Asia III) on simulating the particulate matter (PM) over East Asia (EA) in 2010. The participating models include WRF-CMAQ (v4.7.1 and v5.0.2), WRF-Chem (v3.6.1 and v3.7.1), GEOS-Chem, NHM-Chem, NAQPMS and NU-WRF. Evaluations with ground measurements and satellite data show that the mean biases of multi-model mean (MMM) are -25 µg m-3 (-30 %), -7 µg m-3 (-15 %). -0.7 µg m-3 (-19 %), -0.05 µg m-3 (-3 %) and 0.1 µg m-3 (12 %) for surface PM10, PM2.5, SO42-, NO3- and NH4+ concentrations, respectively. This study investigates four model processes as the possible reasons for different model performances on PM: (1) Using different natural emissions (i.e. dust and sea-salt emissions) brings upmost 0.25 µg m-3 (70 %) of inter-model differences to domain-average black carbon concentrations at surface layer and 756 ppb (22 %) of inter-model differences to domain-average CO column. Adopting different initial/boundary conditions results in 10-20 % differences in PM concentrations in the center of the simulation domain. (2) Models perform very differently in the gas-particle conversion of sulphur (S) and oxidized nitrogen (N). The model differences in sulphur oxidation ratio (50 %) is of the same magnitude as that in SO42- concentrations. The gas-particle conversion is one the main reasons for different model performances on fine mode PM. (3) Models without dust emissions/modules can perform well on PM10 at non-dust-affected sites, but largely underestimate (upmost 50 %) the PM10 concentrations at dust sites. The implementation of dust emissions/modules in models has largely improved the model accuracies at dust sites (reduce model bias to -20 %). However, both the magnitudes and distributions of dust pollutions are not fully captured. (4) The amounts of modelled depositions vary among models by 75 %, 39 %, 21 % and 38 % for S wet, S dry, N wet and N dry depositions, respectively. Large inter-model differences are found in the washout ratios of wet deposition (at most 170 % in India) and dry deposition velocities (general 0.3-2 cm s-1 differences over inland regions). This study investigates the reasons for different model performances on PM over EA and offers suggestions for future model development.
- Subjects
EAST Asia; INDIA; ASIA; PARTICULATE matter; AIR pollutants; DUST; CHEMICAL models; CARBON-black
- Publication
Atmospheric Chemistry & Physics Discussions, 2019, p1
- ISSN
1680-7367
- Publication type
Article
- DOI
10.5194/acp-2019-392