Aerosol concentrations variability over China: two distinct leading modes [post]

Juan Feng, Jianlei Zhu, Jianping Li, Hong Liao
2020 unpublished
<p><strong>Abstract.</strong> Understanding the variability in aerosol concentrations (AC) over China is a scientific challenge and is of practical importance. The present study explored the month-to-month variability in AC over China based on simulations of an atmospheric chemical transport model with a fixed emissions level. The month-to-month variability in AC over China is dominated by two principal modes: the first leading mono-pole mode and the second meridional dipole
more » ... meridional dipole mode. The mono-pole mode mainly indicates enhanced AC over eastern China, and the dipole mode displays a south–north out-of-phase pattern. The two leading modes are associated with different climatic systems. The mono-pole mode relates to the 3-month leading El Niño–South Oscillation (ENSO), while the dipole mode connects with the simultaneous variation in the North Atlantic Oscillation (NAO) or the Northern Hemisphere Annular Mode (NAM). The associated anomalous dynamic and thermal impacts of the two climatic variabilities are examined to explain their contributions to the formation of the two modes. For the mono-pole mode, the preceding ENSO is associated with anomalous convergence, decreased planetary boundary layer height (PBLH), and negative temperature anomalies, which are unfavorable for emissions. For the dipole mode, the positive NAO is accompanied by opposite anomalies in the convergence, PBLH, and temperature over southern and northern China, paralleling the spatial formation of the mode. This result suggests that the variations originating from the tropical Pacific and extratropical atmospheric systems contribute to the dominant variabilities of AC over China.</p>
doi:10.5194/acp-2019-1194 fatcat:v35nmdjo2vferdsm64ykfjbl24