Weekly cycle of aerosol-meteorology interaction over China
Weekly cycles of the concentration of anthropogenic aerosols have been observed in many regions around the world. The phase and the magnitude of these cycles, however, vary greatly depending on region and season. In the present study the authors investigated important features of the weekly cycles of aerosol concentration and the co-variations in meteorological conditions in major urban regions over east China, one of the most polluted areas in the world, in summertime during the period 2001-2005/2006. The PM10 (aerosol particulate matters of diameter < 10μm) concentrations at 29 monitoring stations show significant weekly cycles with the largest values around midweek and smallest values in weekend. Accompanying the PM10 cycle, the meteorological variables also show notable and consistent weekly cycles. The wind speed in lower troposphere is relatively small in the early part of the week, and increases after about Wednesday. At the same time, the air temperature anomalies in low levels are positive, and then become negative in the later part of the week. The authors hypothesized that the changes in the atmospheric circulation may be triggered by the accumulation of PM10 through diabatic heating of lower troposphere. During the early part of a week the anthropogenic aerosols are gradually accumulated in the lower troposphere. Around midweek, the accumulated aerosols could induce radiative heating, likely destabilizing the mid- to lower troposphere and generating anomalously vertical air motion, and thus resulting in stronger winds. The resulting circulation could promote ventilation to reduce aerosol concentrations in the boundary layer during the later part of the week. Corresponding to this cycle in anthropogenic aerosols the frequency of precipitation, particularly the light rain events, tends to be suppressed around mid-weekdays through indirect aerosol effects. This is consistent with the observed anthropogenic weather cycles, i.e., more (less) solar radiation near surface, higher (lower) maximum temperature, larger (smaller) diurnal temperature range, less (more) precipitation events in mid-weekday (weekend).
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC05-76RL01830
- OSTI ID:
- 985050
- Report Number(s):
- PNNL-SA-56377; KP1703010; TRN: US201016%%1739
- Journal Information:
- Journal of Geophysical Research. D. (Atmospheres), 112(D22):Art. No. D22202, Vol. 112, Issue d22; ISSN 0148-0227
- Country of Publication:
- United States
- Language:
- English
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