空气污染抑制小雨:华南与青藏高原对比分析

Suppression of light precipitation by air pollution:A comparison between observations in South China and the Tibetan Plateau

  • 摘要: 以能见度作为气溶胶浓度表征物,采用1980—2011年青藏高原和华南共10个台站资料,分析空气污染对降雨的影响。结果显示:青藏高原空气质量一直维持在很好状态,而华南地区存在严重的空气污染;华南地区的南宁、北海、百色3站小雨下降趋势明显,而青藏高原5站和华南地区的梧州、桂林2站的小雨趋势变化不明显;南宁、北海、百色3站20时能见度与随后24 h(当日20时至次日20时)小雨雨量正相关显著,而青藏高原5站和梧州、桂林2站20时能见度与随后24 h 小雨雨量正相关不显著,这可能表明南宁、北海、百色3站小雨下降趋势与空气污染抑制有关;定量分析显示能见度每降低1 km,南宁、北海、百色3站小雨雨量分别减少0.019、0.028和0.027 mm;南宁、北海、百色3站出现小雨时20时能见度与未来24 h内各时次归一化对流有效位能正相关显著,这一现象与空气污染抑制小雨现象吻合;归一化对流有效位能对地面能见度/气溶胶激励效应的响应时间每日有两个高值。

     

    Abstract: Precipitation and visibility (surrogate for aerosol loading) records at the 10 weather stations in the Tibetan Plateau and South China were examined with the span of 32 years (1980—2011). It was shown that the values of visibility were high in the Tibetan Plateau and low in South China. The light rainfall decreased at the 3 stations in South China (Nanning, Beihai and Baise) while the other 7 stations ( 2 in South China and 5 in the Tibetan Plateau) showed little fluctuation. A significant positive correlation was observed between the visibility at 20:00 BT and the light rainfall during the following 24 hours in the stations Nanning, Beihai and Baise with the other 7 stations having no significant correlation, which might suggest that the decrease trends of the light rainfall were caused by air pollution suppressing precipitation. The quantitative analysis showed that for each reduction of 1 kilometer of the visibility at 20:00 BT, the light rainfall of the following 24 hours would decrease by 0.019, 0.028 and 0.027 mm in the stations Nanning, Beihai and Baise, respectively. The correlation coefficients were significantly positive between the visibility at 20:00 BT and the normalization convective available potential energy (NCAPE) of the following 24 hours, which was consistent with the phenomenon of air pollution suppressing light rainfall. It was also observed that the response of NCAPE to the invigoration effect of visibility/aerosol had 2 peaks for each day.

     

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