工廠排放的煙霧讓空氣變得更差
龍卷風(fēng)破壞力增強(qiáng)
近幾年,，中東和東南亞地區(qū)曾遭受幾次具有破壞性的龍卷風(fēng)襲擊。一項(xiàng)新研究發(fā)現(xiàn),，中東和東南亞發(fā)展中國家因煤煙和浮質(zhì)造成的空氣污染提高了龍卷風(fēng)的破壞性,。刊登在《自然》雜志上的研究論文指出,，燃燒化石燃料產(chǎn)生的排放與風(fēng)模式之間的相互作用減弱了風(fēng)切變作用,，進(jìn)而導(dǎo)致龍卷風(fēng)規(guī)模增大，更具有破壞性,。通常情況下,，風(fēng)切變會在龍卷風(fēng)達(dá)到確定規(guī)模時將其“撕裂”。
研究過程中,，科學(xué)家將1979年至1996年出現(xiàn)的龍卷風(fēng)與1997年至2010年出現(xiàn)的龍卷風(fēng)進(jìn)行比較,，結(jié)果發(fā)現(xiàn)最近出現(xiàn)的龍卷風(fēng)強(qiáng)度是此前的3倍，不僅風(fēng)速更快,，風(fēng)切變層也更低。此外,，他們還發(fā)現(xiàn)這兩個地區(qū)的浮質(zhì)數(shù)量自上世紀(jì)30年代以來增加了5倍,，在印度洋上空形成3公里厚的污染層,，被稱之為“東南亞大氣褐云”。大氣褐云吸收陽光,，導(dǎo)致海洋溫度降低,，進(jìn)而影響風(fēng)循環(huán)。
科學(xué)家長久以來就認(rèn)為空氣污染能夠影響季風(fēng),，但證明空氣污染與破壞性更強(qiáng)的風(fēng)暴有關(guān)還是第一次,。研究論文主執(zhí)筆人阿馬托·埃文在接受SciDev.Net網(wǎng)站采訪時表示：“我認(rèn)為浮質(zhì)對龍卷風(fēng)的影響與對季風(fēng)環(huán)流和降雨的影響存在密切聯(lián)系，它們往往減弱季風(fēng)環(huán)流和減少降雨,。”
埃文說：“我們的研究顯示人類活動造成的空氣污染——例如燒木頭或者駕駛柴油機(jī)汽車——能夠以一種非常顯著的方式改變這些大規(guī)模大氣現(xiàn)象,。這一研究發(fā)現(xiàn)再一次強(qiáng)調(diào)了減少當(dāng)?shù)匚廴疚锱欧诺闹匾浴Ｈ绻钤谝粋€強(qiáng)龍卷風(fēng)登陸的地區(qū),，遏制空氣污染就顯得尤為重要,。阿拉伯海歷史上曾多次出現(xiàn)強(qiáng)熱帶氣旋登陸印度、巴基斯坦,、阿曼和伊朗等地區(qū),，每一次都造成巨大的人員財產(chǎn)損失。”這項(xiàng)研究有助于提高公眾對空氣污染的關(guān)注,，空氣污染不僅會導(dǎo)致呼吸系統(tǒng)疾病,，同時也會提高龍卷風(fēng)的破壞性，必須采取措施加以遏制,。(生物谷 Bioon.com)
doi:10.1038/nature10552
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Arabian Sea tropical cyclones intensified by emissions of black carbon and other aerosols
Amato T. Evan,1 James P. Kossin,2, 3 Chul ‘Eddy’ Chung4 & V. Ramanathan5
Throughout the year, average sea surface temperatures in the Arabian Sea are warm enough to support the development of tropical cyclones1, but the atmospheric monsoon circulation and associated strong vertical wind shear limits cyclone development and intensification, only permitting a pre-monsoon and post-monsoon period for cyclogenesis1, 2, 3, 4. Thus a recent increase in the intensity of tropical cyclones over the northern Indian Ocean5 is thought to be related to the weakening of the climatological vertical wind shear3, 4. At the same time, anthropogenic emissions of aerosols have increased sixfold since the 1930s, leading to a weakening of the southwesterly lower-level and easterly upper-level winds that define the monsoonal circulation over the Arabian Sea6, 7, 8, 9. In principle, this aerosol-driven circulation modification could affect tropical cyclone intensity over the Arabian Sea, but so far no such linkage has been shown. Here we report an increase in the intensity of pre-monsoon Arabian Sea tropical cyclones during the period 1979–2010, and show that this change in storm strength is a consequence of a simultaneous upward trend in anthropogenic black carbon and sulphate emissions. We use a combination of observational, reanalysis and model data to demonstrate that the anomalous circulation, which is radiatively forced by these anthropogenic aerosols, reduces the basin-wide vertical wind shear, creating an environment more favourable for tropical cyclone intensification. Because most Arabian Sea tropical cyclones make landfall1, our results suggest an additional impact on human health from regional air pollution.
