Equatorial Superrotation on Earth Induced by Optically Thick Dust Clouds

由光学厚尘埃云引起的地球赤道超自转

• 批准号: 0730158
• 负责人: Xun Zhu
• 金额: --
• 依托单位: Johns Hopkins University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-10-01 至 2009-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0730158&HistoricalAwards=false
• 关键词: Equatorial; Superrotation; Earth; Induced; Optically

The atmosphere of Venus displays extreme equatorial superrotation, in that upper-level winds over the equator blow in the direction of planetary rotation at speeds nearly a hundred times greater than the absolute motion of the solid surface. This project is based on the idea that the phenomenon of equatorial superrotation is not confined to slowly rotating planets, such as Venus, but, given sufficiently strong solar tides, occurs on Earth. Very strong tides could result from the presence of dense dust clouds, such as were produced by the asteroid impact believed to have caused the extinction of the dinosaurs. The stratospheric overturning circulation in the presence of equatorial superrotation may have played an important role in spreading the dust cloud over the entire globe, and, therefore, in causing the extinctions. Atmospheric superrotation could also be important for the response of the climate to a nuclear exchange (so-called "nuclear winter") or to extreme vulcanism.Zhu has demonstrated, in an idealized two-dimensional (latitude-altitude) model, that strong solar tides in the stratosphere can cause Earth's atmosphere to superrotate. Now he and his collaborators will conduct a set of exploratory experiments using a three-dimensional global climate model with a well resolved stratosphere, incorporating stratospheric particles with distributions and physical properties relevant to volcano super-eruptions. These experiments will test, in a fully three-dimensional dynamical context, the new and intriguing hypothesis that tidal forcing from strong solar absorption in the stratosphere can cause equatorial superrotation on Earth.The results of this work should be of general interest to the public, and the investigators plan to describe them in an article in a general-audience science magazine.

金星的大气层显示出极端的赤道超旋转，赤道上空的上层风以比固体表面绝对运动快近一百倍的速度吹向行星旋转的方向。 该项目基于这样的想法，即赤道超旋转现象并不局限于缓慢旋转的行星，如金星，但如果太阳潮汐足够强，地球上也会发生。 非常强烈的潮汐可能是由于密集的尘埃云的存在，例如被认为导致恐龙灭绝的小行星撞击所产生的。 在赤道超旋转存在下的平流层翻转环流可能在尘埃云在整个地球仪的扩散中发挥了重要作用，因此，在引起对流层中。 大气的超旋转对于气候对核交换（所谓的“核冬天”）或极端火山活动的反应也很重要。朱在一个理想化的二维（纬度-高度）模型中证明，平流层中强烈的太阳潮汐可以导致地球大气的超旋转。 现在，他和他的合作者将使用一个具有良好分辨率的平流层的三维全球气候模型进行一系列探索性实验，将平流层颗粒与火山超级喷发相关的分布和物理特性结合起来。 这些实验将在一个完全三维的动力学背景下测试一个新的有趣的假设，即平流层强烈的太阳吸收引起的潮汐力可以引起地球上的赤道超旋转。这项工作的结果应该引起公众的普遍兴趣，研究人员计划在一本普通科学杂志上发表一篇文章。