Equatorial Superrotation on Earth Induced by Optically Thick Dust Clouds

金星的大气层表现出极端的赤道超自转，因为赤道上空的高层风以比固体表面绝对运动大近一百倍的速度向行星自转的方向吹动。这个项目基于这样的想法，即赤道超级自转现象不仅限于金星等旋转缓慢的行星，而且如果太阳潮汐足够强，地球上也会发生这种现象。非常强的潮汐可能是由密集尘埃云的存在引起的，例如小行星撞击产生的尘埃云，据信是导致恐龙灭绝的原因。在赤道超自转的情况下，平流层的翻转环流可能在将尘埃云扩散到整个地球上，从而导致物种灭绝方面发挥了重要作用。大气超旋转对于气候对核交换(所谓的核冬季)或极端硫化作用的响应也可能是重要的。朱在一个理想化的二维(纬度-海拔)模型中证明了，平流层中强烈的太阳潮汐可以导致地球大气超级旋转。现在，他和他的合作者将使用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，将具有与火山超级喷发相关的分布和物理特性的平流层粒子结合在一起。这些实验将在完全三维的动力学背景下测试一个新的有趣的假设，即平流层强烈吸收太阳的潮汐强迫可以导致地球上的赤道超级自转。这项工作的结果应该会引起公众的普遍兴趣，研究人员计划在一本大众科学杂志上发表一篇文章来描述这些结果。

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.