火星沙尘暴的起动临界风速

发布时间：2018-05-11 14:10

本文选题：火星 + 沙尘暴　；参考：《中国科学技术大学》2011年硕士论文

【摘要】：火星是一个沙漠化的行星,拥有稀薄的大气层。自从1971年水手9号飞船进入绕火星飞行轨道后,就有很多关于火星沙尘暴的观测资料传回地球。火星上存在有利于沙尘暴形成的条件,不过由于火星的大气密度非常低,火星沙尘暴的起动风速要比地球上大许多。海盗1号和海盗2号着陆器在火星表面工作数年,测得火星沙尘暴的起动一般需要离火星表面2m高处的风速达到30m/s,这相当于地球上的12级飓风。本文通过建立地表风-沙物理模型对火星沙尘暴起动临界风速的理论值进行计算,根据中性层结大气边界层风速廓线,得到火星表面粒径为100μm的沙粒的起动风速为2m高处28.7m/s。由于火星上100μm粒径的沙粒是最容易起动的,其起动风速也就是火星沙尘暴起动风速的临界值。本文还对沙尘扬起的机制以及沙尘暴发生后空气中悬浮尘粒的粒径大小进行了研究。在沙粒起动的临界风速下,沙粒一般需要在地表滚动一个粒径的距离然后通过与其他沙粒碰撞而跳起。粒径较小的尘粒由于受到的凝聚力较大,并非最容易起动的,而是靠最先跳起的较大颗粒沙粒与地表碰撞时溅射起来的。本文通过计算表明,在风速为临界值时,火星大气中能被维持悬浮的尘粒粒径小于31μm。
[Abstract]:Mars is a desert planet with a thin atmosphere. Since mariner's 9 spacecraft entered the Martian orbit in 1971, there were many observations about the Martian dust storm back to earth. There was a condition for the formation of a sandstorm on Mars, but because of the very low atmospheric density of Mars, the starting wind of the Martian dust storm The pirate 1 and pirate 2 lander work on the surface of Mars for several years, and the start of the Martian dust storm usually requires a wind speed of 30m/s at the height of 2m from the surface of the Mars, which is equivalent to the 12 hurricane on the earth. This paper establishes the theory of the ground wind sand physical model to start the critical wind speed of the Martian dust storm. The value is calculated. According to the wind velocity profile of the atmospheric boundary layer on the neutral layer, the starting wind speed of the sand particles with the particle size of 100 m on the Martian surface is 2m high, because the grain size of 100 mu m on Mars is the most easy to start, and the starting wind speed is the critical value of the starting wind speed of the Martian dust storm.
In this paper, the mechanism of dust lifting and the size of the suspended particles in the air after the dust storm have been studied. Under the critical wind speed, the sand particles generally need to roll a particle distance at the surface and jump through the collision with other sand grains. It is the most easy to start, but by sputter when the larger particle sand, which is the first jump, is sputter when it collides with the surface. This paper shows that the particle size of the suspended particles in the Martian atmosphere is less than 31 u M. when the wind speed is the critical value.

【学位授予单位】：中国科学技术大学
【学位级别】：硕士
【学位授予年份】：2011
【分类号】：P185.3

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