气溶胶核化清除对云滴化学的作用

将气溶胶核化的物理过程与气体、气溶胶在云滴内的化学过程相结合,研究了气溶胶核化清除对云滴化学的影响。计算表明:气溶胶核化可造成形成的云滴中化学成分及其浓度随云滴尺度的非均匀性。气溶胶浓度、化学组成及云滴内液相氧化反应可较显著地影响这种非均匀程度及变化趋势。大陆性粗模态气溶胶上形成的云滴对总体云水化学的影响是可略的。这些结果表明,使用显式方法(粒子尺度分档)处理气溶胶核化清除的化学过程是重要的。     

非线性Rossby波及其相互作用——Ⅰ.Rossby包络弧立波的碰撞

本文利用多重尺度摄动法,推得了描述正压大气中两非线性Rossby波相互作用的方程组。根据此方程组,本文讨论了两Rossby包络孤立波的碰撞相互作用,认为两包络孤立波的碰撞,在某些参数范围内呈现包络孤立子特性,在另外一些参数范围又观测到“非弹性”效应:改变传播方向,分裂孤立波,频散能量等。在相互作用过程中,两波各自能量守恒。     

DYNAMICS OF EKMAN MOMENTUM FLOW AND FRONTOGENESIS

With the Ekman momentum approximation, the four important pseudo-conservation relations in the boundary layer dynamics are derived. In order to simplify the problem, the so-called Ekman coordinates is introduced. The motion in Ekman coordinates is classical Ekman flow. However, the solution in Ekman coordinates should be converted into the physical coordinates. In this paper, an approximation transformation is used to discuss the inuflence of the turbulence friction on the baroclinic wave of Eady type and frontogenesis. The results show that, on one hand, Ekman momentum flow implicates the ageostrophic component which enhances frontogenesis in the boundary layer, on the other hand, it implies the turbulence friction which weakens the frontogenesis in the boundary layer. The critical time of the discontinuity occurring in the boundary layer is longer than that in the free atmosphere. Ekman momentum flow is dualistic.