Quantifying the importance of galactic cosmic rays in cloud microphysical processes
Quantifying the importance of galactic cosmic rays in cloud microphysical processes
复制标题
DOI：
10.1016/j.jastp.2013.05.017
复制
发表时间：
2013-09
影响因子：
1.9
通讯作者：
A. Rawal;S. N. Tripathi;M. Michael;A. Srivastava;R. Harrison
中科院分区：
文献类型：
--
作者：
A. Rawal;S. N. Tripathi;M. Michael;A. Srivastava;R. Harrison
银河宇宙线是对流层和平流层中离子产生的主要来源之一。最近的研究表明，离子形成带电簇，这些簇可能长大成为云滴。气溶胶颗粒通过离子和电子的附着而带电。如果颗粒带电，则颗粒和水滴之间的碰撞效率会增加，从而可以增强气溶胶-云相互作用。由于这些微物理过程可能会改变云的辐射特性并影响地球气候，因此评估这些过程的定量影响非常重要。将独立开发的五个不同模型结合起来对此进行研究。第一个模型根据露点温度和温度剖面估计云高。第二个模型使用云块概念模拟气溶胶颗粒的云滴生长。在第三个模型中，使用带电粒子和液滴之间的碰撞效率来计算气溶胶粒子的清除率。第四个模型计算云内水滴和气溶胶的电场和电荷分布。第五个模型模拟全局电路 (GEC)，它计算 0-45 公里海拔范围内大气中的电导率和离子浓度。前四个模型首先耦合计算云的高度、云的边界条件，然后计算液滴的生长、气溶胶和云滴的电荷分布计算，最后进行清除。这些模型与 GEC 模型合并。该模拟通过不同高度的带电气溶胶的实验数据进行了验证。我们的计算表明，气溶胶充电对云内 CCN 浓度有影响，因为气溶胶充电增加了 0.1 µm 至 1 µm 尺寸范围内颗粒的清除。
Galactic Cosmic Rays are one of the major sources of ion production in the troposphere and stratosphere. Recent studies have shown that ions form electrically charged clusters which may grow to become cloud droplets. Aerosol particles charge by the attachment of ions and electrons. The collision efficiency between a particle and a water droplet increases, if the particle is electrically charged, and thus aerosol-cloud interactions can be enhanced. Because these microphysical processes may change radiative properties of cloud and impact Earth's climate it is important to evaluate these processes' quantitative effects. Five different models developed independently have been coupled to investigate this. The first model estimates cloud height from dew point temperature and the temperature profile. The second model simulates the cloud droplet growth from aerosol particles using the cloud parcel concept. In the third model, the scavenging rate of the aerosol particles is calculated using the collision efficiency between charged particles and droplets. The fourth model calculates electric field and charge distribution on water droplets and aerosols within cloud. The fifth model simulates the global electric circuit (GEC), which computes the conductivity and ionic concentration in the atmosphere in altitude range 0–45 km. The first four models are initially coupled to calculate the height of cloud, boundary condition of cloud, followed by growth of droplets, charge distribution calculation on aerosols and cloud droplets and finally scavenging. These models are incorporated with the GEC model. The simulations are verified with experimental data of charged aerosol for various altitudes. Our calculations showed an effect of aerosol charging on the CCN concentration within the cloud, due to charging of aerosols increase the scavenging of particles in the size range 0.1 µm to 1 µm.