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Quantifying the importance of galactic cosmic rays in cloud microphysical processes

Rawal, A and Tripathi, SN and Michael, M and Srivastava, AK and Harrison, RG (2013) Quantifying the importance of galactic cosmic rays in cloud microphysical processes. Journal of Atmospheric and Solar-Terrestrial Physics, 102. pp. 243-251.

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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.

Item Type: Article
Additional Information: Copyrights of this article belongs to Elsevier.
Uncontrolled Keywords: Aerosol charging; Aerosol-cloud interaction; Cloud formation; Cloud microphysical process; Distribution calculations; Droplet growth; Global electric circuit; Microphysical process, Charge distribution; Climate change; Cosmic rays; Drops; Electric fields; Galaxies; Ions; Scavenging, Aerosols
Subjects: Meteorology and Climatology
Depositing User: IITM Library
Date Deposited: 20 Jun 2014 06:24
Last Modified: 20 Jun 2014 06:24

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