Pakistan Meteorological Department

Climate Change Impact & Integration Cell (CIIC)
Webinar Meeting (Wednesday, 2nd December, 2020 11:30 AM)

Non-Monotonic Aerosol Effect on Convective Rain Producing Systems in Changing Climate

Featured Speakers

  • Dr. Yin Yan
    Professor, NUIST Nanjing China
    (Aerosols impacts in different regions)
  • Dr. Muhammad Hanif
    Chief Meteorologist, PMD
    (Role of Early Warning)
  • Dr. Muhammad Imran Shahzad
    Head - Department of Meteorology, COMSATS University, Islamabad
    (Lead Scientist - EARL)
  • Dr. Azmat Hayat Khan (Convener)
    Chief Meteorologist, PMD

Abstract

Convection is considered to play a key role in the global energy balance and water cycle, producing convective clouds with significant amounts of rain. Aerosols serve as cloud condensation nuclei (CCN) and ice nuclei (IN), affecting cloud microphysics and its coupling with dynamics thereby affecting the planetary scale energy balance. An improved understanding of aerosol effects on clouds is regarded as one of the most important challenges in climate research.

Increase in aerosol concentration has been linked to delay in the onset of rain, invigorated cloud system and stronger rain rates. Observational analysis depicts that a polluted cloud has a narrower distribution of smaller cloud droplets and affect a chain of microphysical and dynamic processes and thus the cloud’s microphysical and optical properties, as well as rain production. Higher concentration of aerosols activate more droplets that compete for available supersaturation. Although the droplets are smaller, their collective surface area increases and therefore diffusion efficiency increases, yielding stronger latent heat flux that strengthens the cloud’s updraft. A larger water mass is pushed above the freezing level, and smaller supercooled droplets freeze at colder temperatures. Thus, the latent heat of freezing is released at higher levels, again boosting the updrafts.

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Increase in aerosol concentration has been linked to delay in the onset of rain, invigorated cloud system and stronger rain rates. Satellite derived products depict that impact of aerosols along coastal regions is different compared to inland and mountainous regions (location specific).

Satellite derived products depict that impact of aerosols along coastal regions is different compared to inland and mountainous regions (location specific). It is highly important to analyse the role of various types of aerosols to determine factors influencing the formation of deep convective clouds leading to heavy rainfall in urban hubs to recommend policy options for technology development to minimize the generation of related aerosols in anthropogenic activities.

For any questions, please email ciic@pmd.gov.pk

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