Effects of solid aerosols on partially glaciated clouds

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Effects of solid aerosols on partially glaciated clouds. / Kudzotsa, Innocent; Phillips, Vaughan T.J.; Dobbie, Steven.

In: Quarterly Journal of the Royal Meteorological Society, Vol. 144, No. 717, 2018, p. 2634-2649.

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TY - JOUR

T1 - Effects of solid aerosols on partially glaciated clouds

AU - Kudzotsa, Innocent

AU - Phillips, Vaughan T.J.

AU - Dobbie, Steven

PY - 2018

Y1 - 2018

N2 - Sensitivity tests were conducted using a state-of-the-art aerosol–cloud to investigate the key microphysical and dynamical mechanisms by which solid aerosols affect glaciated clouds. The tests involved simulations of two contrasting cases of deep convection—a tropical maritime case and a midlatitude continental case, in which solid aerosol concentrations were increased from their pre-industrial (1850) to their present-day (2010) levels. In the midlatitude continental case, the boosting of the number concentrations of solid aerosols weakened the updrafts in deep convective clouds, resulting in reduced snow and graupel production. Consequently, the cloud fraction and the cloud optical thickness increased with increasing ice nuclei (IN), causing a negative radiative flux change at the top of the atmosphere (TOA), that is, a cooling effect of −1.96 ± 0.29 W/m2. On the other hand, in the tropical maritime case, increased ice nuclei invigorated upper-tropospheric updrafts in both deep convective and stratiform clouds, causing cloud tops to shift upwards. Snow production was also intensified, resulting in reduced cloud fraction and cloud optical thickness, hence a positive radiative flux change at the TOA—a warming effect of 1.02 ± 0.36 W/m2 was predicted.

AB - Sensitivity tests were conducted using a state-of-the-art aerosol–cloud to investigate the key microphysical and dynamical mechanisms by which solid aerosols affect glaciated clouds. The tests involved simulations of two contrasting cases of deep convection—a tropical maritime case and a midlatitude continental case, in which solid aerosol concentrations were increased from their pre-industrial (1850) to their present-day (2010) levels. In the midlatitude continental case, the boosting of the number concentrations of solid aerosols weakened the updrafts in deep convective clouds, resulting in reduced snow and graupel production. Consequently, the cloud fraction and the cloud optical thickness increased with increasing ice nuclei (IN), causing a negative radiative flux change at the top of the atmosphere (TOA), that is, a cooling effect of −1.96 ± 0.29 W/m2. On the other hand, in the tropical maritime case, increased ice nuclei invigorated upper-tropospheric updrafts in both deep convective and stratiform clouds, causing cloud tops to shift upwards. Snow production was also intensified, resulting in reduced cloud fraction and cloud optical thickness, hence a positive radiative flux change at the TOA—a warming effect of 1.02 ± 0.36 W/m2 was predicted.

KW - aerosol–cloud interactions

KW - cloud microphysics

KW - cloud-resolving models

KW - clouds

KW - glaciated clouds

KW - indirect effects

U2 - 10.1002/qj.3376

DO - 10.1002/qj.3376

M3 - Article

VL - 144

SP - 2634

EP - 2649

JO - Quarterly Journal of the Royal Meteorological Society

JF - Quarterly Journal of the Royal Meteorological Society

SN - 0035-9009

IS - 717

ER -