Interpretation of aerosol effects on precipitation susceptibility in warm clouds inferred from satellite measurements and model evaluation over Northeast Asia

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  • 1 Department of Atmospheric Sciences, Pusan National University, Busan, Korea
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Abstract

Precipitation susceptibility (So), a parameter of aerosol-cloud-precipitation interaction over Northeast Asia during the Korea-United States Air Quality (KORUS-AQ) campaign, was analyzed using the CLAVR-x satellite data and WRF-Chem model. As Northeast Asia is one of the areas with the highest aerosol emissions, this study is expected to explore more elaborate aerosol-cloud linkages.

Our results obtained from satellite data showed that So increased as the atmospheric condition became stable and humid, and the shift of the water conversion process to precipitation occurred in the LWP range of 300–500 g m-2. The So exhibited a maximum value of 0.61 at an LWP of 350 g m-2 where the dominance of the cloud-water conversion process changed from autoconversion to accretion. In the aerosol–cloud relation, the susceptibility of the cloud-drop effective radius showed a positive response to the cloud droplet number concentration (Nd) regardless of the environmental conditions, whereas the LWP vs. Nd relationship was highly dependent on the meteorological conditions.

The WRF-Chem produced higher So values than those of the satellite data by factors of 2.4–3.3; the simulated results exhibited differences in shape, range, and amplitude. The overestimation of So was mainly due to the high precipitation rate under low LWP conditions as compared to the satellite observations. This result is associated with the initiation and intensity of precipitation, considering both autoconversion and accretion. Our modeling results were verified during KORUS-AQ, which implied that the aerosol–cloud relationship might be elucidated by improved microphysical parameterization schemes based on more detailed measurements such as aircraft-based observations.

Corresponding author: chkim2@pusan.ac.kr (C.-H. Kim)

Abstract

Precipitation susceptibility (So), a parameter of aerosol-cloud-precipitation interaction over Northeast Asia during the Korea-United States Air Quality (KORUS-AQ) campaign, was analyzed using the CLAVR-x satellite data and WRF-Chem model. As Northeast Asia is one of the areas with the highest aerosol emissions, this study is expected to explore more elaborate aerosol-cloud linkages.

Our results obtained from satellite data showed that So increased as the atmospheric condition became stable and humid, and the shift of the water conversion process to precipitation occurred in the LWP range of 300–500 g m-2. The So exhibited a maximum value of 0.61 at an LWP of 350 g m-2 where the dominance of the cloud-water conversion process changed from autoconversion to accretion. In the aerosol–cloud relation, the susceptibility of the cloud-drop effective radius showed a positive response to the cloud droplet number concentration (Nd) regardless of the environmental conditions, whereas the LWP vs. Nd relationship was highly dependent on the meteorological conditions.

The WRF-Chem produced higher So values than those of the satellite data by factors of 2.4–3.3; the simulated results exhibited differences in shape, range, and amplitude. The overestimation of So was mainly due to the high precipitation rate under low LWP conditions as compared to the satellite observations. This result is associated with the initiation and intensity of precipitation, considering both autoconversion and accretion. Our modeling results were verified during KORUS-AQ, which implied that the aerosol–cloud relationship might be elucidated by improved microphysical parameterization schemes based on more detailed measurements such as aircraft-based observations.

Corresponding author: chkim2@pusan.ac.kr (C.-H. Kim)
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