Observational Evidence of Giant Cloud Condensation Nucleus Effects on the Precipitation Sensitivity in Marine Stratocumulus Clouds

초록

Cloud-aerosol interactions are one of the paramount but least understood forcing factors in climate systems. Generally, an increase in the concentration of aerosols increases the concentration of cloud droplet numbers, implying that clouds tend to persist for longer than usual, suppressing precipitation in the warm boundary layer. The cloud lifetime effect has been the center of discussion in the scientific community, partly because of the lack of cloud life cycle observations and partly because of cloud problems. In this study, the precipitation susceptibility (S-o) matrix was employed to estimate the aerosols' effect on precipitation, while the non-aerosol effect is minimized. The S-o was calculated for the typical coupled, well-mixed maritime stratocumulus decks and giant cloud condensation nucleus (GCCN) seeded clouds. The GCCN-artificially introduced to the marine stratocumulus cloud decks-is shown to initiate precipitation and reduces S-o to approximately zero, demonstrating the cloud lifetime hypothesis. The results suggest that the response of precipitation to changes in GCCN must be considered for accurate prediction of aerosol-cloud-precipitation interaction by model studies

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