https://scholars.lib.ntu.edu.tw/handle/123456789/571810
標題: | Simulation of Aerosol Indirect Effects on Cloud Streets Over the Northwestern Pacific Ocean | 作者: | Wu C.-K Chen J.-P. JEN-PING CHEN |
關鍵字: | air-sea interaction; albedo; atmospheric forcing; cloud microphysics; drizzle; dynamic response; evaporation; forecasting method; sedimentation; temperature gradient; troposphere; vapor pressure; Pacific Ocean; Pacific Ocean (Northwest) | 公開日期: | 2021 | 卷: | 126 | 期: | 11 | 來源出版物: | Journal of Geophysical Research: Atmospheres | 摘要: | We simulated aerosol effects on cloud streets formed during continental cold-air outbreaks over the Northwestern Pacific using an aerosol-sensitive cloud microphysical scheme coupled with the Weather Research and Forecast model. The micro- and macro-scale responses were examined under a wide range of aerosol concentrations. The cloud streets generally remain in a transient state, indicating that the aerosol particles may significantly affect the cloud system's development. The simulation results revealed a clear Twomey effect, but they were contrary to some of the Albrecht effect, especially under relatively clean conditions. Such reversed Albrecht effects stem mainly from dynamic response to changes in atmospheric stability associated with drizzle evaporation in the sub-cloud layer. The dynamic response works against thermal forcing from the large air-sea temperature gradient in a cold-air outbreak. As the aerosol increases, the drizzle mechanisms weaken, and the boundary layer becomes more convective, leading to stronger dry-air entrainment from the free troposphere. In individual clouds, the effect of entrainment on cloud water content may be compensated by more substantial vertical vapor flux. These mechanisms lead to a reduction in the cloud amount. Furthermore, the reduced moisture flux from drizzle evaporation in the sub-cloud layer, as well as the reduced sedimentation speed of the smaller cloud drops, tend to lessen cloud thickness. The overall reduction in cloud dimensions may offset the Twomey effect by up to 20% in cloud albedo. ? 2021. American Geophysical Union. All Rights Reserved. |
URI: | https://www.scopus.com/inward/record.uri?eid=2-s2.0-85107483114&doi=10.1029%2f2020JD034325&partnerID=40&md5=ffc1f2d8493e60c107cdfe3871aad9cc https://scholars.lib.ntu.edu.tw/handle/123456789/571810 |
ISSN: | 2169897X | DOI: | 10.1029/2020JD034325 |
顯示於: | 大氣科學系 |
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