重力波動對層積雲系統垂直結構及雲量之影響

Impact of Gravity Waves on Marine Stratocumulus Variability: Vertical Structures and Cloud Coverage

林佑宇(Yu-Yu Lin)

指導教授 ： 郭鴻基

共同指導教授 ： 吳健銘(Chien-Ming Wu)

國立臺灣大學/理學院/大氣科學研究所/碩士(2015年)

https://doi.org/10.6342/NTU.2015.00668

摘要

無資料

關鍵字

邊界層 ； 層積雲 ； 邊界層分離 ； 中尺度重力波動 ； 表面通量

並列摘要

This study aims to understand the impacts of gravity waves on the cloud fraction and vertical structures of stratocumulus topped boundary layer (STBL) under two strat-ocumulus regimes. The impact of such gravity waves on STBL is investigated using a high-resolution vector vorticity equation based cloud resolving model (VVM) (Jung and Arakawa 2008; Wu and Arakawa 2011) by adding large-scale convergence that mimics observed mesoscale semidiurnal waves.
The results show that the wave induced vertical velocity causes STBL to become decoupled. During the ascending phase, the cloud is lifted and thickens. With larger cloud amount, Entrainment-Liquid Flux feedback (ELF) starts to adjust by enhancing cloud top entrainment and cloud base warming, which causes STBL to become decou-pled. Furthermore, the results show that the vertical structure and cloud fraction at the end of simulation is largely determined by the sea surface fluxes. The experiment with weaker surface fluxes causes STBL to break up by limiting Surface-based Mixed Layer (SML) cumuliform clouds.

並列關鍵字

stratocumulus ； upsidence wave ； decoupling ； entrainment ； surface flux ； stratocumulus-topped boundary layer ； STBL

參考文獻

Arakawa, a., J. H. Jung, and C. M. Wu, 2011: Toward unification of the multiscale modeling of the atmosphere. Atmos. Chem. Phys., 11, 3731–3742, doi:10.5194/acp-11-3731-2011.

Arakawa, A., and W. H. Schubert, 1974: Interaction of a cumulus cloud ensemble with the large scale environment, {P}art {I}. J. Atmos. Sci., 31, 674–701, doi:10.1175/1520-0469(1974)031<0674:IOACCE>2.0.CO;2.

Bretherton, C. S., and M. C. Wyant, 1997: Moisture Transport, Lower-Tropospheric Stability, and Decoupling of Cloud-Topped Boundary Layers. J. Atmos. Sci., 54, 148–167, doi:10.1175/1520-0469(1997)054<0148:MTLTSA>2.0.CO;2.

——, and P. N. Blossey, 2014: Low cloud reduction in a greenhouse-warmed climate: Results from Lagrangian les of a subtropical marine cloudiness transition. J. Adv. Model. Earth Syst., 6, 91–114, doi:10.1002/2013MS000250.

Connolly, P. J., G. Vaughan, P. Cook, G. Allen, H. Coe, T. W. Choularton, C. Dearden, and a. Hill, 2013: Modelling the effects of gravity waves on stratocumulus clouds observed during VOCALS-UK. Atmos. Chem. Phys., 13, 7133–7152, doi:10.5194/acp-13-7133-2013. http://www.atmos-chem-phys.net/13/7133/2013/.