| DOI: | 10.1175/JCLI-D-17-0693.1
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| Scopus记录号: | 2-s2.0-85047099793
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| 论文题名: | Diurnal circulation adjustment and organized deep convection |
| 作者: | Ruppert J.H.; Jr.; Hohenegger C.
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| 刊名: | Journal of Climate
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| ISSN: | 8948755
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| 出版年: | 2018
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| 卷: | 31, 期:12 | | 起始页码: | 4899
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| 结束页码: | 4916
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| 语种: | 英语
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| 英文关键词: | Atmosphere
; Deep convection
; Large-scale motions
; Mesoscale processes
; Radiative forcing
; Tropics
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| Scopus关键词: | Atmospheric radiation
; Earth atmosphere
; Rain
; Tropics
; Deep convection
; Diurnal precipitation
; Large scale motion
; Large-scale circulation
; Mesoscale process
; Nocturnal precipitation
; Radiative forcings
; Radiative-convective equilibrium
; Natural convection
; atmospheric circulation
; atmospheric convection
; atmospheric dynamics
; climate feedback
; diurnal variation
; Hadley cell
; intertropical convergence zone
; mesoscale motion
; radiative forcing
; temperature gradient
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| 英文摘要: | This study investigates the diurnal cycle of tropical organized deep convection and the feedback in large-scale circulation. By considering gravity wave phase speeds, we find that the circulation adjustment into weak temperature gradient (WTG) balance occurs rapidly (<6 h) relative to diurnal diabatic forcing on the spatial scales typical of organized convection (≤500 km). Convection-permitting numerical simulations of self-aggregation in diurnal radiative-convective equilibrium (RCE) are conducted to explore this further. These simulations depict a pronounced diurnal cycle of circulation linked to organized convection, which indeed maintains WTG balance to first order. A set of sensitivity experiments is conducted to assess what governs the diurnal cycle of organized convection. We find that the "direct radiation-convection interaction" (or lapse-rate) mechanism is of primary importance for diurnal precipitation range, while the "dynamic cloudy-clear differential radiation" mechanism amplifies the range by approximately 30%, and delays the nocturnal precipitation peak by around 5 h. The differential radiation mechanism therefore explains the tendency for tropical heavy rainfall to peak in the early morning, while the lapse-rate mechanism primarily governs diurnal amplitude. The diurnal evolution of circulation can be understood as follows. While nocturnal deep convection invigorated by cloud-top cooling (i.e., the lapse-rate mechanism) leads to strong bottom-heavy circulation at nighttime, the localized (i.e., differential) top-heavy shortwave warming in the convective region invigorates circulation at upper levels in daytime. A diurnal evolution of the circulation therefore arises, from bottom heavy at nighttime to top heavy in daytime, in a qualitatively consistent manner with the observed diurnal pulsing of the Hadley cell driven by the ITCZ. © 2018 American Meteorological Society. |
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| 资源类型: | 期刊论文
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| 标识符: | http://119.78.100.158/handle/2HF3EXSE/111514
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| Appears in Collections: | 气候减缓与适应
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作者单位: | Max Planck Institute for Meteorology, Hamburg, Germany
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| Recommended Citation: | |
Ruppert J.H.,Jr.,Hohenegger C.. Diurnal circulation adjustment and organized deep convection[J]. Journal of Climate,2018-01-01,31(12)
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