气候变化领域集成服务门户(CCPortal): Momentum fluxes from airborne wind measurements in three cumulus cases over land

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DOI	10.5194/acp-22-7373-2022
	Momentum fluxes from airborne wind measurements in three cumulus cases over land
	Koning, Ada Mariska; Nuijens, Louise; Mallaun, Christian
发表日期	2022
ISSN	1680-7316
EISSN	1680-7324
起始页码	7373
结束页码	7388
卷号	22 期号:11 页码:16
英文摘要	Measurements of wind and momentum fluxes are not typically at the centre of field studies on (shallow) cumulus convection, but the mesoscale organization of convection is likely closely tied to patterns in wind. This study combines in situ high-frequency turbulence measurements from a gust probe onboard a Cessna aircraft with downward profiling Doppler wind lidar (DWL) measurements onboard a Falcon aircraft to study variability in the wind profile and momentum fluxes in regions of convection. The dual-aircraft measurements were made during three prototype flights in shallow convective regimes over German agricultural areas (two of which had hilly topography, one flat) in late spring 2019, including forced cumulus humilis under weak winds and popcorn cumuli during stronger wind and wind shear after front passages. All flights show pronounced meso-gamma (2-20 km) scale variability in the wind, with the largest wind variance (on the order of 2-4 m(2) s(-2)) towards cloud base and in the cloud layer on flights with large vertical wind shear. The wind and wind variance profiles measured in situ and by lidar compare very well, despite the DWL's coarse (similar to 8 km) horizontal footprint. This highlights the presence of wind fluctuations on scales larger than a few kilometres and that wind lidars can be used more deliberately in field studies to map (mesoscale) flows. Cloudy transects are associated with more than twice the momentum flux compared with cloud-free transects. The contribution of the updraft to the total momentum flux, typically one-third to two-thirds, is far less than the typical contribution of the updraft to buoyancy flux. Even on the same flight day, momentum flux profiles can differ per track, with one case of counter-gradient momentum transport when the updraft does carry substantial momentum flux. Scales beyond 1 km contribute significantly to the momentum flux and there is clear evidence for compensating flux contributions across scales. The results demonstrate that momentum flux profiles and their variability require understanding of motions across a range of scales, with non-negligible contributions of the clear-sky fluxes and of mesoscales that are likely coupled to the convection.
学科领域	Environmental Sciences; Meteorology & Atmospheric Sciences
语种	英语
WOS研究方向	Environmental Sciences & Ecology ; Meteorology & Atmospheric Sciences
WOS记录号	WOS:000807590600001
来源期刊	ATMOSPHERIC CHEMISTRY AND PHYSICS
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/273821
作者单位	Delft University of Technology; Helmholtz Association; German Aerospace Centre (DLR)
推荐引用方式 GB/T 7714	Koning, Ada Mariska,Nuijens, Louise,Mallaun, Christian. Momentum fluxes from airborne wind measurements in three cumulus cases over land[J],2022,22(11):16.
APA	Koning, Ada Mariska,Nuijens, Louise,&Mallaun, Christian.(2022).Momentum fluxes from airborne wind measurements in three cumulus cases over land.ATMOSPHERIC CHEMISTRY AND PHYSICS,22(11),16.
MLA	Koning, Ada Mariska,et al."Momentum fluxes from airborne wind measurements in three cumulus cases over land".ATMOSPHERIC CHEMISTRY AND PHYSICS 22.11(2022):16.