Koning, Ada Mariska and Nuijens, Louise and Mallaun, Christian and Witschas, Benjamin and Lemmerz, Christian (2022) Momentum fluxes from airborne wind measurements in three cumulus cases over land. Atmospheric Chemistry and Physics (ACP), 22 (11), pp. 7373-7388. Copernicus Publications. doi: 10.5194/acp-22-7373-2022. ISSN 1680-7316.
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Official URL: https://dx.doi.org/10.5194/acp-22-7373-2022
Abstract
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 m2 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 (∼ 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
Item URL in elib: | https://elib.dlr.de/198369/ | ||||||||||||||||||||||||
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Document Type: | Article | ||||||||||||||||||||||||
Title: | Momentum fluxes from airborne wind measurements in three cumulus cases over land | ||||||||||||||||||||||||
Authors: |
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Date: | 8 June 2022 | ||||||||||||||||||||||||
Journal or Publication Title: | Atmospheric Chemistry and Physics (ACP) | ||||||||||||||||||||||||
Refereed publication: | Yes | ||||||||||||||||||||||||
Open Access: | Yes | ||||||||||||||||||||||||
Gold Open Access: | Yes | ||||||||||||||||||||||||
In SCOPUS: | Yes | ||||||||||||||||||||||||
In ISI Web of Science: | Yes | ||||||||||||||||||||||||
Volume: | 22 | ||||||||||||||||||||||||
DOI: | 10.5194/acp-22-7373-2022 | ||||||||||||||||||||||||
Page Range: | pp. 7373-7388 | ||||||||||||||||||||||||
Publisher: | Copernicus Publications | ||||||||||||||||||||||||
ISSN: | 1680-7316 | ||||||||||||||||||||||||
Status: | Published | ||||||||||||||||||||||||
Keywords: | Wind lidar, airborne, momentum flux, turbulence | ||||||||||||||||||||||||
HGF - Research field: | Aeronautics, Space and Transport | ||||||||||||||||||||||||
HGF - Program: | Space | ||||||||||||||||||||||||
HGF - Program Themes: | Earth Observation | ||||||||||||||||||||||||
DLR - Research area: | Raumfahrt | ||||||||||||||||||||||||
DLR - Program: | R EO - Earth Observation | ||||||||||||||||||||||||
DLR - Research theme (Project): | R - Project ADM III cont., R - Wind lidar technology development | ||||||||||||||||||||||||
Location: | Oberpfaffenhofen | ||||||||||||||||||||||||
Institutes and Institutions: | Institute of Atmospheric Physics > Lidar Flugexperimente > Mess- und Sensortechnik OP | ||||||||||||||||||||||||
Deposited By: | Witschas, Dr. Benjamin | ||||||||||||||||||||||||
Deposited On: | 23 Oct 2023 09:06 | ||||||||||||||||||||||||
Last Modified: | 24 Oct 2023 12:23 |
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