Modified ultrafast thermometer UFT-M and temperature measurements during Physics of Stratocumulus Top (POST)

Kumala, Wojciech; Haman, Krzysztof E.; Kopec, M. K.; Khelif, D.; Malinowski, Szymon P.

doi:10.5194/amt-6-2043-2013

Cited by 14 publications

(11 citation statements)

References 33 publications

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“…A unique data set containing the highest currently available spatial resolution, i.e. close to 1 m for three components of wind velocity and humidity, 5 cm for LWC and 5 mm for temperature (see Kumala et al , ), was acquired and is publicly available (http://www.eol.ucar.edu/projects/post/). Another important and unique aspect of the campaign was the flight pattern: most of the measurement time was spent on manoeuvres called porpoises (shallow vertical profiles), covering a layer ± 100 m from the cloud top.…”

Section: Physics Of the Stratocumulus Top (Post) Field Campaignmentioning

confidence: 99%

“…A unique data set containing the highest currently available spatial resolution, i.e. close to 1 m for three components of wind velocity and humidity, 5 cm for LWC and 5 mm for temperature (see Kumala et al, 2013), was acquired and is publicly available (http://www.eol.ucar.edu/projects/post/). A mixing proportion equal to 0 means that no cloud-top air was mixed with air from above the inversion; 1 -only cloud air was mixed.…”

Section: Physics Of the Stratocumulus Top (Post) Field Campaignmentioning

confidence: 99%

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Effects of wind shear and radiative cooling on the stratocumulus‐topped boundary layer

Kopec

Malinowski

Piotrowski

2016

Quart J Royal Meteoro Soc

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The effects of wind shear and radiative cooling on the stratocumulus‐topped boundary layer (STBL) were investigated via a set of large‐eddy simulations. The set‐up of the numerical experiments was based on Flight TO13 from the Physics of Stratocumulus Top (POST) field campaign, in which sensible and latent heat fluxes at the surface were small and thermodynamic conditions prevented cloud‐top entrainment instability. The results demonstrate that the presence of radiative cooling invigorated convective circulations across the STBL and sharpened the inversion above the cloud, while wind shear at the top of the STBL was a source of turbulence in the capping inversion and caused dilution of the cloud top. The flux and gradient Richardson numbers in the capping inversion and in the topmost layer of the cloud were nearly critical. Analysis of the turbulent kinetic energy (TKE) budget and its transport indicated that turbulence in the inversion capping the cloud was produced locally by wind shear and was dynamically decoupled from the turbulence driven by convective circulations across the STBL. Similar conclusions were derived for the topmost part of the cloud.

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Section: Physics Of the Stratocumulus Top (Post) Field Campaignmentioning

confidence: 99%

“…A unique data set containing the highest currently available spatial resolution, i.e. close to 1 m for three components of wind velocity and humidity, 5 cm for LWC and 5 mm for temperature (see Kumala et al, 2013), was acquired and is publicly available (http://www.eol.ucar.edu/projects/post/). A mixing proportion equal to 0 means that no cloud-top air was mixed with air from above the inversion; 1 -only cloud air was mixed.…”

Section: Physics Of the Stratocumulus Top (Post) Field Campaignmentioning

confidence: 99%

Effects of wind shear and radiative cooling on the stratocumulus‐topped boundary layer

Kopec

Malinowski

Piotrowski

2016

Quart J Royal Meteoro Soc

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“…3 of Gerber et al (2010). In this study we focus on fine-scale measurements collected with the modernized Ultra Fast Thermometer (UFT-M) (Kumala et al, 2013), Particulate Volume Monitor PVM-100 (Gerber et al, 1994), and other fast-response instruments collocated in close proximity around the radome of the aircraft (Fig. 1).…”

Section: Post: Physics Of Stratocumulus Top Research Campaignmentioning

confidence: 99%

Physics of Stratocumulus Top (POST): turbulent mixing across capping inversion

Malinowski¹,

Gerber²,

Plante³

et al. 2013

Preprint

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High spatial resolution measurements of temperature and liquid water content, accompanied by moderate resolution measurements of humidity and turbulence, collected during the Physics of Stratocumulus Top experiment are analyzed. Two thermodynamically, meteorologically and even optically different cases are investigated. An algorithmic division of the cloud top region into layers is proposed. Analysis of dynamic stability across these layers leads to the conclusion that the inversion capping the cloud and the cloud top region are turbulent due to the wind shear, which is strong enough to compensate for high static stability of the inversion. The thickness of this mixing layer adapts to wind and temperature jumps such that the gradient Richardson number stays close to its critical value. Turbulent mixing governs transport across the inversion, but the consequences of this mixing depend on the thermodynamic properties of cloud top and free troposphere. The effects of buoyancy-sorting of the mixed parcels in the cloud top region are different in conditions that permit or prevent cloud top entrainment instability. Removal of negatively buoyant air from the cloud top is observed in the first case, while buildup of the diluted cloud top layer is observed in the second one

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“…More recently, Kumala et al . [] report variation in liquid water content on scale of 5 m and small‐scale filaments of temperature fluctuations on scale of 10 cm. Beals et al .…”

Section: Discussionmentioning

confidence: 65%

“…Siebert et al [2006] presented in situ measurements showing a change in turbulent energy dissipation rate by 4 orders of magnitude within 50 m in the vicinity of cloud edges. More recently, Kumala et al [2013] report variation in liquid water content on scale of 5 m and small-scale filaments of temperature fluctuations on scale of 10 cm. Beals et al [2015], on the basis of in situ holographic measurements, report turbulence structure in clouds down to scales of 1 cm.…”

Section: 1002/2016jd025384mentioning

confidence: 98%

High‐resolution photography of clouds from the surface: Retrieval of optical depth of thin clouds down to centimeter scales

2017

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This paper describes the approach and presents initial results, for a period of several minutes in north central Oklahoma, of an examination of clouds by high‐resolution digital photography from the surface looking vertically upward. A commercially available camera having 35 mm equivalent focal length up to 1200 mm (nominal resolution as fine as 6 µrad, which corresponds to 9 mm for cloud height 1.5 km) is used to obtain a measure of zenith radiance of a 30 m × 30 m domain as a two‐dimensional image consisting of 3456 × 3456 pixels (12 million pixels). Downwelling zenith radiance varies substantially within single images and between successive images obtained at 4 s intervals. Variation in zenith radiance found on scales down to about 10 cm is attributed to variation in cloud optical depth (COD). Attention here is directed primarily to optically thin clouds; COD less than about 2. A radiation transfer model used to relate downwelling zenith radiance to COD and to relate the counts in the camera image to zenith radiance permits determination of COD on a pixel‐by‐pixel basis. COD for thin clouds determined in this way exhibits considerable variation, for example, an order of magnitude within 15 m, a factor of 2 within 4 m, and 25% (0.12 to 0.15) over 14 cm. This approach, which examines cloud structure on scales 3 to 5 orders of magnitude finer than satellite products, opens new avenues for examination of cloud structure and evolution.

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Modified ultrafast thermometer UFT-M and temperature measurements during Physics of Stratocumulus Top (POST)

Cited by 14 publications

References 33 publications

Effects of wind shear and radiative cooling on the stratocumulus‐topped boundary layer

Effects of wind shear and radiative cooling on the stratocumulus‐topped boundary layer

Physics of Stratocumulus Top (POST): turbulent mixing across capping inversion

High‐resolution photography of clouds from the surface: Retrieval of optical depth of thin clouds down to centimeter scales

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