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

Malinowski, Szymon P.; Gerber, H.; Plante, I. Jen-La; Kopec, M. K.; Kumala, Wojciech; Nurowska, Katarzyna; Chuang, P. Y.; Khelif, D.; Haman, Krzysztof E.

doi:10.5194/acp-13-12171-2013

Cited by 62 publications

(130 citation statements)

References 40 publications

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“…In order to present the more detailed properties of the procedure, we used the velocity signal from one of the horizontal flight segments that took place within the turbulent atmospheric boundary layer. This segment was a part of flight 13 of the POST airborne research campaign Malinowski et al, 2013). The data were provided in the east, north, up (ENU) coordinate system.…”

Section: Methods Based On Recovering the Missing Part Of The Spectrummentioning

confidence: 99%

“…We have chosen horizontal segments at various levels within the boundary layer from flights TO10 and TO13. These flights were investigated in detail by Malinowski et al (2013), due to the fact that they represent two thermodynamically and microphysically different types of stratocumulus-topped boundary layer. The dissipation rates of turbulent kinetic energy estimated from the standard structure function method SF and dissipation rates estimated from the modified zero-crossing methods NCF and NCR introduced in Sect.…”

Section: Broader Overview Of the Methods' Performancementioning

confidence: 99%

“…The new approaches are tested on velocity signals obtained during the Physics of Stratocumulus Top (POST) research campaign, which was designed to investigate the marine stratocumulus clouds and the details of vertical structure of the stratocumulus-topped boundary layer (STBL; Gerber et al, 2013;Malinowski et al, 2013). The observed winds were measured using the CIRPAS Twin Otter research aircraft with sampling frequency f s = 40 Hz, which corresponds to a resolution of 2.75 m for the speed of the aircraft 55 m s −1 .…”

Section: Introductionmentioning

confidence: 99%

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Novel approaches to estimating the turbulent kinetic energy dissipation rate from low- and moderate-resolution velocity fluctuation time series

Wacławczyk

Kopeć

et al. 2017

Atmos. Meas. Tech.

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Abstract. In this paper we propose two approaches to estimating the turbulent kinetic energy (TKE) dissipation rate, based on the zero-crossing method by Sreenivasan et al. (1983). The original formulation requires a fine resolution of the measured signal, down to the smallest dissipative scales. However, due to finite sampling frequency, as well as measurement errors, velocity time series obtained from airborne experiments are characterized by the presence of effective spectral cutoffs. In contrast to the original formulation the new approaches are suitable for use with signals originating from airborne experiments. The suitability of the new approaches is tested using measurement data obtained during the Physics of Stratocumulus Top (POST) airborne research campaign as well as synthetic turbulence data. They appear useful and complementary to existing methods. We show the number-of-crossings-based approaches respond differently to errors due to finite sampling and finite averaging than the classical power spectral method. Hence, their application for the case of short signals and small sampling frequencies is particularly interesting, as it can increase the robustness of turbulent kinetic energy dissipation rate retrieval.

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Section: Methods Based On Recovering the Missing Part Of The Spectrummentioning

confidence: 99%

Section: Broader Overview Of the Methods' Performancementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Novel approaches to estimating the turbulent kinetic energy dissipation rate from low- and moderate-resolution velocity fluctuation time series

Wacławczyk

Kopeć

et al. 2017

Atmos. Meas. Tech.

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“…The top of the EIL is not as well defined as its base due to weaker vertical gradients of dynamic and thermodynamic properties relaxing to FT values over tens of meters at times (Wood, 2012). A method adopted and modified from that of Malinowski et al (2013) is applied, where the top of the EIL is taken to be the highest point where turbulent kinetic energy (TKE) and the variance of potential temperature (θ ) simultaneously exceed 0.1 m 2 s −2 and 10 % of maximum variance, respectively. This location is identified based on the smoothed moving variance and average of 75 points of 10 Hz data used to calculate both the θ variance and TKE for spiral soundings.…”

Section: Layer Definitionsmentioning

confidence: 99%

“…This layer exhibits strong gradients in thermodynamic and dynamic properties. Although numerous airborne and modeling studies have attempted to increase our understanding about the thermodynamic and dynamic nature of the EIL (e.g., Caughey et al, 1982;Moeng et al, 2005;Haman et al, 2007;Wang et al, 2008;Carman et al, 2012;Katzwinkel et al, 2012;Gerber et al, 2013;Malinowski et al, 2013;Jen-La Plante et al, 2016), aerosol characteristics in this thin layer have not been studied in detail.…”

Section: Introductionmentioning

confidence: 99%

Aerosol characteristics in the entrainment interface layer in relation to the marine boundary layer and free troposphere

et al. 2018

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Abstract. This study uses airborne data from two field campaigns off the California coast to characterize aerosol size distribution characteristics in the entrainment interface layer (EIL), a thin and turbulent layer above marine stratocumulus cloud tops, which separates the stratocumulus-topped boundary layer (STBL) from the free troposphere (FT). The vertical bounds of the EIL are defined in this work based on considerations of buoyancy and turbulence using thermodynamic and dynamic data. Aerosol number concentrations are examined from three different probes with varying particle diameter (D p ) ranges: > 3 nm, > 10 nm, and 0.11-3.4 µm. Relative to the EIL and FT layers, the sub-cloud (SUB) layer exhibited lower aerosol number concentrations and higher surface area concentrations. High particle number concentrations between 3 and 10 nm in the EIL are indicative of enhanced nucleation, assisted by high actinic fluxes, cool and moist air, and much lower surface area concentrations than the STBL. Slopes of number concentration versus altitude in the EIL were correlated with the particle number concentration difference between the SUB and lower FT layers. The EIL aerosol size distribution was influenced by varying degrees from STBL aerosol versus subsiding FT aerosol depending on the case examined. These results emphasize the important role of the EIL in influencing nucleation and aerosol-cloudclimate interactions.

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Resolution and domain‐size sensitivity in implicit large‐eddy simulation of the stratocumulus‐topped boundary layer

Pedersen

Malinowski

Grabowski

2016

J Adv Model Earth Syst

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As a complement to measurements, numerical modeling facilitates improved understanding of the complex turbulent processes in the stratocumulus-topped boundary layer (STBL). Due to limited computational resources simulations are often run at too coarse resolutions to resolve details of cloud-top turbulence and potentially in computational domains too small to account for the largest scales of boundary layer circulations. The effects of such deficiencies are not fully understood. Here the influence of resolution/ anisotropy of the computational grid and domain size in under-resolved implicit large-eddy simulation of the STBL is investigated. The performed simulations are based on data from the first research flight of the DYCOMS-II campaign. Regarding cloud cover and domain-averaged liquid water path, simulations with horizontal/vertical grid spacing of 35/5 m, 70/10 m, and 105/15 m are found to agree better with measurements than more computationally expensive simulations with isotropic grid boxes, e.g., with 10/10 m or 15/15 m grid spacing. While decreasing the vertical grid spacing allows more representative simulation of the thin, turbulent, stably stratified interfacial layer between the STBL and the free troposphere, coarsening the horizontal resolution dampens vertical velocity fluctuations in this region and mimics the observed anisotropy of stably stratified small-scale turbulence near the cloud top. The size of the computational domain is found to have almost no impact on mean cloud properties. However, increasing it from 3:533:5 km 2 to 14314 km 2 does lead to the occurrence of larger coherent updraft structures. Increasing it further to 21321 km 2 shows little or no increase in the updraft size.

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

Cited by 62 publications

References 40 publications

Novel approaches to estimating the turbulent kinetic energy dissipation rate from low- and moderate-resolution velocity fluctuation time series

Novel approaches to estimating the turbulent kinetic energy dissipation rate from low- and moderate-resolution velocity fluctuation time series

Aerosol characteristics in the entrainment interface layer in relation to the marine boundary layer and free troposphere

Resolution and domain‐size sensitivity in implicit large‐eddy simulation of the stratocumulus‐topped boundary layer

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