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  • Author or Editor: Szymon P. Malinowski x
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Krzysztof E. Haman
,
Szymon P. Malinowski
,
Bożena D. Struś
,
Reinhold Busen
, and
Andrzej Stefko

Abstract

A new version of an ultrafast aircraft resistance thermometer (UFT-F) with a time constant of the order 10−4 s,for use in both cloudy and cloudless air, is described. It evolved from an earlier version (UFT-S). Its sensing element is similar to that in UFT-S and consists of a 5-mm-long and 2.5-μm-thick platinum-coated tungsten wire, located on a rotatable vane behind a thin vertical rod that protects the sensor against direct impact of cloud droplets and other objects. Such construction introduces much smaller thermal disturbances than do more massive housings of other types of immersion thermometers and permits taking full advantage of low thermal inertia of the sensing wire. However, aerodynamic disturbances created by vortex shedding from the protective rod induce adiabatic fluctuations of temperature, which appear on the temperature records as “noise.” In the case of the UFT-S the level of this noise has become intolerable at airspeeds of about 40 m s−1, limiting applicability of this instrument to slow aircraft or gliders. For UFT-F the shape of the protective rod has been redesigned and endowed with a special system of reducing aerodynamic disturbances behind it, which made it usable at airspeeds up to 100 m s−1 in cloudless air or warm clouds. For use in supercooled clouds, a special variety of UFT-F (denoted here UFT-D) has been designed. As in its predecessor, its sensing element is a 5-mm-long, 2.5-μm-thick, platinum-coated tungsten resistive wire protected against impact of cloud droplets by an airfoil-shaped rod, but all its icing-sensitive parts are electrically heated to prevent buildup of ice. This modification required a total change of mechanical structure of the instrument. Tests during the Third Canadian Freezing Drizzle Experiment showed that UFT-D can perform fairly well in water clouds supercooled down to at least −8°C and that its heating system introduces no intolerable disturbances into the record. Use of UFT-D in ice or mixed clouds is limited by the fact that the protective rod is not effective enough against ice crystals bigger than about 200 μm, which can quickly destroy the delicate sensing element.

The paper gives details of construction as well as results of wind tunnel and in-flight tests of these instruments.

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Yong-Feng Ma
,
Szymon P. Malinowski
,
Katarzyna Karpińska
,
Hermann E. Gerber
, and
Wojciech Kumala

Abstract

The authors have analyzed the scaling behavior of marine boundary layer (MBL) clouds using high-resolution temperature (T) and liquid water content (LWC) fluctuations from aircraft measurements collected over the Pacific Ocean during the Physics of Stratocumulus Top (POST) research campaign in summer of 2008. As an extension of the past studies for scale-invariant properties of MBL clouds, the authors studied the variability of scaling exponents with height. The results showed that both LWC and T have two distinct scaling regimes: the first one displays scale invariance over a range from about 1–5 m to at least 7 km, and the second one goes from about 0.1–1 to 1–5 m. For the large-scale regime (r > 1–5 m), turbulence in MBL clouds is multifractal, while scale break and scaling exponents vary with height, most significantly in the cloud-top region. For example, LWC spectral exponent β increases from 1.42 at cloud base to 1.58 at cloud top, while scale break decreases from ~5 m at cloud base to 0.8 m at cloud top. The bifractal parameters (H 1, C 1) for LWC increase from (0.14, 0.02) at cloud base to (0.33, 0.1) at cloud top while maintaining a statistically significant linear relationship C 1 ≈ 0.4H 1 − 0.04 in MBL clouds. From near surface to cloud top, (H 1, C 1) for T also increase with height, but above cloud top H 1 increases and C 1 decreases with height. The results suggest the existence of three turbulence regimes: near the surface, in the middle of the boundary layer, and in the cloud-top region, which need to be distinguished.

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Emmanuel O. Akinlabi
,
Marta Wacławczyk
,
Juan Pedro Mellado
, and
Szymon P. Malinowski

Abstract

In this work, direct numerical simulation (DNS) of the stratocumulus cloud-top mixing layer is used to test various approaches to estimate the turbulence kinetic energy (TKE) dissipation rate ε from one-dimensional (1D) intersections that resemble experimental series. Results of these estimates are compared with “true” (DNS) values of ε in buoyant and inhomogeneous atmospheric flows. We focus on recently proposed methods of the TKE dissipation-rate retrievals based on zero crossings and recovering the missing part of the spectrum. These methods are tested on fully resolved turbulence fields and compared to standard retrievals from power spectra and structure functions. Anisotropy of turbulence due to buoyancy is shown to influence retrievals based on the vertical velocity component. TKE dissipation-rate estimates from the number of crossings correspond well to spectral estimates. The method based on the recovery of the missing part of the spectrum works best for Pope’s model of the dissipation spectrum and is sensitive to external intermittency. This allows for characterization of external intermittency by the Taylor-to-Liepmann scale ratio. Further improvements of this method are possible when the variance of the velocity derivative is used instead of the number of zero crossings per unit length. In conclusion, the new methods of TKE dissipation-rate retrieval from 1D series provide a valuable complement to standard approaches.

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Andreas Muhlbauer
,
Wojciech W. Grabowski
,
Szymon P. Malinowski
,
Thomas P. Ackerman
,
George H. Bryan
,
Zachary J. Lebo
,
Jason A. Milbrandt
,
Hugh Morrison
,
Mikhail Ovchinnikov
,
Sarah Tessendorf
,
Julie M. Thériault
, and
Greg Thompson
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Holger Siebert
,
Kai-Erik Szodry
,
Ulrike Egerer
,
Birgit Wehner
,
Silvia Henning
,
Karine Chevalier
,
Janine Lückerath
,
Oliver Welz
,
Kay Weinhold
,
Felix Lauermann
,
Matthias Gottschalk
,
André Ehrlich
,
Manfred Wendisch
,
Paulo Fialho
,
Greg Roberts
,
Nithin Allwayin
,
Simeon Schum
,
Raymond A. Shaw
,
Claudio Mazzoleni
,
Lynn Mazzoleni
,
Jakub L. Nowak
,
Szymon P. Malinowski
,
Katarzyna Karpinska
,
Wojciech Kumala
,
Dominika Czyzewska
,
Edward P. Luke
,
Pavlos Kollias
,
Robert Wood
, and
Juan Pedro Mellado

Abstract

We report on the Azores Stratocumulus Measurements of Radiation, Turbulence and Aerosols (ACORES) campaign, which took place around Graciosa and Pico Islands/Azores in July 2017. The main objective was to investigate the vertical distribution of aerosol particles, stratocumulus microphysical and radiative properties, and turbulence parameters in the eastern North Atlantic. The vertical exchange of mass, momentum, and energy between the free troposphere (FT) and the cloudy marine boundary layer (MBL) was explored over a range of scales from submeters to kilometers. To cover these spatial scales with appropriate measurements, helicopter-borne observations with unprecedented high resolution were realized using the Airborne Cloud Turbulence Observation System (ACTOS) and Spectral Modular Airborne Radiation Measurement System–Helicopter-Borne Observations (SMART-HELIOS) instrumental payloads. The helicopter-borne observations were combined with ground-based aerosol measurements collected at two continuously running field stations on Pico Mountain (2,225 m above sea level, in the FT), and at the Atmospheric Radiation Measurement (ARM) station on Graciosa (at sea level). First findings from the ACORES observations we are discussing in the paper are as follows: (i) we have observed a high variability of the turbulent cloud-top structure on horizontal scales below 100 m with local temperature gradients of up to 4 K over less than 1 m vertical distance, (ii) we have collected strictly collocated radiation measurements supporting the relevance of small-scale processes by revealing significant inhomogeneities in cloud-top brightness temperature to scales well below 100 m, and (iii) we have concluded that aerosol properties are completely different in the MBL and FT with often-complex stratification and frequently observed burst-like new particle formation.

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Bjorn Stevens
,
Donald H. Lenschow
,
Gabor Vali
,
Hermann Gerber
,
A. Bandy
,
B. Blomquist
,
J. -L. Brenguier
,
C. S. Bretherton
,
F. Burnet
,
T. Campos
,
S. Chai
,
I. Faloona
,
D. Friesen
,
S. Haimov
,
K. Laursen
,
D. K. Lilly
,
S. M. Loehrer
,
Szymon P. Malinowski
,
B. Morley
,
M. D. Petters
,
D. C. Rogers
,
L. Russell
,
V. Savic-Jovcic
,
J. R. Snider
,
D. Straub
,
Marcin J. Szumowski
,
H. Takagi
,
D. C. Thornton
,
M. Tschudi
,
C. Twohy
,
M. Wetzel
, and
M. C. van Zanten

The second Dynamics and Chemistry of Marine Stratocumulus (DYCOMS-II) field study is described. The field program consisted of nine flights in marine stratocumulus west-southwest of San Diego, California. The objective of the program was to better understand the physics a n d dynamics of marine stratocumulus. Toward this end special flight strategies, including predominantly nocturnal flights, were employed to optimize estimates of entrainment velocities at cloud-top, large-scale divergence within the boundary layer, drizzle processes in the cloud, cloud microstructure, and aerosol–cloud interactions. Cloud conditions during DYCOMS-II were excellent with almost every flight having uniformly overcast clouds topping a well-mixed boundary layer. Although the emphasis of the manuscript is on the goals and methodologies of DYCOMS-II, some preliminary findings are also presented—the most significant being that the cloud layers appear to entrain less and drizzle more than previous theoretical work led investigators to expect.

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