New microphysics sensor for aircraft use

Gerber, H.; Arends, B. G.; Ackerman, Andrew S.

doi:10.1016/0169-8095(94)90001-9

Cited by 191 publications

(121 citation statements)

References 22 publications

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“…A detailed description of the ACTOS payload and its general performance is given in Siebert et al (2006a). The analysis of this work is mainly based on measurements of the three-dimensional wind vector measured with an ultra-sonic anemometer (hereafter called "sonic"), Solent HS (Gill Instruments, Lymington, UK), the liquid water content (LW C) measured with a particle volume monitor (PVM-100A; Gerber et al 1994), the temperature (T ) measured with a special cloud thermometer (UltraFast Thermometer, UFT, Haman et al 1997), the absolute humidity (a) measured with an open-pass infrared absorption hygrometer (Licor, LI-7500) and the number concentration of interstitial aerosol (N ) measured with a condensation particle counter (CPC, model 3762A, TSI Inc., St. Paul, Minnesota, USA). A comprehensive description of the measurement equipment can be found in Siebert et al (2003).…”

Section: Methodsmentioning

confidence: 99%

Observation of a Self-Limiting, Shear-Induced Turbulent Inversion Layer Above Marine Stratocumulus

Katzwinkel

Siebert

Shaw

2011

Boundary-Layer Meteorol

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High-resolution measurements of thermodynamic, microphysical, and turbulence properties inside a turbulent inversion layer above a marine stratocumulus cloud layer are presented. The measurements are performed with the helicopter-towed measurement payload Airborne Cloud Turbulence Observation System (ACTOS), which allows for sampling with low true air speeds and steep profiles through cloud top. Vertical profiles show that the turbulent inversion layer consists of clear air above the cloud top, with nearly linear profiles of potential temperature, horizontal wind speed, absolute humidity, and concentration of interstitial aerosol. The layer is turbulent, with an energy dissipation rate nearly the same as that in the lower cloud, suggesting that the two are actively coupled, but with significant anisotropic turbulence at the large scales within the turbulent inversion layer. The turbulent inversion layer is traversed six times and the layer thickness is observed to vary between 37 and 85 m, whereas the potential temperature and horizontal wind speed differences at the top and bottom of the layer remain essentially constant. The Richardson number therefore increases with increasing layer thickness, from approximately 0.2 to 0.7, suggesting that the layer develops to the point where shear production of turbulence is sufficiently weak to be balanced by buoyancy suppression. This picture is consistent with prior numerical simulations of the evolution of turbulence in localized stratified shear layers. It is observed that the large eddy scale is suppressed by buoyancy and is on the order of the Ozmidov scale, much less than the thickness of the turbulent inversion layer, such that direct mixing between the cloud top and the free troposphere is inhibited, and the entrainment velocity tends to decrease with increasing turbulent inversion-layer thickness. Qualitatively, the turbulent inversion layer likely grows through nibbling rather than engulfment.

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Section: Methodsmentioning

confidence: 99%

Observation of a Self-Limiting, Shear-Induced Turbulent Inversion Layer Above Marine Stratocumulus

Katzwinkel

Siebert

Shaw

2011

Boundary-Layer Meteorol

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“…9. The left panel shows in-cloud average liquid water at different heights measured using the Gerber PVM-100 probe (Gerber et al 1994) during the C130 RICO flights. The mean liquid water sampled within a height interval, conditioned on the presence of liquid water, increases nearly adiabatically for the first few hundred meters above cloudbase, and somewhat less rapidly thereafter.…”

Section: Zoom In On Rico Conditionsmentioning

confidence: 99%

Revealing differences in GCM representations of low clouds

2009

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Aquaplanet configurations of four atmospheric general circulation models (GCMs) are compared with standard, Earth-like configurations and observations. The focus here is on tropical, low-level clouds, which have been identified as important for estimates of climate sensitivity. Investigating the distribution of the monthly mean vertical velocity and lower-tropospheric stability, the aquaplanets are seen to capture the core of the distribution of the more Earth-like configurations, whose distributions are, in turn, similar to that of reanalysis data. By conditionally sampling over these distributions, low-cloud regimes are defined, separating shallow cumulus convection from stratocumulus. Within each regime, the GCMs produce similar large-scale environments, yet disparate depictions of the clouds. Aquaplanets lack stratocumulus because of their zonally symmetric boundary conditions, but produce extensive trade-wind regions populated by shallow cumulus clouds just like those in the Earth-like setting. The analysis shows that aquaplanets can be compared with observations, just as well as the Earth-like configuration, with the added ability to focus on particular regimes without complications from geographical or temporal biases.

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“…The measured wind vector is transformed into an earth-fixed system using information about the payload position, attitude, and velocity taken from the GPS and inertial navigation systems (see Wendisch and Brenguier, 2013 for details). In addition to a PVM-100A (Gerber et al, 1994), which measures the integral properties of the cloud droplet spectrum, a Phase Doppler Interferometer (PDI) for single droplet measurements in the size range of 1 to 180 µm is included Wendisch and Brenguier, 2013).…”

Section: The Actos Payloadmentioning

confidence: 99%

The fine-scale structure of the trade wind cumuli over Barbados – an introduction to the CARRIBA project

et al. 2013

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Abstract. The CARRIBA (Cloud, Aerosol, Radiation and tuRbulence in the trade wInd regime over BArbados) project, focused on high resolution and collocated measurements of thermodynamic, turbulent, microphysical, and radiative properties of trade wind cumuli over Barbados, is introduced. The project is based on two one-month field campaigns in November 2010 (climatic wet season) and April 2011 (climatic dry season). Observations are based on helicopterborne and ground-based measurements in an area of 100 km 2 off the coast of Barbados. CARRIBA is accompanied by long-term observations at the Barbados Cloud Observatory located at the East coast of Barbados since early in 2010 and which provides a longer-term context for the CARRIBA measurements. The deployed instrumentation and sampling strategy are presented together with a classification of the meteorological conditions. The two campaigns were influenced by different air masses advected from the Caribbean area, the Atlantic Ocean, and the African continent which led to distinct aerosol conditions. Pristine conditions with low aerosol particle number concentrations of ∼100 cm 3 were alternating with periods influenced by Saharan dust or aerosol from biomass burning resulting in comparably high number concentrations of ∼ 500 cm 3 . The biomass burning aerosol was originating from both the Caribbean area and Africa. The shallow cumulus clouds responded to the different aerosol conditions with a wide range of mean droplet sizes and number concentrations. Two days with different aerosol and cloud microphysical properties but almost identical meteorological conditions have been analyzed in detail. The differences in the droplet number concentration and droplet sizes appear not to show any significant change for turbulent cloud mixing, but the relative roles of droplet inertia and sedimentation in initiating coalescence, as well as the cloud reflectivity, do change substantially.

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New microphysics sensor for aircraft use

Cited by 191 publications

References 22 publications

Observation of a Self-Limiting, Shear-Induced Turbulent Inversion Layer Above Marine Stratocumulus

Observation of a Self-Limiting, Shear-Induced Turbulent Inversion Layer Above Marine Stratocumulus

Revealing differences in GCM representations of low clouds

The fine-scale structure of the trade wind cumuli over Barbados – an introduction to the CARRIBA project

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