scholarly journals PHIPS-HALO: the airborne particle habit imaging and polar scattering probe – Part 2: Characterization and first results

2018 ◽  
Vol 11 (1) ◽  
pp. 341-357 ◽  
Author(s):  
Martin Schnaiter ◽  
Emma Järvinen ◽  
Ahmed Abdelmonem ◽  
Thomas Leisner
Keyword(s):  
Light Scattering ◽  
Mixed Phase ◽  
Proper Function ◽  
The Novel ◽  
Scattering Function ◽  
Airborne Particle ◽  
Microphysical Properties ◽  
Ice Particles ◽  
First Results ◽  
Mixed Phase Clouds

Abstract. The novel aircraft optical cloud probe PHIPS-HALO has been developed to establish clarity regarding the fundamental link between the microphysical properties of single atmospheric ice particles and their appropriated angular light scattering function. After final improvements were implemented in the polar nephelometer part and the acquisition software of PHIPS-HALO, the instrument was comprehensively characterized in the laboratory and was deployed in two aircraft missions targeting cirrus and Arctic mixed-phase clouds. This work demonstrates the proper function of the instrument under aircraft conditions and highlights the uniqueness, quality, and limitations of the data that can be expected from PHIPS-HALO in cloud-related aircraft missions.

scholarly journals PHIPS-HALO: the airborne Particle Habit Imaging and Polar Scattering probe – Part 2: Characterization and first results

2017 ◽  
Author(s):  
Martin Schnaiter ◽  
Emma Järvinen ◽  
Ahmed Abdelmonem ◽  
Thomas Leisner
Keyword(s):  
Light Scattering ◽  
Mixed Phase ◽  
Proper Function ◽  
The Novel ◽  
Scattering Function ◽  
Airborne Particle ◽  
Microphysical Properties ◽  
Ice Particles ◽  
First Results ◽  
Mixed Phase Clouds

Abstract. The novel aircraft optical cloud probe PHIPS-HALO has been developed to establish clarity regarding the fundamental link between the microphysical properties of single atmospheric ice particles and their appropriated angular light scattering function. After final improvements have been implemented to the polar nephelometer part and the acquisition software of PHIPS-HALO, the instrument was comprehensively characterized in the laboratory and was deployed in two aircraft missions targeting cirrus and Arctic mixed-phase clouds. This work demonstrates the proper function of the instrument under aircraft conditions and highlights the uniqueness, quality, and limitations of the data that can be expected from PHIPS-HALO in cloud-related aircraft missions.

scholarly journals Cloud condensation nuclei as a modulator of ice processes in Arctic mixed-phase clouds

2011 ◽  
Vol 11 (15) ◽  
pp. 8003-8015 ◽  
Author(s):  
S. Lance ◽  
M. D. Shupe ◽  
G. Feingold ◽  
C. A. Brock ◽  
J. Cozic ◽  
...  
Keyword(s):  
Droplet Size ◽  
Indirect Effect ◽  
Cloud Condensation Nuclei ◽  
Droplet Size Distribution ◽  
Mixed Phase ◽  
Condensation Nuclei ◽  
Microphysical Properties ◽  
Ice Particles ◽  
Northern Alaska ◽  
Mixed Phase Clouds

Abstract. We propose that cloud condensation nuclei (CCN) concentrations are important for modulating ice formation of Arctic mixed-phase clouds, through modification of the droplet size distribution. Aircraft observations from the Aerosol, Radiation, and Cloud Processes affecting Arctic Climate (ARCPAC) study in northern Alaska in April 2008 allow for identification and characterization of both aerosol and trace gas pollutants, which are then compared with cloud microphysical properties. Consistent with previous studies, we find that the concentration of precipitating ice particles (>400 μm) is correlated with the concentration of large droplets (>30 μm). We are further able to link the observed microphysical conditions to aerosol pollution, originating mainly from long range transport of biomass burning emissions. The case studies demonstrate that polluted mixed-phase clouds have narrower droplet size distributions and contain 1–2 orders of magnitude fewer precipitating ice particles than clean clouds at the same temperature. This suggests an aerosol indirect effect leading to greater cloud lifetime, greater cloud emissivity, and reduced precipitation. This result is opposite to the glaciation indirect effect, whereby polluted clouds are expected to precipitate more readily due to an increase in the concentration of particles acting as ice nuclei.

scholarly journals Cloud condensation nuclei as a modulator of ice processes in Arctic mixed-phase clouds

2011 ◽  
Vol 11 (2) ◽  
pp. 6737-6770 ◽  
Author(s):  
S. Lance ◽  
M. D. Shupe ◽  
G. Feingold ◽  
C. A. Brock ◽  
J. Cozic ◽  
...  
Keyword(s):  
Droplet Size ◽  
Indirect Effect ◽  
Cloud Condensation Nuclei ◽  
Droplet Size Distribution ◽  
Mixed Phase ◽  
Condensation Nuclei ◽  
Microphysical Properties ◽  
Ice Particles ◽  
Northern Alaska ◽  
Mixed Phase Clouds

Abstract. We propose that cloud condensation nuclei (CCN) concentrations are important for modulating ice formation of Arctic mixed-phase clouds, through modification of the droplet size distribution. Aircraft observations from the Aerosol, Radiation, and Cloud Processes affecting Arctic Climate (ARCPAC) study in northern Alaska in April 2008 allow for identification and characterization of both aerosol and trace gas pollutants, which are then compared with cloud microphysical properties. Consistent with previous studies, we find that the concentration of precipitating ice particles (>400 μm) is correlated with the concentration of large droplets (>30 μm). We are further able to link the observed microphysical conditions to aerosol pollution, originating mainly from long range transport of biomass burning emissions. The case studies demonstrate that polluted mixed-phase clouds have narrower droplet size distributions and contain 1–2 orders of magnitude fewer precipitating ice particles than clean clouds at the same temperature. This suggests an aerosol indirect effect leading to greater cloud lifetime, greater cloud emissivity, and reduced precipitation. This result is opposite to the glaciation indirect effect, whereby polluted clouds are expected to precipitate more readily due to an increase in the concentration of particles acting as IN.

scholarly journals Predicting the morphology of ice particles in deep convection using the super-droplet method: development and evaluation of SCALE-SDM 0.2.5-2.2.0, -2.2.1, and -2.2.2

2020 ◽  
Vol 13 (9) ◽  
pp. 4107-4157 ◽  
Author(s):  
Shin-ichiro Shima ◽  
Yousuke Sato ◽  
Akihiro Hashimoto ◽  
Ryohei Misumi
Keyword(s):  
Method Development ◽  
Cloud Condensation Nuclei ◽  
Deep Convection ◽  
Cloud Microphysics ◽  
Mixed Phase ◽  
Computational Time ◽  
Ice Particles ◽  
Mass Dimension ◽  
Mixed Phase Clouds ◽  
Droplet Method

Abstract. The super-droplet method (SDM) is a particle-based numerical scheme that enables accurate cloud microphysics simulation with lower computational demand than multi-dimensional bin schemes. Using SDM, a detailed numerical model of mixed-phase clouds is developed in which ice morphologies are explicitly predicted without assuming ice categories or mass–dimension relationships. Ice particles are approximated using porous spheroids. The elementary cloud microphysics processes considered are advection and sedimentation; immersion/condensation and homogeneous freezing; melting; condensation and evaporation including cloud condensation nuclei activation and deactivation; deposition and sublimation; and coalescence, riming, and aggregation. To evaluate the model's performance, a 2-D large-eddy simulation of a cumulonimbus was conducted, and the life cycle of a cumulonimbus typically observed in nature was successfully reproduced. The mass–dimension and velocity–dimension relationships the model predicted show a reasonable agreement with existing formulas. Numerical convergence is achieved at a super-particle number concentration as low as 128 per cell, which consumes 30 times more computational time than a two-moment bulk model. Although the model still has room for improvement, these results strongly support the efficacy of the particle-based modeling methodology to simulate mixed-phase clouds.

scholarly journals Vertical redistribution of moisture and aerosol in orographic mixed-phase clouds

2020 ◽  
Author(s):  
Annette K. Miltenberger ◽  
Paul R. Field ◽  
Adrian H. Hill
Keyword(s):  
Air Temperature ◽  
Unified Model ◽  
Mixed Phase ◽  
Atmospheric Models ◽  
Microphysical Properties ◽  
Cloud Microphysical Processes ◽  
Microphysical Processes ◽  
Mixed Phase Clouds ◽  
Natural Laboratory

Abstract. Orographic wave clouds offer a natural laboratory to investigate cloud microphysical processes and their representation in atmospheric models. Wave clouds impact the larger-scale flow by the vertical redistribution of moisture and aerosol. Here we use detailed cloud microphysical observations from the ICE-L campaign to evaluate the recently developed Cloud Aerosol Interacting Microphysics (CASIM) module in the Met Office Unified Model (UM) with a particular focus on different parameterisations for heterogeneous freezing. Modelled and observed thermodynamic and microphysical properties agree very well (deviation of air temperature

scholarly journals Some effects of ice crystals on the FSSP measurements in mixed phase clouds

2012 ◽  
Vol 12 (19) ◽  
pp. 8963-8977 ◽  
Author(s):  
G. Febvre ◽  
J.-F. Gayet ◽  
V. Shcherbakov ◽  
C. Gourbeyre ◽  
O. Jourdan
Keyword(s):  
Particle Size ◽  
Mixed Phase ◽  
Ice Crystals ◽  
Crystal Surfaces ◽  
Hexagonal Ice ◽  
Ice Particles ◽  
Second Mode ◽  
Ice Production ◽  
Bulk Parameters ◽  
Mixed Phase Clouds

Abstract. In this paper, we show that in mixed phase clouds, the presence of ice crystals may induce wrong FSSP 100 measurements interpretation especially in terms of particle size and subsequent bulk parameters. The presence of ice crystals is generally revealed by a bimodal feature of the particle size distribution (PSD). The combined measurements of the FSSP-100 and the Polar Nephelometer give a coherent description of the effect of the ice crystals on the FSSP-100 response. The FSSP-100 particle size distributions are characterized by a bimodal shape with a second mode peaked between 25 and 35 μm related to ice crystals. This feature is observed with the FSSP-100 at airspeed up to 200 m s−1 and with the FSSP-300 series. In order to assess the size calibration for clouds of ice crystals the response of the FSSP-100 probe has been numerically simulated using a light scattering model of randomly oriented hexagonal ice particles and assuming both smooth and rough crystal surfaces. The results suggest that the second mode, measured between 25 μm and 35 μm, does not necessarily represent true size responses but corresponds to bigger aspherical ice particles. According to simulation results, the sizing understatement would be neglected in the rough case but would be significant with the smooth case. Qualitatively, the Polar Nephelometer phase function suggests that the rough case is the more suitable to describe real crystals. Quantitatively, however, it is difficult to conclude. A review is made to explore different hypotheses explaining the occurrence of the second mode. However, previous cloud in situ measurements suggest that the FSSP-100 secondary mode, peaked in the range 25–35 μm, is likely to be due to the shattering of large ice crystals on the probe inlet. This finding is supported by the rather good relationship between the concentration of particles larger than 20 μm (hypothesized to be ice shattered-fragments measured by the FSSP) and the concentration of (natural) ice particles (CPI data). In mixed cloud, a simple estimation of the number of ice crystals impacting the FSSP inlet shows that the ice crystal shattering effect is the main factor in observed ice production.

scholarly journals HOLIMO II: a digital holographic instrument for ground-based in-situ observations of microphysical properties of mixed-phase clouds

2013 ◽  
Vol 6 (3) ◽  
pp. 4183-4221 ◽  
Author(s):  
J. Henneberger ◽  
J. P. Fugal ◽  
O. Stetzer ◽  
U. Lohmann
Keyword(s):  
Spatial Resolution ◽  
High Spatial Resolution ◽  
Mixed Phase ◽  
Size Spectrum ◽  
Research Station ◽  
Resolution Limit ◽  
Microphysical Properties ◽  
Cloud Particles ◽  
Mixed Phase Clouds

Abstract. Measurements of the microphysical properties of mixed-phase clouds with high spatial resolution are important to understand the processes inside these clouds. This work describes the design and characterization of the newly developed ground-based field instrument HOLIMO II (HOLographic Imager for Microscopic Objects II). HOLIMO II uses digital in-line holography to in-situ image cloud particles in a well defined sample volume. By an automated algorithm, two-dimensional images of single cloud particles between 6 and 250 μm in diameter are obtained and the size spectrum, the concentration and water content of clouds are calculated. By testing the sizing algorithm with monosized beads a systematic overestimation near the resolution limit was found, which has been used to correct the measurements. Field measurements from the high altitude research station Jungfraujoch, Switzerland, are presented. The measured number size distributions are in good agreement with parallel measurements by a fog monitor (FM-100, DMT, Boulder USA). The field data shows that HOLIMO II is capable of measuring the number size distribution with a high spatial resolution and determines ice crystal shape, thus providing a method of quantifying variations in microphysical properties. A case study over a period of 8 h has been analyzed, exploring the transition from a liquid to a mixed-phase cloud, which is the longest observation of a cloud with a holographic device. During the measurement period, the cloud does not completely glaciate, contradicting earlier assumptions of the dominance of the Wegener–Bergeron–Findeisen (WBF) process.

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