scholarly journals A Phase Separation Inlet for Droplets, Ice Residuals, and Interstitial Aerosol Particles

2021 ◽  
Author(s):  
Libby Koolik ◽  
Michael Roesch ◽  
Lesly J. Franco Deloya ◽  
Chuanyang Shen ◽  
A. Gannet Hallar ◽  
...  
Keyword(s):  
Phase Separation ◽  
Rocky Mountains ◽  
Individual Component ◽  
Aerosol Particles ◽  
Ice Crystals ◽  
Research Facility ◽  
Flow Tube ◽  
Evaporation Chamber ◽  
Virtual Impactor ◽  
Mixed Phase Clouds

Abstract. A new inlet for studying the aerosol particles and hydrometeor residuals that compose mixed-phase clouds – the phaSe seParation Inlet for Droplets icE residuals and inteRstitial aerosol particles (SPIDER) – is described here. SPIDER combines a Large-Pumped Counterflow Virtual Impactor (L-PCVI), a flow tube evaporation chamber, and a Pumped Counterflow Virtual Impactor (PCVI) to separate droplets, ice crystals, and interstitial aerosol particles for simultaneous sampling. Laboratory verification tests of each individual component and then the composite SPIDER system were conducted. SPIDER was then deployed at Storm Peak Laboratory (SPL), a mountain-top research facility at 3210 m a.s.l. in the Rocky Mountains. SPIDER performance as a field instrument is presented with data that demonstrates its capability of separating cloud elements and interstitial aerosol particle. Possible design improvements of SPIDER are also suggested.

scholarly journals A Phase Separation Inlet for Droplets, Ice Residuals, and Interstitial Aerosols

2020 ◽  
Author(s):  
Libby Koolik ◽  
Michael Roesch ◽  
Lesly J. Franco Deloya ◽  
Chuanyang Shen ◽  
A. Gannet Hallar ◽  
...  
Keyword(s):  
Phase Separation ◽  
Rocky Mountains ◽  
Individual Component ◽  
Ice Crystals ◽  
Research Facility ◽  
Flow Tube ◽  
Evaporation Chamber ◽  
Field Campaign ◽  
Virtual Impactor ◽  
Mixed Phase Clouds

Abstract. A new inlet for studying the aerosols and hydrometeor residuals that compose mixed-phase clouds – the phaSe seParation Inlet for Droplets icE residuals and inteRstitial aerosols (SPIDER) – is described here. SPIDER combines an omni-directional inlet, a Large-Pumped Counterflow Virtual Impactor (L-PCVI), a flow tube evaporation chamber, and a Pumped Counterflow Virtual Impactor (PCVI) to separate droplets, ice crystals, and interstitial aerosols for simultaneous sampling. Laboratory verification tests of each individual component and the composite SPIDER system were conducted. SPIDER was deployed to Storm Peak Laboratory (SPL), a mountain-top research facility at 3210 m a.s.l. in the Rocky Mountains, for a three-week field campaign. SPIDER performance as a field instrument is presented with data that demonstrates its capability of separating distinct cloud elements and interstitial aerosol. Possible design improvements of SPIDER are also suggested.

scholarly journals Scavenging of black carbon in mixed phase clouds at the high alpine site Jungfraujoch

2007 ◽  
Vol 7 (7) ◽  
pp. 1797-1807 ◽  
Author(s):  
J. Cozic ◽  
B. Verheggen ◽  
S. Mertes ◽  
P. Connolly ◽  
K. Bower ◽  
...  
Keyword(s):  
Black Carbon ◽  
Cloud Condensation Nuclei ◽  
Aerosol Particles ◽  
Liquid Water Content ◽  
Mixed Phase ◽  
Ice Crystals ◽  
Research Station ◽  
Liquid Droplets ◽  
Cloud Droplets ◽  
Mixed Phase Clouds

Abstract. The scavenging of black carbon (BC) in liquid and mixed phase clouds was investigated during intensive experiments in winter 2004, summer 2004 and winter 2005 at the high alpine research station Jungfraujoch (3580 m a.s.l., Switzerland). Aerosol residuals were sampled behind two well characterized inlets; a total inlet which collected cloud particles (droplets and ice particles) as well as interstitial (unactivated) aerosol particles; an interstitial inlet which collected only interstitial aerosol particles. BC concentrations were measured behind each of these inlets along with the submicrometer aerosol number size distribution, from which a volume concentration was derived. These measurements were complemented by in-situ measurements of cloud microphysical parameters. BC was found to be scavenged into the condensed phase to the same extent as the bulk aerosol, which suggests that BC was covered with soluble material through aging processes, rendering it more hygroscopic. The scavenged fraction of BC (FScav,BC), defined as the fraction of BC that is incorporated into cloud droplets and ice crystals, decreases with increasing cloud ice mass fraction (IMF) from FScav,BC=60% in liquid phase clouds to FScav,BC~5–10% in mixed-phase clouds with IMF>0.2. This can be explained by the evaporation of liquid droplets in the presence of ice crystals (Wegener-Bergeron-Findeisen process), releasing BC containing cloud condensation nuclei back into the interstitial phase. In liquid clouds, the scavenged BC fraction is found to decrease with decreasing cloud liquid water content. The scavenged BC fraction is also found to decrease with increasing BC mass concentration since there is an increased competition for the available water vapour.

scholarly journals Scavenging of black carbon in mixed phase clouds at the high alpine site Jungfraujoch

2006 ◽  
Vol 6 (6) ◽  
pp. 11877-11912 ◽  
Author(s):  
J. Cozic ◽  
B. Verheggen ◽  
S. Mertes ◽  
P. Connolly ◽  
K. Bower ◽  
...  
Keyword(s):  
Black Carbon ◽  
Cloud Condensation Nuclei ◽  
Aerosol Particles ◽  
Liquid Water Content ◽  
Mixed Phase ◽  
Ice Crystals ◽  
Research Station ◽  
Liquid Droplets ◽  
Cloud Droplets ◽  
Mixed Phase Clouds

Abstract. The scavenging of black carbon (BC) in liquid and mixed phase clouds was investigated during intensive experiments in winter 2004, summer 2004 and winter 2005 at the high alpine research station Jungfraujoch (3580 m a.s.l., Switzerland). Aerosol residuals were sampled behind two well characterized inlets; a total inlet which collected cloud particles (drops and ice particles) as well as interstitial aerosol particles; an interstitial inlet which collected only interstitial (unactivated) aerosol particles. BC concentrations were measured behind each of these inlets along with the submicrometer aerosol number size distribution, from which a volume concentration was derived. These measurements were complemented by in-situ measurements of cloud microphysical parameters. BC was found to be scavenged into the cloud phase to the same extent as the bulk aerosol, which suggests that BC was covered with soluble material through aging processes, rendering it more hygroscopic. The scavenged fraction of BC (FScav,BC), defined as the fraction of BC that is incorporated into cloud droplets and ice crystals, decreases with increasing cloud ice mass fraction (IMF) from FScav,BC=60% in liquid phase clouds to FScav,BC~10% in mixed-phase clouds with IMF>0.2. This is explained by the evaporation of liquid droplets in the presence of ice crystals (Wegener-Bergeron-Findeisen process), releasing BC containing cloud condensation nuclei back into the interstitial phase. In liquid clouds, the scavenged BC fraction is found to decrease with decreasing cloud liquid water content. The scavenged BC fraction is also found to decrease with increasing BC mass concentration since there is an increased competition for the available water vapour.

scholarly journals Microscopic Evidence for Phase Separation of Organic Species and Inorganic Salts in Fine Ambient Aerosol Particles

2021 ◽  
Vol 55 (4) ◽  
pp. 2234-2242
Author(s):  
Weijun Li ◽  
Lei Liu ◽  
Jian Zhang ◽  
Liang Xu ◽  
Yuanyuan Wang ◽  
...  
Keyword(s):  
Phase Separation ◽  
Aerosol Particles ◽  
Inorganic Salts ◽  
Ambient Aerosol ◽  
Organic Species ◽  
Microscopic Evidence

scholarly journals Measurements of Ice Nucleating Particles and Ice Residuals

2017 ◽  
Vol 58 ◽  
pp. 8.1-8.13 ◽  
Author(s):  
Daniel J. Cziczo ◽  
Luis Ladino ◽  
Yvonne Boose ◽  
Zamin A. Kanji ◽  
Piotr Kupiszewski ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Condensed Phase ◽  
Atmospheric Aerosols ◽  
Aerosol Particles ◽  
Ice Crystals ◽  
Ice Formation ◽  
Similar Amount ◽  
Residual Material ◽  
History Of ◽  
Phase Water

Abstract It has been known that aerosol particles act as nuclei for ice formation for over a century and a half (see Dufour). Initial attempts to understand the nature of these ice nucleating particles were optical and electron microscope inspection of inclusions at the center of a crystal (see Isono; Kumai). Only within the last few decades has instrumentation to extract ice crystals from clouds and analyze the residual material after sublimation of condensed-phase water been available (see Cziczo and Froyd). Techniques to ascertain the ice nucleating potential of atmospheric aerosols have only been in place for a similar amount of time (see DeMott et al.). In this chapter the history of measurements of ice nucleating particles, both in the field and complementary studies in the laboratory, are reviewed. Remaining uncertainties and artifacts associated with measurements are described and suggestions for future areas of improvement are made.

scholarly journals Simulating the influence of primary biological aerosol particles on clouds by heterogeneous ice nucleation

2018 ◽  
Vol 18 (20) ◽  
pp. 15437-15450 ◽  
Author(s):  
Matthias Hummel ◽  
Corinna Hoose ◽  
Bernhard Pummer ◽  
Caroline Schaupp ◽  
Janine Fröhlich-Nowoisky ◽  
...  
Keyword(s):  
Pseudomonas Syringae ◽  
Aerosol Particles ◽  
Fungal Spores ◽  
Ice Nucleation ◽  
Ice Crystals ◽  
Atmospheric Measurements ◽  
Cloud Ice ◽  
Biological Aerosol Particles ◽  
Ice Phase ◽  
Heterogeneous Ice Nucleation

Abstract. Primary ice formation, which is an important process for mixed-phase clouds with an impact on their lifetime, radiative balance, and hence the climate, strongly depends on the availability of ice-nucleating particles (INPs). Supercooled droplets within these clouds remain liquid until an INP immersed in or colliding with the droplet reaches its activation temperature. Only a few aerosol particles are acting as INPs and the freezing efficiency varies among them. Thus, the fraction of supercooled water in the cloud depends on the specific properties and concentrations of the INPs. Primary biological aerosol particles (PBAPs) have been identified as very efficient INPs at high subzero temperatures, but their very low atmospheric concentrations make it difficult to quantify their impact on clouds. Here we use the regional atmospheric model COSMO–ART to simulate the heterogeneous ice nucleation by PBAPs during a 1-week case study on a domain covering Europe. We focus on three highly ice-nucleation-active PBAP species, Pseudomonas syringae bacteria cells and spores from the fungi Cladosporium sp. and Mortierella alpina. PBAP emissions are parameterized in order to represent the entirety of bacteria and fungal spores in the atmosphere. Thus, only parts of the simulated PBAPs are assumed to act as INPs. The ice nucleation parameterizations are specific for the three selected species and are based on a deterministic approach. The PBAP concentrations simulated in this study are within the range of previously reported results from other modeling studies and atmospheric measurements. Two regimes of PBAP INP concentrations are identified: a temperature-limited and a PBAP-limited regime, which occur at temperatures above and below a maximal concentration at around −10 ∘C, respectively. In an ensemble of control and disturbed simulations, the change in the average ice crystal concentration by biological INPs is not statistically significant, suggesting that PBAPs have no significant influence on the average state of the cloud ice phase. However, if the cloud top temperature is below −15 ∘C, PBAP can influence the cloud ice phase and produce ice crystals in the absence of other INPs. Nevertheless, the number of produced ice crystals is very low and it has no influence on the modeled number of cloud droplets and hence the cloud structure.

scholarly journals Possible Aerosol Effects on Lightning Activity and Structure of Hurricanes

2008 ◽  
Vol 65 (12) ◽  
pp. 3652-3677 ◽  
Author(s):  
A. Khain ◽  
N. Cohen ◽  
B. Lynn ◽  
A. Pokrovsky
Keyword(s):  
Tropical Cyclone ◽  
Mesoscale Model ◽  
Cloud Model ◽  
Aerosol Particles ◽  
Supercooled Water ◽  
Lightning Activity ◽  
Ice Crystals ◽  
Cloud Base ◽  
Weekly Cycle ◽  
Aerosol Effects

Abstract According to observations of hurricanes located relatively close to the land, intense and persistent lightning takes place within a 250–300-km radius ring around the hurricane center, whereas the lightning activity in the eyewall takes place only during comparatively short periods usually attributed to eyewall replacement. The mechanism responsible for the formation of the maximum flash density at the tropical cyclone (TC) periphery is not well understood as yet. In this study it is hypothesized that lightning at the TC periphery arises under the influence of small continental aerosol particles (APs), which affect the microphysics and the dynamics of clouds at the TC periphery. To show that aerosols change the cloud microstructure and the dynamics to foster lightning formation, the authors use a 2D mixed-phase cloud model with spectral microphysics. It is shown that aerosols that penetrate the cloud base of maritime clouds dramatically increase the amount of supercooled water, as well as the ice contents and vertical velocities. As a result, in clouds developing in the air with high AP concentration, ice crystals, graupel, frozen drops and/or hail, and supercooled water can coexist within a single cloud zone, which allows collisions and charge separation. The simulation of possible aerosol effects on the landfalling tropical cyclone has been carried out using a 3-km-resolution Weather Research and Forecast (WRF) mesoscale model. It is shown that aerosols change the cloud microstructure in a way that permits the attribution of the observed lightning structure to the effects of continental aerosols. It is also shown that aerosols, which invigorate clouds at 250–300 km from the TC center, decrease the convection intensity in the TC center, leading to some TC weakening. The results suggest that aerosols change the intensity and the spatial distribution of precipitation in landfalling TCs and can possibly contribute to the weekly cycle of the intensity and precipitation of landfalling TCs. More detailed investigations of the TC–aerosol interaction are required.

scholarly journals Development and characterization of an ice-selecting pumped counterflow virtual impactor (IS-PCVI) to study ice crystal residuals

2016 ◽  
Vol 9 (8) ◽  
pp. 3817-3836 ◽  
Author(s):  
Naruki Hiranuma ◽  
Ottmar Möhler ◽  
Gourihar Kulkarni ◽  
Martin Schnaiter ◽  
Steffen Vogt ◽  
...  
Keyword(s):  
Transmission Efficiency ◽  
Number Concentration ◽  
Ice Crystals ◽  
Ice Crystal ◽  
Cloud Droplets ◽  
Virtual Impactor ◽  
Wide Range ◽  
Aerosol Cloud Interactions ◽  
Cloud Activation ◽  
Dynamics Simulations

Abstract. Separation of particles that play a role in cloud activation and ice nucleation from interstitial aerosols has become necessary to further understand aerosol-cloud interactions. The pumped counterflow virtual impactor (PCVI), which uses a vacuum pump to accelerate the particles and increase their momentum, provides an accessible option for dynamic and inertial separation of cloud elements. However, the use of a traditional PCVI to extract large cloud hydrometeors is difficult mainly due to its small cut-size diameters (< 5 µm). Here, for the first time we describe a development of an ice-selecting PCVI (IS-PCVI) to separate ice in controlled mixed-phase cloud system based on the particle inertia with the cut-off diameter  ≥  10 µm. We also present its laboratory application demonstrating the use of the impactor under a wide range of temperature and humidity conditions. The computational fluid dynamics simulations were initially carried out to guide the design of the IS-PCVI. After fabrication, a series of validation laboratory experiments were performed coupled with the Aerosol Interaction and Dynamics in the Atmosphere (AIDA) expansion cloud simulation chamber. In the AIDA chamber, test aerosol particles were exposed to the ice supersaturation conditions (i.e., RHice > 100 %), where a mixture of droplets and ice crystals was formed during the expansion experiment. In parallel, the flow conditions of the IS-PCVI were actively controlled, such that it separated ice crystals from a mixture of ice crystals and cloud droplets, which were of diameter  ≥  10 µm. These large ice crystals were passed through the heated evaporation section to remove the water content. Afterwards, the residuals were characterized with a suite of online and offline instruments downstream of the IS-PCVI. These results were used to assess the optimized operating parameters of the device in terms of (1) the critical cut-size diameter, (2) the transmission efficiency and (3) the counterflow-to-input flow ratio. Particle losses were characterized by comparing the residual number concentration to the rejected interstitial particle number concentration. Overall results suggest that the IS-PCVI enables inertial separation of particles with a volume-equivalent particle size in the range of  ~ 10–30 µm in diameter with small inadvertent intrusion (~  5 %) of unwanted particles.

Sign in / Sign up

Export Citation Format

Share Document