scholarly journals The portable ice nucleation experiment PINE: a new online instrument for laboratory studies and automated long-term field observations of ice-nucleating particles

2020 ◽  
Author(s):  
Ottmar Möhler ◽  
Michael Adams ◽  
Larissa Lacher ◽  
Franziska Vogel ◽  
Jens Nadolny ◽  
...  
Keyword(s):  
Pure Water ◽  
Full Range ◽  
Field Measurements ◽  
Ice Nucleation ◽  
Spatial And Temporal Variation ◽  
High Time Resolution ◽  
Expansion Chamber ◽  
Field Campaign ◽  
New Instrument ◽  
Term Field

Abstract. Atmospheric ice-nucleating particles (INP) play an important role in determining the phase of clouds, which affects their albedo and lifetime. A lack of data on the spatial and temporal variation of INPs around the globe limits our predictive capacity and understanding of clouds containing ice. Automated instrumentation that can robustly measure INP concentrations across the full range of tropospheric temperatures is needed in order to address this knowledge gap. In this study, we demonstrate the functionality and capacity of the new Portable Ice Nucleation Experiment (PINE) to study ice nucleation processes and to measure INP concentrations under conditions pertinent for mixed-phase clouds, with temperatures from about −10 °C to about −38 °C. PINE is a cloud expansion chamber which avoids frost formation on the cold walls, and thereby omits frost fragmentation and related background ice signals during the operation. The development, working principle, and treatment of data for the PINE instrument is discussed in detail. We present extensive laboratory based tests where PINE measurements were compared with those from the established AIDA (Aerosol Interaction and Dynamics in the Atmosphere) cloud chamber. The results show good agreement of PINE with AIDA for homogeneous freezing of pure water droplets and the immersion freezing activity of mineral aerosols. Results from a first field campaign conducted at the Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) observatory in Oklahoma, USA, from October 1 to November 14, 2019 with the latest PINE design (a commercially available PINE chamber) are also shown, demonstrating PINE’s ability to make automated field measurements of INP concentrations at high time resolution of about 8 minutes with continuous wall temperature scans between −5 and −35 °C. During this field campaign, PINE was continuously operated for 45 days in a fully automated and semi-autonomous way, demonstrating the capability of this new instrument to be also used for longer term field measurements and INP monitoring activities in observatories.

scholarly journals The Portable Ice Nucleation Experiment (PINE): a new online instrument for laboratory studies and automated long-term field observations of ice-nucleating particles

2021 ◽  
Vol 14 (2) ◽  
pp. 1143-1166
Author(s):  
Ottmar Möhler ◽  
Michael Adams ◽  
Larissa Lacher ◽  
Franziska Vogel ◽  
Jens Nadolny ◽  
...  
Keyword(s):  
Pure Water ◽  
Full Range ◽  
Field Measurements ◽  
Ice Nucleation ◽  
Spatial And Temporal Variation ◽  
Expansion Chamber ◽  
Predictive Capacity ◽  
Field Campaign ◽  
New Instrument ◽  
Term Field

Abstract. Atmospheric ice-nucleating particles (INPs) play an important role in determining the phase of clouds, which affects their albedo and lifetime. A lack of data on the spatial and temporal variation of INPs around the globe limits our predictive capacity and understanding of clouds containing ice. Automated instrumentation that can robustly measure INP concentrations across the full range of tropospheric temperatures is needed in order to address this knowledge gap. In this study, we demonstrate the functionality and capacity of the new Portable Ice Nucleation Experiment (PINE) to study ice nucleation processes and to measure INP concentrations under conditions pertinent for mixed-phase clouds, with temperatures from about −10 to about −40 ∘C. PINE is a cloud expansion chamber which avoids frost formation on the cold walls and thereby omits frost fragmentation and related background ice signals during the operation. The development, working principle and treatment of data for the PINE instrument is discussed in detail. We present laboratory-based tests where PINE measurements were compared with those from the established AIDA (Aerosol Interaction and Dynamics in the Atmosphere) cloud chamber. Within experimental uncertainties, PINE agreed with AIDA for homogeneous freezing of pure water droplets and the immersion freezing activity of mineral aerosols. Results from a first field campaign conducted at the Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) observatory in Oklahoma, USA, from 1 October to 14 November 2019 with the latest PINE design (a commercially available PINE chamber) are also shown, demonstrating PINE's ability to make automated field measurements of INP concentrations at a time resolution of about 8 min with continuous temperature scans for INP measurements between −10 and −30 ∘C. During this field campaign, PINE was continuously operated for 45 d in a fully automated and semi-autonomous way, demonstrating the capability of this new instrument to also be used for longer-term field measurements and INP monitoring activities in observatories.

scholarly journals Online Ice-Nucleating Particle Measurements in the Southern Great Plains (SGP) Using the Portable Ice Nucleation Experiment (PINE) Chamber

2020 ◽  
Vol 4 (1) ◽  
pp. 25
Author(s):  
Hemanth S. K. Vepuri ◽  
Larissa Lacher ◽  
Jens Nadolny ◽  
Ottmar Möhler ◽  
Naruki Hiranuma
Keyword(s):  
Great Plains ◽  
Cloud Condensation Nuclei ◽  
Active Surface ◽  
Freezing Temperature ◽  
Statistical Correlation ◽  
Ice Nucleation ◽  
High Time Resolution ◽  
Field Campaign ◽  
Southern Great Plains ◽  
Immersion Freezing

We present our field results of ice-nucleating particle (INP) measurements from the commercialized version of the Portable Ice Nucleation Experiment (PINE) chamber from two different campaigns. Our first field campaign, TxTEST, was conducted at West Texas A&M University (July–August 2019), and the other campaign, ExINP-SGP, was held at the Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) site (October–November 2019). In both campaigns, the PINE made semi-autonomous INP measurements at a high-time-resolution of 8 min for individual expansions with continuous temperature scans from −5 to −35 °C in 90 min. The PINE instrument was set to have a minimum detection capability of ~0.3 INPs per liter of air. To complement our online PINE measurements, polycarbonate filter impactor and liquid impinger samples were also collected next to the PINE. Offline droplet-freezing assays were later conducted from the filter and impinger samples for the immersion freezing mode. Our preliminary results suggested that the immersion freezing mode was the dominant ice-nucleation mechanism at the SGP site compared to the deposition mode. We did not find any statistical correlation between cloud condensation nuclei (CCN) and INP concentration during our ExINP-SGP period, suggesting that CCN activation is not a significant prerequisite for ice nucleation at the SGP site. In addition, we analyzed the relationship between various aerosol particle size ranges and INP abundance. At SGP, we found an increase in INPs with the super-micron particles, especially for diameters >2 μm across the entire heterogeneous freezing temperature range examined by PINE. Lastly, we computed a variety of INP parameters, such as, ice nucleation active surface site density, water activity-based freezing, and cumulative INP per liter of air, representing the ambient INPs in the SGP. Our field campaign results demonstrated the PINE’s ability to make remote INP measurements, promising future long-term operations including at isolated locations.

scholarly journals Measurements of OH and HO<sub>2</sub> concentrations during the MCMA-2006 field campaign – Part 1: Deployment of the Indiana University laser-induced fluorescence instrument

2008 ◽  
Vol 8 (4) ◽  
pp. 13689-13739 ◽  
Author(s):  
S. Dusanter ◽  
D. Vimal ◽  
P. S. Stevens ◽  
R. Volkamer ◽  
L. T. Molina
Keyword(s):  
Mexico City ◽  
Signal To Noise Ratio ◽  
Field Measurements ◽  
Laser Induced Fluorescence ◽  
Urban Site ◽  
Indiana University ◽  
Field Campaign ◽  
Direct Excitation ◽  
Stage Of Development ◽  
New Instrument

Abstract. Measurements of tropospheric hydroxyl (OH) and hydroperoxy (HO2) radicals were made during the MCMA (Mexico City Metropolitan Area) field campaign as part of the MILAGRO (Megacity Initiative: Local and Global Research Observations) project during March 2006. These radicals were measured using a laser-induced fluorescence instrument developed at Indiana University. This new instrument takes advantage of the Fluorescence Assay by Gas Expansion technique (FAGE) together with direct excitation and detection of OH at 308 nm. HO2 is indirectly measured as OH by titration with NO inside the fluorescence cell. At this stage of development, IU-FAGE is capable of detecting 3.9×105molec cm−3 of both OH and HO2, with a signal to noise ratio of 1, an averaged laser power of 10 mW and an averaging time of 5 min. The calibration accuracies (1σ) are ±17% for OH and ±18% for HO2 using the water-vapor photolysis/O2 actinometry calibration technique. OH and HO2 concentrations were successfully measured at an urban site in Mexico City, with observed concentrations comparable to those measured in other polluted environments. Enhanced levels of OH and HO2 radicals were observed on several days between 09:30–11 a.m. and suggest an intense photochemistry during morning hours that may be due to elevated sources of HOx (OH+HO2) and a fast cycling between the radicals under the high NOx conditions of the MCMA. A comparison with other urban and sub-urban field measurements suggests that OH concentrations are highly buffered under these conditions. In contrast, HO2 concentrations are highly variable between different urban sites.

scholarly journals Technical Note: Determination of formaldehyde mixing ratios in polluted air with PTR-MS: laboratory experiments and field measurements

2007 ◽  
Vol 7 (5) ◽  
pp. 12845-12876
Author(s):  
S. Inomata ◽  
H. Tanimoto ◽  
S. Kameyama ◽  
U. Tsunogai ◽  
H. Irie ◽  
...  
Keyword(s):  
Proton Transfer ◽  
Field Measurements ◽  
Proton Transfer Reaction ◽  
Technical Note ◽  
Detection Sensitivity ◽  
Optical Absorption Spectroscopy ◽  
High Time Resolution ◽  
Mixing Ratios ◽  
Proton Transfer Reactions ◽  
Humidity Dependence

Abstract. Formaldehyde (HCHO), the most abundant carbonyl compound in the atmosphere, is generated as an intermediate product in the oxidation of nonmethane hydrocarbons. Proton transfer reaction mass spectrometry (PTR-MS) has the capability to detect HCHO from ion signals at m/z 31 with high time-resolution. However, the detection sensitivity is low compared to other detectable species, and is considerably affected by humidity, due to back reactions between protonated HCHO and water vapor prior to analysis. We performed a laboratory calibration of HCHO by PTR-MS and examined the detection sensitivity and humidity dependence at various field strengths. Subsequently, we deployed the PTR-MS instrument in a field campaign at Mount Tai in China in June 2006 to measure HCHO in various meteorological and photochemical conditions; we also conducted intercomparison measurements by Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS). Correction of interference in the m/z 31 signals by fragments from proton transfer reactions with methyl hydroperoxide, methanol, and ethanol greatly improves agreement between the two methods, giving the correlation [HCHO]MAX-DOAS = (0.99±0.16) [HCHO]PTR-MS + (0.02±0.38), where error limits represent 95% confidence levels.

scholarly journals Ice nucleation activity of silicates and aluminosilicates in pure water and aqueous solutions – Part 2: Quartz and amorphous silica

2019 ◽  
Vol 19 (9) ◽  
pp. 6035-6058 ◽  
Author(s):  
Anand Kumar ◽  
Claudia Marcolli ◽  
Thomas Peter
Keyword(s):  
Aqueous Solutions ◽  
Amorphous Silica ◽  
Pure Water ◽  
Ice Nucleation ◽  
Water Volume ◽  
Special Focus ◽  
Quartz Surface ◽  
Mineral Surface ◽  
Glass Vial ◽  
Immersion Freezing

Abstract. Divergent ice nucleation (IN) efficiencies of quartz, an important component of atmospheric mineral dust, have been reported in previous studies. We show here that quartz particles obtain their IN activity from milling and that quartz aged in water loses most of its IN efficiency relative to freshly milled quartz. Since most studies so far reported IN activities of commercial quartz dusts that were milled already by the manufacturer, IN active samples prevailed. Also, the quartz surface – much in contrast to that of feldspars – is not prone to ammonia-induced IN enhancement. In detail we investigate the influence of solutes on the IN efficiency of various silica (SiO2) particles (crystalline and amorphous) with special focus on quartz. We performed immersion freezing experiments and relate the observed variability in IN activity to the influence of milling, the aging time and to the exposure conditions since milling. Immersion freezing with silica particles suspended in pure water or aqueous solutions of NH3, (NH4)2SO4, NH4HSO4, Na2SO4 and NaOH, with solute concentrations corresponding to water activities aw=0.9–1.0, were investigated in emulsified droplets by means of differential scanning calorimetry (DSC) and analyzed in terms of the onset temperature of the heterogeneous freezing signal Thet and the heterogeneously frozen water volume fraction Fhet. Quartz particles, which originate from milling coarse samples, show a strong heterogeneous freezing peak in pure water with Thet equal to 247–251 K. This IN activity disappears almost completely after aging for 7 months in pure water in a glass vial. During this time quartz slowly grew by incorporating silicic acid leached from the glass vial. Conversely, the synthesized amorphous silica samples show no discernable heterogeneous freezing signal unless they were milled. This implies that defects provide IN activity to silica surfaces, whereas the IN activity of a natural quartz surface is negligible, when it grew under near-equilibrium conditions. For suspensions containing milled quartz and the solutes (NH4)2SO4, NH4HSO4 or Na2SO4, Thet approximately follows ThetΔawhet(aw), the heterogeneous freezing onset temperatures that obey Δawhet criterion, i.e., ThetΔawhet(aw)=Tmelt(aw+Δawhet) with Δawhet being a constant offset with respect to the ice melting point curve, similar to homogeneous IN. This water-activity-based description is expected to hold when the mineral surface is not altered by the presence of the solutes. On the other hand, we observe a slight enhancement in Fhet in the presence of these solutes, implying that the compliance with the Δawhet criterion does not necessarily imply constant Fhet. In contrast to the sulfates, dilute solutions of NH3 or NaOH (molality ≥5×10-4 mol kg−1) reveal Thet by 3–8 K lower than ThetΔawhet(aw), indicating a significant impact on the mineral surface. The lowering of Thet of quartz suspended in dilute NH3 solutions is opposite to the distinct increase in Thet that we found in emulsion freezing experiments with aluminosilicates, namely feldspars, kaolinite, gibbsite and micas. We ascribe this decrease in IN activity to the increased dissolution of quartz under alkaline conditions. The defects that constitute the active sites appear to be more susceptible to dissolution and therefore disappear first on a dissolving surface.

Freezing of micrometer-sized liquid droplets of pure water evaporatively cooled in a vacuum

2018 ◽  
Vol 20 (45) ◽  
pp. 28435-28444 ◽  
Author(s):  
Kota Ando ◽  
Masashi Arakawa ◽  
Akira Terasaki
Keyword(s):  
Pure Water ◽  
Ice Nucleation ◽  
Nucleation Theory ◽  
Liquid Droplets ◽  
Freezing Time ◽  
Water Droplets

The freezing time of pure-water droplets is measured in a vacuum and simulated by ice nucleation theory.

scholarly journals Cleaning up our water: reducing interferences from nonhomogeneous freezing of “pure” water in droplet freezing assays of ice-nucleating particles

2018 ◽  
Vol 11 (9) ◽  
pp. 5315-5334 ◽  
Author(s):  
Michael Polen ◽  
Thomas Brubaker ◽  
Joshua Somers ◽  
Ryan C. Sullivan
Keyword(s):  
Pure Water ◽  
Freezing Temperature ◽  
Cloud Microphysics ◽  
Ice Nucleation ◽  
Great Promise ◽  
Water Control ◽  
Temperature Spectra ◽  
Droplet Sizes ◽  
Mixed Phase Clouds ◽  
Insight Into

Abstract. Droplet freezing techniques (DFTs) have been used for half a century to measure the concentration of ice-nucleating particles (INPs) in the atmosphere and determine their freezing properties to understand the effects of INPs on mixed-phase clouds. The ice nucleation community has recently adopted droplet freezing assays as a commonplace experimental approach. These droplet freezing experiments are often limited by contamination that causes nonhomogeneous freezing of the “pure” water used to generate the droplets in the heterogeneous freezing temperature regime that is being measured. Interference from the early freezing of water is often overlooked and not fully reported, or measurements are restricted to analyzing the more ice-active INPs that freeze well above the temperature of the background water. However, this avoidance is not viable for analyzing the freezing behavior of less active INPs in the atmosphere that still have potentially important effects on cold-cloud microphysics. In this work we review a number of recent droplet freezing techniques that show great promise in reducing these interferences, and we report our own extensive series of measurements using similar methodologies. By characterizing the performance of different substrates on which the droplets are placed and of different pure water generation techniques, we recommend best practices to reduce these interferences. We tested different substrates, water sources, droplet matrixes, and droplet sizes to provide deeper insight into what methodologies are best suited for DFTs. Approaches for analyzing droplet freezing temperature spectra and accounting and correcting for the background “pure” water control spectrum are also presented. Finally, we propose experimental and data analysis procedures for future homogeneous and heterogeneous ice nucleation studies to promote a more uniform and reliable methodology that facilitates the ready intercomparison of ice-nucleating particles measured by DFTs.

scholarly journals Design and Optimization of a High-Time-Resolution Magnetic Plasma Analyzer (MPA)

2020 ◽  
Vol 10 (23) ◽  
pp. 8483
Author(s):  
Benjamin Criton ◽  
Georgios Nicolaou ◽  
Daniel Verscharen
Keyword(s):  
Magnetic Field ◽  
Time Resolution ◽  
Permanent Magnets ◽  
Instrument Design ◽  
High Time ◽  
Acquisition Time ◽  
High Time Resolution ◽  
Design And Optimization ◽  
New Instrument ◽  
Α Particles

In-situ measurements of space plasma throughout the solar system require high time resolution to understand the plasma’s kinetic fine structure and evolution. In this context, research is conducted to design instruments with the capability to acquire the plasma velocity distribution and its moments with high cadence. We study a new instrument design, using a constant magnetic field generated by two permanent magnets, to analyze solar wind protons and α-particles with high time resolution. We determine the optimal configuration of the instrument in terms of aperture size, sensor position, pixel size and magnetic field strength. We conduct this analysis based on analytical calculations and SIMION simulations of the particle trajectories in our instrument. We evaluate the velocity resolution of the instrument as well as Poisson errors associated with finite counting statistics. Our instrument is able to resolve Maxwellian and κ-distributions for both protons and α-particles. This method retrieves measurements of the moments (density, bulk speed and temperature) with a relative error below 1%. Our instrument design achieves these results with an acquisition time of only 5 ms, significantly faster than state-of-the-art electrostatic analyzers. Although the instrument only acquires one-dimensional cuts of the distribution function in velocity space, the simplicity and reliability of the presented instrument concept are two key advantages of our new design.

scholarly journals Ice nucleation activity of silicates and aluminosilicates in pure water and aqueous solutions. Part 2 – Quartz and amorphous silica

2018 ◽  
Author(s):  
Anand Kumar ◽  
Claudia Marcolli ◽  
Thomas Peter
Keyword(s):  
Aqueous Solutions ◽  
Amorphous Silica ◽  
Pure Water ◽  
Ice Nucleation ◽  
Water Volume ◽  
Special Focus ◽  
Quartz Surface ◽  
Mineral Surface ◽  
Glass Vial ◽  
Immersion Freezing

Abstract. Divergent ice nucleation (IN) efficiencies of quartz, an important component of atmospheric mineral dust, have been reported in previous studies. We show here that quartz particles obtain their IN activity from milling and that quartz aged in water loses most of its IN efficiency relative to freshly milled quartz. Also, the quartz surface – much in contrast to that of feldspars – is not prone to ammonia-induced IN enhancement. In detail we investigate the influence of solutes on the IN efficiency of various silica (SiO2) particles (crystalline and amorphous) with special focus on quartz. We performed immersion freezing experiments and relate the reported contradictory behavior to the influence of milling, and to the aging time and conditions since milling. Immersion freezing with silica particles suspended in pure water or aqueous solutions of NH3, (NH4)2SO4, NH4HSO4, Na2SO4 and NaOH, with solute concentrations corresponding to water activities aw = 0.9–1.0, were investigated in emulsified droplets by means of differential scanning calorimetry (DSC) and analyzed in terms of the onset temperature of the heterogeneous freezing signal Thet and the heterogeneously frozen water volume fraction Fhet. Quartz particles, which originate from milling coarse samples, show a strong heterogeneous freezing peak in pure water with Thet = 247–251 K. This IN activity disappears almost completely after aging for 7 months in pure water in a glass vial. During this time quartz slowly grew by incorporating silicic acid leached from the glass vial. Conversely, the synthesized amorphous silica samples show no discernable heterogeneous freezing signal unless they were milled. This implies that defects provide IN activity to silica surfaces, whereas the IN activity of a natural quartz surface is negligible, when it grew under near-equilibrium conditions. For suspensions containing milled quartz and the solutes (NH4)2SO4, NH4HSO4 or Na2SO4, Thet approximately follows Thet(Δawhet) (aw), the heterogeneous freezing onset temperatures that obey Δawhet-criterion, i.e. Thet(Δawhet) (aw) = Tmelt (aw + Δawhet) with Δawhet being a constant offset with respect to the ice melting point curve, similar to homogeneous IN. This water-activity-based description is expected to hold when the mineral surface is not altered by the presence of the solutes. On the other hand, we observe a slight enhancement in Fhet in the presence of these solutes, implying that the compliance with the Δawhet-criterion does not necessarily imply constant Fhet. In contrast to the sulfates, dilute solutions of NH3 or NaOH (molality &amp;geq; 5 × 10−4 mol kg−1) reveal Thet by 3–8 K lower than Thet(Δawhet) (aw), indicating a significant impact on the mineral surface. The lowering of Thet of quartz suspended in dilute NH3 solutions is opposite to the distinct increase in Thet that we found in emulsion freezing experiments with aluminosilicates, namely feldspars, kaolinite, gibbsite and micas. We ascribe this decrease of IN activity to the increased dissolution of quartz under alkaline conditions. The defects that constitute the active sites appear to be more susceptible to dissolution and therefore disappear first on a dissolving surface.

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