Comparison of INP Parameterizations for Dust Minerals in Climatological Simulations With a Global Model

2020 ◽  
Author(s):  
Jan Perlwitz ◽  
Daniel Knopf ◽  
Ron Miller
Keyword(s):  
Size Range ◽  
Ice Nucleation ◽  
Number Concentration ◽  
Size Distributions ◽  
Sources Of Uncertainty ◽  
Dust Size Distribution ◽  
Weather And Climate ◽  
Immersion Freezing ◽  
The Mean ◽  
Mixed Phase Clouds

<p>The effect of aerosol particles on ice nucleation and, in turn, the formation of ice and mixed phase clouds is recognized as one of the largest sources of uncertainty in weather and climate prediction.  We utilize an improved sectional dust module in NASA GISS Earth System ModelE2.1, which distinguishes eight different mineral species and accretions between iron oxides and the other minerals.  Simulations over a period of 20 years have been carried out with this model, and the mineral fields and other model variables (temperature, relative humidity) are used to calculate the ice nucleating particle (INP) number concentration, applying time-independent and time-dependent INP parameterizations, such as active site parameterization and water activity based immersion freezing model (ABIFM).  We study how the dependence of the parameterizations on different model variables affects the mean INP number concentration.  The sensitivity of the INP number concentration to fundamental dust properties such as emitted mineral size distributions and mixing state between minerals is also investigated.  Results show that the sensitivity of the total INP number concentration to the emitted dust size distribution is rather small, but the sensitivity over the whole size range obscures offsetting differences in the magnitude and the sign of the sensitivity between smaller and larger particles.</p>

scholarly journals An instrument for quantifying heterogeneous ice nucleation in multiwell plates using infrared emissions to detect freezing

2018 ◽  
Vol 11 (10) ◽  
pp. 5629-5641 ◽  
Author(s):  
Alexander D. Harrison ◽  
Thomas F. Whale ◽  
Rupert Rutledge ◽  
Stephen Lamb ◽  
Mark D. Tarn ◽  
...  
Keyword(s):  
Active Sites ◽  
Freezing Temperature ◽  
Equilibrium Temperature ◽  
Ice Nucleation ◽  
Ir Camera ◽  
Low Concentrations ◽  
Immersion Freezing ◽  
Mixed Phase Clouds ◽  
The City ◽  
Good Agreement

Abstract. Low concentrations of ice-nucleating particles (INPs) are thought to be important for the properties of mixed-phase clouds, but their detection is challenging. Hence, there is a need for instruments where INP concentrations of less than 0.01 L−1 can be routinely and efficiently determined. The use of larger volumes of suspension in drop assays increases the sensitivity of an experiment to rarer INPs or rarer active sites due to the increase in aerosol or surface area of particulates per droplet. Here we describe and characterise the InfraRed-Nucleation by Immersed Particles Instrument (IR-NIPI), a new immersion freezing assay that makes use of IR emissions to determine the freezing temperature of individual 50 µL droplets each contained in a well of a 96-well plate. Using an IR camera allows the temperature of individual aliquots to be monitored. Freezing temperatures are determined by detecting the sharp rise in well temperature associated with the release of heat caused by freezing. In this paper we first present the calibration of the IR temperature measurement, which makes use of the fact that following ice nucleation aliquots of water warm to the ice–liquid equilibrium temperature (i.e. 0 ∘C when water activity is ∼1), which provides a point of calibration for each individual well in each experiment. We then tested the temperature calibration using ∼100 µm chips of K-feldspar, by immersing these chips in 1 µL droplets on an established cold stage (µL-NIPI) as well as in 50 µL droplets on IR-NIPI; the results were consistent with one another, indicating no bias in the reported freezing temperature. In addition we present measurements of the efficiency of the mineral dust NX-illite and a sample of atmospheric aerosol collected on a filter in the city of Leeds. NX-illite results are consistent with literature data, and the atmospheric INP concentrations were in good agreement with the results from the µL-NIPI instrument. This demonstrates the utility of this approach, which offers a relatively high throughput of sample analysis and access to low INP concentrations.

scholarly journals Fluorescent biological aerosol particle concentrations and size distributions measured with an Ultraviolet Aerodynamic Particle Sizer (UV-APS) in Central Europe

2010 ◽  
Vol 10 (7) ◽  
pp. 3215-3233 ◽  
Author(s):  
J. A. Huffman ◽  
B. Treutlein ◽  
U. Pöschl
Keyword(s):  
Particle Number ◽  
Fungal Spores ◽  
Number Concentration ◽  
Size Distributions ◽  
Bacterial Cells ◽  
Spores And Pollen ◽  
Measurement Results ◽  
The Mean ◽  
Particle Sizer ◽  
Biological Aerosol Particles

Abstract. Primary Biological Aerosol Particles (PBAPs), including bacteria, spores and pollen, are essential for the spread of organisms and disease in the biosphere, and numerous studies have suggested that they may be important for atmospheric processes, including the formation of clouds and precipitation. The atmospheric abundance and size distribution of PBAPs, however, are largely unknown. At a semi-urban site in Mainz, Germany we used an Ultraviolet Aerodynamic Particle Sizer (UV-APS) to measure Fluorescent Biological Aerosol Particles (FBAPs), which provide an estimate of viable bioaerosol particles and can be regarded as an approximate lower limit for the actual abundance of PBAPs. Fluorescence of non-biological aerosol components are likely to influence the measurement results obtained for fine particles (<1 μm), but not for coarse particles (1–20 μm). Averaged over the four-month measurement period (August–December 2006), the mean number concentration of coarse FBAPs was ~3×10−2 cm−3, corresponding to ~4% of total coarse particle number. The mean mass concentration of FBAPs was ~1μg m−3, corresponding to ~20% of total coarse particle mass. The FBAP number size distributions exhibited alternating patterns with peaks at various diameters. A pronounced peak at ~3 μm was essentially always observed and can be described by the following campaign-average lognormal fit parameters: geometric mean diameter 3.2 μm, geometric standard deviation 1.3, number concentration 1.6×10−2 cm−3. This peak is likely due to fungal spores or agglomerated bacteria, and it exhibited a pronounced diel cycle (24-h) with maximum intensity during early/mid-morning. FBAP peaks around ~1.5 μm, ~5 μm, and ~13 μm were also observed, but less pronounced and less frequent. These may be single bacterial cells, larger fungal spores, and pollen grains, respectively. The observed number concentrations and characteristic sizes of FBAPs are consistent with microscopic, biological and chemical analyses of PBAPs in aerosol filter samples. To our knowledge, however, this is the first exploratory study reporting continuous online measurements of bioaerosol particles over several months and a range of characteristic size distribution patterns with a persistent bioaerosol peak at ~3 μm. The measurement results confirm that PBAPs account for a substantial proportion of coarse aerosol particle number and mass in continental boundary layer air. Moreover, they suggest that the number concentration of viable bioparticles is dominated by fungal spores or agglomerated bacteria with aerodynamic diameters around 3 μm rather than single bacterial cells with diameters around 1 μm.

Characterization of Particle Size, Number, and Mass Emissions From a Diesel Powered Generator

2006 ◽  
Author(s):  
Imad A. Khalek
Keyword(s):  
Particle Size ◽  
Solid Particle ◽  
Particle Distribution ◽  
Size Range ◽  
Number Concentration ◽  
Solid Particles ◽  
Size Distributions ◽  
Particle Size Distributions ◽  
Engine Operation ◽  
Size Number

Total (volatile plus solid) and solid particle size, number, and mass emitted from a 3.8 kW diesel powered generator were characterized using a Scanning Mobility Particle Sizer (SMPS) that measures the size distribution of particles, and a catalytic stripper that facilitates the measurement of solid particles. The engine was operated at a constant speed for six steady-state engine operations ranging from idle to rated power. The solid particle size distributions were mainly monomodal lognormal distributions in nature reflecting a typical soot agglomerate size distribution with a number mean diameter in the size range from 98 nm to 37 nm as the load decreases from high to low. At idle, M6, however, the solid particle distribution was bimodal in nature with a high number of solid nanoparticles in the sub-20 nm size range. It is likely that these solid particles nucleated later in the combustion process from metallic ash typically present in the lube oil. The total particle size distributions exhibited a bimodal structure only at light load, M5, engine operation, where a high number of volatile nanoparticles were observed. The rest of the operating conditions exhibited monomodal distributions although the nature of the particles was vastly different. For the medium load modes, M2, M3, and M4, the particles were mainly solid particles. For the rated power, M1, and idle, M6, modes of engine operation, significant number of volatile particles grew to a size nearing that of soot particles making the distribution monomodal, similar to that of a solid particle distribution. This shows that monomodal distributions are not necessarily solid particle but they can be strongly dominated with volatile particles if significant particle growth takes place like the case at M1, and M6. The total number and mass concentration were extremely high at engine rated power. The number concentration exceeded 1.2 billion particles per cubic centimeter and the mass exceeded 750 milligrams per cubic meter. The number concentration is more than five orders of magnitude higher than a typical ambient level concentration, and the mass concentration is more than four orders of magnitude higher. It is important to indicate, however, that if the engine power rating is lowered by 35 percent from its designated level, both particle mass and number emissions will be reduced by two orders of magnitude. By measuring total and solid particle size and number concentration of particles, one can calculate other metrics such as surface area and mass to provide detail information about particle emissions. Such information can serve as an important database where all metrics of particle emissions are captured.

Influence of organic and biogenic substances on the ice nucleation properties of mineral dust particles

2020 ◽  
Author(s):  
Kristian Klumpp ◽  
Claudia Marcolli ◽  
Thomas Peter
Keyword(s):  
Amino Acids ◽  
Organic Acids ◽  
Mineral Dust ◽  
Particle Surface ◽  
Ice Nucleation ◽  
Dust Particles ◽  
Biogenic Substances ◽  
Immersion Freezing ◽  
Mixed Phase Clouds ◽  
Ice Nucleation Activity

&lt;p&gt;The formation of ice in mixed phase clouds occurs in the presence of aerosol particles with the ability to nucleate ice on their surface. These ice-nucleating particles (INPs) represent usually a small fraction of particles in an atmospheric aerosol. One of the main particle types which act as INPs are mineral dust particles. Among other factors, the accumulation of semivolatile substances on the particle surface can alter the ice nucleation properties of such particles.&lt;/p&gt;&lt;p&gt;In recent immersion freezing experiments, we investigated the influence of organic acids, amino acids and polyols on the highly ice nucleation active K-feldspar microcline. Microcline dust was suspended in solutions of the above-mentioned substances and frozen in a differential scanning calorimeter (DSC). These experiments give us insight into the ice nucleation characteristics of the particles in the presence of the tested organic and biogenic substances. Our measurements show an overall decrease in ice nucleation activity of microcline in the presence of organic acids and amino acids. &lt;br&gt;&lt;br&gt;&lt;/p&gt;

scholarly journals Impacts of Secondary Ice Production on Arctic Mixed-Phase Clouds based on ARM Observations and CESM2

2020 ◽  
Author(s):  
Xi Zhao ◽  
Xiaohong Liu ◽  
Vaughan T. J. Phillips ◽  
Sachin Patade
Keyword(s):  
Global Climate Model ◽  
Single Layer ◽  
Ice Nucleation ◽  
Number Concentration ◽  
Mixed Phase ◽  
Department Of Energy ◽  
Cloud Base ◽  
Ice Crystal ◽  
Ice Production ◽  
Mixed Phase Clouds

Abstract. For decades, measured ice crystal number concentrations have been found to be orders of magnitude higher than measured ice nucleating particles in moderately cold clouds. This observed discrepancy reveals the existence of secondary ice production (SIP) in addition to the primary ice nucleation. However, the importance of SIP relative to primary ice nucleation remains highly unclear. Furthermore, most weather and climate models do not represent well the SIP processes, leading to large biases in simulated cloud properties. This study demonstrates a first attempt to represent different SIP mechanisms (frozen raindrop shattering, ice-ice collisional break-up, and rime splintering) in a global climate model (GCM). The model is run in the single column mode to facilitate comparisons with the Department of Energy (DOE)'s Atmospheric Radiation Measurement (ARM) Mixed-Phase Arctic Cloud Experiment (M-PACE) observations. We show the SIP importance in the four types of clouds during M-PACE (i.e., multilayer, and single-layer stratus, transition, and front clouds), with the maximum enhancement in ice crystal number concentration by up to 4 orders of magnitude in the moderately-cold clouds. We reveal that SIP is the dominant source of ice crystals near the cloud base for the long-lived Arctic single-layer mixed-phase clouds. The model with SIP improves the occurrence and phase partitioning of the mixed-phase clouds, reverses the vertical distribution pattern of ice number concentration, and provides a better agreement with observations. The findings of this study highlight the importance of considering the SIP in GCMs.

scholarly journals The contribution of fungal spores and bacteria to regional and global aerosol number and ice nucleation immersion freezing rates

2013 ◽  
Vol 13 (12) ◽  
pp. 32459-32481 ◽  
Author(s):  
D. V. Spracklen ◽  
C. L. Heald
Keyword(s):  
Cloud Condensation Nuclei ◽  
Fungal Spores ◽  
Ice Nucleation ◽  
Model Studies ◽  
Modelling Studies ◽  
Climate Interactions ◽  
Immersion Freezing ◽  
Simulated Surface ◽  
Mixed Phase Clouds ◽  
Ice Nucleation Activity

Abstract. Primary biological aerosol particles (PBAP) may play an important role in aerosol–climate interactions, in particular through affecting ice formation in mixed phase clouds. However, the role of PBAP is poorly understood because the sources and distribution of PBAP in the atmosphere are not well quantified. Here we include emissions of fungal spores and bacteria in a global aerosol microphysics model and explore their contribution to concentrations of supermicron particle number, cloud condensation nuclei (CCN) and immersion freezing rates. Simulated surface annual mean concentrations of fungal spores are ~2.5 × 104 m−3 over continental midlatiudes and 1 × 105 m−3 over tropical forests. Simulated surface concentrations of bacteria are 2.5 × 104 m−3 over most continental regions and 5 × 104 m−3 over grasslands of central Asia and North America. These simulated surface number concentrations of fungal spores and bacteria are broadly in agreement with the limited available observations. We find that fungal spores and bacteria contribute 8% and 5% respectively to simulated continental surface mean supermicron number concentrations, but have very limited impact on CCN concentrations, altering regional concentrations by less than 1%. In agreement with previous global modelling studies we find that fungal spores and bacteria contribute very little (3 × 10−3 % even when we assume upper limits for ice nucleation activity) to global average immersion freezing ice nucleation rates, which are dominated by soot and dust. However, at lower altitudes (400 hPa to 600 hPa), where warmer temperatures mean that soot and dust may not nucleate ice, we find that PBAP controls the immersion freezing ice nucleation rate. This demonstrates that PBAP can be of regional importance for IN formation, in agreement with case study observations but in contrast to recent global model studies that have concluded PBAP are unimportant as ice nuclei.

scholarly journals Enhanced ice nucleation efficiency of microcline immersed in dilute NH<sub>3</sub> and NH<sub>4</sub><sup>+</sup>-containing solutions

2018 ◽  
Author(s):  
Anand Kumar ◽  
Claudia Marcolli ◽  
Beiping Luo ◽  
Thomas Peter
Keyword(s):  
Volume Fraction ◽  
Pure Water ◽  
Freezing Temperature ◽  
Ice Nucleation ◽  
Ice Melting ◽  
Salt Solutions ◽  
Point Curve ◽  
Mineral Dusts ◽  
Immersion Freezing ◽  
Mixed Phase Clouds

Abstract. Potassium containing feldspars (K-feldspars) have been considered key mineral dusts for ice nucleation (IN) in mixed-phase clouds. To investigate the effect of solutes on their IN efficiency, we performed immersion freezing experiments with the K-feldspar microcline, which is highly IN active. Freezing of emulsified droplets with microcline suspended in aqueous solutions of NH3, (NH4)2SO4, NH4HSO4, NH4NO3, NH4Cl, Na2SO4, H2SO4, K2SO4 and KCl, with solute concentrations corresponding to water activities aw = 0.9–1.0, were investigated by means of a differential scanning calorimeter (DSC). The measured heterogeneous ice nucleation onset temperatures, Thet (aw) deviate strongly from Thet∆awhet (aw), the values calculated from the water-activity-based approach (where Thet∆awhet (aw) = Tmelt (aw + ∆awhet) with a constant offset ∆awhet with respect to the ice melting point curve). Surprisingly, for very dilute solutions of NH3 and NH4+-salts (molalities  ~ 0.96), we find IN temperatures raised by up to 4.5 K above the onset freezing temperature of microcline in pure water (Thet (aw = 1)) and 5.5 K above Thet∆awhet (aw), revealing NH3 and NH4+ to significantly enhance the IN of the microcline surface. Conversely, more concentrated NH3 and NH4+ solutions show a depression of the onset temperature below Thet∆awhet (aw) by as much as 13.5 K caused by a decline in IN ability accompanied with a reduction in the volume fraction of water frozen heterogeneously. All salt solutions not containing NH4+ as cation exhibit nucleation temperatures Thet (aw)  ~ 0.96) at warm (252–257 K) and NH3/NH4+-rich conditions.

scholarly journals On the Parameterization of Evaporation of Raindrops as Simulated by a One-Dimensional Rainshaft Model

2008 ◽  
Vol 65 (11) ◽  
pp. 3608-3619 ◽  
Author(s):  
Axel Seifert
Keyword(s):  
Reference Model ◽  
Number Concentration ◽  
High Variability ◽  
Cloud Base ◽  
Size Distributions ◽  
One Dimensional ◽  
Raindrop Size Distribution ◽  
The Mean ◽  
Raindrop Size ◽  
Bin Microphysics

Abstract The process of evaporation of raindrops below cloud base is investigated by numerical simulations using a one-dimensional rainshaft model with bin microphysics. The simulations reveal a high variability of the shape of the raindrop size distributions, which has important implications for the efficiency of evaporation below cloud base. A new parameterization of the shape of the raindrop size distribution as a function of the mean volume diameter is suggested and applied in a two-moment microphysical scheme. In addition, the effect of evaporation on the number concentration of raindrops is parameterized. A comparison of results of the revised two-moment scheme and the bin microphysics rainshaft model shows that the two-moment scheme is able to reproduce the results of the reference model in a wide parameter range.

scholarly journals Urban aerosol number size distributions

2004 ◽  
Vol 4 (2) ◽  
pp. 391-411 ◽  
Author(s):  
T. Hussein ◽  
A. Puustinen ◽  
P. P. Aalto ◽  
J. M. Mäkelä ◽  
K. Hämeri ◽  
...  
Keyword(s):  
Particle Number ◽  
Size Range ◽  
Particle Diameter ◽  
Temporal Variations ◽  
Number Concentration ◽  
Building Construction ◽  
Urban Aerosol ◽  
Size Distributions ◽  
Arithmetic Means ◽  
Accumulation Mode

Abstract. Aerosol number size distributions have been measured since 5 May 1997 in Helsinki, Finland. The presented aerosol data represents size distributions within the particle diameter size range 8-400nm during the period from May 1997 to March 2003. The daily, monthly and annual patterns of the aerosol particle number concentrations were investigated. The temporal variation of the particle number concentration showed close correlations with traffic activities. The highest total number concentrations were observed during workdays; especially on Fridays, and the lowest concentrations occurred during weekends; especially Sundays. Seasonally, the highest total number concentrations were observed during winter and spring and lower concentrations were observed during June and July. More than 80% of the number size distributions had three modes: nucleation mode (Dp<30nm), Aitken mode (20-100nm) and accumulation mode (Dp>90nm). Less than 20% of the number size distributions had either two modes or consisted of more than three modes. Two different measurement sites were used; in the first (Siltavuori, 5.5.1997-5.3.2001), the arithmetic means of the particle number concentrations were 7000cm-3, 6500cm-3, and 1000cm-3 respectively for nucleation, Aitken, and accumulation modes. In the second site (Kumpula, 6.3.2001-28.2.2003) they were 5500cm-3, 4000cm-3, and 1000cm-3. The total number concentration in nucleation and Aitken modes were usually significantly higher during workdays than during weekends. The temporal variations in the accumulation mode were less pronounced. The lower concentrations at Kumpula were mainly due to building construction and also the slight overall decreasing trend during these years. During the site changing a period of simultaneous measurements over two weeks were performed showing nice correlation at both sites.

scholarly journals The contribution of fungal spores and bacteria to regional and global aerosol number and ice nucleation immersion freezing rates

2014 ◽  
Vol 14 (17) ◽  
pp. 9051-9059 ◽  
Author(s):  
D. V. Spracklen ◽  
C. L. Heald
Keyword(s):  
Cloud Condensation Nuclei ◽  
Fungal Spores ◽  
Ice Nucleation ◽  
Modelling Studies ◽  
Climate Interactions ◽  
Immersion Freezing ◽  
Simulated Surface ◽  
Global Modelling ◽  
Mixed Phase Clouds ◽  
Ice Nucleation Activity

Abstract. Primary biological aerosol particles (PBAPs) may play an important role in aerosol–climate interactions, in particular by affecting ice formation in mixed phase clouds. However, the role of PBAPs is poorly understood because the sources and distribution of PBAPs in the atmosphere are not well quantified. Here we include emissions of fungal spores and bacteria in a global aerosol microphysics model and explore their contribution to concentrations of supermicron particle number, cloud condensation nuclei (CCN) and immersion freezing rates. Simulated surface annual mean concentrations of fungal spores are ~ 2.5 × 104 m−3 over continental midlatitudes and 1 × 105 m−3 over tropical forests. Simulated surface concentrations of bacteria are 2.5 × 104 m−3 over most continental regions and 5 × 104 m−3 over grasslands of central Asia and North America. These simulated surface number concentrations of fungal spores and bacteria are broadly in agreement with the limited available observations. We find that fungal spores and bacteria contribute 8 and 5% respectively to simulated continental surface mean supermicron number concentrations, but have very limited impact on CCN concentrations, altering regional concentrations by less than 1%. In agreement with previous global modelling studies, we find that fungal spores and bacteria contribute very little (3 × 10−3%, even when we assume upper limits for ice nucleation activity) to global average immersion freezing ice nucleation rates, which are dominated by soot and dust. However, at lower altitudes (400 to 600 hPa), where warmer temperatures mean that soot and dust may not nucleate ice, we find that PBAP controls the immersion freezing ice nucleation rate. This demonstrates that PBAPs can be of regional importance for IN formation, in agreement with case study observations.

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