Ice Nucleating Particle (INP) Measurements at YMC: ETH - PINC and HINC

Transcription

1 Ice Nucleating Particle (INP) Measurements at YMC: ETH - PINC and HINC Portable Ice Nucleation Chamber Horizontal Icee Nucleation Chamber Zamin A. Kanji ETH Zurich Year of the Maritime Continent (YMC) Workshop Centre for Climate Research Singapore January 28 30, 2015

2 liquid droplet Homogeneous Freezing solid particle (INP) Heterogeneous Freezing By Immersion/ /Condensation (RH w 100%) ice particle T 235 K RH i 140% Spontaneous Freezing By Deposition (RH w < 100%, RH i >120%) By Contact (RH w 100)

3 T- RH Space we can Investigate Water Sauration WDS Hom. Freez. Ice Saturation Ratio Deposition nucleation Temperature (K) Limit of Optical Particle Counter Particle Trajectory (Immersion) Particle Trajectory (Dep/Cond.)

4 Thermal Gradient Diffusion Principle S i 1.8 Vapour Pressure (e, hpa) cold wall e cold Temperature (K) RH calculated at sample position (mid-way between chamber walls). S w 223 K e s e i e warm warm wall Saturation Ratio (S) Residence time: HINC: 3 28 s Kanji and Abbatt, AS&T (2009)

5 Growth and Detection of Ice Crystals PINC/(HINC) Deposition/Condensation Growth Section Evaporation Section RH w << 100% RH i = 100% OPC: Large particles Ice! T < -20 CC RH w < 100% Deposition OR T < -6 CC RH w > 100% Condensation Concentration Concentration Aerosol Size Bins Ice Nucleation Aerosol Ice Size Bins

6 Type of Data Collected: DeMott et al., 2010, PNAS Test existing param. Come up with new typically based on aerosol physical properties (size, number, surface area) and at time chemical properties

7 Connecting Both Ends of Scale

8 Motivation: INP Measurement Sites Increase Network/ /Density of Observations

9 Motivation: Convection At YMC: marine (biological), industrial/urban and biomass burning Rosenfeld et al., 2008 (Science)

10 Transport of Aerosol to Mid Upper (Free) Troposphere by Convection

11 Major Research Question at YMC: What is the contribution of the changing aerosol environment to [INP]?

12 Specific Questions (1) What is the INP concentration? Mixed phase regimee (T > -38 C, RH w > 100%) Cirrus Regime (T < -38 C, RH w < 100%) How do [INP] change with environmental and meteorological conditions? Ocean biological activity/marine air masses Precipitation events contributing to INP Air masses from urban polluted/dust regions

13 Specific Questions (2) Chemical & Physical Properties Is there a correlation of IN with particle properties? Size, concentration, PM mass Composition Organics vs. inorganics BC or Dust Biologically active material Is the Sea Surface Microlayer (SML) a source of IN particles Chance (permission from Federal Research Office?) to sample the SML?

14 Wish List of Auxiliary Measurements Instrument Information Acquired Time Resolution HINC/PINC IN ~ 20 mins SMPS Aerosol SD ~ 3 mins APS Aerosol SD > 0.7µm ~ 20 seconds CPC WIBS/UV-APS PM10/2.5 AMS SP AMS? ATOFMS/LAABTOFMS Lidar/Cloud Radar Aerosol Conc. Biologically active Aerosol SD/Conc Mass Conc. Chemical Comp? Chemical Composition Aerosol mixing state BC? Single particle Refractory Material Cloud Phase above measurement site 5 10 seconds 20 seconds 12 or 24 hours? ~ 1 3 mins ~ 3 minutes

15 Questions How do INP measurements inform contribute the YMC framework? Aerosol (cold or mixed-phase) cloud interactions? Are ice forming processes represented? Are there precipitation forming mechanisms dependent on ice phase formation? Importance for cumulus? Ice nucleation important for dehydration/water vapour budget in UT Exchange for UT/LS

16 Ice Particle Detection Concentration Aerosol Ice Nucleation Concentration Aerosol Ice Size Bins Size Discrimination with an T between ice coated walls ice evaporates creates S i at sample position freezing initiation Optical Particle Counter (OPC) ice crystal growth OPC detects crystals by size distinction Size Bins Ice!

17 Mechanisms Investigated in Field Both PINC and HINC use an OPC to distinguish ice from interstitial particles by size discrimination Homogeneous Freezing can be used for in-field calibration Deposition Nucleation Condensation/Immersion Freezing

18 HINC Schematic Field Courtesy of Larissa Lacher OPC/CPC => Activated Fraction (AF)

19 Validation T/RH PINC: (NH 4 ) 2 SO 4 Phase Change Hom. Freez. (-40 C) Deliquescence (-30 C)

20 Power and Chemical Requirements for IN Chemicals Required Nitrogen, Ethanol, Molecular sieves/silica gel Drying oven on site to regenerate drying agent CPC/SMPS 200 W each, 2 laptops 100 W Compressor with Zero-air generator (220 W) Re-circulating Chiller 3.5 kw (max) R404a and R508a (refrigerants, in permanent sealing) Ethanol used as a re-circulating fluid Total Power Required 4.3 kw

21 Ice Nucleation CFDC Principle Residence time: PINC: 5-6 s RH calculated at sample position accounting for displacement due to buoyancy in vertical chamber Stetzer et al., AS&T (2008) Kanji et al., ACP (2013)

22 PINC Schematic T between ice coated walls ice evaporates creates S i at sample position Modified from Stetzer et al., AS&T (2008) Kanji et al., ACP (2013) OPC/C freezing initiation, ice crystal growth OPC detects crystals & interstitial distinction by size CPC counts => Activated Fraction (AF)

23 Benefits and Limitations Parallel flat plate allows for in-situ detector New particle phase discriminator being developed to increase sensitivity Vertical orientation: large particles not lost to settling Frost build-up falls off walls and sampled Longer operation times (> 4 hrs) yield poor background (LOD) Flow chamber eliminates substrate effect, opt. det. Low S/N compared to cold stage methods which are sensitive to a single ice crystal from optical imaging Horizontal orientation: Better sensitivity due to low background, frost grows on bottom wall Particles that grow large enough can be lost to settling HINC: Added advantage of time dependent exps.

24 Calibration of INP Chambers RH w =100% Hom. Freez.(Koop, 2000) Water drop survival RH w = 82-84% AS-DRH (Cziczo et al., 1999) Cloud Droplet Formation 200 nm (NH 4 ) 2 SO 4 Ice Saturation Ratio Temperature (K) 100 nm H 2 SO 4 Phase Changes 200 nm DRH, AS 100 nm Homo. freez., SA

25 IMCA ZINC: Immersion mode Welti et al., ACP (2012) Supercooled region (ZINC) maintained at RH w = 100% Detection Ports for kinetic studies (time dependence) Particles singly immersed in IMCA forced CCN activation IODE gives a Frozen Fraction (FF)

26 Validation IMCA: AS homogeneous freezing

27 Growth and Detection of Ice Crystals IMCA ZINC - Immersion Into ZINC CCN activation T ~ 30 C RH w >>100% ΔT ~ 15 K IODE FF = 0.5 Ice Nucleation T < -10 C RH w =100% ΔT > 0 K Evaporation T < -10 C RH w << 100% ΔT = 0 K

28 Envisioned Ideal Set up Inlet 1 Inlet 2 Dryer Dilution CPC (PIMCA ) Auxiliary measurements: Meteo Data PM filters Pollen detection Dropfreezing (liquid impinger) Condensation/Depostion Ice nucleation SMPS/AP S WIBS-4 Number & size distribution, bioparticles

29 Validation ZINC with AgI Stetzer et al. (2008)

30 Motivation to study ice nucleation in the atmosphere interest in understanding the primary formation of ice in clouds (and how it can be modified) characterisation (of requirements) and spatial distribution of ice forming nuclei Insolubility Size Active-sites Chemical bonding Crystallography functional description of ice nucleation e.g. for modelling.

31 General Research Objectives (Lab) Understand ice nucleation mechanisms Can theory predict empirical observations? Test CNT and non-cnt based models to describe data Understand behaviour of IN with changing size Size represents change in surface area for homogeneous surfaces For complex particles like mineral dust, size represents change in composition or soluble material Effects of particle type (composition and ageing of particles) Natural mineral dusts (ozone aged, SOA coated), soot particles, clay minerals, biological IN, AgI

32 HOLIMO(II) Amsler et al., Applied Optics (2009) Henneberger et al., AMT (2013)

33 1 2 Rotating brush generator Dry dispersal Particle Generation the Lab Mixing Fan IN instruments 3000 L RH Sensor Polydisperse particles (aged) Vacuum Kanji et al., ACP (2013) Lüönd et al., JGR (2010) Fan Motor ( rpm) 3 Wet generation IN instruments SMPS/APS/ CPC

34 Improved size selection with DMA/CPMA: Kaolinite Lüönd et al., 2010

35 Silver Iodide AgI is also hydrophobic (from water adsorption isotherms)

36 Size Selection: AgI

37 Comparison

38 Fitting of the Data with Nucleation Th heory All IN have the same contact angle α f 1 exp( J ( T, ) 4 r t 2 i, stoch N ZINC ) Courtesy of F. Lüönd IN have different contact angles, α is constant over each IN surface (Marcolli et. al., 2007) 2 fi, pdf 1 p( ) exp( J ( T, ) 4 rn tzinc ) d 0 Active sites with varying α are randomly distributed over the IN surface (Marcolli et. al., 2007) f m i, AS 1 exp( J ( T, i ) Ai tzinc ) i 1 Active sites with distinct freezing temperatures are randomly distributed over the IN surface (Connolly et. al., 2009) f 1 exp( n ( T ) 4 r 2 i, det s N )

39 Ice Nuclei Active Site Density - n s (T) (INAS) AF( FF) n n s s ( T ) ( T ) SA SA [ IceCrystals 1 for AF < 0.1 particle AF [ Particle] particle ln(1 AF) SA total Temperature more important than time Particle composition is uniform across sizes N ice ] det ected (1) chamber (2) (3)

40 T 50 fitted with CNT or active sites

41 T 50 Birch water AgI Cast Black Pine water 4