Indian Institute of Technology Kanpur, India.

1
Indian Institute of Technology Kanpur, India.
First European Space Weather Week, ESTEC,
Noordwijk, (The Netherlands), 29th November-3rd
December 2004.
Model Studies on atmospheric ion-induced
nucleation of sulfuric acid and water
Interpretation of in-situ measurements
Vijay Kanawade, Sanjeev Kumar and S. N.
Tripathi Department of Civil Engineering, Indian
Institute of Technology Kanpur,
India (snt_at_iitk.ac.invijaypk_at_iit.ac.in)

• Motivation
• To develop an efficient and fast ion induced
  nucleation model, which will be implemented in a
  global model to study nucleation of particle on
  global scale.
• To interpret observed atmospheric nucleation
  events and to understand the role of cosmic ray
  induced ionization on particle microphysics.

Table 1 Observed and Model predicted particle
concentrations for TOPSE Experiment
Flight/ location Local Time Alt. km Temp. K RH P (press.) mb TH2SO4 106 cm-3 SA Q Max. Observed particle Model Predicted particle number conc. cm-3 number Conc. cm-3 3-4nm 3-8nm gt3nm 3-4nm 3-8nm gt3nm Max. Observed particle Model Predicted particle number conc. cm-3 number Conc. cm-3 3-4nm 3-8nm gt3nm 3-4nm 3-8nm gt3nm Max. Observed particle Model Predicted particle number conc. cm-3 number Conc. cm-3 3-4nm 3-8nm gt3nm 3-4nm 3-8nm gt3nm Max. Observed particle Model Predicted particle number conc. cm-3 number Conc. cm-3 3-4nm 3-8nm gt3nm 3-4nm 3-8nm gt3nm Max. Observed particle Model Predicted particle number conc. cm-3 number Conc. cm-3 3-4nm 3-8nm gt3nm 3-4nm 3-8nm gt3nm Max. Observed particle Model Predicted particle number conc. cm-3 number Conc. cm-3 3-4nm 3-8nm gt3nm 3-4nm 3-8nm gt3nm
Flight 16 1330 4.2 240.1 5.6 573.0 9.21 15 10 65 289 3361 56 256 3031
(within SO2   4.2 241.2 5.3 574.4 9.19 15 10 20 80 2324 29 135 1889
 Plume)   4.1 241.2 4.9 574.6 8.24 15 10 5 10 2021 11 33 1567
Flight 16 1330 4.3 237.9 5.5 519.6 1.85 15 10 0.0 0.0 137 4 14 78.0
( Above Plume)   4.3 240.0 4.6 548.1 3.88 15 10 0.01 0.06 830 8 21 230.0

• Introduction
• Particle nucleation has been observed in
  atmosphere that has not been explained by
  Homogenous Nucleation theory
• Ion-induced nucleation is shown to be an
  effective pathway for explaining new particle
  formation in the UTLS region (Lee et al., 2003).
  Ions are formed by Galactic Cosmic Rays (GCRs) at
  the rate of 1-30 ion pairs (Q) cm-3.s-1 in the
  background lower atmosphere .
• Several factors favouring ion-induced nucleation
  exist in the UTLS region including high sulfuric
  acid concentration (H2SO4), low temperatures (T),
  relatively low surface area (SA) of preexisting
  aerosols, and sufficient sun exposure.

TH2SO4 Observed H2SO4 plus Calculated H2SO4
(H2SO4 calculated with the observed SO2 and OH
concentration by using rate limiting reaction OH
SO2 H2SO4 (DeMore et al., 1997))

• Model
• Ion induced nucleation parameterization based on
  Kinetic model (SAWNUC) (Lovejoy et al., 2004) is
  implemented in the H2SO4-H2O Aerosol
  Microphysical model (SAMIN) (Tripathi et al.,
  2004).
• Nucleation parameterization is valid in the
  ranges 200T280K, 5Relative Humidity(RH)95,
  105 H2SO4 108 molecules.cm-3, 2
  SA200µm2.cm-3, and 2Q30 ion pairs cm-3.s-1.
• Besides ion induced nucleation (IIN), SAMIN
  simulates H2SO4 condensational growth, water
  vapour equilibrium, particle-particle coagulation
  and sedimentation.
• The particle size range in the SAMIN model covers
  particles having radii between 0.3 nm to 1.0 µm.
  The size range is geometrically divided into 40
  bins and integration time step used is 60
  seconds.
• SAMIN and SAWNUC predicted aerosol
  size distributions for the enviormental codition
  T236K, RH4, SA15 µm2.cm-3, Q12 ion pairs
  cm-3.s-1 for different H2SO4 gas concentration is
  presented in Figure 1(a,b,c). It can be seen that
  SAMIN and SAWNUC predicted aerosol size
  distributions are in good agreement.

Figure 3(c)
Figure 3(a)
Figure 3(b)
Figure 3. (a) 2-day Back Trajectory plot for air
parcel height, T and RH during TOPSE experiment.
(b) Comparison between observed and model
predicted UCNgt3nm for the observed environmental
parameters during TOPSE experiment. (c)
Sensitivity test for preexisting particle surface
area on ultra fine particle (3-4nm) during TOPSE
experiment.


Figure 4(c)
Figure 4(a)
Figure 4(b)
Figure 4. (a) Comparison between observed and
model predicted ultra fine particle (3-4nm) for
PEMT A experiment flight 10. (b) Comparison
between observed and model predicted UCNgt3nm for
PEMT A experiment. flight 10. (c) Comparison
between observed and model predicted ultra fine
particle (3-10nm) for ACE 1 experiment. Flight 17.
(a)
(c)
(b)
Table 2 Observed and model predicted particle
number concentration for atmospheric Nucleation
events

Model Predictions

PEM Tropics A (Pacific Exploratory Mission in
the Tropics-Phase A)
Flight/ location Local Time Alt. km Temp. K RH P mb TH2SO4 106 cm-3 SA Q Max. Obs. Particle Model Predicted particle conc. cm-3 Particle conc. cm-3 3-9nm 3-9nm Max. Obs. Particle Model Predicted particle conc. cm-3 Particle conc. cm-3 3-9nm 3-9nm
Flight 10 1300 4.9 273.2 74.5 671.1 10.5 15.0 10 382.0 272.0
  1800-1900 8.3 249.8 55.3 433.6 3.89 15.0 10 1568 1038
Evolution of the size distribution of particle
predicted by the model for a typical
environmental condition within UTLS region is
plotted in the Fig. 2(a,b). Figure 2(a) shows
the particle growth from 3 nm to 100 nm for 40
hr. model run. Figure 2(b) depicts the evolution
of size distribution for radius range from 0.3 nm
to 100 nm over a 24 hr. period. The model
run was from sun rise until sunset to predict
size distribution of aerosol particles.
ACE 1 (First Aerosol Characterization
Experiment-one)
Flight/ location Local Time Alt. km Temp. K RH P (press.)mb TH2SO4 106 cm-3 SA Q Max. Obs. Particle Model Predicted Particle Conc. cm-3 Particle Conc. cm-3 3-10nm 3-10nm Max. Obs. Particle Model Predicted Particle Conc. cm-3 Particle Conc. cm-3 3-10nm 3-10nm
Flight 16 1600-1700 5.5 254.5 62.5 505.5 3.12 15.0 10 350 194
    6.1 250.0 55.0 480.4 2.68 15.0 10 230 105
Flight 17  1600-1800  3.2 262.5 62.5 686.6 7.66 15.0 10 2117 2188
Flight 27 1200-1400 3.6 265.5 67.7 650.5 7.68 15.0 10 350 260
PEM Tropics B (Pacific Exploratory Mission in
the Tropics-Phase B)
(a)
(b)
Flight/ location Local Time Alt km Temp deg.K RH P mb TH2SO4 106 cm-3 SAa Qb Max. Obs. Particle Model Predicted Particle Conc. cm-3 Particle Conc. cm-3 3-4nm 3-10nm 3-4nm 3-10nm Max. Obs. Particle Model Predicted Particle Conc. cm-3 Particle Conc. cm-3 3-4nm 3-10nm 3-4nm 3-10nm Max. Obs. Particle Model Predicted Particle Conc. cm-3 Particle Conc. cm-3 3-4nm 3-10nm 3-4nm 3-10nm Max. Obs. Particle Model Predicted Particle Conc. cm-3 Particle Conc. cm-3 3-4nm 3-10nm 3-4nm 3-10nm
Flight 13 1130-1230 0.2 295.3 78.3 990.2 26.3 15.0 10 8.0 230 0.0 0.0
    0.3 288.4 67.7 975.5 47.8 15.0 10 13.0 376 0.8 9.0
Figure 2.(a,b) SAMIN predicted particle size
distribution curve and particle production for
environmental condition within UTLS region.

• Interpretation of Observed Nucleation Events
• SAMIN was run using measured
  environmental parameters e.g. T, RH, H2SO4, SO2
  (Sulfur dioxide, pptv), OH, to interpret
  different observed atmospheric nucleation events
  viz., (i) TOPSE (Tropospheric Ozone Production
  about the Spring Equinox), (ii) ACE-1 (First
  Aerosol Characterization Experiment-One), (iii)
  PEM Tropics A (Pacific Exploratory Mission in the
  Tropics-Phase A), (iv) PEM Tropics B (Pacific
  Exploratory Mission in the Tropics-Phase B), (v)
  TRACE P (TRAnsport and Chemical Evolution over
  Pacific)
• TOPSE (Tropospheric Ozone Production about the
  Spring Equinox)
• Table 1 summarizes the observed environmental
  parameters during TOPSE experiment, where
  in-situ new particle production were observed. We
  have calculated new particle production (3-4nm,
  3-8nm) for the observed environmental parameters,
  by running the model from sunrise until the
  observation time (see Table 1).
• The direct comparison between the model
  predicted and observed Ultra fine Condensation
  Nuclei (UCN)gt3nm is problematic because the
  history of the air parcel containing the fresh
  ultra fine particles as well as aged particles is
  uncertain and also temperature and relative
  humidity is changing along the path of air
  parcel. To interpret UCN gt3nm, we have computed
  back trajectory of the air parcel using HYSPLIT
  model for TOPSE flight 16 observed environmental
  parameters (Figure 3(a)) and SAMIN model run for
  2 days with these HYSPLIT calculated T and RH to
  interpret on UCNgt3nm.

• Conclusion
• It was found that SAMIN predicted ultra fine
  particle (3-4nm,3-8nm,3-10nm) number
  concentrations are in good agreement with the
  observed one during different nucleation events
  in the middle and upper troposphere. Also UCNgt3nm
  number concentration is also matching quite well
  with the observed one during TOPSE experiment.
• We conclude that ion induced nucleation play key
  role in the formation of ultra fine particles in
  the cold middle and upper troposphere (4-7km)
  for a range of parameters T235-280K, RH4-66,
  H2SO42'106-9'107molecules.cm-3, SA2-200µm2.cm-3
  and Q2-30 ion pairs cm-3.s-1, for which SAMIN is
  able to predict observed new particle formation.

• Future Work
• Present aerosol microphysical model is being
  modified to study the effect of ions on particle
  formation, which activates into cloud
  condensation nuclei and to study cloud
  microphysics.

• References\
• DeMore, W. B., S.P.Sandar, D.M.Golden,R.P.Hampson,
  M.J.Kurylo,C.J.Howard,A.R.Ravishankar,C.E.Kolb,
  and Molina, Chemical kinetics and photochemical
  data for use in stratospheric mo0deling, JPL
  Publ.,97-4, 1997
• Modgil, M. S., Kumar, S., Tripathi, S. N., and
  E.R. Lovejoy, A Parameterization of Ion Induced
  Nucleation of Sulphuric Acid and Water for
  Atmospheric Conditions, Under reviewJ. Geophys.
  Res.
• Lee,S..H., J.M. Reeves, J.C. Wilson, D.E. Hunton,
  A.A. Viggiano, T.M. Miller, J. O. Ballenthin, and
  L.R. Lait, Particle formation by ion nucleation
  in the upper troposphere and lower stratospheer,
  Science, 301, 1886-1889.
• Lovejoy, E. R., J. Curtius, and K. D. Froyd,
  Atmospheric ion-induced nucleation of sulfuric
  acid and water, J. Geophys. Res., Vol. 109, No.
  D8, D08204, 10.1029/2003JD004460, 2004.
• Tripathi, S. N., X. P. Vancassel, R. G. Grainger,
  and H. L. Rogers, A Fast Stratospheric Aerosol
  Microphysical Model (SAMM) H2SO4-H2O Aerosol
  Development and Validation, AOPP Memorandum
  2004.1 , Department of Physics, University of
  Oxford, 2004.

Acknowledgment This work has been
supported through a research grant of
ISRO-RESPOND programme of Indian Space Research
Organization. We thankfully acknowledge the
encouragement and support received from the
Director, IIT Knapur. We also acknowledge Data
Manger, RAF, NCAR for data provided for the
purpose of analysis and validation and their
continuous help during study.
.