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 measurementsVijay Kanawade, Sanjeev Kumar and S. N. Tripathi

Department of Civil Engineering, Indian Institute of Technology Kanpur, India(snt@iitk.ac.in;vijaypk@iit.ac.in)

MotivationMotivationTo 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.

IntroductionIntroductionParticle 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.

ModelModelIon 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: 200≤T≤280K, 5≤Relative Humidity(RH)≤95%, 105 ≤H2SO4 ≤108 molecules.cm-3, 2 ≤SA≤200µm2.cm-3, and 2≤Q≤30 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 T=236K, RH=4%, SA=15 µm2.cm-3, Q=12 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 1(a,b,c). Comparison between SAMIIN model and SAWNUC model predicted aerosol size distribution for different sulfuric acid gas cocnetrations.

1 10 100101

102

103

104

105

Particle Size Distribution

dN/d

Log(

r) N

.cm

-3

Radius (nm)

T=236oKRH=4%

SA=15 m2.cm-2

Q=12 ion pairs cm-3.s-1

H2SO

4=1.E+07 molecules.cm-3

SAWNUC

SAMIIN

Model PredictionsModel Predictions

Rp>3nm

Time (Hrs.)10 20 30 40

1e+0

1e+1

1e+2

1e+3

1e+4

1e+5

1e+6

RP>10nm

RP>20nm

RP>30nm

RP>50nm

T=236oK, RH=6 %, H

2SO

4=1.E+07 molecules. cm

- 3,

SA= 15 m2.cm

- 3, Q=12 ion pairs cm

- 3.s

- 1

RP>100nm

UCN

num

ber

conc

entr

atio

n N

.cm

-3

15min

Radius (nm)1 10 100

dN/d

Log(

r) c

m-3

1.0e+1

1.0e+2

1.0e+3

1.0e+4

1.0e+5

30min

1h

2h

16h

8h

24h

T=236oK, RH=4 %, H2SO4=1.E+07 molecules. cm- 3

SA=15 m2.cm- 3, Q=12 ion pairs cm- 3.s- 1

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.

Figure 2.(a,b): SAMIN predicted particle size distribution curve and particle production for environmental condition within UTLS region.

Interpretation of Observed Nucleation EventsInterpretation 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 TOPSE (Tropospheric Ozone Production about the Spring Equinox)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)>3nm 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 >3nm, 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 UCN>3nm.

Table 1: Observed and Model predicted particle concentrations for TOPSE Experiment

Flight/location

LocalTime

Alt.km

Temp.K

RH%

P (press.)

mb

T[H2SO4]106 cm-3

SA Q Max. Observed particle Model Predicted particle number conc. cm-3 number Conc. cm-3

3-4nm 3-8nm >3nm 3-4nm 3-8nm >3nm

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 21 230.0TOPSE Flight 16 : SO2 Plume

T=239- 243K, RH=5- 12%, H2SO4=7.6- 9.E+06molecules.cm- 3,

SO2=3464pptv, OH=1.91E+05molecules.cm- 3,SA=15m2.cm- 3

Q=2- 30 ion pairs cm- 3.s- 1

30002500

2000

2000

3500

2500

2500

4500

4000

Observed UCN>3nm N. cm- 32200 2400 2600 2800 3000 3200

Q (

ion p

air

s c

m-3 .s-

1 )

5

10

15

20

25

Model Predicted UCN>3nm N. cm- 3

20

30

40

50

60

70

80

2040

6080

100120140160180

510

1520

25

TOPSE Flight 16: SO2 Plume

T=240K, RH=5.6%, SO2=3464pptv,Q=2- 30 cm- 3.s- 1

H2SO4=9.21E+06 molecules.cm

- 3,SA=2- 200 m2.cm- 3

20

30

40

50

60

70

80

Figure 3(a) Figure 3(b) Figure 3(c)

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 UCN>3nm 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.

PEM Tropics A: Flight 10T=273.2K, RH=74.5%, H2SO4=10.5E+06molecules.cm- 3

SA=15m2,cm- 3, Q=2- 30 ion pairs cm- 3.s- 1

I on production rate (Q) ion pairs cm- 3.s- 15 10 15 20 25 30

Ult

rafi

ne p

arti

cles

3-9

nm n

umbe

r co

nc.

cm-3

0

500

1000

1500

2000

2500

Observed ultrafine particles 3- 9nm number conc. cm- 3

Model Predicted ultrafine particle 3- 9nm number conc. cm- 3

PEM Tropics A: Flight 10 (UCN>3nm)

Env.A) T=249.8K, RH=55.3%, H2SO4=3.89E+06molecules.cm- 3

Env.B) T=273.2K, RH=74.5%, H2SO4=10.5E+06molecules.cm- 3

Env.C) T=267.8K, RH=78.2%, H2SO4=7.87E+06molecules.cm- 3

SA=15 m2.cm- 3, Q=2- 30 ion pairs cm- 3.s- 1

I on production rate (Q) ion pairs cm- 3.s- 15 10 15 20 25 30

UCN

>3nm

num

ber

conc

. cm

-3

0

1000

2000

3000

4000

5000

Env. A): Model Predicted UCN>3nm conc. cm-3

Env. A): Observed UCN>3nm conc. cm-3

Env. B): Model Predicted UCN>3nm conc. cm-3

Env. B): Observed UCN>3nm conc. cm-3

Env. C): Model Predicted UCN>3nm conc. cm-3

Env. C): Observed UCN>3nm conc. cm-3

ACE 1: Flight 17T=255- 262K,RH=32- 69%,H2SO4=3.4- 9.5E+06molecules.cm- 3

SA=15m2.cm- 3,Q=2- 30 ion pairs cm- 3s- 1

10000

8000

6000

4000

12000

2000

Observed Ultrafine particles 3- 10nm number conc. cm- 3500 1000 1500 2000 2500 3000 3500 4000

Q c

m-3.s

-1

5

10

15

20

25

30

Model Predicted ultrafine particles 3- 10nm conc cm- 3

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 UCN>3nm for PEMT A experiment. flight 10. (c) Comparison between observed and model predicted ultra fine particle (3-10nm) for ACE 1 experiment. Flight 17.

T[H2SO4]= 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))

Figure 4(a) Figure 4(b) Figure 4(c)

Conclusion: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 UCN>3nm 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 T=235-280K, RH=4-66%, H2SO4=2106-9107molecules.cm-3, SA=2-200μm2.cm-3 and Q=2-30 ion pairs cm-3.s-1, for which SAMIN is able to predict observed new particle formation.

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.

References:\1.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, 19972.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.3.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, 1886-1889.4.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, 2004.5.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.

Table 2: Observed and model predicted particle number concentration for atmospheric Nucleation events

Flight/location

LocalTime

Alt.km

Temp.K

RH%

Pmb

T[H2SO4]106 cm-3

SA Q 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

Flight/location

LocalTime

Alt.km

Temp.K

RH%

P(press.

)mb

T[H2SO4]106 cm-3

SA Q 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

ACE 1 (First Aerosol Characterization Experiment-one)

PEM Tropics A (Pacific Exploratory Mission in the Tropics-Phase A)

(a) (c)(b)

PEM Tropics B (Pacific Exploratory Mission in the Tropics-Phase B)Flight/

locationLocalTime

Altkm

Tempdeg.K

RH%

Pmb

T[H2SO4]

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

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

1 10 100101

102

103

104

105

SAWNUC

dN/d

Log(

r) N

.cm-3

Radius (nm)

Particle Size Distribution

T=236oKRH=4%

SA=15 m2.cm-2

Q=12 ion pairs cm-3.s-1

H2SO

4=5.E+07 molecules.cm-3

SAMIIN

1 10 100101

102

103

104

105

Radius (nm)

dN/d

Log(

r) N

.cm-3

SAMIIN

T=236oKRH=4%

SA=15 m2.cm-2

Q=12 ion pairs cm-3.s-1

H2SO

4=1.E+08 molecules.cm-3

Particle Size Distribution

SAWNUC

(a) (b)

Future WorkFuture WorkPresent 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.