Experimental study of the “rain effect” on the mobility distribution of air ions. Experiments with water jet.

Experimental study of the “rain effect” on the mobility distribution of air ions.

Experiments with water jet.

U. Hõrrak, H. Tammet, E.Tamm, A. Mirme.

Institute of Environmental Physics, University of Tartu, 18 Ülikooli St., 50090 Tartu, Estonia.

E-mail: Urmas.Horrak@ut.ee

Pikajärve, June 27–29. 2005

Aerosol, air ion and precipitation measurements on 23.08.2003.

Intermediate ion (1.5-3.3 nm)

concentration maximum 2500 cm

Experimental imitation of charged nanometer particle generation by

rainfall. H. Tammet, May 13, 2005.

BSMA measured the mobility distribution in the range of 0.032 - 3.2 cm

V

s

,

the apparent diameter range is 0.4 - 7.5 nm.

The splashing of rain droplets was imitated using a thin water jet streaming from a nozzle of diameter 2.5 mm.

The water stream broke to droplets which hit a vertical ceramic wall in distance of 65 cm

from the nozzle.

Flow rate: 55 cm3/s, ejection speed: 11 m/s, equivalent rain intensity: 36 mm/h

Stream of water droplets

Evolution of negative and positive air ion size distributions.

May 12, 2005. BSMA data. Experiment with water jet.

0 . 4 0 . 6 0 . 8 1 1 . 2 1 . 6 2 3 4 5 6 7 8

M a s s d ia m e t e r ( n m ) N e g a t iv e i o n s . M a y 1 2 , 2 0 0 5 .

0 1 0 0 2 0 0 3 0 0 4 0 0 5 0 0 6 0 0

Fraction concentration (cm-3 ) 1 2 : 4 5 1 2 : 5 5 1 3 : 0 5 1 3 : 1 5 w a t e r 1 3 : 2 5 w a t e r 1 3 : 3 5 w a t e r 1 3 : 4 5 1 3 : 5 5 1 4 : 0 5

0 . 4 0 . 6 0 . 8 1 1 . 2 1 . 6 2 3 4 5 6 7 8

M a s s d ia m e t e r ( n m ) P o s it iv e io n s . M a y 1 2 , 2 0 0 5 .

0 1 0 0 2 0 0 3 0 0 4 0 0 5 0 0 6 0 0

Fraction concentration (cm-3 ) 1 2 : 4 5

1 2 : 5 5 1 3 : 0 5 1 3 : 1 5 w a t e r 1 3 : 2 5 w a t e r 1 3 : 3 5 w a t e r 1 3 : 4 5 1 3 : 5 5 1 4 : 0 5

Time series of small (or cluster) ions and intermediate ions (1.5-3.3 nm).

May 12, 2005. BSMA data. Experiment with water jet.

1 2 : 4 5

1 2 : 5 5

1 3 : 0 5

1 3 : 1 5

1 3 : 2 5

1 3 : 3 5

1 3 : 4 5

1 3 : 5 5

1 4 : 0 5

T i m e

0 5 0 0 1 0 0 0 1 5 0 0 2 0 0 0 2 5 0 0

Io n c on ce nt ra tio n (c m

)

S m a ll ( + ) i o n s I n t e r m e d . ( + ) i o n s S m a ll ( - ) i o n s I n t e r m e d . ( - ) i o n s

Meteorological parameters during the experiment with water jet.

May 12, 2005.

1 2 : 3 5

1 2 : 4 5

1 2 : 5 5

1 3 : 0 5

1 3 : 1 5

1 3 : 2 5

1 3 : 3 5

1 3 : 4 5

1 3 : 5 5

1 4 : 0 5

1 4 : 1 5

T i m e

1 7 . 6 1 7 . 8 1 8 . 0 1 8 . 2 1 8 . 4 1 8 . 6

A ir te m pe ra tu re ( °C )

3 0 4 0 5 0 6 0 7 0

R ela tiv e hu m id ity ( % )

T e m p e r a t u r e R e la t i v e h u m i d i t y

A t m o s p h e r i c p r e s s u r e : 1 0 1 6 . 4 ± 0 . 2 m b

Comparison of measurements at Hyytiälä SMEAR station (left) and results of the experiment with water jet (right). Negative ion spectra.

0 . 4 0 . 6 0 . 8 1 1 . 2 1 . 6 2 3 4 5 6 7 8

M a s s d ia m e t e r ( n m ) N e g a t iv e io n s . A u g u s t 2 3 , 2 0 0 3 .

0 1 0 0 2 0 0 3 0 0 4 0 0 5 0 0 6 0 0

Fraction concentration (cm-3 )

1 6 : 1 7 1 6 : 2 2 1 6 : 2 7 1 6 : 3 2 1 6 : 3 8 1 6 : 4 3 1 6 : 4 8

0 . 4 0 . 6 0 . 8 1 1 . 2 1 . 6 2 3 4 5 6 7 8

M a s s d ia m e t e r ( n m ) N e g a t iv e i o n s . M a y 1 2 , 2 0 0 5 .

0 1 0 0 2 0 0 3 0 0 4 0 0 5 0 0 6 0 0

Fraction concentration (cm-3 ) 1 2 : 4 5 1 2 : 5 5 1 3 : 0 5 1 3 : 1 5 w a t e r 1 3 : 2 5 w a t e r 1 3 : 3 5 w a t e r 1 3 : 4 5 1 3 : 5 5 1 4 : 0 5

Rain event. Hyytiälä Water-jet. Tartu

Comparison of measurements at Hyytiälä SMEAR station (left) and results of the experiment with water jet (right). Positive ion spectra.

0 . 4 0 . 6 0 . 8 1 1 . 2 1 . 6 2 3 4 5 6 7 8

M a s s d ia m e t e r ( n m ) P o s it iv e i o n s . A u g u s t 2 3 , 2 0 0 3 .

0 1 0 0 2 0 0 3 0 0 4 0 0 5 0 0 6 0 0

Fraction concentration (cm-3 )

1 6 : 1 4 1 6 : 1 9 1 6 : 2 4 1 6 : 3 0 1 6 : 3 5 1 6 : 4 0 1 6 : 4 5

0 . 4 0 . 6 0 . 8 1 1 . 2 1 . 6 2 3 4 5 6 7 8

M a s s d ia m e t e r ( n m ) P o s it iv e io n s . M a y 1 2 , 2 0 0 5 .

0 1 0 0 2 0 0 3 0 0 4 0 0 5 0 0 6 0 0

Fraction concentration (cm-3 ) 1 2 : 4 5

1 2 : 5 5 1 3 : 0 5 1 3 : 1 5 w a t e r 1 3 : 2 5 w a t e r 1 3 : 3 5 w a t e r 1 3 : 4 5 1 3 : 5 5 1 4 : 0 5

Rain event. Hyytiälä Water-jet. Tartu

Comparison of the time series of small (or cluster) ions and intermediate ions (1.5-3.3 nm) measured at Hyytiälä SMEAR station (left) and results of the experiment with water jet (right).

1 2 : 4 5 1 2 : 5 5

1 3 : 0 5 1 3 : 1 5

1 3 : 2 5 1 3 : 3 5

1 3 : 4 5 1 3 : 5 5

1 4 : 0 5 T im e

0 5 0 0 1 0 0 0 1 5 0 0 2 0 0 0 2 5 0 0

Ion concentration (cm-3 )

S m a ll ( + ) i o n s I n t e r m e d . ( + ) i o n s S m a ll ( - ) i o n s I n t e r m e d . ( - ) i o n s

1 6 . 0 1 6 . 2 1 6 . 4 1 6 . 6 1 6 . 8 1 7 . 0

T i m e ( h o u r ) 0

2 0 0 4 0 0 6 0 0 8 0 0 1 0 0 0

Small ions (cm-3 )

0 5 0 0 1 0 0 0 1 5 0 0 2 0 0 0

Intermediate ions (cm-3 ) S m a ll ( + )

S m a ll ( - ) I n t e r m e d ( + )

I n t e r m e d ( - )

Rain event. Hyytiälä Water-jet. Tartu

Water jet experiment with extended instrumentation. June 17, 2005.

Balanced Scanning Mobility Analyzer (BSMA) diameter range of singly

charged particles: 0.4 - 7.5 nm Air Ion Spectrometer (AIS5)

diameter range of singly charged particles: 0.4 – 43.6 nm

Electrical Aerosol Spectrometer (EAS)

diameter range: 3.2 nm – 10 µm

Instrumentation. June 17, 2005.

Objectives of the study

• To get additional information about the behavior of charged particles in the (apparent) size range above 7 nm during splashing of water droplets.

• Study the evolution of the size distribution of neutralized aerosol particles. To get any

information about the real size of intermediate

ions (apparent size range 2 – 10 nm) formed

during splashing of water droplets.

Three experiments were carried out.

Time series of the concentration of light intermediate air ions measured by AIS and BSMA. June 17, 2005. Tartu.

1 5 1 6 1 7 1 8 1 9 2 0 2 1 2 2

T i m e ( H o u r )

- 2 0 0 0 2 0 0 4 0 0 6 0 0 8 0 0 1 0 0 0 1 2 0 0 1 4 0 0 1 6 0 0 1 8 0 0

In te rm ed ia te io ns ( cm

)

A I S ( + ) ( 1 . 6 - 3 . 6 n m ) A I S ( - )

B S M A ( + ) ( 1 . 5 - 3 . 4 n m ) B S M A ( - )

Variation of the meteorological parameters during the experiment.

1 5 1 6 1 7 1 8 1 9 2 0 2 1 2 2

T im e ( H o u r )

2 1 . 0 2 1 . 2 2 1 . 4 2 1 . 6 2 1 . 8 2 2 . 0 2 2 . 2 2 2 . 4 2 2 . 6 2 2 . 8 2 3 . 0 2 3 . 2 2 3 . 4

A ir te m pe ra tu re ( °C )

4 0 4 2 4 4 4 6 4 8 5 0 5 2 5 4 5 6 5 8 6 0 6 2 6 4

R ela tiv e hu m id ity ( % )

T

R H _{1 5 1 6 1 7 1 8 1 9 2 0 2 1 2 2}

T im e ( H o u r )

1 0 0 7 . 5 1 0 0 8 . 0 1 0 0 8 . 5 1 0 0 9 . 0 1 0 0 9 . 5 1 0 1 0 . 0

Air pressure (mb)

Time series of the concentration of cluster ions measured by AIS and BSMA. June 17, 2005. Tartu.

1 5 1 6 1 7 1 8 1 9 2 0 2 1 2 2

T i m e ( H o u r )

0 2 0 0 4 0 0 6 0 0 8 0 0 1 0 0 0 1 2 0 0 1 4 0 0 1 6 0 0

S m all io n c on ce ntr ati on ( cm

)

B S M A ( + ) B S M A ( - ) A I S ( + ) A I S ( - )

Time series of the concentration of light intermediate air ions measured by AIS and BSMA. June 17, 2005. Tartu.

1 5 1 6 1 7 1 8 1 9 2 0 2 1 2 2

T i m e ( H o u r )

- 2 0 0 0 2 0 0 4 0 0 6 0 0 8 0 0 1 0 0 0 1 2 0 0 1 4 0 0 1 6 0 0 1 8 0 0

In te rm ed ia te io ns ( cm

)

A I S ( + ) ( 1 . 6 - 3 . 6 n m ) A I S ( - )

B S M A ( + ) ( 1 . 5 - 3 . 4 n m ) B S M A ( - )

Time series of the concentration of heavy intermediate air ions measured by AIS and BSMA. June 17, 2005. Tartu.

1 5 1 6 1 7 1 8 1 9 2 0 2 1 2 2

T i m e ( H o u r ) - 2 0 0

0 2 0 0 4 0 0 6 0 0 8 0 0 1 0 0 0

Intermediate ions (cm-3 )

A I S ( + ) ( 3 . 6 - 8 n m ) A I S ( - )

B S M A ( + ) ( 3 . 4 - 7 . 4 n m ) B S M A ( - )

Time series of the concentration of light large ions measured by AIS. June 17, 2005. Tartu

1 5 1 6 1 7 1 8 1 9 2 0 2 1 2 2

T i m e ( H o u r )

- 2 0 0 0 2 0 0 4 0 0 6 0 0 8 0 0 1 0 0 0

La rg e io n c on ce ntr ati on ( cm

)

L a r g e i o n s ( 8 - 1 7 . 4 n m ) . A I S 5 . L a r g e 1 ( + )

L a r g e 1 ( - )

NB! Unipolarity

Time series of the concentration of heavy large ions measured by AIS. June 17, 2005. Tartu

1 5 1 6 1 7 1 8 1 9 2 0 2 1 2 2

T i m e ( H o u r )

- 2 0 0 0 2 0 0 4 0 0 6 0 0 8 0 0 1 0 0 0 1 2 0 0 1 4 0 0

La rg e io n c on ce ntr ati on ( cm

)

L a r g e i o n s ( 1 7 . 4 - 4 3 . 6 n m ) . A I S 5 . L a r g e 2 ( + )

L a r g e 2 ( - )

Original

data

Time series of the concentration of light large ions measured by AIS. June 17, 2005. Tartu.

1 5 1 6 1 7 1 8 1 9 2 0 2 1 2 2

T i m e ( H o u r )

- 2 0 0 0 2 0 0 4 0 0 6 0 0 8 0 0 1 0 0 0 1 2 0 0 1 4 0 0

La rg e io n c on ce ntr ati on ( cm

)

L a r g e i o n s ( 1 7 . 4 - 4 3 . 6 n m ) . A I S 5 . L a r g e 2 ( + )

L a r g e 2 ( - )

NB! Corrected

data

Mean spectra of positive and negative air ions during the third experiment. AIS5 data.

0.4 0.5 0.6 0.8 1 2 3 4 5 6 8 10 20 30 40 50

P a r t ic l e d i a m e t e r ( n m )

0 1 0 0 0 2 0 0 0 3 0 0 0 4 0 0 0 5 0 0 0

D en sit y dis trib ut io n d N /d Lo g( K ) (c m

)

P o s i t i v e i o n s N e g a t i v e i o n s M e a n s p e c t r a o f n e g a t i v e a n d p o s i t i v e i o n s . A I S 5 .

1 9 : 5 5 - 2 0 : 2 0 . 1 7 . 0 6 . 2 0 0 5 .

Mean spectra measured during the third experiment.

AIS5 and BSMA2. 20:00 - 20:20, 17.06.2005.

0.4 0.5 0.6 0.8 1 2 3 4 5 6 8 10 20 30 40 50

P a r t ic l e d i a m e t e r ( n m )

0 1 0 0 0 2 0 0 0 3 0 0 0 4 0 0 0 5 0 0 0

D en sit y dis trib ut io n d N /d Lo g( K ) (c m

)

A I S ( + ) i o n s A I S ( - ) i o n s B S M A ( + ) i o n s B S M A ( - ) i o n s M e a n s p e c t r a o f n e g a t i v e a n d p o s i t i v e i o n s . A I S 5 a n d B S M A 2 .

2 0 : 0 0 - 2 0 : 2 0 . 1 7 . 0 6 . 2 0 0 5 .

Background spectra after the third experiment.

AIS5 and BSMA2. 20:30 - 20:50, 17.06.2005.

0.4 0.5 0.6 0.8 1 2 3 4 5 6 8 10 20 30 40 50

P a r t ic l e d i a m e t e r ( n m )

0 1 0 0 0 2 0 0 0 3 0 0 0 4 0 0 0 5 0 0 0

D en sit y dis trib ut io n d N /d Lo g( K ) (c m

)

A I S ( + ) i o n s A I S ( - ) i o n s B S M A ( + ) i o n s B S M A ( - ) i o n s M e a n s p e c t r a o f n e g a t i v e a n d p o s i t i v e i o n s . A I S 5 a n d B S M A 2 .

2 0 : 3 0 - 2 0 : 5 0 . 1 7 . 0 6 . 2 0 0 5 .

Time series of the concentration of aerosol particles (3.2 – 56 nm) measured by EAS. June 17, 2005. Tartu.

1 5 1 6 1 7 1 8 1 9 2 0 2 1 2 2

T i m e ( H o u r )

0 2 0 0 4 0 0 6 0 0

A er os ol p ar tic le s 3. 2 - 5 .6 n m ( cm

)

0 2 0 0 4 0 0 6 0 0 8 0 0 1 0 0 0 1 2 0 0 1 4 0 0

A er os ol p ar tic le s 5.6 - 56 n m ( cm

)

3 . 2 - 5 . 6 n m 5 . 6 - 1 0 n m 1 0 - 1 8 n m 1 8 - 3 2 n m 3 2 - 5 6 n m

Time series of the concentration of coarse aerosol particles (1.8 – 3.2 µm) and intermediate air ions. June 17, 2005.

1 5 1 6 1 7 1 8 1 9 2 0 2 1 2 2

T i m e ( H o u r )

- 2 0 0 0 2 0 0 4 0 0 6 0 0 8 0 0 1 0 0 0 1 2 0 0 1 4 0 0 1 6 0 0 1 8 0 0

In te rm ed ia te io ns ( cm

)

0 1 2 3 4 5 6 7

A er os ol p ar tic le s (c m

)

P a r t i c le s 1 . 8 - 3 . 2 µ m

I n t e r m e d . i o n s 1 . 6 - 3 . 6 n m

Time series of the concentration of coarse aerosol particles (1 – 10 µm). EAS data. June 17, 2005. Tartu.

1 5 1 6 1 7 1 8 1 9 2 0 2 1 2 2

T im e ( H o u r )

0 . 0 5 0 . 5 0 5 . 0 0 5 0 . 0 0

P ar tic le c on ce nt ra tio n (c m

)

3 . 2 - 5 . 6 µ m

5 . 6 - 1 0 µ m 1 - 1 . 8 µ m

1 . 8 - 3 . 2 µ m

Time series of the concentration of submicron aerosol particles (178 – 316 nm) and intermediate air ions. June 17, 2005.

1 5 1 6 1 7 1 8 1 9 2 0 2 1 2 2

T i m e ( H o u r )

- 2 0 0 0 2 0 0 4 0 0 6 0 0 8 0 0 1 0 0 0 1 2 0 0 1 4 0 0 1 6 0 0 1 8 0 0

In te rm ed ia te io ns ( cm

)

2 0 0 2 5 0 3 0 0 3 5 0 4 0 0 4 5 0 5 0 0 5 5 0 6 0 0

A er os ol p ar tic le s (c m

)

P a r t i c le s 1 7 8 - 3 1 6 n m I n t e r m e d . i o n s 1 . 6 - 3 . 6 n m

p a r t ic le s 1 . 8 - 3 . 2 µ m p a r t ic le s 3 . 2 - 5 . 6 µ m In t e r m e d . io n s 1 . 6 - 3 . 6 n m p a r t ic le s 1 . 8 - 3 . 2 µ m p a r t ic le s 3 . 2 - 5 . 6 µ m In t e r m e d . io n s 1 . 6 - 3 . 6 n m p a r t ic le s 1 . 8 - 3 . 2 µ m p a r t ic le s 3 . 2 - 5 . 6 µ m In t e r m e d . io n s 1 . 6 - 3 . 6 n m p a r t ic le s 1 . 8 - 3 . 2 µ m p a r t ic le s 3 . 2 - 5 . 6 µ m In t e r m e d . io n s 1 . 6 - 3 . 6 n m

Time series of the concentration of submicron aerosol aerosol particles (100 – 560 nm). EAS data. June 17, 2005. Tartu.

1 5 1 6 1 7 1 8 1 9 2 0 2 1 2 2

T i m e ( H o u r )

2 0 4 0 6 0 1 0 08 0 2 0 0 4 0 0 6 0 0 8 0 0 1 0 0 0

P ar tic le c on ce nt ra tio n (c m

)

1 0 0 - 1 7 8 n m 1 7 8 - 3 1 6 n m 3 1 6 - 5 6 0 n m

Evolution of the size distribution of aerosol particles, background spectra and spectra affected by water jet.

Third experiment. EAS data. June 17, 2005. Tartu.

4.2 7.4 13 24 42 75 133 237 421 750 1334 2371 4217 7499

P a r t i c l e d ia m e t e r ( n m )

0 . 0 5 0 . 5 0 5 . 0 5 0 5 0 0 5 0 0 0

F ra cti on c on ce ntr ati on (c m

)

C lo s e d w i n d o w .

B a c k g r o u n d s p e c t r a : 1 9 : 1 0 - 1 9 : 4 0

" W a t e r - je t " s p e c t r a : 1 9 : 4 0 - 2 0 : 2 0

1 9 :1 0 - 1 9 :1 5 1 9 :1 5 - 1 9 :2 0 1 9 :2 0 - 1 9 :2 5 1 9 :2 5 - 1 9 :3 0 1 9 :3 0 - 1 9 :3 5 1 9 :3 5 - 1 9 :4 0 1 9 :4 0 - 1 9 :4 5 1 9 :4 5 - 1 9 :5 0 1 9 :5 0 - 1 9 :5 5 1 9 :5 5 - 2 0 :0 0 2 0 :0 0 - 2 0 :0 5 2 0 :0 5 - 2 0 :1 0 2 0 :1 0 - 2 0 :1 5 2 0 :1 5 - 2 0 :2 0

Recovery of the size distribution of aerosol particles after stopping of water jet. Third experiment. EAS data. June 17, 2005. Tartu.

4.2 7.4 13 24 42 75 133 237 421 750 1334 2371 4217 7499

P a r t i c l e d ia m e t e r ( n m )

0 . 0 5 0 . 5 0 5 . 0 5 0 5 0 0 5 0 0 0

F ra cti on c on ce ntr ati on (c m

)

" W a t e r - je t " s p e c t r u m : 2 0 : 1 5 - 2 0 : 2 0

B a c k g r o u n d s p e c t r a : 2 0 : 2 0 - 2 0 : 4 5

2 0 : 1 5 - 2 0 : 2 0 2 0 : 2 0 - 2 0 : 2 5 2 0 : 2 5 - 2 0 : 3 0 2 0 : 3 0 - 2 0 : 3 5 2 0 : 3 5 - 2 0 : 4 0 2 0 : 4 0 - 2 0 : 4 5

Conclusions

The experiments with water jet indicated that it can be used to simulate the effect of rain to study the generation of intermediate air ions during

rainfall.

The experiments with water jet showed

that the splashing of water drops affects the mobility (size) distribution air ions generating negatively charged particles below the apparent diameter of about 10 nm and with the concentration peak at 2 -3 nm.

The mean size of this mode is nearly constant.

The particles in the size range above about 8 nm and blow 40 nm are mainly positively charged.

The generation of neutral particles in the nucleation mode size range (5.6 – 18 nm) was only few percent (close to measuring uncertainties).

The splashing of water drops affects mainly the size distribution of

large aerosol particles in the size range above 0.5 µm.