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Aerosol impacts on cloud dynamics Instituto Nacional de Pesquisas Espaciais Student: Micael Amore Cecchini Advisor: Prof . Dr. Luiz Augusto Toledo Machado May 2013 Assess if its possible to observe aerosols impacts on precipitation

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SLIDE 1

Aerosol impacts on cloud dynamics

Student: Micael Amore Cecchini Advisor: Prof . Dr. Luiz Augusto Toledo Machado

Instituto Nacional de Pesquisas Espaciais

May 2013

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SLIDE 2

Objectives

  • Assess if it’s possible to observe aerosols impacts on

precipitation characteristics through ground based measurements

  • Analyze its significance
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SLIDE 3

Instrumentation

  • Measurements site: CHUVA container at IEAv,

Vale do ParaΓ­ba

  • CCNC
  • CPC
  • Joss
  • Meteorological station
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SLIDE 4

Methodology

  • Measurement period -> Nov/22/2011 through

Jan/10/2012

  • DSD parameterization -> Tokay and Short (1996) and

Tokay et al. (2001):

  • 𝑂 𝐸 = 𝑂0𝐸𝑛exp(βˆ’Ξ›πΈ)
  • 𝑛 =

11π»βˆ’8+[𝐻 𝐻+8 ]1/2 2(1βˆ’π»)

, 𝐻 =

𝑁4

3

𝑁3

2𝑁6

  • 𝑂0 =

𝛭𝑛+4𝑁3 π›₯(𝑛+4)

  • 𝛭 =

(𝑛+4)𝑁3 𝑁4

=

(𝑛+4) 𝐸𝑛 , 𝐸𝑛 = 𝑁4 𝑁3

  • Where 𝑁𝑦 =

𝐸𝑦𝑂 𝐸 𝑒𝐸

∞

[N0] = mm-1-mm-3 [m] = [] [Ξ›] = mm-1

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SLIDE 5

Methodology

  • Rain Intensity:
  • 𝑆𝐽 = 6𝜌 Γ— 10βˆ’6

π‘Š 𝐸 𝐸3𝑂 𝐸 𝑒𝐸

∞

  • Total droplet concentration:
  • TDC =

𝑂 𝐸 𝑒𝐸

∞

  • Cluster analysis applied to m, N0 and Ξ›
  • k-means method - Kanungo et. al (2002)
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SLIDE 6

Results

0.00 500.00 1000.00 1500.00 2000.00 2500.00 3000.00 3500.00 4000.00 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23

Mean CCN diurnal cycle (local time)

1% 0,8% 0,6% 0,4% 0,2%

CCN1.0 ~200 to ~10.000 cm-3 CN ~400 to 70.000 cm-3

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SLIDE 7

Results

CCN CCN/CN CN

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SLIDE 8

Results

R2 = 0,9996

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SLIDE 9

Results

  • > Adjustments to parameters

values (m/2 and 2*log(N0))

  • > supervised k-means
  • > Centroid number chosen to

best represent DSD data

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SLIDE 10

Results

# Cluster N0 (mm-1-mm-3) m Ξ› (mm-1) RI (mm/h) Rain Accum. (mm) Frequency (%) 1 1.31E+15 25.63 30.18 0.35 1.62 (0.62%) 2.83 2 9.64E+09 16.40 17.52 1.39 4.59 (1.75%) 5.94 3 2.66E+07 10.63 11.69 1.81 11.21 (4.28%) 13.49 4 6.03E+05 7.78 8.20 2.33 29.14 (11.14%) 21.32 5 3.77E+04 5.18 5.52 3.70 82.38 (31.48%) 30.15 6 4.85E+01 14.65 6.20 2.81 5.87 (2.24%) 2.78 7 2.49E+03 3.25 3.30 6.28 126.86 (48.48%) 23.49

1,2,3 -> Stratiform clusters 4 -> Transition cluster 5,6,7 -> Convective cluster

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SLIDE 11

Results

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SLIDE 12

Results

  • > Daily pattern classification based on Ξ”T, Ξ”CCN1.0, rain accumulated, Rim and duration
  • > Local Convection, Stratiform Rain and Organized Convection
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Results

Daily Pattern Cluster Frequency (%) Β± Standard Deviation (%) Stratiform Clusters Transition Cluster Convective Clusters 1 2 3 4 5 6 7 Stratiform Rain 21 Β± 29 24 Β± 11 19 Β± 8 13 Β± 11 12 Β± 12 0 Β± 0 11 Β± 12 Local Convection 1 Β± 2 3 Β± 4 11 Β± 8 13 Β± 8 22 Β± 13 7 Β± 9 43 Β± 17 Organized Convection 4 Β± 8 7 Β± 7 19 Β± 16 19 Β± 11 24 Β± 15 8 Β± 11 19 Β± 15

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Results

  • Events separation:
  • Interval β‰₯ 20 min between two DSD data
  • CCN: 2 hours means, 30 minutes before rain starts
  • Mean DSD calculated for each event
  • Only the first event on each day was selected, avoiding

rainout and washout effects

  • 16 events, total
  • 5 Local Convection, 5 Stratiform Rain, 6 Organized

Convection

  • Polluted X pristine pairs
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SLIDE 15

Results

0.00 50.00 100.00 150.00 200.00 250.00 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 Concentration (mm-1m-3) Diameter (mm) Polluted Pristine 0.00 2.00 4.00 6.00 8.00 10.00 12.00 14.00 16.00 18.00 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 Concentration (%) Diameter (mm) Polluted Pristine 0.00 0.03 0.09 0.11 0.16 0.09 0.51

Polluted

1 2 3 4 5 6 7 0.02 0.05 0.19 0.21 0.27 0.01 0.25

Pristine

1 2 3 4 5 6 7

CCN=4156 cm-3 RI=20.34 mm/h Dm=2.69 mm TDC=216 m-3 CCN=1849 cm-3 RI=19.20 mm/h Dm=2.44 mm TDC=280 m-3 Bold - Significant (T-Student)

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SLIDE 16

Results

0.00 100.00 200.00 300.00 400.00 500.00 600.00 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 Concentration (mm-1m-3) Diameter (mm) Polluted Pristine 0.00 5.00 10.00 15.00 20.00 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 Concentration (%) Diameter (mm) Polluted Pristine 0.25 0.35 0.17 0.03 0.09 0.00 0.12

Polluted

1 2 3 4 5 6 7 0.28 0.16 0.16 0.15 0.13 0.00 0.12

Pristine

1 2 3 4 5 6 7

CCN=2012 cm-3 RI=2.65 mm/h Dm=1.22 mm TDC=388 m-3 CCN=668 cm-3 RI=2.45 mm/h Dm=1.30 mm TDC=301 m-3

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SLIDE 17

Conclusions

  • CCN concentrations between rural and urban levels
  • Mean CCN1.0 ~ 2000 cm-3
  • Clear diurnal cycle and dependent on local circulation
  • Effective momentum DSD parameterization
  • Cluster analysis – DSD patterns identification
  • Stratiform rain: CCN (201%) -> Dm (6%); TDC (29%)
  • Local Convection: CCN (125%) -> Dm (10%); TDC

(23%)

  • CCN favored convective characteristics on Local Convection

cases and stratiform features on Stratiform Rain

  • CCN x DSD -> restrictive analysis, more data needed!