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Spatial Variability of Aerosol - Cloud Interactions over Indo - Gangetic Basin (IGB)

Shani TiwariGraduate School of Environmental StudiesNagoya University, Nagoya, JapanEmail: pshanitiwari@gmail.com

tiwari.shani@i.mbox.nagoya-u.ac.jp

Thanks to ...

Prof. S. Ramachandran (Physical Research Laboratory, Ahmedabad)

Prof. Abhay Kumar Singh (Banaras Hindu University, India)

Prof. T. Shibata, Nagoya University, Japan

Dr. S. Singh (National Physical Laboratory, New Delhi, India)

Dr. Atul Srivastava, (IITM, Pune, India)

NASA team for Satellite data (MODIS, TRMM).

ACAM and Jinan University China for financial supports.

Aerosol Impacts on Earth system and Human Being

Aerosol

Socio-economic system and

human well being

Climate Impacts

Atmospheric Composition and Chemistry

Ecosystem functioning

Biogeochemical cycles

????

Climate Impact of Atmospheric Aerosol

1. Direct Effect : Absorption (dust) and scattering (sulphates) of

solar radiation by aerosols.

2. Indirect Effect: Effects of aerosol on cloud properties.

3. Semi Direct Effect: Evaporation of the cloud, cloud burn off.

Cloud&

Precip.

ClimateAerosol

2. Indirect Effect: Effects of aerosol on cloud properties.

Global Radiative Forcing

Spatial-temporal variation

Inadequate knowledgeabout aerosol-cloud interaction (Model Sensitivity)

Well understood and quantified

“Cloud radiative forcing shows strong cooling effect at top of the atmosphere”

Observations &

Numerical Modeling Tools

Addresses

IPCC, 2013

Low understanding

Terra Satellite

Moderate Resolution Imaging Spectro-radiometer (MODIS) :

36 Spectral band from 0.4 µm to 14.4 µm

At 470, 550 and 660 nm over land and 470, 550, 660, 865, 1200,

1600 and 2100 nm over ocean.

Daily level 3, version 6.0 AOD, and cloud parameters data are used

Spatial resolution of 1°× 1° (http://modis.gsfc.nasa. gov/).

Instruments used for the present study

Tropical Rainfall Measurement Mission (TRMM) :

Daily TRMM_B342_Daily_v7 rainfall data

Very high spatial resolution of 0.250 x 0.250.

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Why Indo-Gangetic Basin ?

Srivastava et al., 2013

http://dx.doi.org/10.5772/47782

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Heterogeneity in aerosol types and annual their contributions

Tiwari et. al, Environ Sci Pollut Res (2015) 22:12246–12260

R1

R2

R3

R4 R5

R6

Divided whole IGB in equal six sub regions (50 x 50)

JJAS – Normal Years: 2000, 01, 03, 05, 06, 07, 10, 11, 12 and 13.

JJAS – Drought Years : 2002, 04, 09, 14 and 15.

Methodology

Preliminary Results and Discussion

Linear regression analysis of cloud parameters as a function of AOD during Normal Years

Cloud Optical Depth (COD)

R1

R2

R3

R4

R5

R6

S = 9.48, I = - 8.20

R = 0.95

S =8.82, I = 3.90

R = 0.92

S = 11.22, I = - 2.51

R = 0.94

S = 11.35 I = - 3.91

R = 0.96

S =10.64, I = - 6.08

R = 0.96

S =10.19, I = - 3.04

R = 0.95

S = -0.07, I = 14.10

R = 0.12

S = -0.11, I = 16.20

R = 0.27

S = -0.02, I = 15.85

R = 0.03

R = 0.09

S = - 0.04, I = 17.79

R = 0.02

S = 0.002, I = 15.95

R = 0.16

S = -0.06, I = 18.57

S = -1.08, I = 278.09

R = 0.21

S = -1.31, I = 288.84

R = 0.39

S = -1.64, I = 285.50

R = 0.44

S = -1.52, I = 278.90

R = 0.37

S = -1.52, I = 269.89

R = 0.38

S = -1.20, I = 269.66

R = 0.38

S = 0.46, I = -1.08

R = 0.40

S = 0.27, I = 1.34

R = 0.29

I = 1.03

R =0.38

S = 0.44

I = 2.88

R =0.32

S = 0.40

S = 0.56

S = 0.30 I = 7.36

R =0.21

I = 3.54

R =0.36

Linear regression analysis of cloud parameters as a function of AOD during Drought Years

Cloud Optical Depth (COD)

R1

R2

R3

R4

R5

R6

S = 8.78, I = 5.98

R = 0.94

S = 8.49, I = 2.94

R = 0.92

S = 10.97, I = 1.31

R = 0.93

S = 11.15 I = - 4.45

R = 0.95

S = 9.98, I = - 2.02

R = 0.96

S = 9.99, I = 5.01

R = 0.96

S = -0.17, I = 14.31

R = 0.28

S = -0.02, I = 15.06

R = 0.04

S = -0.06, I = 15.24

R = 0.18

S = -0.03, I = 15.94

R = 0.06

R = 0.07

S = -0.03, I = 17.45

R = 0.17

S = -0.07, I = 18.27

S = -0.30, I = 275.97

R = 0.06

S = -1.78, I = 291.58

R = 0.39

S = -1.27, I = 284.65

R = 0.42

S = -1.18, I = 273.23

R = 0.28

S = -1.65, I = 271.22

R = 0.39

S = -1.21, I = 271.63

R = 0.36

S = 0.37, I = - 1.30

R = 0.40

S = 0.26, I = 0.45

R = 0.31

S = 0.45, I = - 0.34

R = 0.46

S = 0.29

I = 3.15

R = 0.24

S = 0.47

I = 4.27

R = 0.31

S = 0.30

I = 6.81

R = 0.21

Frequency Distribution of AOD and Cloud Fraction

R1

R2

R3

R4

R5

R6

Frequency Distribution of Cloud Properties

R1

R2

R3

R4

R5

R6

During drought years, CER

decreases for value greater than

20 µm (i.e. CER > 20 µm) over R1 to

R4 while R5 and R6 have nearly

similar value.

Liquid water path have maximum

contribution in the range of 100 -

200 gm-2 except R1 and R6 for

both Normal and Drought Years.

Over R1, LWP decrease for bin

100 -200 gm-2 while it increases

for R3 which may be mainly due to

different emission aerosol source.

Summary

A negative gradient in aerosol loading is observed from western to eastern

IGB.

A slightly increment in AOD can affect the significant contribution cloud

fraction over the region which also show the spatial heterogeneity.

A strong correlation between cloud optical depth and liquid water path is

obtained.

CER (>20 um) decreases from R1 to R4 suggesting the enhancement in cloud

albedo.

A significant spatial variability in aerosol – cloud interaction is observed over

IGB.

A further study is needed to understand the influence of aerosol – cloud

interaction over IGB on Indian Summer Monsoon.

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Thank You !!Suggestions are welcome ...

Liquid Phase Cloud

Liquid Phase Cloud

Ice Phase Cloud

Ice Phase Cloud

R1

R3

Linear regression analysis of cloud parameters as a function of AOD during Normal Years (for Ice Phase Cloud)

Cloud Optical Depth (COD)

Linear regression analysis of cloud parameters as a function of AOD during Drought Years (for Ice Phase Cloud)

Cloud Optical Depth (COD)

Frequency Distribution of Ice Phase Cloud Properties

Tiwari et. al, Environ Sci Pollut Res (2016) 23:8781–8793

Heterogeneity in aerosol types and annual their contributions

What are Aerosols….??

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sea-salt

Volcanic eruption

Biomass Burning

Dust storm

Transportation

Urbanization

Industrial emission

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Indirect Effect

Climate Impact of Atmospheric Aerosol

Solar radiation absorbed

(Warming)

Solar radiation scattered

to space (Cooling)

Absorbing

aerosols

Scattering

aerosols

e.g. Black carbon, mineral dust e.g. Sulphates, nitrates, organics

Most aerosols both absorb and scatter!

Sun SunDirect Effect

Aerosols absorb solar

radiation

Evaporation of the cloud!

Absorbing aerosols

in and around a cloud

• Absorbing aerosols

may reduce low cloud

cover

• Warm the troposphere.

Semi-direct Effect

Cloud burn-off