Spatial Variability of Aerosol - Cloud Interactions over Indo - Gangetic Basin (IGB)
Shani TiwariGraduate School of Environmental StudiesNagoya University, Nagoya, JapanEmail: [email protected]
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