MODELLING SHORT-LIVED CLIMATE FORCERS
OVER PENINSULAR INDIA:
THE BIOMASS AND BLACK CARBON STORY
S. Ghosh (1), A. Samaddar (2), C. R. S. Kumar (2), and A. Rap (3)
1 Senior Professor, School of Mechanical and Building Sciences, VIT University and ICAS
Associate, School of Earth and Environment, University of Leeds, U.K.
2 Research Student, School of Mechanical and Building Sciences, VIT University, Vellore, India
3 Research Fellow, School of Earth and Environment, University of Leeds, U.K.
TALK OUTLINE
• Biomass burning and black carbon emissions
• Multi-component aerosol processes
• Climate modelling challenges
• Interfacing research results in decision making
processes
•
Biomass-material from living, or recently living organisms, such as wood, waste, and
alcohol fuels.
More than 70% of India’s population depends on
biomass and about 32% of the total primary
energy use in the country mainly in rural areas is
still derived from biomass.
In 1999 to 2000, more than 85 percent of India’s
rural population was dependent on traditional
fuels (biomass and cow dung-cake) for their
basic energy needs.
India’s goal is to provide cleaner fuels or other
means of cooking to the entire population by
2012.
Cooking energy consumption was estimated separately for rural and urban regions.
The total cooking energy consumption for India for 2000 was 6325 PJ with rural
population using about 84%. (Habib et al. 2004)
•
Black carbon has contributed the second largest globally averaged radiative forcing after
carbon dioxide (CO2), and that the radiative forcing of black carbon is “as much as 55%
of the CO2 forcing and is larger than the forcing due to the other greenhouse gasses
(GHGs) such as CH4, CFCs, N2O, or tropospheric ozone.”
China and India together account for 25-35% of global black carbon emissions.
Black carbon emissions from China doubled from 2000 to 2006.
Stratocumulus Clouds
Direct Effect
Aerosol
particles
Semi-direct Effect : BC, +
Feedback
(photo courtesy: UKMO)
Indirect Effect :
Cloud processing
DISTRIBUTION OF PM10 Chennai
Percentage of total population
(per division) living in slums in
Chennai
Sathishkumar et al (2011)
Highest Three hour average PM10 concentration over
the study area (µg/m3)
Particles from Traffic
Srimuruganandan and Nagendra (2010)
NATURAL SOURCES OF ATMOSPHERIC
AEROSOL
Volcanic Gas Plume
Sulfate
aerosol
Sea Spray
(Courtesy : S.R. Brantly)
Courtesy : Google Image
BIOMASS AEROSOL
Vegetation Fires
Source of gases and AP.
Fire emissions are
transported by convection
into the FT and lower
stratosphere and are
distributed from local to the
meso-scale and even to the
global scale
(Courtesy : Dr S. Wurzler)
Q. How to model aerosol effects in climate models
Develop Process Models –Parameterize?
AEROSOL PARTICLES AS CCN : COMPLEXITIES AND CHALLENGES
• Atmospheric aerosol particles : hydrophobic, water-insoluble but
possess hydrophilic sites
• Some water-soluble component (when we consider biomass
aerosol internally mixed with sulphate aerosol)
• Soluble gases : dissolve into a growing solution droplet prior to
activation in cloud. This can decrease the critical supersaturation for activation
• In-cloud oxidation of SO 2
AEROSOL MICROSTRUCTURE
Diverse Size Ranges
NaCl 80 μm
(NH4)2SO4
Sub-micron
SEM IMAGE : SEA SALT
(NH4)2SO4
80 µm
BIOMASS AND SOOT AEROSOL : MICROSTRUCTURE
Biomass Aerosol : Leaf debris
(Courtesy : Dr Gunter Helas)
Soot Aerosol
Chains of spherules with
diameters ~ 10 nm
Varghese et. al.(2011) VIT University
THE MODEL
• Adiabatic parcel model, fully interactive chemistry, treats nonideal behaviour of solution droplets (Pitzer calculations) (O’Dowd
et al 1999)
• Micro-physics : dynamic growth equations for the growth of
aerosol solution droplets by condensation of water vapour on a
size resolved droplet spectrum
• Mass transport limitations based on Schwartz (1986).
KOHLER THEORY
Vapor pressure over an
aqueous solution droplet :
(i) Kelvin effect –increases
vapor pressure
(ii)Solute effect –decreases
vapor pressure
S=(1-B/r3)exp(A/r)
=1+A/r -B/r3
A=4Mwσw/RTρw
=0.66/T (μm)
B=6nsMw/πρw
=3.44x1013νms/Ms
(μm3)
KOHLER THEORY
The maxima occur at the
critical radius
Rp=0.05μm
r*=(3B/A)1/2
At this size
Rp=0.5μm
S*=1+(4A3/27B)1/2
MULTI-COMPONENT AEROSOL
PROCESSES : PENINSULAR INDIA
Ghanti and Ghosh (2010) ; Raj et.al. (2009)
GROWTH PROFILE OF THE SMALLEST FINE
MODE SALT PARTICLES.
Ghanti and Ghosh (2010)
Modelled optical properties over the three regions.
Ghanti and Ghosh (2010)
CLIMATE MODELLING CHALLENGES
• Two aerosol components -straightforward
to predict cloud droplet number
concentrations.
• What happens when we sandwich a third
mode corresponding to biomass burning
between the sulfate and salt modes?
2001
TRI-COMPONENT MODEL
a
(nm)
σ
ρ
(kg/m3)
Initial Spectrum
Sulphate 95 1.16 1769
Smoke
120 1.12 1350
Salt (film) 100 1.32 2160
Salt (jet) 1000 1.35 2160
(salt : wind speed dependent)
U=0.2 m/s
Sol.=0.25 (Yamasoe et al 2000)
R(nm)
CURRENT MET OFFICE SIMULATIONS
SENSITIVITY TO SALT LOADINGS
Salt mass : 10.3-27.6 μgm-3
SENSITIVITY TO SMOKE LOADINGS
Smoke mass : 0.4-2.3 μgm-3
SENSITIVITY TO SULPHATE
Sulphate mass : 0.1-0.9μgm-3
Ghosh et al. (2007) Phil. Trans. Roy. Soc. A
Rap, Ghosh and Smith (2009).
JAS
CDNC values (N cm3) before interpolation (top three panels), after
modified Shepard interpolation (middle three panels) ,and after Hardy
VMQ interpolation (bottom three panels).
SENSITIVITY STUDIES : AEROSOL AGEING (SOLUBILITY
PARAMETER)
Amelioration: Policy, Planning, and Decision Making
•
Awareness : dissemination of knowledge-Aggressive media campaign
Date:16/06/2011
CALL FOR CRACKDOWN ON BLACK CARBON
• Global warming could be slowed down if governments
cleaned up what's known as black carbon from industry and
cooking fires
• 50 of the world's leading atmospheric scientists confirmed
that on June 14.
From the Hindu
• The full impact of black carbon is still being assessed
• Linked to the melting of the glaciers in the Himalayas,
• Disruption of traditional rainfall patterns in India and Africa,
• Low yields of maize, rice, wheat and soya bean crops in Asia
and elsewhere.
• Black carbon affects climate by intercepting and absorbing
sunlight, darkening snow and ice when deposited and helping to
form clouds.
• It is most noticeable at the poles, on glaciers and in mountain
regions — all environments which are showing the greatest
impact of climate change.
• Another technology for reducing black carbon emissions from diesel
engines is to shift fuels to compressed natural gas.
• According to a study examining these emissions reductions, “there is a
significant potential for emissions reductions through the [UNFCCC]
Clean Development for such fuel switching projects.”
• Existing and well-tested technologies used by developed countries,
such as clean diesel and clean coal, could be transferred to developing
countries to reduce their emissions.
Phillips Design
NEERI-CSIR Design
SEQUESTER BC : GREEN FACADES
SUMMARY : EVALUATION OF GLOBAL AEROSOL AND
CLOUD MODELS-UPGRADE MODELS!
Size distributed internal mixture
Data
assimilation
Multi-component aerosol as an internal
mixture
Multi-component aerosol as an
external mixture
On-line sulphur cycle
Off-line sulphur
cycle
Increasing
complexity
Role of observations
vis -a- vis models is
changing