s. ghosh (1), a. samaddar (2), c. r. s. kumar (2), and a. rap (3) 1 senior professor, school of...
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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.
MODELLING SHORT-LIVED CLIMATE FORCERS MODELLING SHORT-LIVED CLIMATE FORCERS OVER PENINSULAR INDIA: OVER PENINSULAR INDIA:
THE BIOMASS AND BLACK CARBON STORYTHE BIOMASS AND BLACK CARBON STORY
TALK OUTLINE 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
(photo courtesy: UKMO)
Direct Effect
Indirect Effect : Cloud processing
Aerosol particles
Semi-direct Effect : BC, + Feedback
DISTRIBUTION OF PM10 ChennaiDISTRIBUTION OF PM10 Chennai
Percentage of total population(per division) living in slums in Chennai
Highest Three hour average PM10 concentration over the study area (µg/m3)
Sathishkumar et al (2011)
Srimuruganandan and Nagendra (2010)
Particles from Traffic
NATURAL SOURCES OF ATMOSPHERIC AEROSOLVolcanic Gas PlumeVolcanic Gas Plume
(Courtesy : S.R. Brantly)
Sulfate aerosol
Sea Spray
Courtesy : Google Image
BIOMASS AEROSOLBIOMASS 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 CHALLENGESAEROSOL 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 super-saturation for activation
• In-cloud oxidation of SO2
AEROSOL MICROSTRUCTUREAEROSOL MICROSTRUCTURE
NaCl 80 μm
(NH4)2SO4
Sub-micron
(NH4)2SO4 80 µm
Diverse Size RangesDiverse Size Ranges
SEM IMAGE : SEA SALTSEM IMAGE : SEA SALT
BIOMASS AND SOOT AEROSOL : MICROSTRUCTUREBIOMASS AND SOOT AEROSOL : MICROSTRUCTURE
Biomass Aerosol : Leaf debris
Soot Aerosol
Chains of spherules with diameters ~ 10 nm
(Courtesy : Dr Gunter Helas)
Varghese et. al.(2011) VIT University
THE MODELTHE MODEL
• Adiabatic parcel model, fully interactive chemistry, treats non-ideal 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).
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 THEORYKOHLER THEORY
KOHLER THEORYKOHLER THEORY
The maxima occur at the critical radius
r*=(3B/A)1/2
At this size
S*=1+(4A3/27B)1/2
Rp=0.05μm
Rp=0.5μm
MULTI-COMPONENT AEROSOL MULTI-COMPONENT AEROSOL PROCESSES : PENINSULAR INDIAPROCESSES : PENINSULAR INDIA
Ghanti and Ghosh (2010) ; Raj et.al. (2009)Ghanti and Ghosh (2010) ; Raj et.al. (2009)
GROWTH PROFILE OF THE SMALLEST FINE GROWTH PROFILE OF THE SMALLEST FINE MODE SALT PARTICLES.MODE SALT PARTICLES.
Ghanti and Ghosh (2010)
Modelled optical properties over the three regions.Modelled optical properties over the three regions.
Ghanti and Ghosh (2010)
CLIMATE MODELLING CHALLENGESCLIMATE 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?
20012001
TRI-COMPONENT MODELTRI-COMPONENT MODEL
a σ ρ
(nm) (kg/m3)
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)
Initial Spectrum
CURRENT MET OFFICE SIMULATIONS
SENSITIVITY TO SALT LOADINGSSENSITIVITY TO SALT LOADINGSSalt mass : 10.3-27.6 Salt mass : 10.3-27.6 μgmμgm-3-3
SENSITIVITY TO SMOKE LOADINGSSENSITIVITY TO SMOKE LOADINGSSmoke mass : 0.4-2.3 Smoke mass : 0.4-2.3 μgmμgm-3-3
SENSITIVITY TO SULPHATE
Sulphate mass : 0.1-0.9μgm-3
Ghosh et al. (2007) Phil. Trans. Roy. Soc. A
CDNC values (N cm3) before interpolation (top three panels), after modified Shepard interpolation (middle three panels) ,and after Hardy VMQ interpolation (bottom three panels).
Rap, Ghosh and Smith (2009). JAS
SENSITIVITY STUDIES : AEROSOL AGEING (SOLUBILITY PARAMETER)
Amelioration: Policy, Planning, and Decision Making• Awareness : dissemination of knowledge-Aggressive media campaign
Date:16/06/2011
• 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.
CALL FOR CRACKDOWN ON BLACK CARBONCALL FOR CRACKDOWN ON BLACK CARBON
• 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.
From the HinduFrom the Hindu
• 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 DesignNEERI-CSIR Design
SEQUESTER BC : GREEN FACADES
SUMMARY : EVALUATION OF GLOBAL AEROSOL AND CLOUD MODELS-UPGRADE MODELS!
Increasing
complexityOff-line sulphur cycle
On-line sulphur cycle
Multi-component aerosol as an external mixture
Multi-component aerosol as an internal mixture
Size distributed internal mixture
Data assimilation
Role of observations vis -a- vis models is changing