Accent Plus Symposium, Urbino, Italy, 17-20 Sep2013
Observations of Enhanced Black Carbon radiative forcing over an Urban
Environment
A.S.Panicker, G. Pandithurai, P.D.Safai, S.DipuIndian Institute of Tropical Meteorology
Pashan, Pune-411008, India
Email : [email protected]
ObjectivesObjectives
To estimate Composite (total) aerosol direct To estimate Composite (total) aerosol direct radiative forcing in short wavelength region using radiative forcing in short wavelength region using chemical composition datachemical composition data
To Estimate direct radiative forcing solely due to To Estimate direct radiative forcing solely due to Black Carbon (BC)Black Carbon (BC)
To find the contribution of BC to total aerosol To find the contribution of BC to total aerosol radiative forcingradiative forcing
Accent Plus Symposium, Urbino, Italy, 17-20 Sep2013
Experimental site Experimental site
Observations and Models Used for Observations and Models Used for study…study…
InstrumentsInstruments► AethalometerAethalometer► High volume samplerHigh volume sampler► Sun/Sky radiometerSun/Sky radiometer
ModelsModels► OPTICAL PROPERTIES OF AEROSOLS AND CLOUDS OPTICAL PROPERTIES OF AEROSOLS AND CLOUDS
(OPAC)(OPAC)► SANTA BARBARA DISCRETE ORDINATE RADIATIVE SANTA BARBARA DISCRETE ORDINATE RADIATIVE
TRANSFER MODEL (SBDART)TRANSFER MODEL (SBDART)
Aethalometer, High Volume sampler, Aethalometer, High Volume sampler, Sun/SkyradimeterSun/Skyradimeter
Aethalometer High volume sampler
Prede Sun/Skyradiometer
OPAC (Optical Properties of Aerosols and Clouds)OPAC (Optical Properties of Aerosols and Clouds)
► OPAC Estimates Optical properties of aerosols from 0.2- OPAC Estimates Optical properties of aerosols from 0.2- 4040µm (AOD,SSA,ASP, Extinction coeff etc.).µm (AOD,SSA,ASP, Extinction coeff etc.).
► Uses atmospheric chemistry data sets as InputUses atmospheric chemistry data sets as Input
► Data sets from High volume sampler ( water soluble and acid Data sets from High volume sampler ( water soluble and acid soluble components) and Aethalometer (Black carbon)soluble components) and Aethalometer (Black carbon)
MODELS
SBDARTSBDART(SANTA BARBARA DISCRETE ORDINATE (SANTA BARBARA DISCRETE ORDINATE
RADIATIVE TRANSFER MODEL)RADIATIVE TRANSFER MODEL)
► 1-dimensional model – Incorporates aerosol observations1-dimensional model – Incorporates aerosol observations
► Plane parallel atmospherePlane parallel atmosphere
► Line-by-Line integrationLine-by-Line integration
► Default Temperature & water vapor profiles: Default Temperature & water vapor profiles: TROPICALTROPICAL, , MID-MID-LATITUDE SUMMER , MID-LATITUDE WINTERLATITUDE SUMMER , MID-LATITUDE WINTER , , SUB-ARCTIC SUB-ARCTIC SUMMER , SUB-ARCTIC WINTERSUMMER , SUB-ARCTIC WINTER . .
SBDART.....
Aerosol Optical Depth
Aerosol Single Scattering Albedo
Asymmetry Parameter
Derived from Observations
Surface Albedo (From MODIS)
Water vapor column (From MODIS)
Column ozone(From TOMS/OMI)
Fluxes at different levels (Surface & TOA)Downward, Upward, and Direct Fluxes
cleanaerosol FFFFForcing
Methodology
Aerosol Short wave radiative forcing estimation for composite aerosols
Water soluble, Acid soluble componets and BC data as inputs in OPAC
OPAC derived Composite aerosol optical properties: AOD, SSA and ASP from 0.2-4 μm as inputs in SBDART
Short wave radiative forcing at Surface, TOA and Atmosphere by total aerosol mass
Aerosol Short wave radiative forcing estimation for Black Carbon (BC) aerosols
Black carbon data alone as input in OPAC
OPAC derived BC aerosol AOD, SSA and ASP from 0.2-4 μm as inputs in SBDART
Short wave radiative forcing at Surface, TOA and Atmosphere byBC aerosols
Aerosol Radiative forcing = Fluxes with aerosols- Fluxes with out aerosols
Comparison of aerosol properties by OPAC and Sky radiometer
Oct04 Nov04 Jan05 Feb05 Mar05 Apr05
0.30
0.35
0.40
0.45
0.50
0.55
0.60
0.65
0.70
0.75
0.80
0.85
Month
AO
D,S
SA
(500n
m)
OPAC AOD Observed AOD OPAC SSA Observed SSA
Months
Mass fraction (μg/m3)
Water-Insoluble Water Soluble BC % BC mass
to TSP
October -04
November-04
January-05
February-05
March-05
April-05
140
139.8
85.3
114.1
184.2
188.9
31.3
44.9
56.9
53.8
46.8
55.3
3.91
5.76
6.79
5.87
4.10
3.90
2.23
3.02
4.56
3.4
1.7
1.6
WS/WIS and BC mass
SW radiative forcing by Composite and BC aerosols at surface and TOA
Oct04 Nov04 Jan05 Feb05 March05 Apr05
-50
-40
-30
-20
-10
0
10
Month
Co
mp
os
ite
fo
rcin
g (
Wm
-2) Surface Forcing(Wm -2)
TOA forcing(Wm -2)
Oct04 Nov04 Jan05 Feb05 March05 Apr05
-20
-15
-10
-5
0
5
b
a
BC
fo
rcin
g(W
m-2)
Seasonal averages of shortwave atmospheric forcing for
composite and for BC aerosols over Pune
Post-monsoon winter pre-monsoon0
10
20
30
40
50
Atm
osp
heri
c f
orc
ing
(W
m-2)
Season
CARF@Pune BCAF@Pune
Summary
• OPAC derived aerosol optical properties for composite aerosols and for BC fraction alone has been incorporated in SBDART to derive composite and BC only aerosol forcing respectively for different seasons
• The atmospheric forcing derived for composite aerosols were found to be +35.5, +32.9, +47.6 Wm-2 and for BC fraction alone these were found to be +18.8, + 23.4 and +17.2 Wm-2 during post-monsoon, winter and pre-monsoon, respectively.
• The study suggests that eventhogh BC contributes 1.6-5% by mass in total aerosols loading, on an average, it contributes to around 55% of the total atmospheric aerosol radiative forcing due to strong radiative absorption by BC.
AcknowledgementsAcknowledgements
Prof. Michele Maione, ACCENT plus, W.M.O for supports Prof. Michele Maione, ACCENT plus, W.M.O for supports Director IITMDirector IITM
