Modeling Atmospheric Aerosols

V. Rao Kotamarthi 

and

Yan Feng

Climate Research Section

Environmental Science Division

Argonne National Laboratory
Outline 

 Atmospheric Aerosols and gas phase 

heterogeneous reactions

 Regional Scales and Atmospheric Aerosols

 Regional Scale Aerosols: Ganges Valley Aerosol 

Experiment (GVAX)
Gas – Liquid Reactions – Heterogeneous /Multiphase 

Pathways

Aerosol mediated heterogeneous/multiphase reactions can speed up reactions compared 

to purely gas-phase and affect the steady state concentrations in the atmosphere

Ravishankara, Science, 1996

dxg

dt

= −kxg

k =

ωAγ

4 ; γ =

4RT

ω

H Dx k

over the surface 

area of the aerosol
Sulfate aerosol in the upper troposphere –

hydrolysis of N2O5
NO2

HNO3+ 

HONO

NO2

HONO

HNO3

NO2

HNO3

NO

Soot Particle

Water film

2 to 100 μιχροgrams/m3

Night time/Dawn oxidant production Speedup 
OH (molecules/cm3)
Gas Phase Chemistry and SOA formation 

 Gas phase oxidation drives the formation of precursors that lead 

to SOA formation

• Volatility of these VOC degradation products and primary 

emissions is key for determining the aerosol mass.

• Oxidant levels, oxidant precursors in the gas phase thus will 

influence SOA formation.

• Several new studies indicate increasing SOA yields with increasing 

NOx mixing ratios.

• The SOA cycle seems closely linked to gas-phase chemistry and 

would be interesting to see if there are any coupled systems in this 

SOA-Oxidant/heterogeneous reactions-SOA cycle. 
AERONET Data (spring – 1992-2004) – v2 500nm 

(AOT)

90 -80 N

80-70 N

70-60 N

60-50 N

50-40 N

40-30 N

30 -20 N

20 -10 N

10 -0 N
MODIS Data shows high AOD’s in the Ganges Valley Region

Multi-angle imaging spectroradiometer AOD values at mid visible wavelengths (558 nm) averaged over the years 2005-2008.
10-year AERONET AOT data at Kanpur

0

0.2

0.4

0.6

0.8

1

1.2

1.4

2001-JAN

2001-JUL

2002-JAN

2002-JUL

2003-JAN

2003-JUL

2004-JAN

2004-JUL

2005-JAN

2005-JUL

2006-JAN

2006-JUL

2007-JAN

2007-JUL

2008-JAN

2008-JUL

2009-JAN

2009-JUL

2010-JAN

AOT 500nm

Yearly
KANPUR

2001 Kanpur

Comparison of Model (IMPACT) and Data (AERONET and MISR)
CALIPSO extinction Profiles

January April
Estimated Changes in All-sky Surface Solar Radiation due to Anthropogenic 

Aerosols (1975 - 2000)
We Plan To Understand The Anthropogenic Aerosol Behavior, Aerosol 

Composition and its Affect on Heating Rates: (Winter)
Typical Mobile Facility Setup

Nainital
Winter Intensive will need G-1 to characterize the aerosol plume:

Base of operations is Likely Lucknow

Western Sector Central Sector Eastern Sector

Flight Plan for the Central Sector

AMF

MAOS, 

G-1

Supersite
Regional Scale BC forecasting for GVAX: WRF-CHEM with MOZART gas phase chemistry 

and GOCART aerosols (12 km grid size)

T=0; Initial conditions from GOCART model T=24, WRF-CHEM calculated
Regional Scale BC forecasting for GVAX: WRF-CHEM with MOZART gas phase chemistry 

and GOCART aerosols (12 km grid size)

Longitude-Height cross section Latitude-Height Cross Section
Transport of particles near Nainital/Pantnagar; 

2008 January
Acknowledgement

– DOE ASR program for the support

– Many colleagues from DOE National Laboratories. ISRO , ARIES and 

IISc for collaborating on the GVAX experiment

– NOAA/NCAR WRF-CHEM developers for providing the support in our 

efforts to establish a forecasting system for GVAX

– ANL LCRC for computational support

– More information on GVAX, updates and progress at: 

http://www.arm.gov/sites/amf/pgh/
BC instrumentation during GVAX (ground sites)

 Nainital (June 2011 - April 2012):

– PSAP (Particle Soot Absorption photometer)

– Other aerosol instrument (AERI, Nephelometer, MFRSR)

 Lucknow ( January 2012 - March 2012)

– SP2 (Soot Photometer)

– PSAP (particle Soot absorption photometer)

– PASS-3 (Photo acoustic Spectrometer)

– Aethalometer

 Pantanagar (January 2012 – March 2012)

– MAAP (Multiangle absorption photometer)

– SP-AMS (soot particle aerosols mass spectrometer)

– SP2 (soot photometer)

– PASS-3 (photo acoustic spectrometer)