Wintertime characteristics of aerosols at middle Indo-Gangetic Plain:
Impacts of regional meteorology and long range transport
M. Kumar
a
, S. Tiwari
b
, V. Murari
a
, A.K. Singh
b
, T. Banerjee
a, *
a
Institute of Environment and Sustainable Development, Banaras Hindu University, Varanasi, India
b
Atmospheric Research Laboratory, Department of Physics, Banaras Hindu University, Varanasi, India
highlights
Exceptionally high aerosol mass loading for both PM
10
and PM
2.5
at middle IGP.
Space borne & ground based AOD reveal variability and moderate association with PM.
CALIPSO cross-section profiles depicts altitudinal distributions of aerosols.
At lower altitude continental wind accumulate fine PM from north-western dry part.
At higher altitude coarser PM accumulate due to strong intercontinental westerly.
article info
Article history:
Received 17 November 2014
Received in revised form
4 January 2015
Accepted 5 January 2015
Available online 6 January 2015
Keywords:
Aerosol
Aerosol optical depth
CALIPSO
Indo-Gangetic Plain
MODIS
Trans-boundary
abstract
To develop a coherent picture of possible origin of Asian aerosol, transport and meteorological inter-
action; wintertime aerosol (January,1 to March, 31, 2014 (n ¼ 90)) were measured in middle IGP in terms
of aerosol mass loading, optical properties, altitudinal distributions and both high and low altitude
transportation. Both space-borne passive (Aqua and Terra MODIS) and active sensor (CALIPSO-CALIOP)
based measurements were concurrently used over the selected transect (25
10
0
e25
19
0
N and 82
54
0
e83
4
0
E). Exceptionally high aerosol mass loading was recorded for PM
10
(233 ± 58.37 mgm
3
) and PM
2.5
(138 ± 47.12 mgm
3
). Daily variations of PM
2.5
/PM
10
persist in a range of 0.25e0.97 (mean ¼ 0.60 ± 0.14;
n ¼ 90) and were in accordance to computed Angstrom exponent (0.078e1.407; mean: 1.002 ± 0.254)
explaining concurrent contribution of both PM
2.5
and PM
10
for the region. Space borne (Aqua MODIS-
AOD: 0.259e2.194) and ground based (MTP-AOD: 0.066e1.239) AODs revealed significant temporal
variability and moderate association in terms of PM
10
(MODIS-AOD: 0.46; MTP-AOD: 0.56) and PM
2.5
(MODIS-AOD: 0.54; MTP-AOD: 0.39). Varying association of AOD and aerosol mass loading was also
explained in terms of meteorological variables. CALIPSO altitude-orbit-cross-section profiles revealed
presence of non-spherical coarse particulates (altitude: 1.2e5.4 km) and dominance of spherical fine
particulates (altitude: 0.1e4.2 km). Contribution of trans-boundary aerosols transportation to mass
loadings at middle IGP were recognized through lagrangian particle dispersion model, synoptic vector
wind profiles at different geopotential heights and satellite images.
© 2015 Elsevier Ltd. All rights reserved.
1. Introduction
Aerosols are multi-component mixtures originate from a range
of regional and global sources and have potential to alter Earth's
climatic balance by affecting physical, chemical or optical proper-
ties. Aerosol-climate chemistry includes heterogeneity at spatial
levels and hence their effects vary with topography, climate and
meteorological conditions (Murari et al., 2014). Among several
identified regional hotspots around the globe, Indo-Gangetic Plains
(IGP) is considered to be most vulnerable to aerosol induced
climate impacts. Thus creates the essentiality of conducting a
comprehensive research to identify local and transboundary sour-
ces of aerosol, its association with regional meteorology, transport
mechanism and altitudinal distribution. The nature of aerosols at
middle IGP is mostly characterized by presence of mineral dust,
organic aerosols and elemental carbon produced through burning
* Corresponding author. Institute of Environment and Sustainable Development,
Banaras Hindu University, Varanasi 221005, India.
E-mail addresses: tb.iesd@bhu.ac.in, tirthankaronline@gmail.com (T. Banerjee).
Contents lists available at ScienceDirect
Atmospheric Environment
journal homepage: www.elsevier.com/locate/atmosenv
http://dx.doi.org/10.1016/j.atmosenv.2015.01.014
1352-2310/© 2015 Elsevier Ltd. All rights reserved.
Atmospheric Environment 104 (2015) 162e175