Atinderpal Singh

Effects of crop residue burning on aerosol properties, plume characteristics, and long‐range transport over northern India

Aerosol emissions from biomass burning are of specific interest over the globe due to their strong radiative impacts and climate implications. The present study examines the impact of paddy crop residue burning over northern India during the postmonsoon (October–November) season of 2012 on modification of aerosol properties, as well as the long-range transport of smoke plumes, altitude characteristics, and affected areas via the synergy of ground-based measurements and satellite observations. During this period, Moderate Resolution Imaging Spectroradiometer (MODIS) images show a thick smoke/hazy aerosol layer below 2–2.5 km in the atmosphere covering nearly the whole Indo-Gangetic Plains (IGP). The air mass trajectories originating from the biomass-burning source region over Punjab at 500 m reveal a potential aerosol transport pathway along the Ganges valley from west to east, resulting in a strong aerosol optical depth (AOD) gradient. Sometimes, depending upon the wind direction and meteorological conditions, the plumes also influence central India, the Arabian Sea, and the Bay of Bengal, thus contributing to Asian pollution outflow. The increased number of fire counts (Terra and Aqua MODIS data) is associated with severe aerosol-laden atmospheres (AOD500 nm > 1.0) over six IGP locations, high values of Angstrom exponent (>1.2), high particulate mass 2.5 (PM2.5) concentrations (>100–150 µgm−3), and enhanced Ozone Monitoring Instrument Aerosol Index gradient (~2.5) and NO2 concentrations (~6 × 1015 mol/cm2), indicating the dominance of smoke aerosols from agricultural crop residue burning. The aerosol size distribution is shifted toward the fine-mode fraction, also exhibiting an increase in the radius of fine aerosols due to coagulation processes in a highly turbid environment. The spectral variation of the single-scattering albedo reveals enhanced dominance of moderately absorbing aerosols, while the aerosol properties, modification, and mixing atmospheric processes differentiate along the IGP sites depending on the distance from the aerosol source, urban influence, and local characteristics.

Chemical characteristics of PM2.5 at a source region of biomass burning emissions: Evidence for secondary aerosol formation

A systematic study on the chemical characteristics of ambient PM2.5, collected during October-2011 to March-2012 from a source region (Patiala: 30.2°N, 76.3°E; 250 m amsl) of biomass burning emissions in the Indo-Gangetic Plain (IGP), exhibit pronounced diurnal variability in mass concentrations of PM2.5, NO3(-), NH4(+), K(+), OC, and EC with ~30-300% higher concentrations in the nighttime samples. The average WSOC/OC and SO4(2-)/PM2.5 ratios for the daytime (~0.65, and 0.18, respectively) and nighttime (0.45, and 0.12, respectively) samples provide evidence for secondary organic and SO4(2-) aerosol formation during the daytime. Formation of secondary NO3(-) is also evident from higher NH4NO3 concentrations associated with lower temperature and higher relative humidity conditions. The scattering species (SO4(2-) + NO3(-) + OC) contribute ~50% to PM2.5 mass during October-March whereas absorbing species (EC) contribute only ~4% in October-February and subsequently increases to ~10% in March, indicating significance of these species in regional radiative forcing.

Black Carbon and Elemental Carbon from Postharvest Agricultural-Waste Burning Emissions in the Indo-Gangetic Plain

We compare the mass concentrations of black carbon (BC) and elemental carbon (EC) from different emissions in the Indo-Gangetic Plain (IGP), using optical (Aethalometer; 880 nm) and thermooptical technique (EC-OC analyzer; 678 nm), respectively. The fractional contribution of BC mass concentration measured at two different channels (370 and 880 nm), OC/EC ratio, and non-sea-salt K

Optical and Radiative Properties of Aerosols over Two Locations in the North-West Part of India during Premonsoon Season

The present study examines the aerosol characteristics over two locations in the northwest region of India (Dehradun and Patiala) during premonsoon season of 2013. The average mass concentrations of particulates (PM10; PM2.5; PM1) were found to be , , and µgm−3 and , , and µgm−3 over Dehradun and Patiala, respectively. The average aerosol optical depth () is observed to be over Dehradun and over Patiala. Angstrom exponent and fine mode fraction show higher values over Dehradun as compared to Patiala. The average mass concentration of black carbon was found to be ngm−3 and ngm−3 over Dehradun and Patiala, respectively. The diurnal pattern of BC is mainly controlled by boundary layer dynamics and local anthropogenic activities over both the stations. The average single scattering albedo () exhibited low value over Patiala () in comparison to Dehradun (), suggesting the abundance of absorbing type aerosols over Patiala. The average atmospheric aerosol radiative forcing is

The impact of three different cumulus parameterization schemes on the Indian summer monsoon circulation

In the present paper, the regional model (MM5) has been used to evaluate the performance of three cumulus parameterization schemes (CPSs, namely, the Anthes-Kuo, Bette-Miller and Grell) over the Indian summer monsoon season of 1998. The model was integrated at 90 km horizontal resolution for the peak monsoon period of July, 1998. The initial and boundary conditions were taken from the National Center for Environmental Prediction (NCEP) reanalysis available at 2.5° horizontal resolution. The performance of these CPSs has been examined using precipitation, wind, surface air temperature and heat – moisture data. Features of the Indian summer monsoon are found to be fairly well simulated by these three schemes; however, some differences are found in the typical features of the Indian summer monsoon. The strength of low level westerly jet, the cross equatorial flow, and the tropical easterly Jet have emerged clearly in the simulation using Grell compared to other CPSs. The Grell cumulus convection scheme shows ascending motion over whole tropical monsoon region and descending motion in mid latitude and is found to show close resemblance with the reanalysis data. The model simulation with Kuo cumulus scheme shows descending motion over tropical region, which is found to be unrealistic during monsoon and provide under estimation of rainfall over the Indian region. Strong upward motion over oceanic region by the model using Betts-Miller and Kuo schemes is also found to be unrealistic. The simulation of heat and moisture budget, and distribution of rainfall during monsoon period over Indian subcontinent are found to be improved considerably using Grell scheme as compared to other CPSs, whereas using Kuo scheme, rainfall is found to be underestimated over Indian subcontinent.