Probable mixing state of aerosols in the Indo‐Gangetic Basin, northern India

Dey, Sagnik; Tripathi, S. N.; Mishra, Sumit

doi:10.1029/2007gl032622

Cited by 71 publications

(44 citation statements)

References 20 publications

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“…Present study, for the first time, is focused on the monthly variation of clear sky direct aerosol radiation forcing (DARF) over a north Indian station, Delhi, for the whole year during January 2006 to January 2007. Being a part of the Indo-Gangetic Basin the aerosol optical properties over Delhi may resemble what it has been reported earlier from the Indo-Gangetic basin (Dey et al, 2008). It is expected that the anthropogenic aerosols rich in its black carbon (BC) content, present in the atmosphere throughout the year, gets mixed with the mineral dust aerosols from deserts during premonsoon months, April-June.…”

Section: Introductionmentioning

confidence: 59%

Clear-sky direct aerosol radiative forcing variations over mega-city Delhi

et al. 2010

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Abstract. The direct aerosol radiative forcing (DARF) has been estimated for the clear-sky conditions over Delhi from January 2006 to January 2007 using Santa Barbara DISORT Atmospheric Radiative Transfer model (SBDART) in the wavelength range 300-3000 nanometer. The single scattering albedo (SSA) and the asymmetry parameter used in this model were estimated using the Optical Properties of Aerosol and Cloud (OPAC) model. The annual average AOD observed at 500 nm was ∼0.86±0.42 with an average Angstrom exponent ∼0.68±0.35. The average monthly AOD throughout the year over Delhi was found to be in the range 0.56 to 1.22 with the Angstrom exponent in the range 0.38 to 0.96. A high monthly average BC concentration in the range 4-15 µg m −3 led to monthly average SSA in the range 0.90±0.4 to 0.74±0.3 during the year. Consequently, the monthly average clear-sky DARF at the surface was found to vary in the range −46±8 W m −2 to −110±20 W m −2 , at TOA in the range −1.4±0.4 to 21±2 W m −2 , whereas in the atmosphere it was in the range 46±9 W m −2 to 115±19 W m −2 throughout the year. As the dust concentration in the atmosphere was highest (May-June) the SSA showed an increase with wavelength however when dust concentration was low the SSA decreased with the wavelength.

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Section: Introductionmentioning

confidence: 59%

Clear-sky direct aerosol radiative forcing variations over mega-city Delhi

et al. 2010

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“…Measurement of polydisperse CCN concentrations and submicron aerosol size distributions and total particle (i.e., condensation nuclei, CN) concentrations were made from 26 January- (Dey et al 2008). In terms of weather and seasonal variability, Kanpur experiences four seasons: winter (December-February), premonsoon (March-May), monsoon (June-August), and postmonsoon (September-November) Tripathi et al 2005).…”

Section: Measurement Sitementioning

confidence: 99%

First Surface Measurement of Cloud Condensation Nuclei over Kanpur, IGP: Role of Long Range Transport

Patidar

Tripathi

Bharti

et al. 2012

Aerosol Science and Technology

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INTRODUCTIONThe concentration of cloud condensation nuclei (CCN) can significantly affect cloud microphysical processes, and in turn, several aspects of weather and climate. The aerosol-cloud interactions and its impact on climate is the least understood and therefore is a subject of intense research in recent years. For more details pertaining to the effects of aerosols on climate and on cloud processes and precipitation, one can look into the excellent reviews by (Lohmann and Feichter 2005;Rosenfeld et al. 2008).Aerosols, by acting as CCN, can perturb clouds. Their effect on earth radiative balance is the largest source of uncertainty in anthropogenic climate change (Houghton et al. 2001). A strong positive correlation exists between cloud droplet number concentration and CCN concentration, implying an increase in CCN number results in increased droplet concentration that increases reflectivity leading to climate cooling . This has been confirmed by both modeling results and field observations in marine and continental environments . Therefore, simultaneous in-situ measurements of cloud condensation nuclei and aerosol properties are crucial for establishing a quantitative relationship between cloud microphysics and the microphysical (size) and chemical properties of aerosol (Rissman et al. 2006). Amongst several outstanding issues, the most important is the creation of seasonal 3-D maps of the global distribution of CCN, which is most relevant to warm cloud formation. Considerable efforts have been made in recent years to construct a global CCN climatology, e.g., Southern Ocean (Hudson et al. 1998

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“…They found that LAC was externally mixed in the urban area. Dey et al (2008) did a similar optical closure study in India to infer the mixing states and made an improvement by assuming six cases of aerosol mixing state in the calculation. They found that the probable aerosol mixing state had seasonal variations.…”

Section: Introductionmentioning

confidence: 99%

A new method to determine the mixing state of light absorbing carbonaceous using the measured aerosol optical properties and number size distributions

Zhao

Müller

et al. 2012

Atmos. Chem. Phys.

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Abstract. In this paper, the mixing state of light absorbing carbonaceous (LAC) was investigated with a two-parameter aerosol optical model and in situ aerosol measurements at a regional site in the North China Plain (NCP). A closure study between the hemispheric backscattering fraction (HBF) measured by an integrating nephelometer and that calculated with a modified Mie model was conducted. A new method was proposed to retrieve the ratio of the externally mixed LAC mass to the total mass of LAC (r ext-LAC ) based on the assumption that the ambient aerosol particles were externally mixed and consisted of a pure LAC material and a core-shell morphology in which the core is LAC and the shell is a less absorbing material. A Monte Carlo simulation was applied to estimate the overall influences of input parameters of the algorithm to the retrieved r ext-LAC . The diurnal variation of r ext-LAC was analyzed and the PartMC-MOSAIC model was used to simulate the variation of the aerosol mixing state. Results show that, for internally mixed particles, the assumption of core-shell mixture is more appropriate than that of homogenous mixture which has been widely used in aerosol optical calculations. A significant diurnal pattern of the retrieved r ext-LAC was found, with high values during the daytime and low values at night. The consistency between the retrieved r ext-LAC and the model results indicates that the diurnal variation of LAC mixing state is mainly caused by the diurnal evolution of the mixing layer.

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Probable mixing state of aerosols in the Indo‐Gangetic Basin, northern India

Cited by 71 publications

References 20 publications

Clear-sky direct aerosol radiative forcing variations over mega-city Delhi

Clear-sky direct aerosol radiative forcing variations over mega-city Delhi

First Surface Measurement of Cloud Condensation Nuclei over Kanpur, IGP: Role of Long Range Transport

A new method to determine the mixing state of light absorbing carbonaceous using the measured aerosol optical properties and number size distributions

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